Patent Publication Number: US-2022220950-A1

Title: Pump drive system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/313,677 filed May 6, 2021 for “PUMP DRIVE SYSTEM,” which in turn is a continuation of International PCT Application No. PCT/US2021/025086 Filed Mar. 31, 2021, which claims the benefit of U.S. Provisional Application No. 63/002,676 filed Mar. 31, 2020, and entitled “OUTER ROTATOR DRIVEN PUMP,” and claims the benefit of U.S. Provisional Application No. 63/002,681 filed Mar. 31, 2020, and entitled “EXOSKELETON FRAME FOR PUMP DRIVE SYSTEM,” and claims the benefit of U.S. Provisional Application No. 63/002,687 filed Mar. 31, 2020, and entitled “ECCENTRIC ROTATOR DRIVEN PUMP,” and claims the benefit of U.S. Provisional Application No. 63/002,691 filed Mar. 31, 2020, and entitled “INTEGRATED PUMP-MOTOR BEARINGS,” and claims the benefit of U.S. Provisional Application No. 63/088,810 filed Oct. 7, 2020, and entitled “FLUID SPRAYER HAVING RESPONSIVE MOTOR CONTROL,” the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     The present disclosure relates generally to fluid displacement systems and, more particularly, to drive systems for reciprocating fluid displacement pumps. 
     Fluid displacement systems, such as fluid dispensing systems for paint, typically utilize positive displacement pumps such as axial displacement pumps to pull a fluid from a container and to drive the fluid downstream. The axial displacement pump is typically mounted to a drive housing and driven by a motor. A pump rod is attached to a reciprocating drive that drives reciprocation of the pump rod, thereby pulling fluid from a container into the pump and then driving the fluid downstream from the pump. In some cases, electric motors can power the pump. The electric motor is attached to the pump via a gear reduction system that increases the torque of the motor. 
     SUMMARY 
     In one example, a fluid displacement pump assembly includes an electric motor, a drive, a pump having a fluid displacement member, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor at a first end of the electric motor. The fluid displacement member is mechanically coupled to the drive. The drive converts the rotational output to a linear, reciprocating input to the fluid displacement member. The pump frame is mechanically coupled to the electric motor. 
     In another example, a method of driving a reciprocating pump includes powering an electric motor to cause rotation of a rotor of the motor, receiving a rotational output from the rotor at a drive connected to the rotor, translating the rotational output, by the drive, to linear, reciprocating motion, providing, by the drive, a linear reciprocating input to a fluid displacement member connected to the drive to cause the pump rod to pump fluid by reciprocation, and mechanically supporting, by a pump frame, the reciprocating pump and the electric motor. 
     In yet another example, a pumping system includes an electric motor, a drive, a pump, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor to receive a rotational output from the rotor and convert the rotational output to linear reciprocating motion. The pump includes a piston and a cylinder. The piston receives the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize both the stator relative to the rotor and the cylinder relative to the piston. 
     In yet another example, a drive system for a reciprocating fluid displacement pump includes an electric motor, a drive, and a fluid displacement member. The motor includes a stator defining an axis and a rotor disposed coaxially around the stator. The drive is directly connected to the rotor to receive a rotational output from the rotor. The fluid displacement member is mechanically coupled to the drive. The drive member converts the rotational output to a linear, reciprocating input to the fluid displacement member. 
     In yet another example, a method of driving a reciprocating pump includes powering an electric motor to cause rotation of a rotor of the motor, the rotor disposed outside of and around a stator of the motor, receiving a rotational output from the rotor at a drive directly connected to the rotor, translating the rotational output, by the drive, directly to linear, reciprocating motion, and providing, by the drive, a linear reciprocating input to a fluid displacement member connected to the drive to cause the pump rod to pump fluid by reciprocation. 
     In yet another example, a fluid displacement apparatus includes an electric motor, a drive, a pump, and a pump frame. The motor includes a stator defining an axis and a rotor disposed around the stator. The drive is connected to the rotor to receive a rotational output from the rotor and convert the rotational output to linear reciprocating motion. The pump includes a piston and a cylinder, the piston receiving the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize both the stator relative to the rotor and the cylinder relative to the piston. 
     In yet another example, a drive system for a reciprocating fluid displacement pump includes an electric motor, a drive, a fluid displacement member, and a support frame. The electric motor includes a stator disposed on an axis and supported by an axle and a rotor disposed coaxially around the stator. The drive is directly connected to the rotor to receive a rotational output from the rotor. The fluid displacement member is mechanically coupled to the drive, wherein the drive is configured to convert the rotational output to a linear, reciprocating input to the fluid displacement member. The support frame is configured to mechanically support the electric motor and the fluid displacement pump, wherein the support frame is mechanically coupled to the stator. 
     In yet another example, a support frame for a reciprocating fluid displacement pump drive system having an electric motor with an inner stator and an outer rotor includes a first frame member, a second frame member, and at least one connecting member. The second frame member is disposed at an opposite end of the electric motor from the first frame member and separated from the first frame member. The at least one connecting member extends between and connecting the first frame member and the second frame member. The second frame member and the at least one connecting member are configured to at least partially house and to mechanically support the electric motor with the outer rotor. 
     In yet another example, fluid displacement apparatus includes an electric motor extending along an axis to have a first end and a second end, a drive, a pump, a pump frame, and a motor frame. The electric motor includes a stator extending along the axis and a rotor disposed around the stator and extending along the axis. The drive is connected to the rotor to receive a rotational output from the rotor and convert the rotational output to linear reciprocating motion. The pump includes a piston and a cylinder, the piston receiving the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize the cylinder relative to the piston. The motor frame that stabilizes stator. The motor frame includes a plurality of connecting members that extend from the first end of the motor to the second end of the motor. The plurality of connecting members are arrayed around the rotor. 
     In yet another example, a drive system for a reciprocating pump for pumping fluid includes an electric motor and a drive. The electric motor includes a rotor. The rotor includes an eccentric drive member extending from the rotor. The drive is directly coupled to the eccentric drive member and is configured to drive reciprocation of a fluid displacement member. 
     In yet another example, a method of driving a reciprocating pump includes powering an electric motor to cause rotation of a rotor on a rotational axis, providing rotational output of an electric motor directly to a drive, providing, by the drive, a linear reciprocating input to a pump rod of the pump, and spraying a fluid from the fluid displacement pump onto a surface. For one revolution of the rotor, the fluid displacement pump proceeds through one pump cycle. 
     In yet another example, a pumping system includes and electric motor, a drive, and a reciprocating pump. The electric motor includes a rotor. The rotor includes an eccentric drive member extending from the rotor. The drive is directly coupled to the eccentric drive member. The reciprocating pump includes a fluid displacement member coupled to the drive and a pump cylinder at least partially housing the fluid displacement member. The drive is configured to drive reciprocation of the fluid displacement member. 
     In yet another example, a drive system for powering a reciprocating pump for pumping fluid to generate a fluid spray includes an electric motor, an eccentric drive member, and a drive. The electric motor includes a stator and a rotor. The rotor is configured to rotate on a rotational axis. The eccentric drive member extends from the rotor. The drive is coupled to the eccentric driver and is configured to drive reciprocation of a fluid displacement member. 
     In yet another example, a method of driving a reciprocating pump for generating a pressurized fluid spray for spraying onto a surface includes powering an electric motor to cause rotation of a rotor on a rotational axis, providing a rotational output from the rotor to a drive, and providing, by the drive, a linear reciprocating input to a fluid displacement member of the pump to cause reciprocation of the fluid displacement member along a pump axis to pump fluid. The rotor is connected to the fluid displacement member by the drive such that for one revolution of the rotor the fluid displacement pump proceeds through one pump cycle. 
     In yet another example, a pumping system for pumping a fluid to generate a pressurized fluid spray includes an electric motor, an eccentric drive member, a drive, and a reciprocating pump. The electric motor includes a stator and a rotor. The rotor is configured to rotate on a rotational axis. The eccentric drive member extends from the rotor. The drive is coupled to the eccentric drive member to receive a rotational output from the rotor. The reciprocating pump includes a fluid displacement member coupled to the drive and a pump cylinder at least partially housing the fluid displacement member. The drive is configured to receive the rotational output from the motor and convert the rotational output into a linear reciprocating motion to drive reciprocation of the fluid displacement member. 
     In yet another example, a drive system for a fluid displacement pump includes an electric motor, a drive, a fluid displacement member, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor at a first end of the electric motor. The fluid displacement member is mechanically coupled to the drive, such that the electric motor experiences a pump load generated by reciprocation of the fluid displacement member during pumping. The pump frame is mechanically coupled to the electric motor and configured to support the fluid displacement pump and the electric motor. 
     In yet another example, a drive system for a reciprocating fluid displacement system includes an electric motor, a drive, a fluid displacement member, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor at a first end of the electric motor. The fluid displacement member is mechanically coupled to the drive, wherein the drive converts rotational output from the rotor to linear, reciprocating input to the fluid displacement member. The pump frame is mechanically coupled to the electric motor. The pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive and the rotor. 
     In yet another example, a pumping apparatus includes a frame, at least two bearing, an electric motor, a drive, and a pump. The electric motor includes a stator and a rotor configured to output rotational motion. The rotor is supported by the at least two bearings, the at least two bearings supporting rotation of the rotor. The drive is configured to receive the rotational motion and convert the rotational motion into linear reciprocating motion. The pump includes a piston and a cylinder. The piston is configured to receive the linear reciprocating motion to reciprocate within the cylinder through an upstroke and a down stroke. The piston receives a downward reaction force when moving through the up stroke and an upward reaction force when moving through the down stroke. Both of the upward reaction force and the downward reaction force travel through the drive, the rotor, and then to the at least two bearings. 
     In yet another example, a sprayer includes the drive system of any one of the preceding paragraphs includes a pump and a controller. The pump includes a piston configured to be linearly reciprocated by the drive. The controller is configured to output electrical energy to the electric motor to control operation of the electric motor. 
     In yet another example, a fluid displacement pump includes an electric motor having a first end and a second end, a drive, and a pump having a fluid displacement member linked to the drive to be reciprocated by the drive. The electric motor includes a stator; and a rotor that rotates about an axis, the stator located radially within the rotor such that the rotor rotates around the stator, the rotor comprising a housing having an opening located on the second end of the electric motor, the housing containing a plurality of magnets that rotate with the housing, and a stator support that extends through the opening to hold the stator stationary while the housing rotates around the stator. The drive is connected to the rotor at the first end of the electric motor, the drive configured to convert rotational output from the rotor to reciprocating motion. The fluid displacement member located closer to the first end of the electric motor than to the second end of the electric motor. 
     In yet another example, a fluid sprayer includes an electric motor comprising a stator and a rotor; a drive connected to the rotor, the drive configured to convert rotational output from the rotor to reciprocating motion; a pump comprising a fluid displacement member linked to the drive to be reciprocated by the drive; a fluid outlet that sprays the fluid output by the pump; a fluid sensor that outputs a signal indicative of pressure of the fluid output by the pump; and a controller that receives the signal from the fluid sensor and outputs operating power to the stator that causes the rotor to rotate relative to the stator. 
     The controller configured to deliver a first level of operating power to the stator when the signal indicates that the pressure of the fluid output by the pump is below a pressure setting, the first level of operating power causing the rotor to reciprocate the fluid displacement member via the drive, deliver a second level of operating power to the stator when the signal indicates that the pressure of the fluid output by the pump is one of at or above the pressure setting while the rotor and the fluid displacement member remain stalled while the fluid outlet is closed, the second level of operating power causing the rotor to urge against the drive to cause the fluid displacement member to apply pressure to the fluid while the fluid outlet is closed and the rotor and the fluid displacement member remain stalled. 
     In yet another example, a fluid sprayer includes an electric motor comprising a stator and a rotor; a drive connected to the rotor, the drive configured to convert rotational output from the rotor to reciprocating motion; a pump comprising a fluid displacement member linked to the drive to be reciprocated by the drive; a fluid outlet that sprays the fluid output by the pump; and a controller that outputs operating power to the stator that causes the rotor to rotate relative to the stator. The controller configured to cause the rotor to reverse rotational direction between two modes in which in a first mode the rotor rotates clockwise making a plurality of consecutive complete revolutions to drive the piston through a first plurality of consecutive pumping strokes, each pumping stroke comprising a fluid intake phase in which the fluid displacement member moves in a first direction and a fluid output phase in which the fluid displacement member moves in a second direction opposite the first direction, and in a second mode the rotor rotates counterclockwise making a plurality of complete consecutive revolutions to drive the piston through a second plurality of consecutive pumping strokes, each pumping stroke comprising the fluid intake phase and the fluid output phase. 
     The present summary is provided only by way of example, and not limitation. Other aspects of the present disclosure will be appreciated in view of the entirety of the present disclosure, including the entire text, claims, and accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a front elevational schematic block diagram of a spray system. 
         FIG. 1B  is a side elevational schematic block diagram of the spray system of  FIG. 1A . 
         FIG. 2  is an isometric front side view of a drive system and displacement pump. 
         FIG. 3  is an exploded view of the drive system and displacement pump of  FIG. 2 . 
         FIG. 4  is cross-sectional view of the drive system and displacement pump taken along the line  4 - 4  of  FIG. 2 . 
         FIG. 4A  is an enlarged view of portion  4 A of  FIG. 4 . 
         FIG. 5  is an isometric front side view of a support frame for the drive system and displacement pump of  FIG. 2 . 
         FIG. 6  is an isometric rear side view of the support frame for the drive system and displacement pump of  FIG. 2 . 
         FIG. 7  is an exploded view of eccentric driver of the drive system of  FIG. 2 . 
         FIG. 8  is an isometric front side view of another embodiment of a drive system and displacement pump. 
         FIG. 9  is an isometric cross-sectional view of the drive system and displacement pump of  FIG. 8 . 
         FIG. 10A  is an isometric rear side view of a support frame for the drive system and displacement pump of  FIG. 8 . 
         FIG. 10B  is an isometric rear side view of another embodiment of a support frame. 
         FIG. 10C  is an isometric rear side view of yet another embodiment of a support frame. 
         FIG. 11  is an isometric front side cross-sectional view of yet another embodiment of a drive system and displacement pump. 
         FIG. 12  is an isometric front side view of the drive system of  FIG. 11 . 
         FIG. 13  is a cross-sectional side view of yet another embodiment of a drive system and displacement pump. 
         FIG. 14  is a cross-sectional side view of yet another embodiment of a drive system and displacement pump. 
         FIG. 15  is an isometric front side view of yet another embodiment of a drive system and displacement pump. 
         FIG. 16  is an isometric cross-sectional view of the drive system and displacement pump taken along the line  16 - 16  of  FIG. 15 . 
         FIG. 17  is a block diagram of a control system. 
     
    
    
     While the above-identified figures set forth embodiments of the present invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features, steps and/or components not specifically shown in the drawings. 
     DETAILED DESCRIPTION 
     The present disclosure is directed to a drive system for a reciprocating fluid displacement pump. The drive system of the present disclosure has an electric motor with an eccentric driver. The drive member converts rotational output of the rotor to linear, reciprocating input to the fluid displacement member. The rotor can be disposed outside of the stator to rotate about the stator such that the motor is an outer rotator motor. 
       FIG. 1A  is a front elevational schematic block diagram of spray system  1 .  FIG. 1B  is a side elevational schematic block diagram of spray system  1 .  FIGS. 1A and 1B  are discussed together. Support  2 , reservoir  3 , supply line  4 , spray gun  5 , and drive system  10  are shown. Drive system  10  includes electric motor  12 , drive mechanism  14 , pump frame  18 , and displacement pump  19 . Support  2  includes support frame  6  and wheels  7 . Fluid displacement member  16  and pump body  19   a  of displacement pump  19  are shown. Spray gun  5  includes a handle  8  and trigger  9 . 
     Spray system  1  is a system for applying sprays of various fluids, examples of which include paint, water, oil, stains, finishes, aggregate, coatings, and solvents, amongst other options, onto a substrate. Drive system  10 , which can also be referred to as a pump assembly, can generate high fluid pumping pressures, such as about 3.4-69 megapascal (MPa) (about 500-10,000 pounds per square inch (psi)) or even higher. In some examples, the pumping pressures are in the range of about 20.7-34.5 MPa (about 3,000-5,000 psi). High fluid pumping pressure is useful for atomizing the fluid into a spray for applying the fluid to a surface. 
     Drive system  10  is configured to draw spray fluid from reservoir  3  and pump the fluid downstream to spray gun  5  for application on the substrate. Support  2  is connected to drive system  10  and supports drive system  10  relative reservoir  3 . Support  2  can receive and react loads from drive system  10 . For example, support frame  6  can be connected to pump frame  18  to react the loads generated during pumping. Support frame  6  is connected to pump frame  18 . Wheels  7  are connected to support frame  6  to facilitate movement between job sites and within a job site. 
     Pump frame  18  supports other components of drive system  10 . Motor  12  and displacement pump  19  are connected to pump frame  18 . Motor  12  is an electric motor having a stator and a rotor. Motor  12  can be configured to be powered by any desired power type, such as direct current (DC), alternating current (AC), and/or a combination of direct current and alternating current. The rotor is configured to rotate about a motor axis MA in response to current, such as direct current or alternating current signals, through the stator. In some examples, the rotor can rotate about the stator such that motor  12  is an outer rotator motor. Drive mechanism  14  is connected to motor  12  to be driven by motor  12 . Drive mechanism  14  receives a rotational output from motor  12  and converts that rotational output into a linear input along pump axis PA. Drive mechanism  14  is connected to fluid displacement member  16  to drive reciprocation of fluid displacement member  16  along pump axis PA. As illustrated in  FIG. 1B , motor axis MA is disposed transverse to pump axis PA. More specifically, motor axis MA can be orthogonal to pump axis PA. In other embodiments, motor  12 , drive mechanism  14 , and fluid displacement member  16  can be disposed coaxially such that motor axis MA and pump axis PA are coaxial. Fluid displacement member  16  reciprocates within a pump body  19   a , such as cylinder  94  discussed below, to pump spray fluid from reservoir  3  to spray gun  5  through supply line  4 . 
     During operation, the user can maneuver drive system  10  to a desired position relative the target substrate by moving support  2 . For example, the user can maneuver drive system  10  by tilting support frame  6  on wheels  7  and rolling drive system  10  to a desired location. Displacement pump  19  can extend into reservoir  3 . Motor  12  provides the rotational input to drive mechanism  14  and drive mechanism  14  provides the linear input to fluid displacement member  16  to cause reciprocation of fluid displacement member  16 . Fluid displacement member  16  draws the spray fluid from reservoir  3  and drives the spray fluid downstream through supply line  4  to spray gun  5 . The user can manipulate spray gun  5  by grasping the handle  8  of the spray gun  5 , such as with a single hand of the user. The user causes spraying by actuating trigger  9 . In some examples, the pressure generated by drive system  10  atomizes the spray fluid exiting spray gun  5  to generate the fluid spray. In some examples, spray gun  5  is an airless sprayer. In some examples, a handle can extend from drive system  10  and the user can maneuver drive system  10  within a job site or between job sites by grasping the handle and carrying drive system  10 . 
       FIG. 2  is an isometric view of a front side of drive system  10 .  FIG. 3  is an exploded view of drive system  10 .  FIG. 4  is a cross-sectional view of drive system  10 .  FIG. 4A  is an enlarged view of portion  3 A of  FIG. 4 .  FIG. 5  is an isometric front side view of a support frame for the drive system and displacement pump of  FIG. 2 .  FIG. 6  is an isometric rear side view of the support frame for the drive system and displacement pump of  FIG. 2 .  FIG. 7  is an exploded view of an eccentric driver of  FIG. 2 .  FIGS. 2-7  are discussed together. Electric motor  12 , control panel  13 , drive mechanism  14 , fluid displacement member  16 , support frame  18 , and displacement pump  19  are shown.  FIGS. 2-4 and 7  illustrate one embodiment of drive mechanism  14  coupled to an outer rotor electric motor  12  and configured to power reciprocation of a fluid displacement member of pump  19 .  FIGS. 5 and 6  illustrate one embodiment of support frame  18  configured to mechanically support electric motor  12  and pump  19 . 
     Electric motor  12  includes stator  20 , rotor  22 , and axle  23 . In the example shown, electric motor  12  can be a reversible motor in that stator  20  can cause rotation of rotor  22  in either of two rotational directions about motor axis A (e.g., clockwise or counterclockwise), which can be the same as motor axis MA shown in  FIGS. 1A and 1B . Electric motor  12  is disposed on axis A and extends from first end  24  to second end  26 . First end  24  can be an output end configured to provide a rotational output from motor  12 . Second end  26  can be an electrical input end configured to receive electrical power to provide to stator  20  to power operation of motor  12 . For example, one or more wires w can extend into electrical input end  26  and to stator  20  to provide electrical power to operate stator  20 . Rotor  22  can be formed of a housing, having cylindrical body  28  disposed between first wall  30  and second wall  32 . Cylindrical body extends axially relative to motor axis A between first and second walls  30 ,  32 . First and second walls  30 ,  32  extend substantially radially inward from cylindrical body  28  and towards motor axis A. Cylindrical body  28  and/or first and/or second walls  30 ,  32  can have fins  31  projecting radially and/or axially from body  28  and/or walls  30 ,  32 . Rotor  22  includes permanent magnet array  34  disposed on inner circumferential face  35 . Inner circumferential face  35  can be the radially inner side of cylindrical body  28 . Second wall  32  can have axially extending flange  36  configured to be received in an inner diameter of cylindrical body  28 . Second wall  32  can be fastened to cylindrical body  28  by fasteners, adhesive, welding, press-fit, interference fit, or other desired manners of connection. For example, bolts  37  or another fastener can connect wall  32  and cylindrical body  28 . Second wall  32  can have radially extending annular flange  38  at an inner diameter opening. Annular flange  38  can be rotationally coupled to axle  23 , such as by bearing  48 . Annular flange  38  can at least partially define a receiving shoulder for receiving the outer race  49  of bearing  48  and preloading bearing  48 . Rotor  22  can include a plurality of cylindrical projections  40 ,  41  extending axially from first wall  30 . Cylindrical projections  40 ,  41  can rotationally couple rotor  22  to stator  20  and support frame  18 . 
     Bearing  42 , having inner race  43 , outer race  44 , and rolling elements  45 , rotationally couples rotor  22  to stator  20  at axle end  46  opposite second end  26 . Bearing  48 , having outer race  49 , inner race  50 , and rolling elements  51 , rotationally couples rotor  22  to stator  20  at second end  26 . 
     Support frame  18  is mechanically coupled to rotor  22  at output end  24  via bearing  52 , having outer race  53 , inner race  54 , and rolling elements  55 . Rotor  22  can be received in support frame  18 , such that a portion of rotor  22  extends into support frame  18  and is radially surrounded by a portion of support frame  18 . Bearing  52  can be disposed between rotor  22  and support frame  18  such that both bearing  52  and support frame  18  are positioned radially outward from the portion of rotor  22  at output end  24 . Wave spring washer  56  can be disposed between bearing  52  and support frame  18 . An additional wave spring washer  57  can be disposed between bearing  42  and axle  23 . 
     Support frame  18  includes pump frame  58  (best seen in  FIG. 5 ) and support member  60  (best seen in  FIG. 6 ). It is understood that the term member can refer to a single piece or multiple pieces fixed together. Pump frame  58  mechanically supports pump  19  and electric motor  12 . Pump frame  58  is mechanically coupled to rotor  22  at output end  24  via bearing  52 . Pump frame  58  can include pump housing portion  62 , outer frame body  63 , projections  64   a , support ribs  65 , handle attachment  66 , and hub  67 . Support member  60  provides a frame for motor  12 . Support member  60  is mechanically coupled pump frame  58  and motor  12  and supports both pump and electric motor reaction forces. Support member  60  extends from pump frame  58  at output end  24  to axle  23  at electrical input end  26 . Support member  60  can include connecting members  68 , base plate  70 , and frame member  72 . Frame member  72  can include projections  64   b , support posts  73 , hub  74 , ribs  75 , and support rings  76 . Base plate  70  can include support posts  71 . Pump frame  58  and frame member  72  are disposed on opposite axial ends of motor  12  relative to axis A. A first plane that motor axis A is normal to at output end  24  can extend through pump frame  58 . A second plane that motor axis A is normal to at input end  26  can extend through frame member  72 . The two planes are spaced axially apart along motor axis A and do not intersect. 
     Control panel  13  can be mounted to and supported by support frame  18 . Specifically, control panel  13  can be mounted to frame member  72  on an opposite axial side of frame member  72  from motor  12  relative to axis A, such that frame member  72  separates control panel  13  from motor  12  and is disposed directly between control panel  13  and motor  12  along axis A. Control panel  13  can be cantilevered from motor  12  via frame member  72 . Control panel  13  can be cantilevered from support frame  18 . In the example shown, control panel  13  is mounted to frame member at control support posts  73 . Control support posts  73  extend axially from frame member  72  and away from motor  12 . Control support posts  73  can provide directly contact between thermally conductive elements of frame member  72  and control panel  13 , such as a metal-to-metal contact, to facilitate heat transfer, as discussed in more detail below. 
     Control panel  13  can include and/or support controller  15  and various other control and/or electrical elements of drive system  10 . Controller  15  is operably connected to motor  12 , electrically and/or communicatively, to control operation of motor  12  thereby controlling pumping by displacement pump  19 . Controller  15  can be of any desired configuration for controlling pumping by displacement pump  19  and can include control circuitry and memory. Controller  15  is configured to store software, store executable code, implement functionality, and/or process instructions. Controller  15  is configured to perform any of the functions discussed herein, including receiving an output from any sensor referenced herein, detecting any condition or event referenced herein, and controlling operation of any components referenced herein. Controller  15  can be of any suitable configuration for controlling operation of drive system  10 , controlling operation of motor  12 , gathering data, processing data, etc. Controller  15  can include hardware, firmware, and/or stored software, and controller  15  can be entirely or partially mounted on one or more boards. Controller  15  can be of any type suitable for operating in accordance with the techniques described herein. While controller  15  is illustrated as a single unit, it is understood that controller  15  can be disposed across one or more boards. In some examples, controller  15  can be implemented as a plurality of discrete circuitry subassemblies. In some examples, controller  15  can be implemented across one or more locations such that one or more, but less than all, components forming controller  15  are disposed in and/or supported by control panel  13 . 
     Controller  15  can include any one or more of a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry. Computer-readable memory can be configured to store information during operation. The computer-readable memory can be described, in some examples, as computer-readable storage media. In some examples, a computer-readable storage medium can include a non-transitory medium. The term “non-transitory” can indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium can store data that can, over time, change (e.g., in RAM or cache). Computer-readable memory of controller  15  and/or motor controller  22  can include volatile and non-volatile memories. Examples of volatile memories can include random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), and other forms of volatile memories. Examples of non-volatile memories can include magnetic hard discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In some examples, the memory is used to store program instructions for execution by the control circuitry. The memory, in one example, is used by software or applications running on the controller  15  or motor controller  22  to temporarily store information during program execution. 
     Control panel  13  is further shown as including user interface  17 . User interface  17  can be configured as an input and/or output device. For example, user interface  17  can be configured to receive inputs from a data source and/or provide outputs regarding the bounded area and pathways therein. Examples of user interface  17  can include one or more of a sound card, a video graphics card, a speaker, a display device (such as a liquid crystal display (LCD), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, etc.), a touchscreen, a keyboard, a mouse, a joystick, or other type of device for facilitating input and/or output of information in a form understandable to users or machines. While user interface  17  is shown as being formed as a portion of control panel  13 , it is understood that user interface  17  can, in some examples, be disposed remote from control panel  13  and communicatively connected to other components, such as controller  15 . 
     Drive mechanism  14  is connected to motor  12  and pump  19 . Drive mechanism  14  is configured to receive the rotational output from rotor  22  and convert that rotational output into a linear reciprocating input to fluid displacement member  16 . In the example shown, drive mechanism  14  includes eccentric driver  78 , drive member  80 , and drive link  82 . Eccentric driver  78  can include sleeve  83  and fastener  84 . Drive member  80  can include follower  86  and bearing member  89 . Drive link  82  can include connecting slot  90  and pin  92 . 
     Pump  19  includes fluid displacement member  16  configured to reciprocate within cylinder  94  to pump fluid. In the example shown, fluid displacement member  16  is a piston configured to reciprocate on pump axis PA to pump fluid. It is understood, however, that fluid displacement member  16  can be of other desired configurations, such as a diaphragm, plunger, etc. among other options. In the example shown, fluid displacement member  16  includes shaft  91  and connector  93 . Pump  19  includes cylinder  94  that is connected to support frame  18 . Check valves  95 ,  96  are disposed within cylinder  94  and regulated flow through pump  19 . In the example shown, check valve  95  is mounted to the piston forming fluid displacement member  16  to travel with the piston. 
     Support frame  18  supports motor  22  and pump  19 . As discussed in further detail below, support frame  18  is dynamically connected to rotor  22  by a bearing interface and statically connected to stator  20 . Support frame  18  is statically connected to pump  19 . Electric motor  12  is dynamically connected to support frame  18  via rotor  22  and statically connected to support frame  18  via stator  20 . Electric motor  12  is dynamically connected to pump  19  via fluid displacement member  16 . Pump  19  is statically connected to support frame  18  and dynamically connected to electric motor  12 . 
     In the example shown, motor  12  is an electric motor having inner stator  20  and outer rotor  22 . Motor  12  can be configured to be powered by any desired power type, such as direct current (DC), alternating current (AC), and/or a combination of direct current and alternating current. Stator  20  includes armature windings  21  and rotor  22  includes permanent magnets  34 . Rotor  22  is configured to rotate about motor axis A in response to current signals through stator  20 . Rotor  22  is connected to the fluid displacement member  16  at an output end  24  of rotor  22  via drive mechanism  14 . Drive mechanism  14  receives a rotary output from rotor  22  and provides a linear, reciprocating input to fluid displacement member  16 . Support frame  18  mechanically supports electric motor  12  at the output end  24  and mechanically supports reciprocating fluid displacement pump  19  by the connection between cylinder  94  and pump  19 . Support frame  18  at least partially houses fluid displacement member  16  of reciprocating pump  19 . In the example shown, cylinder  94  is mounted to pump frame  58  by clamp  25  receiving a portion of the support frame between a first member of the clamp  25  and a second member of the clamp  25 . For example, flange  59  can be received between the two members of clamp  25 . 
     Stator  20  defines axis A of electric motor  12 . Stator  20  is disposed around and supported by axle  23 . Axle  23  is mounted to be stationary relative to motor axis A during operation. Stator  20  is fixed to axle  23  to maintain a position of stator  20  relative to motor axis A. Power can be supplied to armature windings  21  by electrical connection made at or through electrical input end  26  of electric motor  12 . Each winding  21  can be a part of a phase of the motor  15 . In some examples, motor  15  can include three phases. The power can be provided to each phase according to electrically offset sinusoidal waveforms. For example, a motor with three phases can have each phase receive a power signal 120-degrees electrically offset from the other phases. Axle  23  can be a hollow shaft open to electrical input end  26  for receiving electrical wiring from outside of motor  12 . In alternative embodiments, axle  23  can be solid, can have a key, can be D-shaped, or other similar design. In some embodiments, axle  23  can be defined by a plurality of cylindrical cross-sections taken perpendicular to axis A that are of varying diameters to accommodate mechanical coupling with support frame  18  at electrical input end  26  of axle  23  and coupling with rotor  22  at an axially opposite end  46  of axle  23 . For example, a first end of axle  23  can be disposed radially between stator  20  and rotor  22  and have a larger diameter than the axially opposite end  46  for receiving electrical inputs. 
     Rotor  22  is disposed coaxially with stator  20  and around stator  20  and is configured to rotate about axis A. Rotor  22  can be formed from a housing having cylindrical body  28  extending between first wall  30  and second wall  32 , such that rotor  22  is positioned to extend around three sides of stator  20 . Rotor  22  includes a permanent magnet array  34 . Permanent magnet array  34  can be disposed on an inner circumferential face  35  of cylindrical body  28 . An air gap separates permanent magnet array  34  from stator  20  to allow for rotation of rotor  22  with respect to stator  20 . Rotor  22  can overlap stator  20  and axle  23  over a full radial extent of stator  20  and axle  23  at output end  24  of electric motor  12 . In some examples, rotor  22  can fully enclose stator  20  and axle  23  at output end  24  of electric motor  12 . Rotor  22  can partially or fully overlap stator  20  over a radial extent of stator  20  at electrical input end  26  of electric motor  12 . Second wall  32  extends from cylindrical body  28  radially inward toward axle  23 . Axle  23  can extend through an opening in second wall  32  concentric with axle  23  and can extend axially outward of second wall  32  in axial direction AD 2 . Second wall  32  is radially separated from axle  23 , by bearing  48  in the example shown, at electrical input end  26  of electric motor  12  to allow rotation of rotor  22  with respect to axle  23 . 
     Generally, stator  20  generates electromagnetic fields that interact with a plurality of magnetic elements of rotor  22  to rotate rotor  22  about stator  20 . More specifically, stator  20  includes a plurality of windings  21  that generate electromagnetic fields. The electromagnetic fields generated by windings  21  are radially outward facing, toward rotor  22 . Rotor  22  includes either a plurality of permanent magnets  34  circumferentially arrayed within rotor  22 , or a plurality of windings that temporarily magnetize metallic material both of which are circumferentially arrayed within rotor  22 . In either configuration of rotor  22 , the electromagnetic fields generated by the plurality of solenoids  21  of stator  20  attract and/or repel the magnetic elements of rotor  22  to rotate rotor  22  about stator  20 . 
     First and/or second walls  30 ,  32  of rotor  22  can be formed integrally with cylindrical body  28  or can be mechanically fastened to cylindrical body  28 . The mechanical connection to cylindrical body  28  can be formed in any desired manner, such as by fasteners, interference fitting, welding, adhesive, etc. Rotor  22  is formed such that a closed end of rotor  22  is oriented towards the axis PA of reciprocation of pump  19  and such that an open end of rotor  22  in oriented towards control panel  13 . The closed end of rotor  22  (formed by wall  30 ) faces the pump  19  and the open end (formed by wall  32 , that is open to facilitate electrical connections) is oriented away from pump  19  along the motor axis A. The open end of rotor  22  is oriented towards control panel  13 . In the example shown, the opening through wall  32  is open to the space directly between control panel  13  and motor  22 . 
     First wall  30  can have a tapered thickness and/or can be angled between axle  23  and cylindrical body  28 . First wall  30  can have a tapered thickness with thickness increasing in a radial direction from cylindrical body  28  toward axis A. In the example shown, the axially-oriented face of first wall  30  is contoured such that first wall  30  is domed outwards in first axial direction. In the example shown, first wall  30  is integrally formed with cylindrical body  28 . 
     In the example shown, second wall  32  is formed separately from cylindrical body  28  and connected to cylindrical body  28 . In the example shown, second wall  32  is fastened to an outer diameter portion of cylindrical body  28  with a plurality of fasteners, more specifically by bolts  37 . Second wall  32  can include axially extending flange  36  at a radially outer end, which can form a sliding fit with an inner diameter of cylindrical body  28 . Axially extending flange  36  aligns second wall  32  with cylindrical body  28  to provide proper alignment during assembly and to prevent rotor  22  from being unbalanced due to misalignment. Axially extending flange  36  facilitates concentricity between cylindrical body  28  and second wall  32 . Axially extending flange  36  can be annular. Cylindrical body  28  and/or one or both of first and second walls  30 ,  32  can include one or more of fins  31  that extend outward (axially and/or radially) to push air as rotor  22  rotates. Fins  31  can be used, for example, to direct cooling air toward control panel  13 . Fins  31  can be formed from thermally conductive material to act as heat sinks to conduct heat away from motor  12 . 
     Bearings  42 ,  48 , and  52  are disposed coaxially on rotational axis A, such that rotating members of bearings  42 ,  48 , and  52  rotate on rotational axis A. Bearings  42 ,  48 , and  52  can be substantially similar in size or can vary in size to support differing loads and to accommodate space constraints. Bearings  42  and  48  can be substantially similar in size, while bearing  52  at output end  24  can be larger to accommodate reciprocating load received by rotor  22  at output end  24 . In some examples, all three bearings  42 ,  48 ,  52  can have different sizes. In the example shown, the end bearing  52  is larger than the end bearing  48 , and the end bearing  48  is larger than the intermediate bearing  42 . Rolling elements of bearings  42 ,  48 , and  52  can vary in radial position from axis A. Rolling elements  55  of bearing  52  can be disposed at a first radius R 1  from rotational axis A of electric motor  12 , rolling elements  51  of bearing  48  can be disposed at a second radius R 2  from rotational axis A, and rolling elements  45  of bearing  42  can be disposed at a third radius R 3  from rotational axis A. As illustrated in  FIG. 4A , first radius R 1  can be greater that a second radius R 2  and third radius R 3  can be greater the second radius R 2  and less than the first radius R 1 . In some examples, second radius R 2  is one of greater than and equal to third radius R 3 . First wall  30  can be rotationally coupled to a radially inner side of axle  23  via bearing  42  at axle end  46 . Bearing  42  includes inner race  43 , outer race  44 , and rolling elements  45 . In some examples, bearing  42  can be a roller or ball bearing in which rolling elements  45  are formed by cylindrical members or balls. First wall  30  can be coupled to inner race  43 . Stator  20  can be coupled to outer race  44 , such as by axle  23  interfacing with outer race  44 . Rolling elements  45  allow rotation of rotor  22  with respect to stator  20 . Bearing  42  supports rotor  22  rotationally relative to stator  20  and maintains the air gap between permanent magnet array  34  and stator  20 , thereby balancing motor  12 . Bearing  42  can be provided to ensure that stator  20  and rotor  22  deflect the same amount through each pump cycle, such that with each up-down pump load, the air gap between stator  20  and rotor  22  is maintained and rotor  22  does not contact stator  20 . Bearing  42  minimizes the unsupported length of rotor  22  and provides an intermediate support between bearing  52  and bearing  48 . In some examples, bearing  42  can support torque load generated by electric motor  12 . Bearing  42  can primarily align stator  20  and rotor  22  while experiencing minimal pump reaction loads. The radius R 3  of bearing  42  can be determined by the size of axle  23  at axle end  46  as bearing  42  is positioned inside axle  23 . 
     Components can be considered to axially overlap when the components are disposed at a common position along an axis (e.g., along the motor axis A for axle  23  and wall  30 ) such that a radial line projecting that axis extends through each of those axially-overlapped components. Similarly, components can be considered to radially overlap when the components are disposed at common positions spaced radially from the axis (e.g., relative to motor axis A for axle  23  and wall  30 ) such that an axial line parallel to the axis extends through each of those radially-overlapped components. 
     First wall  30  of rotor  22  can extend into axle  23  at output end  24  such that a portion of axle  23  and a portion of first wall  30  radially overlap. As such, an axial line parallel to axis A can extend through each of first wall  30  and axle  23 . Cylindrical projection  40  of rotor  22  can extend in axial direction AD 2  from output end  24  of motor  12  and into axle  23  at axle end  46 . As such, cylindrical projection  40  extends from a front end of the housing of rotor  22  and axially away from pump frame  58 . Cylindrical projection  40  is coaxial with rotor  22  and stator  20  on rotational axis A and rotates about rotational axis A. Cylindrical projection  40  can extend into axle  23  such that cylindrical projection  40  axially overlaps with axle  23 . As such, a radial line extending from axis A can pass through each of cylindrical projection  40  and axle  23 . Cylindrical projection  40  is rotationally coupled to axle  23  by bearing  42 . An outer diameter surface of cylindrical projection  40  can be coupled to inner race  43 , such that rotor  22  rides inside of bearing  42 . Axle  23  can be coupled to outer race  44 . In some embodiments, at least a portion of each of cylindrical projection  40  and bearing  42  can axially overlap a portion of permanent magnet array  34  and, in some examples, stator  20 . In an alternative embodiment, first wall  30  can be rotationally coupled to an outer diameter of axle  23  such that rotor  22  is coupled to an outer race  44  and axle  23  is coupled to an inner race  43 . 
     Rotor  22  can be rotationally coupled to stator  20  at electrical input end  26  via bearing  48 . Bearing  48  includes outer race  49 , inner race  50 , and rolling elements  51 . Rotor  22  can be coupled to outer race  49  and axle  23  can be coupled to inner race  50 . Rolling elements  51  allow rotation of rotor  22  with respect to stator  20  such that rotor  22  rides outside of bearing  48 . In some examples, bearing  48  can be a roller or ball bearing in which rolling elements  51  are cylindrical members or balls. Second wall  32  can be coupled to an outer diameter surface of outer race  49  and can extend around an axially outer end face of outer race  49 . Second wall  32  can include annular flange  38 , which projects radially inward from rotor  22  towards axis A. Annular flange  38  can extend radially inward relative to the outer diameter surface of outer race  49 . Flange  38  can radially overlap and abut the axially outer end face of outer race  49 . Flange  38  can extend to radially overlap and abut a full circumferential axially outer end face of outer race  49 . Axle  23  can extend through rotor  22  at electrical input end  26  and can project axially outward of bearing  48  in axial direction AD 2  to allow for coupling of axle  23  with support frame  18 , such as via support member  60 . The radius R 2  of bearing  48  can be determined by the size of axle  23  at input end  26  and to react the pump loads generated during operation. 
     Bearing  52  can support both dynamic motor loads and the pump reaction forces generated by reciprocation of fluid displacement member  16  during pumping. Bearing  48  can support both dynamic motor loads and the pump reaction loads generated by reciprocation of fluid displacement member  16  during pumping. 
     The pump reaction forces experienced by bearing  48  are in a generally opposite axial direction (PAD 1 , PAD 2 ) as compared to the pump reaction forces simultaneously experienced by bearing  52 . For example, bearing  52  experiences an upward pump reaction force caused by fluid displacement member  16  being driven through a downstroke, while bearing  48  experiences a downward pump reaction force during to the downstroke. Similarly, bearing  52  experiences a downward pump reaction force caused by fluid displacement member  16  being driven through an upstroke, while bearing  54  experiences an upward pump reaction force during the upstroke. The pump reaction loads are transmitted through bearing  52  to support frame  18 . 
     One or both of bearings  42  and  48  can be omitted from drive system  10  in some embodiments. In such embodiments, rotor  22  can be fully separated from and free of mechanical coupling with stator  20  and axle  23  on all three sides. First wall  30  on output end  24  can extend across axis A to fully cover a radial extent of stator  20  and axle  23  at output end  24 , while maintaining axial and radial separation from stator  20  and axle  23 . Axle  23  can extend through second wall  32  and can be radially separated therefrom by a gap to allow rotation of rotor  22  with respect to axle  23  in the absence of bearing  48 . In such configurations, rotation of rotor  22  can be supported by a bearing coupling between rotor  22  and pump frame  58  (discussed further herein), alone or in combination with one of bearings  42  and  48 . 
     Rotor  22  is mechanically coupled to support frame  18  at output end  24  via bearing  52 . Bearing  52  includes inner race  54 , outer race  53 , and rolling elements  55 . Bearing  52  can be a roller or ball bearing, in which rolling elements  55  are cylindrical members or balls. Rotor  22  can be received in pump frame  58 , such that a portion of rotor  22  extends into pump frame  58  and is radially surrounded by a portion of pump frame  58 . Bearing  52  can be disposed between rotor  22  and pump frame  58  such that both bearing  52  and pump frame  58  are positioned radially outward from rotor  22  at output end  24 . Rotor  22  can be coupled to inner race  54  and pump frame  58  can be coupled to outer race  53 , such that rotor  22  rides inside of bearing  52 . Rolling elements  55  allow rotational motion of rotor  22  relative to pump frame  58 . 
     Bearing  52  is positioned proximate drive mechanism  14  and most directly experiences the pump load generated by reciprocation of fluid displacement member  16  and transmitted via rotor  22  and, more specifically, cylindrical projection  41  to which drive mechanism  14  is coupled. Bearing  52  can have a relatively large radius R 1  as compared to other motor support bearings (e.g., bearings  42 ,  48 ) to accommodate both pump load generated by reciprocation of fluid displacement member  16  and torque load generated by electric motor  12 . Bearing  52  can support both dynamic motor load including torque load generated by electric motor  12  and an up-down pump load generated substantially along pump axis PA by reciprocation of fluid displacement member  16  during pumping. Such pump reaction loads can be experienced by electric motor  12  and are particularly noticeable in direct drive configurations, which exclude intermediate gearing between rotor  22  and drive mechanism  14 . For example, the drive system  10  shown in  FIGS. 2-4  has a direct drive configuration. 
     Rotor  22  can include cylindrical projection  41  extending in axial direction AD 1  from wall  30  of rotor  22 . Cylindrical projection  41  can extend axially outward in direction AD 1  from the output end  24  or front end of electric motor  12  and can extend into an opening in pump frame  58 . Cylindrical projection  41  is centered on rotational axis A and rotates about rotational axis A with rotor  22 . Bearing  52  can be disposed on an outer diameter portion of cylindrical projection  41  to couple rotor  22  to pump frame  58  by the cylindrical projection  41 . Cylindrical projection  41  can be coupled to inner race  54  and pump frame  58  can be coupled to outer race  53 . Inner race  54  can be disposed on an outer diameter surface of cylindrical projection  41 . Rolling elements  55  allow rotational motion of rotor  22  relative to pump frame  58 . Cylindrical projection  41  can extend at least partially into pump frame  58  along axis A. In some examples, cylindrical projection  41  does not extend fully through pump frame  58  such that cylindrical projection  41  does not project in the first axial direction AD 1  beyond the structure of pump frame  58 . In some examples, cylindrical projection  41  does extend fully through pump frame  58  such that a portion of cylindrical projection  41  projects in axial direction AD 1  beyond the structure of pump frame  58 . 
     As used herein, the term “axially outer” refers to a surface facing outward of electric motor  12  (i.e., away from stator  20  along axis A) and the term “axially inner” refers to a surface facing an inner portion (i.e., towards stator  20  along axis A) of electric motor  12 . A portion of an axially outer end face of wall  30  can radially overlap with and abut an axially oriented end face of inner race  54  (oriented in axial direction AD 2  in the example shown). Wall  30  can thereby form a support for bearing  52 . The portion of the axially outer end face of wall  30  can extend radially outward from cylindrical projection  41  and fully annularly around cylindrical projection  41  to radially overlap and abut a full circumferential axially inner end face of inner race  54 . For example, wall  30  can include an annular axially extending projection circumscribing cylindrical projection  41  and extending approximately equal to or less than a height of inner race  54  to interface with inner race  54 . The projection is configured to fix an axially inner location of bearing  52  and to axially separate wall  30 , which rotates, from outer race  53 , which is stationary. 
     Bearings  42 ,  48 , and  52  can be preloaded by pump frame  58  and support member  60 . Pump frame  58  can radially overlap an axial end face of bearing  52 . Frame member  72  of support member  60  can radially overlap an axial end face of bearing  48 . An axial inward force is applied to axial end faces of bearings  52  and  48  as bearings  52 ,  42 , and  48  are compressed between pump frame  58  and frame member  72  when support member  60  is secured to connect frame members  58 ,  72  together. An axial inward force in the direction AD 2  is applied to the radially extending axial end face of bearing  52 , and specifically, to the outer axial end face of outer race  53 . An axial inward force in the direction AD 1  is applied to the radially extending axial end face of bearing  48 , and specifically, to the outer axial end face of inner race  50 . The axial forces preload bearings  42 ,  48 , and  52  to remove play from bearings  42 ,  48 , and  52  during operation of drive system  10 . Wave spring washers can be used to reduce bearing noise. In some embodiments, a first wave spring washer  56  can be disposed between pump frame  58  and the axial end face of outer race  53  of bearing  52  at output end  24 . A second wave spring washer  57  can be disposed between a portion of axle  23  and an axial end face of outer race  44  of bearing  42 . Alternatively, or additionally, a wave spring washer can be disposed between a portion of axle  23  and an axial end face of inner race  50  of bearing  48 . 
     The bearing arrangement of drive system  10  provides significant advantages. 
     Bearings  52  and  48  react to pump reaction loads generated during pumping. Bearings  52 ,  48  facilitate a direct drive configuration of drive system  10 . Bearings  52  and  48  stabilize rotor  22  to facilitate the direct drive connection to fluid displacement member  16 . The pump reaction forces experienced at output end  24  and input end  26  by bearings  52 ,  48  are transmitted to the portion of support frame  18  connected to a stand or otherwise supporting drive system  10  on a support surface. In the example shown, the pump reaction forces are transmitted to base plate  70  via pump frame  58 , frame member  72 , and connecting members  68 , balancing the forces across support frame  18 . Base plate  70  reacts the forces, such as to a stand connected to mounts  71 , and the forces are thereby transmitted away from motor  12 . All pump and motor forces are reacted through base plate  70 , which can be integrally formed with or directly connected to pump frame  58  and is mechanically coupled to motor axle  23  via frame member  72 . The connection balances motor  12 , providing longer life, less wear, less downtime, more efficient operation, and cost savings. Bearing  42  further aligns rotor  22  on pump axis A. Bearing  42  minimizes the unsupported span of rotor  22 , aligning rotor  22  and preventing undesired contact between rotor  22  and stator  20 . Bearing  42  thereby increases the operational life of motor  12 . 
     Support frame  18  mechanically supports electric motor  12  at output end  24  and at least partially houses fluid displacement member  16 . Support frame  18  can be mechanically coupled to both rotor  22  and stator  20 . Support frame  18  can be mechanically coupled to rotor  22  at output end  24  and mechanically coupled to axle  23  at electrical input end  26 . As such, support frame  18  can extend fully around motor  12  and be coupled to axially opposite ends of motor  12  to support motor  12 . Axle  23  is mechanically coupled to support frame  18  to fix stator  20  relative to support frame  18 . Axle  23  is fixed with respect to support frame  18  such that stator  20 , which is fixed to axle  23 , does not rotate relative to support frame  18  or motor rotational axis A. 
     Support member  60  can extend around an exterior of rotor  22  from pump frame  58  to axle  23  to connect pump frame  58  to axle  23  such that stator  20 , via support member  60 , is fixed relative to support frame  18 . Support member  60  can be removably fastened to axle  23 . Support member  60  fixes axle  23  to pump frame  58  to prevent relative movement between stator  20  and support frame  18 . Neither axle  23  nor stator  20  are fixed to support frame  18  at output end  24 . Instead, a portion of rotor  22  is disposed axially between and separates axle  23  and stator  20  from support frame  18 . As such, motor  12  is dynamically supported by support frame  18  at the output end  24  and statically supported by support frame  18  at the input end  26 . 
     Support member  60  can extend from a location radially inward of an exterior of cylindrical body  28  of rotor  22  to a location radially outward of cylindrical body  28 . Support member  60  can extend circumferentially around rotor  22  with sufficient radial spacing therefrom to allow unobstructed rotation of rotor  22  inside of support member  60 . In the example shown, support frame  18  does not completely enclose rotor  22 . It is understood that not all examples are so limited. In the example shown, no parts exist between support frame  18  and the exterior of rotor  22 . Thus, support frame  18  allows airflow through itself and over rotor  22 . 
     Support member  60  includes one or more connecting members  68 , base plate  70 , and frame member  72 . It is understood that each connecting member  68  can be formed by a single component or multiple components fixed together. Each connecting member  68  can also be referred to as a connector. Base plate  70  can also be referred to as a connector. Connecting members  68  and base plate  70  extend across cylindrical body  28  and are spaced therefrom. Frame member  72  is disposed at electrical input end  26  and coupled to axle  23 . Frame member  72  can also be referred to as a frame end. Frame member  72  extends radially with respect to motor axis A and is mechanically coupled to connecting members  68  and base plate  70 . Connecting members  68  and base plate  70  can extend axially outward from pump frame  58  in axial direction AD 2 . Connecting members  68 ,  70  are spaced radially from cylindrical body  28 . Connecting members  68  of support member  60  can extend parallel to motor axis A or can be angled such that an end of the connecting member  68  at output end  24  can be circumferentially offset about axis A from an end of the connecting member at electrical input end  26 . 
     Frame member  72  of support member  60  can extend substantially parallel to second wall  32  of rotor  22  and can be axially spaced therefrom. Frame member  72  can be disposed substantially parallel to pump frame  58 . Frame member  72  extends from axle  23  to a location radially outward of cylindrical body  28  where frame member  72  joins with connecting members  68  and base plate  70 . Frame member  72  is fixed to axle  23 . 
     Support member  60  connects to pump frame  58  at output end  24 . Support member  60  can connect to pump frame  58  at one or more locations radially outward of cylindrical body  28  or at one or more locations radially inward of cylindrical body  28  and then extend radially to a location radially outward of cylindrical body  28 . Support member  60  fixes an axial location of stator  20  with respect to rotor  22  and pump axis PA and axially secures components of electric motor  12  together along the motor axis A. Support member  60  can be a unitary body or can include multiple components fastened together and capable of connecting stator  20  to pump frame  58  to maintain stator  20  in a fixed axial location relative to rotor  22  and pump frame  58  on axis A. 
     In a non-limiting embodiment, connecting members  68  can be tie rods, which can be circumferentially spaced around a top portion of motor  12 . The tie rods can be removably mounted to one or both of pump frame  58  and frame member  72 . Base plate  70  can be a substantially solid base plate or bracket disposed under a bottom portion of motor  12 . Base plate  70  can have a width substantially equal to a width of pump housing portion  62 . In some embodiments, base plate  70  can have a width substantially equal to or greater than a diameter of cylindrical body  28  of rotor  22 . 
     Frame member  72  can include hub  74 . Frame member  72  can be removably coupled to axle  23 . For example, frame member  72  can be slidingly engaged with axle  23 . In some examples, frame member  72  can be fixed to axle  23 . For example, hub  74  of frame member  72  can be bolted to axle  23  or secured to axle  23  with a retaining nut (not shown). Connecting members  68  and base plate  70  can be secured to frame member  72  and can fix hub  74  to axle  23 . 
     In addition to providing mechanical support to motor  12 , support member  60  can conduct heat away from motor  12  during operation. Axle  23  extends through rotor  22  and axially outward from rotor at electrical input end  26  and can project in axial direction AD 2  outward of bearing  48 . The portion extending axially beyond bearing  48  can connect with support member  60  and provide a route for conductive heat transfer from stator  20  to support member  60  and away from electric motor  12 . More specifically, frame member  72  is fixed to axle and in a direct heat exchange relationship therewith. As discussed in more detail below, frame member  72  is configured to conduct heat both from motor  12  and control panel  13 , which are the main heat generating components of drive system  10 . 
     Both axle  23  and support member  60  can be formed of a thermally conductive material (e.g., metal). Axle  23  can be placed in direct contact with support member  60  (e.g., with frame member  72 ) to provide a direct conductive heat path to route heat away from motor  12 . As illustrated in  FIG. 4 , axle  23  axially overlaps stator  20  along a full axial length of stator  20 . Axle  23  is capable of drawing heat from stator  20  and conducting heat toward electrical input end  26  and axially outward of stator  20 . Axle  23  transfers heat to frame member  72  via conduction at locations where frame member  72  is in contact with axle  23 . As such, the conductive pathway for heat transfer from stator  20  extends through axle  23  to frame member  72 . In some embodiments, frame member  72  can be in fixed contact with both an axially extending surface of axle  23  and a radially extending end face of axle  23 . For example, a portion of frame member  72 , such as a lip extending from hub  74 , can extend radially over an end of axle  23  to increase the surface area of the direct contact and transfer heat away from axle  23  and away from electric motor  12 . A shape and surface area of frame member  72  can be selected to facilitate heat transfer away from electric motor  12 . 
       FIG. 5  shows a front isometric view of one embodiment of pump frame  58  with base plate  70 . Pump frame  58  and base plate  70  can be integrally formed, such as by, for example, casting as a unitary component, or can be formed from multiple components mechanically fixed together. For example, pump frame  58  and base plate  70  can be removably connected together, such as by bolts or other fasteners. Pump frame  58  can include drive link housing  61 , pump housing portion  62 , inner frame body  63   a , outer frame body  63   b , mid-frame body  63   c , projections  64   a  with distal ends disposed radially outward of electric motor  12 , support ribs  65 , handle attachment  66 , and hub  67 . Pump frame  58  provides mechanical support and housing for pump  19 . 
     Pump frame  58  provides mechanical support for motor  22 . Pump frame  58  can extend radially outward from bearing  52 . Bearing  52  can be received in hub  67 . Rotor  22  can be received through an opening in inner frame body  63   a . Outer frame body  63   b  is positioned radially outward of inner frame body relative to motor axis A. Mid-frame body  63   c  is positioned between inner frame body  63   a  and outer frame body  63   b . Ribs  65  can extend between inner frame body  63   a  and mid-frame body  63   c , between inner frame body  63   a  and outer frame body  63   b , and between mid-frame body  63   c  and outer frame body  63   b . Ribs  65  can be used to reduce a weight of pump frame  58  while providing structural support. In some embodiments, a plurality of ribs  65  can extend between hub  67  and outer frame body  63   b  (best shown in  FIG. 6 ). Ribs  65  can support load from bearing  52  and can reduce weight of pump frame  58 . Ribs  65  can be spaced substantially circumferentially around a portion of hub  67 . Ribs  65  can vary in length depending on a shape of outer frame body  63   b  or positioning relative to bearing  52 , inner frame body  63   a , or mid-frame body  63   c . As illustrated in  FIG. 5 , outer frame body  63   b  can have a different shape than bearing  52   b , which is cylindrical. As such, a perimeter of outer frame body  63  is not evenly spaced from a perimeter of bearing  52  or hub  67  and ribs  65  connecting hub  67  to outer frame body  63   b  vary in length accordingly. A size and shape of outer frame body  63   b  and quantity, thickness, and positioning of ribs  65  can be selected to support bearing  52  and electric motor  12  while reducing weight of pump frame  58 . Projections  64   a  can be substantially solid triangular projections extending from hub  67 . Projections  64   a  can form attachment points for members  68  to secure frame member  72  to pump frame  58 . 
     Drive link housing  61  can positioned in the opening in inner frame body  63   a . As illustrated in the example in  FIG. 5 , drive link housing  62  is a cylindrical body positioned below the opening (in the axial direction PAD 1  (shown in  FIG. 4 ) and above pump housing portion  62 . An opening of drive link housing  61  is orthogonal to the opening through inner frame body  62   a . Drive link housing  61  limits movement of drive link  82  to up and down motion along pump axis PA. 
     Pump housing portion  62  of pump frame  58  at least partially houses fluid displacement member  16  and supports displacement pump  19 . Pump  19  is disposed at output end  24  on pump axis PA orthogonal to motor axis A and axially aligned with drive mechanism  14  along axis A. Pump housing portion  62  of pump frame  58  can extend in an axial direction AD 1  outward of drive mechanism  14  to house fluid displacement member  16 . As illustrated in the example in  FIG. 5 , pump housing portion  62  is formed by U-shaped walls opening to a front end of pump frame  58  away from motor  12  in axial direction AD 1  and toward pump  19  in axial direction PAD 2 . A portion of pump  19  is disposed in the chamber of pump housing portion  62  during operation. 
       FIG. 6  shows a rear isometric view of one embodiment of support frame  18  including pump frame  58  and support member  60  assembled together. Electric motor  12  has been removed from the view shown for clarity.  FIG. 6  shows support frame  18 , including pump frame  58  and support member  60 . Support member  60  includes connecting members  68 , base plate  70 , and frame member  72 . Frame member  72  includes hub  74  configured to receive a portion of axle  23  such that axle  23  is supported by frame member  72  and frame member  72  is in contact with axle  23 . Frame member  72  is positioned in contact with an outer surface of axle  23 . By maintaining contact with axle  23 , frame member  72  can draw heat away from stator  20  via thermal conduction. Both axle  23  and frame member  72  can be formed from a thermally conductive material (e.g., aluminum) capable of conducting heat from inside stator  20  to input end  26  and frame member  72 . As discussed with respect to  FIG. 4 , axle  23  axially overlaps stator  20  along a full axial length of stator  20  and is capable of drawing heat from stator  20  and conducting heat toward electrical input end  26  and axially outward of stator  20 . Axle  23  transfers heat to frame member  72  via conduction at locations where frame member  72  is in contact with axle  23 . As such, the conductive pathway for heat transfer from stator  20  extends through axle  23  to frame member  72 . 
     Hub  74  of frame member  72  is configured to be in fixed contact with an axially extending surface of axle  23 . Frame member  72  extends radially from axle  23  to transfer heat radially away from axle  23  and away from electric motor  12 . A shape and surface area of frame member  72  can be selected to facilitate heat transfer away from electric motor  12 . Projecting members  64   b  on frame member  72  can extend from hub  74  radially outward to direct heat radially outward from axle  23 . Projections  64   b  provide increased surface area relative a plate  72  to further facilitate heat transfer and cooling of motor  12 . A quantity, shape, and positional arrangement of projections  64   b  on frame member  72  can be selected to provide effective heat transfer away from stator  20  via axle  23  and away from control panel  13 . As illustrated in the example in  FIG. 6 , projections  64   b  can be substantially open bodies formed by a plurality of ribs  75  extending from hub  74  to distal ends or projections  64   b  in a converging shape. In the example shown, the plurality of ribs  75  form triangular projections that narrow as the projections extend radially away from axis A. Projections  64   b  provide structural rigidity to support frame  18  and surface area for conductive heat transfer from stator  20  while allowing airflow between motor  12  and control panel  13 . Projections  64   b  can be arranged in a star-like shape around hub  74  with bases at hub  74  extending to pointed distal ends. As illustrated in  FIG. 6 , two lower projections  64   b  are connected to base plate  70  and are each formed by two ribs  75 , and two upper projections  64   b  are connected to connecting members  68  and are each formed by three ribs. 
     Frame member  72  can additionally include a plurality of concentric support rings  76  formed around hub  74  and connecting projections  64   b . Support rings  76  can provide increased rigidity to frame member  72  while allowing airflow between motor  12  and control panel  13 . Support rings  76  also increase the surface area of frame member  72 , providing for heat transfer. Openings are formed through frame member  72  that further increase the surface area and allow for air flow through frame member  72  to further facilitate heat transfer. Alternative designs to increase surface area of frame member  72  are contemplated and can be used without departing from the scope of the invention. 
     Frame member  72  can be connected to axle  23  in any desired manner that prevents axial displacement and rotation of frame member  72  relative to axle  23  and fixes an axial position of stator  20  relative to rotor  22 . In some embodiments, frame member  72  can be slip fit onto the outer surface of axle  23 . The compressive connection between pump frame  58  and frame member  72  can secure axle  23  and stator  20  to prevent movement relative to pump axis A. The connection between frame member  72  and pump frame  58  by way of members  68 ,  70  prevents relative movement of frame member  72  about axis A and can clamp stator  20  and axle  23 . 
     In some examples, frame member  72  can be fastened to the outer surface of axle  23  with one or more fasteners, such that axle  23  is fixed relative to frame member  72 , which is fixed to pump frame  58  by base plate  70  and members  68 . Axle  23  is thereby fixed relative to pump axis A. Frame member  72  is in contact with axle  23  along the outer surface of axle  23 . Frame member  72  can be secured to axle  23  such that contact is maintained between frame member  72  and axle  23  during operation to provide a conductive pathway for heat transfer from stator  20  to frame member  72 . 
     An axial length of frame member  72  in an axial direction at hub  74  can be selected to increase a contact surface area between frame member  72  and axle  23  and thereby increase heat transfer capacity. Frame member  72  can be connected to interface with axle  23  in any desired manner. For example, as shown in  FIG. 4 , hub  74  can be slip fit onto an outer diameter surface of axle  23 . The opening through hub  74  can be sized to allow an inner diameter surface of hub  74  to maintain contact with axle  23  to provide a conductive heat path from axle  23  to frame member  72 . 
     Frame member  72  can support control panel  13 . As illustrated in  FIGS. 2 and 4 , control panel  13  can be mounted to an aft side of frame member  72  opposite motor  12 . Control panel  13  can be fastened to mounting posts  73  of frame member  72  via bolts or other retention mechanisms as known in the art. A conductive material on control panel  13  can interface with frame member  72  via mounting posts  73  to provide a conductive heat path from control panel  13  to frame member  72 . As such, frame member  72  can draw heat away from both motor  12  and control panel  13  and transfer heat to the environment. In the example shown, control panel  13  is mounted to frame member  72  at mounting posts  73 . Mounting posts  73  space control panel  13  from frame member  72  along axis A. A cooling plenum is thereby formed between frame member  72  and control panel  13  to facilitate airflow therebetween. Mounting posts  73  and portion of control panel  13  and/or fasteners connecting control panel  13  to frame member  72  can be formed from thermally conductive material. Direct thermal pathways are thereby formed between control panel  13  and frame member  72 . Control panel  13  is mounted such that control panel  13  is cantilevered off of the heat sink formed by frame member  72 . In other embodiments, control panel  13  can be mounted on a side of motor  12  disposed axially between pump frame  58  and frame member  72  along axis A. 
     Frame member  72  is disposed axially between motor  12  and control panel  13 , which are the main heat generating components of drive system  10 . Frame member  72  conducts heat away from components disposed on both axial sides of frame member  72 . Frame member  72  is configured to provide a large surface area and extends radially away from axis A to facilitate heat transfer. Both the motor  12  and control panel  13  can have direct thermal pathways to frame member  72  (e.g., by direct metal-to-metal contact). Frame member  72  thereby structurally supports both of motor  12  and control panel  13  and provides heat dissipation for motor  12  and control panel  13 . 
     Pump frame  58  and frame member  72  can each include at least two projections  64   a ,  64   b , respectively. Projections  64   a ,  64   b  can extend radially outward from axis A such that a distal end of each projecting member  64   a ,  64   b  is disposed radially outward of rotor  22 . Connecting members  68  can be fastened to distal ends of the projections  64   a ,  64   b . Base plate  70  can be fastened to distal ends of the projections  64   b  disposed on a bottom side of frame member  72 . Connecting members  68  can be fastened to distal ends of projections  64   a ,  64   b  disposed on a top side of motor  12  to connect pump frame  58  with frame member  72  across a top exterior surface of rotor  22 . Base plate  70  can be fastened to distal ends of lower projections  64   b  to connect pump frame  58  with frame member  72  across a bottom exterior surface of rotor  22 . Projections  64   a  and  64   b  can be shaped to provide structural integrity to support frame  18  during operation, while limiting an amount of weight added to drive system  10 . As illustrated in the example in  FIG. 6 , projections  64   a  are substantially solid triangular bodies with ribs  65  provided to increase rigidity while reducing weight. 
     Projections  64   a ,  64   b  on each of pump frame  58  and frame member  72  can be arranged symmetrically or asymmetrically and with equal or unequal spacing relative to each other. As illustrated in  FIGS. 2, 3, and 5 , pump frame  58  can have two projections  64   a , which are axially aligned with projections  64   b  on frame member  72  (shown in  FIG. 6 ). Frame member  72  can have four projections  64   b  arranged in an X-configuration unequally spaced about axis A. 
     Connecting members  68  and base plate  70  connect pump frame  58  to frame member  72 . Connecting members  68  and base plate  70  are rigid and capable of maintaining a fixed relationship between pump frame  58  and frame member  72  during operation of drive system  10 . Additionally, connecting members  68  and base plate  70  are configured to support torque loads generated by electric motor  12  and transmitted through pump frame  58  and frame member  72  and to further support pump reaction loads generated by reciprocation of fluid displacement member  16  and also transmitted through pump frame  58  and frame member  72 . Connecting members  68  can be tie rods, which can be fastened by bolts or other retention mechanisms to projections  64   a  and  64   b , among other options. Base plate  70  can be a plate or bracket designed to provide additional structural rigidity to support frame  18 . 
     Base plate  70  can be configured to mount to a cart or stationary assembly for ease of operation and transport. Base plate  70  can include a plurality of mounting posts  71  or bosses configured to receive fasteners to secure drive system  10  to a cart or stationary assembly. In other embodiments, pump frame  58  and/or base plate  70  can be configured to mount to a cart or stationary assembly for ease of operation and transport. In some embodiments, pump frame  58  can include attachment feature  66  for securing a handle for ease of carrying drive system  10 . 
     As described further herein, support member  60  is not limited to the embodiments illustrated and can include any single component or combination of components capable of fixing stator  20  relative to pump frame  58  and relative to pump axis A. Support member  60  can fully or partially enclose rotor  22 , as illustrated in  FIG. 2 , or can be disposed across a single side of rotor  22  extending from output end  24  to electrical input end  26 , as illustrated in  FIG. 12 . In some embodiments, support member  60  can include a second frame member. The second radially extending member can be disposed between pump frame  58  and first wall  30  of rotor  22 . The second frame member can be fixed to pump frame  58  and axially spaced from first wall  30  to allow unobstructed rotation of rotor  22 . Support member  60  can include a single connecting member  68  and/or base plate  70  or multiple connecting members  68  and/or base plate  70  or any desired combination thereof, as described in further detail below. A size, shape, quantity, and location of connecting members  68  and base plate  70  can be selected to reduce weight while providing structural integrity to drive system  10 . Likewise, a size, shape, and quantity of frame member  72  can be selected to reduce weight while providing structural integrity to drive system  10 . 
     Rotor  22  can extend through pump frame  58  and axially outward of bearing  52  in axial direction AD 1 . In the example shown, drive mechanism  14  is directly connected to rotor  22  at output end  24  at a location axially outward of bearing  52  in axial direction AD 1 . Drive mechanism  14  is configured to receive a rotational output from rotor  22  and to translate the rotational output to a linear, reciprocating input to fluid displacement member  16 . In the example shown, drive system  10  does not include intermediate gearing between motor  12  and drive mechanism  14 . It is understood, however, that some examples of drive system  10  include intermediate gearing between motor  12  and drive mechanism  14 . In such examples the axis of rotation of eccentric  78  can be radially offset from the axis of rotation of rotor  22 . 
     Drive mechanism  14  includes eccentric driver  78 , drive member  80 , and drive link  82 . Eccentric driver  78  is provided on rotor  22  of electric motor  12  and rotates with rotor  22 . Eccentric driver  78  is offset radially from rotational axis A. As such, rotation of rotor  22  causes eccentric driver  78  to move in a circular path about rotational axis A. Eccentric driver  78  provides a eccentric crankshaft that powers drive mechanism  14  and can be referred to as such. Drive member  80  is mechanically coupled to eccentric driver  78  and is configured to drive reciprocation of fluid displacement member  16 . Eccentric driver  78  is directly coupled to drive member  80  without intermediate gearing. The direct connection between rotor  22  and fluid displacement member  16  provides a 1:1 ratio of rotor rotation to pump cycle. As such, for each one rotation of rotor  22  about axis A, fluid displacement member  16  proceeds through one full pump cycle, which includes an upstroke and a downstroke. 
     Eccentric driver  78  projects axially outward from output end  24  of rotor  22  and is offset radially from rotational axis A. More specifically, eccentric driver  78  projects in the axial direction AD 1  from cylindrical projection  41  of rotor  22 . In some embodiments, eccentric driver  78  can be integrally formed with cylindrical projection  41 . In alternative embodiments, eccentric driver  78  can be formed from one or more components and assembled with rotor  22 . As illustrated in  FIGS. 2-4 and 7 , eccentric drive crankshaft  78  can be a cylindrical body, which extends into a bore  79  of rotor  22 . In some examples, bore  79  can extend through cylindrical projection  41  and into cylindrical projection  40 . In such an example, the bore  79  can axially overlap with both bearing  52  and bearing  42 . Bore  79  is offset from a rotational axis of the rotational input to eccentric driver  78  (e.g., axis A in the direct drive arrangement shown) and, therefore, has a center offset from a center of cylindrical projection  41 . As illustrated in  FIG. 7 , bore  79  can be positioned adjacent to an outer diameter of cylindrical projection  41 . Bore  79  can be substantially located between the center of cylindrical projection  41  and the outer diameter of cylindrical projection  41 . Bore  79  can be configured to receive at least a portion of eccentric driver  78  with a slip fit. Cylindrical projections  40  and  41  can be configured to support eccentric driver  78  as pump reaction forces are applied to eccentric driver  78  via drive member  80 . 
     Cylindrical projection  41  can include boss  88 . Boss  88  can define an opening of bore  79 , can be used to locate eccentric driver  78 , and can support eccentric driver  78  as reciprocating loads are applied to eccentric driver  78  via drive member  80 . Boss  88  projects axially outward in the first axial direction AD 1  from cylindrical projection  41  toward drive member  80 . Boss  88  can be a cylindrical projection extending from cylindrical projection  41 . Boss  88  supports eccentric driver  78  by reducing a length of eccentric driver  78  cantilevered from rotor  22 . Boss  88  can have a smaller outer diameter than cylindrical projection  41 . A centerline through boss  88  is radially offset from axis A. 
     In some embodiments, cylindrical projection  41  can have a substantially hollow body with cavities defined by a plurality of ribs  87 . Ribs  87  can extend radially outward from eccentric driver  78  to an outer cylindrical wall of cylindrical projection  41 . More specifically, ribs  87  can extend radially outward of bore  79  and boss  88 . Ribs  87  can be configured to support a load of bearing  52  and eccentric driver  78 . Additionally, use of ribs  87  can reduce a weight of rotor  22 , particularly at output end  24  where rotor  22  is coupled to support frame  18 . Ribs  87  can be spaced circumferentially around eccentric driver  78 . Ribs  87  can extend around a portion of eccentric driver  78  that is less than a full circumference of eccentric driver  78 . Ribs  87  can vary in a radial length between eccentric driver  78  and the wall of cylindrical projection  41  depending on the location of ribs  87 . Ribs  87  extending from a position around eccentric driver  78  adjacent to the center of cylindrical projection  41  can be longer than ribs  87  extending from a position around eccentric driver  78  nearer the outer wall of cylindrical projection  41 . Eccentric driver  78  projects further in axial direction AD 1  than cylindrical projection  41 . As such, eccentric driver  78  can represent the most-axially-forward part of rotor  22 . In some examples, crankshaft  78  at least partially axially overlaps with support frame  18 . 
     Eccentric driver  78  can include a sleeve  83  and bolt  84  (shown in  FIGS. 4, 4A, and 7 ). Sleeve  83  can be received in bore  79  with a press fit or transitional slip fit. Bolt  84  can be slidingly received in sleeve  83 . Bolt  84  can be threadedly fastened to bore  79  at an axially inner end of bore  79 . The axial inner end of bore  79  can be positioned in cylindrical projection  40 . Bore  79  can have multiple inner diameters. In the example shown, bore  79  includes two inner diameters D 1 , D 2  (shown in  FIG. 4A ) to accommodate a larger diameter of sleeve  83  and a smaller diameter of bolt  84 . Inner diameter D 1  can be larger than inner diameter D 2  to accommodate sleeve  83 . Inner diameter D 2  can be smaller than inner diameter D 1  to accommodate bolt  84 . A portion of bore  79  having inner diameter D 1  can extend in axial direction AD 2  from boss  88  a first axial length L 1 . A portion of bore  79  having inner diameter D 2  can extend in axial direction AD 2  from an end of L 1  to a second axial length L 2 . The portion of bore  79  having inner diameter D 1  can have a substantially smooth surface to provide a sliding fit with sleeve  83 . The portion of bore  79  having inner diameter D 2  can be threaded to fix bolt  84 . Bolt  84  can retain sleeve  83  in rotor  22 . Bolt  84  can extend into cylindrical projection  40  and can be positioned radially within stator  20 . Bolt  84  is provided in rotor  22 , which holds permanent magnet array  34 . Bolt  84  can be formed of a non-ferrous material to prevent interference with electric motor  12 . 
     Eccentric driver  78  extends from rotor  22  in axial direction AD 1  and is offset from rotational axis A. Drive member  80  can be rotationally coupled to crankshaft  78 . Drive member  80  can be a connecting rod. Drive member includes follower  86  at a first end configured to receive sleeve  83  of eccentric driver  78 . Follower  86  can include a bearing member  89  disposed between follower  86  and sleeve  83  to allow drive member  80  to move in a rocking motion about eccentric driver  78  as eccentric driver  78  moves with rotor  22 . Drive member  80  can be coupled to fluid displacement member  16  via drive link  82 . Drive link  82  can be a cylindrical shaft and can include connecting slot  90  at a first end configured to receive a second end of drive member  80  opposite follower  86 . Pin  92  can extend through connecting slot  90  and an aperture in the second end of drive member  80  in a manner that allows drive member  80  to pivot about pin  92  within drive link  82  and allows drive member  80  to follow eccentric driver  78 . Drive member  80  translates rotational motion of crankshaft  78  into reciprocating motion of drive link  82 , which drives fluid displacement member  16  in a reciprocating manner. Drive member  80  can be axially spaced from boss  88  such that boss  88  does not interface or interfere with the movement of drive member  80  relative to eccentric driver  78 . 
     Fluid displacement member  16  is mechanically coupled to drive mechanism  14  at output end  24 . Connector  93  of fluid displacement member  16  can be secured to drive link  82  at a second end opposite the first end through which pin  92  extends. Fluid displacement member  16  can be connected to drive link  63  in any desired manner, such as by a slotted connection like that shown or a pinned connection, among other options. Fluid displacement member  16  can be a piston, which moves fluid in and out of a pump cylinder  94  as rotor  22  drives fluid displacement member  16  down through a downstroke and pulls fluid displacement member  16  up through an upstroke via drive mechanism  14 . In some examples, fluid displacement member  16  can be a piston for a double displacement pump such that the pump  19  outputs fluid both as rotor  22  drives fluid displacement member  16  down through a downstroke and pulls fluid displacement member  16  up through an upstroke via drive mechanism  14 . Fluid displacement member  16  can be cylindrical, elongated along, and coaxial with pump axis PA. Fluid displacement member  16  can be a piston, which can be elongate along and coaxial with pump axis PA. 
     Pump  19  can include cylinder  94  and check valves  95 ,  96 . Pump  19  is statically connected to support frame  18  via cylinder  94  and dynamically connected to electric motor  12  by the connection between fluid displacement member  16  and drive mechanism  14 . More specifically, pump  19  is statically connected to support frame by clamp  25 . Check valve  95  is a one-way valve disposed in cylinder  94 . Check valve  96  is a one-way valve disposed in fluid displacement member  16  to reciprocate with fluid displacement member  16 . Pump  19  is disposed on pump axis PA, which is orthogonal to motor axis A. Pump  19  is a double displacement pump, such that pump  19  outputs fluid during both the upstroke of fluid displacement member  16  in axial direction PAD 2  and the downstroke of fluid displacement member  16  in axial direction PAD 1 . Pump  19  can include both dynamic seals between cylinder  94  and fluid displacement member  16 . In the example shown, the first dynamic seal is mounted to fluid displacement member  16  and travels with fluid displacement member  16  while the second dynamic seal remains static relative to cylinder  94  and pump axis PA. As such, the first dynamic seal reciprocates relative to cylinder  94  and pump axis PA while fluid displacement member  16  reciprocates relative to the second dynamic seal. In some examples, the first dynamic seal can be mounted to cylinder  94  to remain stationary as fluid displacement member  16  reciprocates. The piston forming fluid displacement member  16  can extend out of cylinder  94  through the second dynamic seal. 
     During operation of drive system  10 , power is supplied to electric motor  12  causing rotor  22  to rotate about rotational axis A and causing eccentric driver  78  to move with rotor  22 . Eccentric driver  78  moves along a circular path radially offset from rotational axis A. Eccentric driver  78  completes a single circular path with each revolution of rotor  22 . Follower  86 , which receives eccentric driver  78  moves with eccentric driver  78 . As such, with each revolution of rotor  22 , follower  86  also completes a full circular path. As follower  86  moves along the circular path, follower  86  changes a position with respect to rotational axis A. With each revolution of rotor  22 , eccentric driver  78  pulls drive member  80  via follower  86  in the circular path. The end of drive member  80  opposite follower  86  is secured to drive link  82  via pin  92 . Drive link  82  is secured in support frame  18 . As eccentric driver  78  moves through an upward arc from a bottom dead center position to a top dead center position, eccentric driver  78  pulls drive member  80  away from drive link  82  such that drive link  82  is pulled in a linear upward direction toward rotational axis A of electric motor  12 . As eccentric driver  78  moves through a downward arc from a top dead center position to a bottom dead center position, eccentric driver  78  pushes drive member  80  toward drive link  82  such that drive link  82  is forced in a linear downward direction away from rotational axis A. With each revolution of rotor  22 , drive link  82  is forced both upward and downward once each. In this manner, drive mechanism  14  translates each revolution of rotor  22  into a linear up and down motion of fluid displacement member  16 . Drive link  82  is coupled to fluid displacement member  16  and accordingly pulls fluid displacement member  16  through an upstroke and pushes fluid displacement member  16  through a downstroke. As such, for each revolution of rotor  22 , pump  19  proceeds through a full pump cycle, including an upstroke and a downstroke. 
     During operation, the pump reaction forces generated by fluid displacement member  16  during pumping are transmitted to support frame  18  and away from motor  12  via drive mechanism  14 , rotor  22 , bearing  52 , bearing  48 , axle  23 , pump frame  58 , and support member  60 . Fluid displacement member  16  receives a downward reaction force when moving through the upstroke and an upward reaction force when moving through the downstroke. Both the upward reaction force and the downward reaction force travel through drive mechanism  14 , rotor  22 , and then to bearings  52 ,  48 ,  42 . Bearings  52 ,  48 ,  42  transfer rotational forces associated with rotation of rotor  22  and both the upward and downward reaction forces to support frame  18 . With each stroke, pump reaction forces are generated and a load is applied to rotor  22  via drive mechanism  14 . The pump reaction forces are axial loads generally along pump axis PA. 
     This axial pump reaction load is transverse to rotational axis A of electric motor  12  and is experienced at both output and input ends  24  and  26  of electric motor  12 . The load is transmitted to pump frame  58  via bearing  52  and to support member  60  via bearing  48  such that pump reaction forces on bearing  42  are minimized, maintaining proper air gap. At output end  24 , the load is transmitted from rotor  22  to pump frame  58  through bearing  52 . At electrical input end  26 , the load is transmitted from rotor  22  through bearing  48  and axle  23  to frame member  72 . The forces are transmitted from pump frame  58  and frame member  72  to base plate  70 . The forces can be transferred from base plate  70  to a stand or other structure coupled to base plate  70 . Bearings  52  and  48  experience opposite reactionary forces with each pump stroke to provide a force balance across rotor  22 , maintaining the air gap and preventing undesired contact between rotor  22  and stator  20 . In examples where pump frame  58  is directly connected to a stand or other support, the forces are transmitted to frame member  58  via support member  60  and then to the stand or other support. The forces can be transmitted to frame member  58  from frame member  72  via members  68  and base plate  70 . 
     As illustrated in  FIG. 4 , drive system  10  can be used to deliver fluid such as paint, among other spray fluids, to a spray apparatus. Fluid can be drawn from a supply container  97  via hose  98  and pump  19  and delivered to spray apparatus  5 , such as a handheld spray gun, via hose  4  for application. An operator can grasp a handle of apparatus  5  and cause spraying by actuating a trigger  9  of apparatus  5 . 
     The direct drive configuration of drive system  10  can eliminate intermediate gearing (e.g., reduction gears) between electric motor  12  and fluid displacement member  16 . The elimination of intermediate gearing provides a more compact, lower weight, reliable, and simpler pump by reducing the part count and number of moving parts. The direct drive configuration can provide more efficient pumping due to the 1:1 ratio of rotor rotation to pump cycle. Additionally, the elimination of gearing can provide for quieter pump operation. 
     The outer rotator drive system  10  can provide significant advantages over inner rotator motors. Rotor  22  being an outer rotator disposed at least partially radially outside of stator  20  provides increased inertia and torque relative an inner rotator motor. The increased torque facilitates rotor  22  generating sufficiently high pumping pressures with displacement pump  19  to generate an atomized spray at an applicator such as a spray apparatus  5 . For example, drive system  10  can be utilized to pump paint or other fluids to an airless spray gun, whereby the fluid pressure generates the atomized spray. In some examples, rotor  22  can cause pump  19  to generate pumping pressures of about 3.4-69 megapascal (MPa) (about 500-10,000 pounds per square inch (psi)) or even higher. In some examples, the pumping pressures are in the range of about 20.7-34.5 MPa (about 3,000-5,000 psi). High fluid pumping pressure is useful for atomizing the fluid into a spray for applying the fluid to a surface. 
       FIG. 8  is an isometric front side view of drive system  110  and displacement pump  19 .  FIG. 9  is an isometric cross-sectional view of drive system  110  and displacement pump  19  taken along the line  9 - 9  of  FIG. 8 .  FIGS. 10A-10C  are isometric rear side views of alternative support frames  118 A- 118 C for drive system  110  and displacement pump  19  of  FIG. 8 .  FIGS. 8, 9, and 10A-10C  are discussed together. Drive system  110  is an alternative embodiment of an outer rotator drive system, such as drive system  10  (best seen in  FIGS. 2-4 ). Drive system  110  is substantially similar to drive system  10 . 
     Drive system  110  is configured for operation with pump  19  and fluid displacement member  16  of  FIGS. 2-4 .  FIGS. 8 and 9  show drive system  110 , electric motor  112 , drive mechanism  114 , fluid displacement member  16 , support frame  118   a , and displacement pump  19 .  FIG. 10A  shows drive system  110  with support frame  118   a .  FIG. 10B  shows drive system  110  with support frame  118   b .  FIG. 10C  shows drive system  110  with support frame  118   c.    
     Drive mechanism  114  and electric motor  112  are substantially similar to drive mechanism  14  and electric motor  12  of drive system  10 . Electric motor  112  can be a reversible motor in that stator  120  can cause rotation of rotor  122  in either of two rotational directions about motor axis A (e.g., clockwise or counterclockwise). Support frames  118   a - 118   c  are similar to support frame  18  but do not include axially extending base plate  70  of drive system  10 . 
     As described with respect to electric motor  12 , electric motor  112  includes stator  120 , rotor  122 , and axle  123 . Electric motor  112  is disposed on axis A and extends from a first end (output end)  124  to an opposite second end (electrical input end)  126 . Rotor  122  can be a housing having cylindrical body  128 , first wall  130 , and second wall  132 . Rotor  122  includes permanent magnet array  134  disposed on inner circumferential face  135 . Bearing  148 , having outer race  149 , inner race  150 , and rolling elements  151 , rotationally couples rotor  122  to stator  120  at electrical input end  126  of electric motor  112 . Bearing  142 , including inner race  143 , outer race  144 , and rolling elements  145 , rotationally couples rotor  122  to stator  120  at axle end  146 . Bearing  152 , including outer race  153 , inner race  154 , and rolling elements  155 , rotationally couples rotor  122  to support frame  118 A at output end  124 . Bearings  142 ,  148 , and  152  can be preloaded by support frame  118 A between output end  124  and input end  126 . Wave spring washer  156  can be disposed between support frame  118 A and bearing  152  at output end  124 . Wave spring washer  157  can be disposed between support frame  118 A and bearing  148  at input end  126 . Bearing configurations of drive system  110  can be substantially the same as those disclosed with respect to drive system  10 , including the bearing configurations shown and disclosed as alternatives. 
     Rotor  122  can be substantially similar to rotor  22  but can have some structural distinctions as provided below. These structural distinctions are non-limiting. Rotor  122  can be formed from a housing having cylindrical body  128 , first wall  130 , and second wall  132 . Cylindrical body  128  and second wall  132  can be substantially the same as cylindrical body  28  and wall  32  of rotor  22 . As illustrated in  FIG. 9 , first wall  130  can be disposed substantially perpendicular to motor axis A and can have a substantially uniform axial thickness as wall  130  extends in a radial direction. First wall  130  thereby lacks the thickened region present in the corresponding first wall  30  of rotor  22 . Rotor  122  includes cylindrical projections  140  and  141  to support bearing  52  and  42 , respectively. Cylindrical projections  140  and  141  are substantially similar to the corresponding cylindrical projections  40  and  41  on rotor  22 . 
     Electric motor  112  can be cantilevered from support frame  118   a - 118   c  such that electrical input end  126  disposed opposite output end  124  is a free end of the cantilevered electric motor  112 . Support frame  118   a - 118   c  extends from bearing  152  at output end  124  to axle  123  at electrical input end  126 . Support frame  118   a - 118   c  extends around an exterior surface of rotor  122  and is spaced therefrom to allow unobstructed rotation of rotor  122  inside support frame  118   a - 118   c . Support frame  118   a - 118   c  does not completely enclose rotor  122  and no parts exist between support frame  118   a - 118   c  and the exterior of rotor  122 . Thus, support frame  118   a - 118   c  allows airflow through itself and over rotor  122 . Support frame  118   a - 118   c  connects to axle  123  to fix stator  120  in an axial position relative to rotor  122 . Support frame  118   a - 118   c  can be removably fastened to axle  123 . Support frame  118   a - 118   c  fixes axle  123  to prevent relative movement between stator  120  and support frame  118   a - 118   c . Neither axle  123  nor stator  120  are fixed to support frame  118   a - 118   c  at output end  124 . Instead, a portion of rotor  122  is disposed axially between and separates axle  123  and stator  120  from support frame  118   a - 118   c  at output end  124 . 
     As described with respect to support frame  18  of drive system  10 , support frame  118   a - 118   c  is dynamically connected to rotor  122  by a bearing interface and statically connected to stator  120 . Support frame  118   a - 118   c  is statically connected to pump  19 . Electric motor  112  is dynamically connected to support frame  118   a - 118   c  via rotor  122  and statically connected to support frame  118   a - 118   c  via stator  120 . Electric motor  112  is dynamically connected to pump  19  via fluid displacement member  16 . Pump  19  is statically connected to support frame  118   a - 118   c  and dynamically connected to electric motor  112 . 
     Each of support frames  118   a - 118   c  include pump frame  158 . Support frame  118   a  includes support member  160   a . Support frame  118   b  includes support member  160   b . Support frame  118   c  includes support member  160   c . Each of support members  160   a - 160   c  include a plurality of connecting members  168 . Support member  160   a  includes frame member  172   a . Support member  160   b  includes frame member  172   b . Support member  160   c  includes frame member  172   c.    
     As disclosed with respect to drive system  10 , pump frame  158  can be disposed in a first plane normal to motor axis A at output end  124 . Frame member  172   a - 172   c  can be disposed in a second plane normal to motor axis A at input end  126 . The first and second planes are spaced along axis A and do not intersect. Pump frame  158  is separated from frame member  172   a - 172   c  by stator  120  such that pump frame  158  is disposed on one end of stator  120  and frame member  172   a - 172   c  is disposed on an axially opposite end of stator  120 . A portion of rotor  122  is disposed between pump frame  158  and frame member  172   a - 172   c . A portion of rotor  122  extends in axial direction AD 1  through pump frame  158 . A plurality of connecting members  168  can extend across and be spaced radially from an exterior surface of rotor  122  to connect pump frame  158  to frame member  172   a - 172   c . Connecting members  168  are spaced radially from the exterior surface of rotor  122  to allow rotation of rotor  122  within support frame  118   a - 118   c . It is understood that support frame  118   a - 118   c  can include any desired number of connecting members  168  between first pump frame  158  and frame member  172   a - 172   c , such as two, three, four, or more connecting members  168  as needed to support motor  112  and pump  19  and is not limited to the embodiments illustrated in  FIGS. 10A-10C . 
     Pump frame  158  is substantially similar to pump frame  58  of drive system  10 , having pump housing portion  162 , outer frame body  163 , projections  164   a , support ribs  165 , and hub  167 . Bearing  152  is received in hub  167  of pump frame  158  and pump frame  158  extends radially outward from bearing  152 . A plurality of ribs  165  can extend between bearing  152  and outer frame body  163  to support load from bearing  152 , while reducing a weight of pump frame  158 . Ribs  165  can be spaced circumferentially around hub  167  and can vary in length depending on a shape of outer frame body  163 . Pump frame  158  is axially spaced from wall  130  of rotor  122  and radially separated from the portion of rotor  122  extending through pump frame  158  by bearing  152 . 
     Frame members  172   a - 172   c  are substantially similar to frame member  72  of drive system  10 . Each frame member  172   a - 172   c  includes hub  174 , projections  164   b , and ribs  175 . An opening through hub  174  can receive a portion of axle  123  such that frame member  172   a - 172   c  is in direct contact with axle  123 . Frame member  172   a - 172   c  is disposed at the cantilevered, free electrical input end  126  of motor  112 . Frame member  172   a - 172   c  is disposed in contact with an outer surface of axle  123 . By maintaining contact with axle  123 , frame member  172   a - 172   c  can draw heat away from stator  120  via thermal conduction. Both axle  123  and support frame  118   a - 118   c  can be formed from a thermally conductive material (e.g., aluminum) capable of conducting heat from inside stator  120  to electrical input end  126  and frame member  172   a - 172   c . Axle  123  axially overlaps stator  120  along a full axial length of stator  120 . Axle  123  is capable of drawing heat from stator  120  and conducting heat toward electrical input end  126  and axially outward of stator  120 . Axle  123  transfers heat to frame member  172   a - 172   c  via conduction at locations where frame member  172   a - 172   c  is in contact with axle  123 . As such, the conductive pathway for heat transfer from stator  120  extends through axle  123  to frame member  172   a - 172   c . Frame member  172   a - 172   c  can be in fixed contact with both an axially extending surface of axle  123  and a radially extending end face of axle  123 . Frame member  172   a - 172   c  can extend radially from axle  123  to transfer heat radially away from axle  123  and away from electric motor  112 . The heat conduction path can extend radially outward of stator  20  and, in some examples, of motor  12  due to frame members  172   a - 172   c  extending radially outward relative to axis A. A shape and surface area of frame member  172   a - 172   c  can be selected to facilitate heat transfer away from electric motor  112 . 
     Frame member  172   a - 172   c  can be fastened to axle  123  in any desired manner that prevents axial displacement and rotation of frame member  172   a - 172   c  relative to axle  123  and fixes an axial position of stator  120  relative to rotor  122 . In some embodiments, frame member  172   a - 172   c  can be slip fit onto the outer surface of axle  123  and fastened to the outer surface of axle  123  with one or more fasteners  177 , such that frame member  172   a - 172   c  is fixed relative to axle  123  and in contact with axle  123  along the outer surface of axle  123 . Frame member  172   a - 172   c  can be secured to axle  123  such that contact is maintained between frame member  172   a - 172   c  and axle  123  during operation to provide a conductive pathway for heat transfer from stator  120  to frame member  172   a - 172   c . A thickness of frame member  172   a - 172   c  in an axial direction along axis A at hub  174  can be increased to increase a contact surface area between frame member  172   a - 172   c  and axle  123  and thereby increase heat transfer capacity. Fasteners  177  can be bolts, rivets, screws, or other fastening mechanisms known in the art. Fasteners  177  can secure frame member  172   a - 172   c  to an axial end of axle  123  opposite end  146 . Fasteners  177  can be axially extending and can be disposed through an end face of frame member  172   a - 172   c  into axle  123  in axial direction AD 1 . Fasteners  177  can secure frame member  172   a - 172   c  to retaining members disposed on a radially inner surface of axle  123 . In some examples, fasteners  177  can be formed from thermally conductive materials to facilitate heat transfer from axle  123  to frame member  172   a - 172   c.    
     In some embodiments, frame member  172   a - 172   c  can have a lip member  176  that extends radially inward from hub  174 . Lip member  176  can abut and maintain contact with an end face of axle  123 . Lip member  176  can set and maintain an axial position of frame member  172   a - 172   c  with respect to bearing  148 . Fasteners  177  can extend through lip member  176 . Lip member  176  further increases the contact area between axle  123  and frame member  172   a - 172   c  to further facilitate heat transfer. 
     Pump frame  158  and frame member  172   a - 172   c  have projections  164   a  and  164   b , respectively. Projections  164   a ,  164   b  can extend radially outward from motor axis A such that a distal end of each projecting member  164   a ,  164   b  is disposed radially outward of rotor  122 . Projections  164   a ,  164   b  can be shaped to provide structural integrity to support frame  118   a - 118   c , while limiting an amount of weight added to drive system  110 . Projecting member  164   b , which can be referred to as an arm, on frame member  172   a - 172   c  can direct heat radially outward from axle  123 . Projections  164   b  provide increased surface area relative a plate to further facilitate heat transfer and cooling of motor  112 . Projections  164   a ,  164   b  are rigid. Projections  164   a ,  164   b  can be solid or can have openings allowing airflow therethrough and for further increasing surface area for heat transfer. As illustrated in  FIGS. 10A-10C , projections  164   a ,  164   b  can be ribbed or have ridges and troughs, which can increase surface area for heat transfer and can reduce weight while providing structural integrity. Hub  174  can be similarly shaped with ridges and troughs circumferentially spaced to increase surface area for heat transfer. A quantity, shape, and positional arrangement of projections  164   b  on frame member  172   a - 172   c  can be selected to provide effective heat transfer away from stator  120  via axle  123  and away from electric motor  112 . Some of the contemplated arrangements for projections  164   a  are illustrated in  FIGS. 10A-10C . 
     Projections  164   a ,  164   b  on each of pump frame  158  and frame member  172   a - 172   c  can be arranged symmetrically or asymmetrically and with equal or unequal spacing relative each other and about axis A. As illustrated in  FIG. 10A , pump frame  158  and frame member  172   a  can have three axially aligned projections  164   a ,  164   b , arranged in a Y-configuration. Other configurations of projections  164   a ,  164   b  can also provide sufficient structural support and heat transfer capability. As illustrated in  FIG. 10B , pump frame  158  and frame member  172   b  can have three axially aligned projections  164   b ,  164   a  asymmetrically arranged around motor axis A in a T-shape configuration and, in the example shown, predominantly positioned on a lower portion of electric motor  112 . As illustrated in  FIG. 10C , pump frame  158  and frame member  172   c  can have four axially aligned projections  164   b ,  164   a  arranged in an X-configuration, which provides increased surface area to provide for efficient heat transfer away from motor  112 . In alternative embodiments, projections  164   b  on pump frame  158  can be offset from projections  164   a  on frame member  172   a - 172   c  such that connecting members  168  are angled with respect to axis A between pump frame  158  and frame member  172   a - 172   c.    
     In some embodiments, additional projections  164   a  can be provided on pump frame  158  as illustrated in  FIGS. 10A-10C  to accommodate alternative frame members  172   a - 172   c  and connecting members, and to facilitate connection of other components thereto, such as a handle or control panel. 
     Connecting members  168  secure pump frame  158  to frame member  172   a - 172   c . Connecting members  168  are rigid and capable of maintaining a fixed relationship between pump frame  158  to frame member  172   a - 172   c  during operation of drive system  110 . Additionally, connecting members  168  are configured to support torque loads generated by electric motor  112  and transmitted through pump frame  158  to frame member  172   a - 172   c  and to further support pump reaction loads generated by reciprocation of fluid displacement member  16  and transferred through motor  12  and also transmitted through pump frame  158 . 
     Connecting members  168  can be tie rods, which can be received at distal ends of projections  164   a ,  164   b . Connecting members  168  can be fastened to distal ends with a threaded fastener, such as a screw or a bolt. Alternative fastening mechanisms as known in the art can be used to secure connecting members  168  to each of pump frame  158  to frame member  172   a - 172   c . In some embodiments, at least one connecting member  168  can be configured as a handle for ease of carrying drive system  110 . 
     In some embodiments, a single connecting member can connect multiple projections  164   a  on pump frame  158  with multiple projections  164   b  of frame member  172   a - 172   c , as provided in drive system  10  by base plate  70 . In some embodiments, projections  164   a ,  164   b  can support control panel  13  (not shown). As provided in drive system  10 , control panel  13  can be mounted to a frame member  172   a - 172   c . In other embodiments, control panel  13  can be mounted between projections  164   a ,  164   b , such as at a location where control panel  13  axially overlaps with motor  12 . 
     During operation of pump  19 , the pump reaction forces generated by fluid displacement member  16  during pumping are transmitted to pump frame  158  via drive mechanism  114 , rotor  122 , bearing  152 , bearing  148 , axle  123 , and support member  160 . Fluid displacement member  16  receives a downward reaction force when moving through the upstroke and an upward reaction force when moving through the downstroke. Both the upward reaction force and the downward reaction force travel through drive mechanism  114 , rotor  122 , and then to bearings  152 ,  148 ,  142 . Bearings  152 ,  148 ,  142  transfer rotational forces associated with rotation of rotor  122  and both of the upward and downward reaction forces to pump frame  158 . With each stroke, pump reaction forces are generated and a load is applied to rotor  122  due to rotor  122  directly driving fluid displacement member  16  via drive mechanism  114 . The pump reaction forces are axial loads generally along pump axis PA. The pump reaction forces transmitted through drive mechanism  114  to rotor  122  are generally downward during an upstroke and generally upward during a downstroke. 
     This axial pump reaction load is transverse to rotational axis A of electric motor  112  and is experienced at both output and input ends  124  and  126  of electric motor  112 . The load is transmitted to pump frame  158  via bearings  152  and  148  and support member  160  such that pump reaction forces on bearing  142  are minimized, maintaining proper air gap. At output end  124 , the load is transmitted from rotor  122  to pump frame  158  through bearing  152 . At electrical input end  126 , the load is transmitted from rotor  122  to pump frame  158  through bearing  148  and support member  160 . Bearings  152  and  148  experience opposite reactionary forces with each pump stroke to provide a force balance at pump frame  158 . 
     Pump reaction forces are thereby transmitted to rotor  122  from fluid displacement member  16 . Bearings  152  and  148  balance the load across rotor  122  and transmit the load to pump frame  158 . Bearing  152  is directly connected to pump frame  158 . Bearing  148  is connected to pump frame  158  via support member  160 , which transmits loads to pump frame  158  from bearing  148 . Support member  160  thereby transmits pump loads from rotor  122  to pump frame  158 . Pump frame  158  can be mounted to a stand or other support surface and can transmit reaction forces to the stand or other support surface. 
       FIG. 11  is an isometric cross-sectional view of drive system  210  with fluid displacement pump  19  of  FIG. 2 .  FIG. 12  is an isometric front and side view of drive system  210 . Drive system  210  is an alternative embodiment of an outer rotator drive system. The operation of drive system  210  is substantially similar to drive systems  10  and  110 . Drive system  210  utilizes a different eccentric driver, bearing structure, and pump frame configuration, as described herein. The eccentric driver of drive system  210  is integrally formed with the outer rotor and configured to provide a 1:1 ratio of rotor rotation to pump cycle. Drive system  210  is configured for operation with pump  19  and fluid displacement member  16  of  FIGS. 2-4 . Drive system  110  can accommodate fluid displacement member  16  and fluid displacement pump  19  of drive system  10 . 
     Electric motor  212 , drive mechanism  214 , fluid displacement member  16 , support frame  218 , and displacement pump  19  are shown. 
     Electric motor  212  includes stator  220 , rotor  222 , and axle  223 . Electric motor  212  is disposed on axis A and extends from a first end (output end)  224  to an opposite second end (electrical input end)  226 . Electric motor  212  can be a reversible motor in that stator  220  can cause rotation of rotor  222  in either of two rotational directions about motor axis A (e.g., clockwise or counterclockwise). Rotor  222  can be formed of a housing having cylindrical body  229  disposed between first wall  230  and second wall  232 . Rotor  222  includes permanent magnet array  234  disposed on inner circumferential face  235 . Bearing  242 , having inner race  243 , outer race  244 , and rolling elements  245 , couples rotor  222  to stator  220  at axle end  246 . Bearing  248 , having outer race  249 , inner race  250 , and rolling elements  251 , couples rotor  222  to stator  220  at electrical input end  226 . 
     Support frame  218  includes pump frame  258  and support member  260 . Support member  260  extends from pump frame  258  at output end  224  to axle  223  at electrical input end  226 . Support member  260  can include connecting member  268  and frame member  272 . Pump frame  258  is coupled to rotor  222  at output end  224  via bearing  252 , having outer race  253 , inner race  254 , and rolling elements  255 . Pump frame  258  and frame member  272  are disposed in planes tangential to motor axis A and at opposite ends of motor  212 . Connecting member  268  connects pump frame  258  and frame member  272  across motor  212 . 
     Bearings  242 ,  248 , and  252  are disposed about rotational axis A, such that rotating members of bearings  242 ,  248 , and  252  rotate on rotational axis A. Bearings  242 ,  248 , and  252  can be substantially similar in size or can vary in size to support differing loads and to accommodate space constraints. As illustrated in  FIG. 11 , bearings  242  and  248  can be substantially similar in size, while bearing  252  at output end  224  can be smaller. Bearings  242 ,  248 , and  252  can vary in size and the rolling elements of bearing  242 ,  248 , and  252  can vary in radial position from axis A. Rolling elements  255  of bearing  252  can be disposed at a first radius R 4  from rotational axis A of electric motor  112 , rolling elements  245  of bearing  242  can be disposed at a second radius R 5  from rotational axis A, and rolling elements  251  of bearing  248  can be disposed at a third radius R 6  from rotational axis A. As illustrated in  FIG. 11 , first radius R 4  can be smaller than both second and third radii R 5  and R 6 . 
     Drive mechanism  214  includes cylindrical projection  278 , drive member  280 , drive link  282 , follower  286 , bearing surface  289 , slot  290 , and pin  292 . Fluid displacement member  16  includes connector  93 . Pump  19  includes cylinder  94  and check valves  95 ,  96 . 
     As discussed in further detail below, support frame  218  is dynamically connected to rotor  222  by a bearing interface and statically connected to stator  220 . Support frame  218  is statically connected to pump  19 . Electric motor  212  is dynamically connected to support frame  218  via rotor  222  and statically connected to support frame  218  via stator  220 . Electric motor  212  is dynamically connected to pump  19  via fluid displacement member  16 . Pump  19  is statically connected to support frame  218  and dynamically connected to electric motor  212 . 
     Electric motor  212  includes inner stator  220  and outer rotor  222 . Motor  212  can be configured to be powered by any desired power type, such as direct current (DC), alternating current (AC), and/or a combination of direct current and alternating current. Stator  220  includes armature windings (not shown) and rotor  222  includes permanent magnets. Rotor  222  is configured to rotate about motor rotational axis A in response to direct current or alternating current signals through stator  220 . Rotor  222  is connected to fluid displacement member  116  at output end  224  via drive mechanism  214 . Drive mechanism  214  receives a rotary output directly from rotor  222  and provides a linear, reciprocating input to fluid displacement member  16  (best seen in  FIG. 11 ). Pump frame  258  mechanically supports electric motor  212  at the output end  224  and mechanically supports fluid displacement pump  19 . Pump frame  258  at least partially houses fluid displacement member  16  of fluid displacement pump  19 . 
     Stator  220  defines axis A of electric motor  212 . Stator  220  is disposed around and supported by axle  223 . Stator  220  is fixed to axle  223 . Electric current can be supplied to the armature windings through electrical input end  226  of electric motor  212 . Axle  223  can be a hollow shaft open to input end  226  for receiving the electrical wiring. In alternative embodiments, axle  223  can be solid, can have a key, can be D-shaped, or other similar design. In some embodiments, axle  223  can be defined by a plurality of cylindrical cross-sections taken perpendicular to axis A that are of varying diameters to accommodate mechanical coupling with support frame  218  at electrical input end  226  and coupling with rotor  222  at axially opposite ends of axle  223 . 
     Rotor  222  is disposed coaxially around stator  220  and is configured to rotate about axis A. Rotor  222  can be formed from a housing having cylindrical body  229 , extending between first wall  230  and second wall  232 , and positioned such that rotor  222  extends around three sides of stator  220  (e.g., a first axial end, second axial end, and the radial side). Rotor  222  includes a permanent magnet array  234 . Permanent magnet array  234  can be disposed on an inner circumferential face  235  of cylindrical body  229 . An air gap separates permanent magnet array  234  from stator  220  to allow for rotation of rotor  222  with respect to stator  220 . Rotor  222  can overlap stator  220  and axle  223  over a full radial extent of stator  220  and axle  223  at output end  224  of electric motor  212 . Rotor  222  can fully enclose stator  220  and axle  223  at output end  224  of electric motor  212 . Rotor  222  can, in some examples, overlap stator  220  over a full radial extent of stator  220  at electrical input end  226  of electric motor  212 . Second wall  232  can extend from cylindrical body  229  radially inward toward axle  223 . Axle  223  can extend through an opening in second wall  232  concentric with axle  223  and can extend axial outward of second wall  232  in axial direction AD 2 . First and/or second walls  230 ,  232  can be formed integrally with cylindrical body  229  or can be mechanically fastened to cylindrical body  229 . 
     First wall  230  of rotor  222  can be rotationally coupled to an outer diameter of axle  223  via bearing  242  at axle end  246 . Bearing  242  includes inner race  243 , outer race  244 , and rolling elements  245 . In some examples, bearing  242  can be a roller or ball bearing in which rolling elements  245  are formed by cylindrical members or balls. Rotor  222  can be coupled to outer race  244 . Axle  223  can be coupled to inner race  243 . Rolling elements  245  allow rotation of rotor  222  with respect to stator  220 . Bearing  242  support loads and maintain the air gap between permanent magnet array  234  and stator  220 . 
     Second wall  232  of rotor  222  can be rotationally coupled to axle  223  at input end  226  via bearing  248 . Bearing  248  includes outer race  249 , inner race  250 , and rolling elements  251 . Rotor  222  can be coupled to outer race  249  and axle  223  can be coupled to inner race  250 . Rolling elements  251  allow rotation of rotor  222  with respect to stator  220 . In some examples, bearing  248  can be a roller or ball bearing in which rolling elements  251  are cylindrical members or balls. Axle  223  can extend through rotor  222  at electrical input end  226  and can project axially outward of bearing  248  in axial direction AD 2  to allow for coupling of axle  223  with support frame  218 . Bearing  248  can be provided to maintain the air gap between permanent magnet array  234  and stator  220 . 
     In contrast to drive systems  10  and  110 , rotor  222  rides outside of both bearings  242  and  248 . As illustrated in  FIG. 11 , no portion of rotor  222  at end  246  of axle extends into axle  223 . 
     Rotor  222  can include a cylindrical housing  277  that extends in an axial direction AD 1  from wall  230 . Cylindrical housing  277  can be coupled to outer race  244  of bearing  242 , allowing rotor  222  to ride outside of bearing  242 . Cylindrical housing  277  can extend around and end face of outer race  244  to axial retain bearing  242 . Second wall  232  can have radially extending annular flange  238  at an inner diameter opening. Annular flange  238  can be rotationally coupled to axle  223 , such as by bearing  248 . Annular flange  238  can at least partially define a receiving shoulder for receiving the outer race  249  of bearing  248  and preloading bearing  248 . 
     Rotor  222  can include a first cylindrical projection  278  that extends in axial direction AD 1  outward from axle  223  at output end  224 . Cylindrical projection  278  has a center offset from rotational axis A and forms an eccentric driver of drive mechanism  214 . 
     Rotor  222  can further include a second cylindrical projection  279  that extends in axial direction AD 1  outward from cylindrical projection  278 . Cylindrical projection  279  can be rotationally coupled to pump frame  258  via bearing  252 . Cylindrical projection  279  has a center aligned with rotational axis A such that cylindrical projection  279  rotates on rotational axis A. Cylindrical projection  279  can be received in pump frame  258  and separated from pump frame  258  by bearing  252 . Bearing  252  can be of any desired configuration suitable for facilitating relative motion between pump frame  258  and cylindrical projection  279 . For example, bearing  252  can be a roller or ball bearing allowing rotational motion of rotor  222  relative to pump frame  258 . As illustrated in  FIGS. 11 and 12 , cylindrical projection  278 , forming the eccentric driver, is disposed between first wall  230  of rotor  122  and an inner side of pump frame  258 . 
     Pump frame  258  mechanically supports electric motor  212  at output end  224  and at least partially houses fluid displacement member  16 . Pump frame  258  can be mechanically coupled to both rotor  222  and stator  220 . Pump frame  258  can be mechanically coupled to rotor  222  at output end  224  and mechanically coupled to axle  223  at electrical input end. Axle  223  is mechanically coupled to pump frame  258  to fix stator  220  relative to pump frame  258 . Axle  223  is fixed to pump frame  258  such that stator  220 , which is fixed to axle  223 , does not rotate relative to pump frame  258  or motor rotational axis A. 
     Electric motor  212  can be cantilevered from pump frame  258  such that input end  226  disposed opposite output end  224  is a free end of the cantilevered electric motor  212 . Support member  260  can extend around an exterior of rotor  222  from pump frame  258  to axle  223  to connect pump frame  258  to axle  223  such that stator  220 , via axle  223 , is fixed relative to pump frame  258 . Support member  260  can be removably fastened to axle  223 . Support member  260  fixes axle  223  to pump frame  258  to prevent relative movement between stator  220  and pump frame  258 . Neither axle  223  nor stator  220  are fixed to pump frame  258  at output end  224 . Instead, a portion of rotor  222  is disposed axially between and separates axle  223  and stator  220  from pump frame  258 . 
     Support member  260  can extend from a location radially inward of an exterior of cylindrical body  229  of rotor  222  to a location radially outward of cylindrical body  229 . Support member  260  can extend around rotor  222  with sufficient spacing therefrom to allow unobstructed rotation of rotor  222  inside of support member  260 . Support member  260  includes one or more connecting members  268  extending across cylindrical body  229  and at least one frame member  272  disposed on input end  226  and coupled to axle  223 . Connecting member  268  can extend outward of first wall  230  in axial direction AD 1  and can extend axially outward of second wall  232  in axial direction AD 2 . Connecting members  268  of support member  260  can extend parallel to axis A. 
     Frame member  272  of support member  260  can extend substantially parallel to second wall  232  and can be axially spaced therefrom. Frame member  272  extends from axle  223  to a location radially outward of cylindrical body  229  where frame member  272  joins with connecting member  268 . Frame member  272  interfaces with and can be fixed to axle  223 . Support member  260  connects to pump frame  258  at output end  224 . Support member  260  fixes an axial location of stator  220  with respect to rotor  222  and holds electric motor  212  together. Support member  260  can be a unitary body or can include multiple components fastened together and capable of maintaining stator  220  via axle  223  in a fixed axial location relative to rotor  222  and pump frame  258 . 
     Pump frame  258  is mechanically coupled to rotor  222  via bearing  252  at output end  224 . Bearing  252  includes outer race  253 , inner race  254 , and rolling elements  255 . Bearing  252  can be a roller or ball bearing in which rolling elements  255  are cylindrical members or balls. Rotor  222  can be received in pump frame  258 , such that a portion of rotor  222  extends into pump frame  258  and is radially surrounded by a portion of pump frame  258 . As such, rotor  222  is coupled to inner race  254  and pump frame is coupled to outer race  253 . Rolling elements  255  allow rotational motion of rotor  222  relative to pump frame  258 . Pump frame  258  mechanically supports electric motor  212  via bearing  258  and support member  260 . 
     Additionally, pump frame  258  is configured to house a portion of pump  19  and secure pump  19  in fixed position relative to electric motor  212 . Pump frame  258  can be configured to mount to a cart or stationary assembly for ease of operation and transport. 
     Drive mechanism  214  includes cylindrical projection  278 , which forms the eccentric driver, drive member  280 , and drive link  282 . Cylindrical projection  278  is provided on rotor  222  of electric motor  212  and rotates with rotor  222 . In the example shown, cylindrical projection  278  is integrally formed with first wall  230  of rotor  222 . Because cylindrical projection  278  is offset from rotational axis A, rotation of rotor  222  causes cylindrical projection  278  to rotate about rotational axis A. Drive member  280  is mechanically coupled to cylindrical projection  278  and is configured to drive reciprocation of fluid displacement member  16 . Cylindrical projection  278  is directly coupled to drive member  280  without intermediate gearing to provide a 1:1 ratio of rotor rotation to pump cycle. 
     In some embodiments, cylindrical projection  278  can have a substantially hollow body with cavities defined by a plurality of ribs  284 . Ribs  284  can extend radially outward from cylindrical projection  278  to an outer cylindrical wall of cylindrical projection  278 . Ribs  284  support drive member  280  and can reduce a weight of cylindrical projection  278 . Ribs  284  can be spaced circumferentially around cylindrical projection  278 . Ribs  284  can extend around a portion of cylindrical projection  278  that is less than a full circumference of cylindrical projection  278 . Ribs  284  can vary in a radial length between cylindrical projection  278  and the outer wall of cylindrical projection  278  depending on the location of ribs  284 . Cylindrical projection  279  can also have a substantially hollow body with cavities defined by a plurality of ribs as illustrated in  FIGS. 11 and 12 . 
     Drive member  280  can be a connecting rod with follower  286  at one end configured to receive cylindrical projection  278 . Follower  286  can include a bearing member  289  to allow drive member  280  to move in a rocking motion about cylindrical projection  278  as cylindrical projection  278  rotates with rotor  222 . Drive member  280  can be coupled to fluid displacement member  16  via drive link  282  in a manner consistent with that disclosed for drive system  10 . Drive member  280  translates the rotational motion of cylindrical projection  278  into reciprocating motion and drives fluid displacement member  16  via drive link  282  in a reciprocating manner. The operation of drive mechanism  214  and pump  19  is consistent with that disclosed for drive system  10 . With each revolution of rotor  222 , drive link  282  is forced both upward and downward. In this manner, drive mechanism  214  translates each revolution of rotor  222  into a linear up and down motion. Drive link  282  is coupled to fluid displacement member  16  and accordingly pulls fluid displacement member  16  through an upstroke and pushes fluid displacement member  16  through a downstroke. As such, for each revolution of rotor  222 , the pump proceeds through a full pump cycle, including an upstroke and a downstroke. The increased torque facilitates rotor  222  generating sufficiently high pumping pressures with displacement pump  19  to generate an atomized spray at spray apparatus  5  ( FIG. 4 ). In some examples, rotor  22  can cause pump  19  to generate pumping pressures of about 3.4-69 megapascal (MPa) (about 500-10,000 pounds per square inch (psi)) or even higher. In some examples, the pumping pressures are in the range of about 20.7-34.5 MPa (about 3,000-5,000 psi). High fluid pumping pressure is useful for atomizing the fluid into a spray for applying the fluid to a surface. 
     During operation of pump  19 , the pump reaction forces generated by fluid displacement member  16  during pumping are transmitted to pump frame  258  via drive mechanism  214 , rotor  222 , bearing  252 , bearing  248 , axle  223 , and support member  260 . Both the upward reaction force and the downward reaction force travel through drive mechanism  214 , rotor  222 , and then to bearings  252 ,  242 , and  248 . Bearings  252 ,  242 , and  248  transfer rotational forces associated with rotation of rotor  222  and both of the upward and downward reaction forces to pump frame  258 . 
     This axial pump reaction load is transverse to rotational axis A of electric motor  212  and is experienced at both output and electrical input ends  224 ,  226  of electric motor  212 . The load is transmitted to pump frame  258  via bearings  252 ,  248  and support member  260  such that pump reaction forces on bearing  242  are minimized, maintaining proper air gap. At output end  224 , the load is transmitted from rotor  222  to pump frame  258  through bearings  252  and  242 . At electrical input end  246 , the load is transmitted from rotor to pump frame  258  through bearing  248  and support member  260 . Bearing  252  experiences opposite reactionary forces of bearing  248  with each pump stroke to provide a force balance at pump frame  258 . It is understood that the loads can be reacted to support member  260 , such as to member  268 , in examples where member  268  is mounted to an object or surface to support drive system  210 . 
     Pump reaction forces are thereby transmitted to rotor  222  from fluid displacement member  16  during pumping. Bearings  242  and  248  balance the load across rotor  222  and transmit the load to static frame members. 
     The bearing arrangement of system  210  provides significant advantages. Bearings  242 ,  248 , and  252  react pump reaction loads generated during pumping. Bearings  242 ,  248 , and  252  stabilize rotor  222  to facilitate a direct drive connection to fluid displacement member  16 . The pump reaction forces experienced at output end  224  and electrical input end  226  are transmitted to pump frame  258  and connecting member  260 , balancing the forces across pump frame  258 . The connection balances motor  212 , providing longer life, less wear, less downtime, more efficient operation, and cost savings. Bearing  242  further aligns rotor  222  on pump axis A. Bearing  242  minimizes the unsupported span of rotor  222 , aligning rotor  222  and preventing undesired contact between rotor  222  and stator  220 . Bearing  242  thereby increases the operational life of motor  212 . 
     The direct drive configuration of drive system  210  eliminates intermediate gearing (e.g., reduction gears) between electric motor  212  and fluid displacement member  16 . The elimination of intermediate gearing provides a more efficient, compact, lower weight, reliable, and simpler pump by reducing the part count and number of moving parts. Additionally, the elimination of gearing provides for quieter pump operation. 
       FIGS. 13 and 14  are isometric cross-sectional views of drive systems  310  and  410 , respectively, assembled with pump  19  of  FIG. 2 .  FIGS. 13 and 14  are discussed together. Drive systems  310  and  410  are substantially similar to drive system  10  with modifications configured to accommodate direct drive coupling with a coaxially disposed fluid displacement pump  19  and motor  12 . Drive systems  310  and  410  each include electric motor  12  of drive system  10 , including inner stator  20 , outer rotor  22 , and axle  23 . Electric motor  12  and pump  19  are coaxially disposed about motor/pump axis A. In the embodiments illustrated in  FIGS. 13 and 14 , electric motor  312  can be a reversible motor in that stator  20  can cause rotation of rotor  22  in either of two rotational directions about motor/pump axis A (e.g., clockwise or counterclockwise). Drive systems  310  and  410  each include rotor shaft  380  and modified drive mechanism  314  and fluid displacement member  316 . Drive systems  310  and  410  additionally have modified support frames  318 ,  418 , which include pump frames  358  and  458  and support members  360  and  460 , respectively, which differ from one another. Only modifications are discussed herein. All other aspects of electric motor  12  are provided in the description of drive system  10 . 
     Pump frame  358 ,  458  is dynamically connected to rotor  22  by a bearing interface and statically connected to stator  20 . Pump frame  358 ,  458  is statically connected to pump  19 . Electric motor  12  is dynamically connected to pump frame  358 ,  458  via rotor  22  and statically connected to pump frame  358 ,  458  via stator  20 . Electric motor  12  is dynamically connected to pump  19  via fluid displacement member  216 . Pump  19  is statically connected to pump frame  358 ,  458  and dynamically connected to electric motor  12 . 
     Pump frames  358 ,  458  mechanically support electric motor  12  at the output end  324  and mechanically supports fluid displacement pump  19 . Pump frames  358 ,  458  at least partially house fluid displacement member  316  of pump  19 . Pump frames  358 ,  458  are mechanically coupled to both rotor  22  and stator  20 . Pump frames  358 ,  458  are mechanically coupled to rotor  22  at output end  224  via bearing  42  as described with respect to drive system  10  and illustrated in  FIG. 2 . Pump frames  358 ,  458  are mechanically fixed to stator  20  at input end  326  via support members  360 ,  460 , respectively, and axle  23 . Axle  23  is mechanically coupled to pump frames  358 ,  458  such that stator  20 , which is fixed to axle  23 , does not rotate relative to pump frames  358 ,  458  or motor rotational axis A. Pump frames  358 ,  458  are disposed coaxially with electric motor  12  and pump  19 , extending outward from electric motor  12  in axial direction AD 1 . As illustrated in  FIGS. 13 and 14 , pump frames  358 ,  458  can be formed from multiple components assembled together to house and support rotor shaft  380  and drive mechanism  214 . Pump frames  358 ,  458  can be dynamically coupled to rotor shaft  380  by bearing  381  to support and allow rotation of rotor shaft  380  within pump frame  358 ,  458 . 
     As illustrated in  FIG. 13 , support member  360  can include cylindrical body  362 , which can form a housing around rotor  22 . Cylindrical body  262  can extend axially outward from pump frame  358  at output end  24  to input end  26 . Cylindrical body  362  can include radially extending flange  363  at output end  24 , which can be fastened to pump frame  358  with bolts or other fastening mechanisms. Cylindrical body  362  can radially overlap second wall  32  of rotor  22  at input end to substantially enclose rotor  22  at input end  26 . Support member  360  can include frame member  372 , which can fix support member  360  to axle  23 . Frame member  372  can be substantially the same as frame member  72  of drive system  10  and can be secured to axle  23  in the same manner. Frame member  372  can be fastened to cylindrical body  362  by bolts  365  or similar fastening mechanisms. Bolts  365  can extend through one or more radially outer ends of projections of radially extending portion  364  (e.g., projections  64   a  as illustrated in  FIGS. 6 and 10A-10C ). 
     As illustrated in  FIG. 14 , support member  460  can be substantially the same as support member  160  of drive system  110 . Support member  460  can include one or more connecting members  468  and a frame member  472 . Connecting members can be substantially the similar to connecting members  68  and  168  and frame member  472  can be substantially similar to frame members  72 ,  172   a ,  172   b , and  172   c  described with respect to drive system  110 . Connecting members  68  can be mechanically fixed to pump frame  458  by bolts or other fastening mechanisms. 
     Drive mechanism  314  includes drive nut  382 , screw  384 , and rolling elements  386 . Drive mechanism  314  is connected to rotor shaft  380 . Drive mechanism  314  receives a rotational output from rotor  22  via rotor shaft  380 . More specifically, drive nut  382  of drive mechanism  314  is connected to rotor shaft  380  to rotate about motor/pump axis A with rotor shaft  380 . Drive nut  382  can be attached to rotor shaft  380  via fasteners (e.g., screws or bolts), adhesive, or press-fit, amongst other options. Screw  384  is disposed radially within drive nut  382 . Rolling elements  386  are disposed between screw  384  and drive nut  382  and support screw  384  relative drive nut  382 . Rolling elements  386  support screw  384  and drive nut  382  such that a gap is disposed radially between screw  384  and drive nut  382 . Rolling elements  386  maintain the gap and prevent screw  384  and drive nut  382  from directly contacting one another. 
     Screw  384  is configured to reciprocate along motor/pump axis A during operation. As such, screw  384  provides the linear output from drive mechanism  314 . Screw  384  can be coupled to fluid displacement member  316  via connector  388  to provide linear reciprocation of fluid displacement member  316  with reciprocation of screw  384 . Stator  20  causes rotor  22  to rotate in a first rotational direction (e.g., clockwise or counterclockwise) about motor/pump axis A to cause drive nut  382  to rotate in the first rotational direction, causing rolling elements  386  to exert an axial driving force on screw  384  in axial direction AD 1  and drive screw  384  and thereby fluid displacement member  316  linearly along motor/pump axis A in axial direction AD 1  in a downstroke. Stator  20  causes rotor  22  to rotate in a second rotational direction (e.g., the other of clockwise or counterclockwise) about motor/pump axis A to cause drive nut  382  to rotate in the second rotational direction about motor/pump axis A causing rolling elements  386  to exert an axial driving force on screw  384  in axial direction AD 2  and drive screw  384  and thereby fluid displacement member  316  linearly along motor/pump axis A in axial direction AD 2  in an upstroke. 
     Outer rotator drive systems  310  and  410  provide significant advantages. Rotor  22  being an outer rotator disposed at least partially radially outside of stator  20  provides increased inertia and torque relative an inner rotator motor. The increased toque facilitates rotor  22  generating sufficiently high pumping pressures with displacement pump  19  to generate an atomized spray at an applicator such as a spray gun. For example, system  10  can be utilized to pump paint or other fluids to an airless spray gun, whereby the fluid pressure generates the atomized spray. In some examples, rotor  22  can cause pump  19  to generate pumping pressures of about 3.4-69 megapascal (MPa) (about 500-10,000 pounds per square inch (psi)) or even higher. In some examples, the pumping pressures are in the range of about 20.7-34.5 MPa (about 3,000-5,000 psi). High fluid pumping pressure is useful for atomizing the fluid into a spray for applying the fluid to a surface. 
       FIGS. 15 and 16  illustrate drive system  510 .  FIG. 15  is an isometric front view of drive system  510 .  FIG. 16  is an isometric cross-sectional view of drive system  510  taken along the line  16 - 16  of  FIG. 15 .  FIGS. 15 and 16  are discussed together. Drive system  510  is configured for use with drive mechanism  14 , fluid displacement member  16 , and fluid displacement pump  19  of drive system  10 . Electric motor  512 , drive mechanism  14 , fluid displacement member  16 , pump frame  518 , and pump  19  are shown. 
     Electric motor  512  includes stator  520  and rotor  522 . Electric motor  512  is disposed on axis A and extends from first end  524  to second end  526 . Rotor  522  is supported by bearings  542  and  548 . Bearing  242  has inner race  243 , outer race  244 , and rolling elements  245 . Bearing  248  has outer race  249 , inner race  250 , and rolling elements  251 . Rotor  522  includes bore  523  and permanent magnet array  534 . 
     Motor  512  is an electric motor having outer stator  520  and inner rotor  522 . Stator  520  includes armature windings (not shown) in stator housing  521 . Rotor  522  includes a permanent magnet array  534 . Rotor  522  is configured to rotate about pump axis A in response to current signals through stator  520 . Rotor  522  is connected to the fluid displacement member  16  at first end  524  via drive mechanism  14 . Drive mechanism  14  receives a rotary output from rotor  522  and provides a linear, reciprocating input to fluid displacement member  16 . Pump frame  518  is configured to mechanically support electric motor  512  and a fluid displacement pump  19  (shown in  FIG. 4 ). Electric motor  512  can be cantilevered from pump frame  518  such that second end  526  disposed opposite first end  524  is a free end of the cantilevered electric motor  512 . 
     Rotor  522  defines rotational axis A. Stator  520  is disposed coaxially around rotor  522  and includes stator housing  521 . Rotor  522  includes permanent magnet array  534  on an outer diameter surface. An air gap separates permanent magnet array  534  from stator  520  to allow for rotation of rotor  522  with respect to stator  520 . Rotor  522  can be rotationally coupled to stator  520  at first end  524  second end  526  by bearings  542  and  548 , respectively. Bearings  542  and  548  allow rotation of rotor  522  relative to stator  520 . 
     Bearings  542  and  548  can be roller or ball bearings. Bearing  542  can be disposed at first end  524  and can include inner race  543 , outer race  544 , and rolling elements  545 . Rotor  522  can be coupled to inner race  543  such that rotor  522  rides inside of bearing  542 . Stator  520  can be coupled to outer race  544 . Bearing  548  can be disposed at second end  546  and can include outer race  549 , inner race  550 , and rolling elements  551 . Rotor  522  can be coupled to inner race  550  such that rotor  522  rides inside of bearing  548 . Stator  520  can be coupled to outer race  549 . 
     Bearings  542  and  548  are disposed about rotational axis A. Bearings  542  and  548  can vary in size and rolling elements  545  and  551  of bearings  542  and  548 , respectively, can vary radial position from axis A. Rolling elements  545  of bearing  542  can be disposed at a radius R 7  from rotational axis A of electric motor  12 . Rolling elements  551  of bearing  548  can be disposed at a radius R 8  from rotational axis A. Radius R 7  of bearing  542  can be greater that radius R 8  of bearing  548  to accommodate drive mechanism  14 . 
     Bearing  542  can be larger in size than bearing  548  to support a pump load generated by reciprocation of fluid displacement member  16  during pumping and experienced by electric motor  512  as a result of the direct drive configuration. 
     Pump frame  518  mechanically supports electric motor  512  at first end  524  and at least partially houses fluid displacement member  16 . Pump frame  518  can be mechanically coupled stator  520  at first end  524  via a plurality of mounting elements  537 . 
     Eccentric driver  78  is axially offset from rotational axis A, such that rotation of rotor  522  causes eccentric driver  78  to move radially from rotational axis A along a circular path. Bolt  84  can be threadedly fastened to an inner end of bore  523  to secure sleeve  83  to rotor  522 . Bolt  84  can extend axially into rotor  522  such that bolt  84  is disposed in an axial plane with permanent magnet array  534  of rotor  522  and armature windings of stator  520 . Bolt  84  can be formed from a non-ferrous material to prevent interference with operation of electric motor  512 . 
     As described with respect to drive system  10  and as illustrated in  FIG. 4 , drive member  80  can be configured to receive eccentric driver  78  in a manner that allows rotation of drive member  80  relative to eccentric driver  78  as eccentric driver  78  moves with rotor  522 . Drive member  80  can be coupled to fluid displacement member  16  via drive link  82  and pin  92 . Drive member  80  translates the rotational motion of eccentric driver  78  into reciprocating motion and drives fluid displacement member  16  via drive link  82  in a reciprocating manner. 
     As described with respect to drive system  10 , with each revolution of rotor  522 , drive link  82  is forced both upward and downward. In this manner, drive mechanism  14  translates each revolution of rotor  522  into a linear up and down motion. Drive link  82  is coupled to fluid displacement member  16  and accordingly pulls fluid displacement member  16  through an upstroke and pushes fluid displacement member  16  through a downstroke. As such, for each revolution of rotor  522 , the pump proceeds through a full pump cycle, including an upstroke and a downstroke. The increased torque facilitates rotor  522  generating sufficiently high pumping pressures with displacement pump  19  to generate an atomized spray at spray apparatus  5 . In some examples, rotor  522  can cause pump  19  to generate pumping pressures of about 3.4-69 megapascal (MPa) (about 500-10,000 pounds per square inch (psi)) or even higher. In some examples, the pumping pressures are in the range of about 20.7-34.5 MPa (about 3,000-5,000 psi). High fluid pumping pressure is useful for atomizing the fluid into a spray for applying the fluid to a surface. 
     During operation of pump  19 , the pump reaction forces generated by fluid displacement member  16  during pumping are transmitted to pump frame  518  via drive mechanism  14 , rotor  522 , bearing  542 , bearing  548 , and stator housing  521 . Both the upward reaction force and the downward reaction force travel through drive mechanism  14 , rotor  522 , and then to bearings  542  and  548 . Bearings  542  and  548  transfer rotational forces associated with rotation of rotor  522  and both of the upward and downward reaction forces to pump frame  518 . With each stroke, pump reaction forces are generated and a load is applied to rotor  522  due to rotor  522  directly driving fluid displacement member  16  via drive mechanism  14 . 
     This axial pump reaction load is transverse to rotational axis A of electric motor  512  and is experienced at both output and input ends  524 ,  526  of electric motor  512 . The load is transmitted to pump frame  518  via bearings  542 ,  548  and stator housing  521  such that electric motor  512  does not experience the pump reaction forces. At first end  524 , the load is transmitted from rotor  522  to pump frame  518  through bearing  542  and stator housing  521 . At electrical input end  548 , the load is transmitted from rotor  522  to pump frame  518  through bearing  548  and stator housing  521 . Bearings  542 ,  548  experience opposite reactionary forces with each pump stroke to provide a force balance at pump frame  518 . 
     Pump reaction forces are thereby transmitted to rotor  522  from fluid displacement member  16  due to the direct drive connection between rotor  522  and fluid displacement member  16 . Bearings  542 ,  548  balance the load across rotor  522  and transmit the load to pump frame  518 . Bearing  542  is proximal to pump frame  518  and coupled to pump frame  518  via stator housing  521 . Bearing  548  is distal to pump frame  518  but also coupled to pump frame  518  via stator housing  521 , which transmits loads to pump frame  518  from bearing  548 . Stator housing  521  thereby transmits pump loads from rotor  522  to pump frame  518 . 
     The bearing arrangement of system  510  provides significant advantages. Bearings  542 ,  548  react pump reaction loads generated during pumping due to the direct drive arrangement. Bearings  542 ,  548  stabilize rotor  522  to facilitate the direct drive connection to fluid displacement member  16 . The pump reaction forces experienced at first end  524  and electrical input end  528  are transmitted to pump frame  518 , balancing the forces across pump frame  518 . The connection balances motor  512 , providing longer life, less wear, less downtime, more efficient operation, and cost savings. 
     The direct drive configuration of drive system  510  eliminates intermediate gearing (e.g., reduction gears) between electric motor  512  and fluid displacement member  16  that are used in conventional motor-driven pumps. The elimination of intermediate gearing provides a more efficient, compact, lower weight, reliable, and simpler pump by reducing the part count and number of moving parts. Additionally, the elimination of gearing provides for quieter pump operation. 
       FIG. 17  is a block diagram of a control system of any of the drive systems of  FIGS. 1A-16 . Control system  700 , control panel  13 , controller  15 , user interface  17 , fluid sensor  101 , motor sensor  102 , temperature sensor  103 , and additional sensors  104  (e.g., current sensor) are shown. Controller  15  can be included in any of the drive systems disclosed herein and used according to the following disclosure. Controller  15  can be one or more logic circuits such as a chip or microprocessor. Code can be included in the controller  15  for execution by the logic circuitry to perform the functions referenced herein. Controller  15  can receive data, including in the form of analog signals, from any of the sensors or transducers or other components referenced herein. 
     Each of fluid sensor  101 , motor sensor  102 , temperature sensor  103 , and additional sensors  104  provide electronic signals to controller  15 . For example, controller  15  can receive a signal from fluid sensor  101  (shown in  FIGS. 4 and 9 ). Fluid sensor  101  can be included in any of the disclosed drive systems. Fluid sensor  101  can be a pressure transducer which measures fluid pressure output by pump  19 . Fluid sensor  101  can be, for example, a spring gauge sensor. 
     Controller  15  can also receive a signal from a motor sensor  102  (shown in  FIGS. 4 and 9 ). Motor sensor  102  can be included in any of the disclosed drive systems. Motor sensor  102  measures, directly or indirectly, a parameter of the operational state of rotor  22 . For example, motor sensor  102  can register and count revolutions of rotor  22 . Motor sensor  102  can determine the orientation of rotor  22  so that the rotational position of rotor  22  is always known, which can be useful for reversing rotor  22 . For example, motor sensor  102  can be a multi-axis magnetic sensor with multiple magnets on rotor  22  in different orientations and a magnetic field sensor on stator  20  that measures the changes to the magnetic fields to determine the instantaneous rotational position of rotor  22 . In some cases, the position of rotor  22  may not be directly measured but can be inferred. For example, a cycle sensor can sense a cycle of rotor  22  and/or pump  19 , such as by measuring displacement of fluid displacement member  16 , from which the cycle position of rotor  22  can be inferred. 
     Controller  15  is configured to control operation of motor  12 . Controller  15  controls power to stator  20  to control rotation of rotor  22  about the motor axis. Controller  15  can be configured to cause pump  19  to output spray fluid according to a target pressure. Controller  15  provides current to motor  12  to achieve the desired pressure. The current provided to motor  12  is proportional to the pressure output by pump  19 . As such, controller  15  can be configured to control current to motor  12  based on the desired pressure. 
     Pump  19  can maintain constant spray fluid pressure throughout operation. In some examples, pump  19  is configured to output spray fluid at about 500-7500 pounds per square inch (psi), although typically in the range of 1500-3300 psi. Pump  19  can be operable in a pumping state and in a stalled state. In the pumping state, rotor  22  applies torque to drive mechanism  14 , causing fluid displacement member  16  to apply force to the spray fluid. In the stalled state, rotor  22  applies torque to drive mechanism  14  but does not rotate, such that fluid displacement member  16  applies force to the spray fluid but does not displace axially. A stall can occur, for example, when pump  19  is deadheaded due to the closure of a downstream valve, such as when trigger  9  (shown in  FIG. 4 ) is not actuated for spraying. Pump  19  continues to apply pressure to the spray fluid when pump  19  is stalled due to constant urging of rotor  22 . Rotor  22  is urged forward while rotor  22  is stalled such that pressure continues to be applied to fluid displacement member  16  through rotor  22  and the drive mechanism  14 . As such, when trigger  9  is actuated, the spray pressure is already present and instantly provided, minimizing any pressure drop that can occur on the initiation of spraying and adversely impact the spray qualities of the spray fan of the spray fluid. With constant urging of rotor  22 , the spray fan can be consistent from trigger pull (actuation) to trigger release (stalled state). 
     During both the pumping state and the stalled state, controller  15  can be configured to supply current to stator  20  such that rotor  22  applies torque to drive mechanism  14 , causing fluid displacement member  16  to continue to exert force on the spray fluid, urging rotor  22  to rotate even when rotor  22  is stalled due to a back pressure of the spray fluid downstream of the pump  19 . The back pressure, caused, for example, by closure of a downstream valve, prevents axial displacement of fluid displacement member  16  and thereby rotation of rotor  22 . In the stalled state, controller  15  causes a continuous flow of current to motor  12  causing rotor  22  to apply constant torque to drive mechanism  14 . Drive mechanism  14  converts the torque to a linear driving force such that drive mechanism  14  applies constant force to fluid displacement member  16 . Rotor  22  does not rotate during the stall. Rotor  22  applies torque with zero rotational speed when pump  19  is in the stalled state. Pump  19  is entirely mechanically driven in that rotor  22  mechanically causes fluid displacement member  16  to apply pressure to the spray fluid during the stalled state. 
     The amount of current delivered to the motor  12  can be determined based on a pressure setting. The user may set the pressure at which pump  19  is to output the spray fluid. Controller  15  can calculate a motor speed (e.g., via an index relating rotor speed to a set pressure) based on the desired pressure and then can calculate the amount of torque required to achieve the motor speed or pressure. Torque is directly proportional to current and controller  15  can determine the needed current based on the desired torque. Torque is directly proportional to the current and current is directly proportional to the pressure. As such, the pressure setting of drive system  10  can correspond with the amount of current (or other measure of power) supplied to motor  12 , such that a higher pressure setting corresponds with greater current, and a lower pressure setting corresponds with lesser current. Controller  15  can adjust the voltage provided to motor  12  to change the speed of rotor  22 . 
     Controller  15  commands a current corresponding to the set pressure in the urge mode. Controller  15  may not command a motor speed in the urge mode. The current provided to motor  12  causes pump to generate an output pressure, and the actual speed of the motor will be whatever speed is required to hold constant pressure. For example, motor speed is at a maximum if there is no restriction in the downstream flow such that the actual pressure cannot build to the target pressure. If the motor is overloaded (e.g., due to a stall condition), the actual speed of the motor is zero, but the pressure is maintained at the desired pressure. When the downstream pressure drops (e.g., when trigger  9  is actuated), the motor speed will increase to the speed needed to hold the set pressure, which is directly proportional to the current. 
     The disclosed drive systems have an offset crank pump load, which results in spikes in current twice per motor revolution. Controller  15  can be configured to determine the actual pressure based on pressure readings taken over a time period. The multiple pressure readings over a timescale provides a smoother pressure output signal, facilitating more accurate control and smoother pumping. The user can set a desired pressure via user interface  17 . Controller  15  controls operation of motor  12  to cause pump  19  to output fluid based on the desired pressure. Current and motor speed are determined based on the pressure set point. Controller  15  determines target speed and torque to generate the target pressure and commands current to motor  12  based on that information. Current, pressure, and torque can remain the same during pumping state and during the stalled state, while motor speed changes. 
     During operation, the actual pressure is determined based on information generated by pressure transducer  101 . Current can be increased if pressure is lower than the target or set pressure. If the motor speed is not capable of meeting the target pressure and current is at a maximum operating current, voltage can be increased to increase the speed of motor  12 . The amount of current delivered to motor  12  to maintain a constant pressure at a set pressure is dependent on the material composition of the spray fluid. For example, the current required to generate 3000 psi will vary between systems depending on the viscosity of the pumped material, among other factors. Controller  15  can be configured to determine the needed current based on the pressure information provided by pressure transducer  101 . 
     The amount of current delivered to motor  12  can be about the same whether rotor  22  is rotating or stalled, although in some embodiments, more current can be delivered to motor  12  when the rotor  22  is rotating and less current can be delivered to motor  12  when rotor  22  is stalled but urging. The continuous current flow regulated by controller  15  causes pump  19  to apply constant pressure to the spray fluid via fluid displacement member  16 . Controller  15  can provide more power to motor  12  with motor  12  rotating than when the motor  12  is stalled. Current can remain constant both in the stall and when rotating, but voltage can change due to the speed changes. Voltage increases to increase the speed of motor  12 , resulting in additional power during rotation. As such, voltage is at a minimum when at zero speed and with pressure at the desired level, because no additional speed is required to get to pressure. As the motor  12  is commutated, power is applied according to a sinusoidal waveform. For example, motor  12  can receive AC power. For example, the power can be provided to the phases of the motor  12  according to electrically offset sinusoidal waveform. With motor  12  stalled, the signals are maintained at the point of stall such that a constant signal is provided with motor  12  in the stalled state. As such, at least one phase of motor  12  can be considered to receive a DC signal with motor  12  in the stalled state. Motor  12  can thereby receive two types of electrical signals during operation, a first during rotation and a second during stall. The first can be sinusoidal and the second can be constant. The first can be AC and the second can be considered to be DC. The first power signal can be greater than the second power signal. 
     In some examples, a set current can be provided to motor  12  throughout the stall. For example, the maximum current can be provided to motor  12  throughout the stall. The maximum current can be a maximum operating current of motor  12 , a maximum current as set by the user, or other form of maximum current. In some examples, controller  15  can vary the current provided to motor  12 . For example, the current can be pulsed such that current is constantly supplied to stator  20 , but at different levels. As such, pump  19  can apply continuous and variable force to the spray fluid with motor  12  in the stalled state. In some examples, the current can be pulsed between the maximum current and one or more currents lesser than the maximum current. Pump  19  returns to the pumping state when the back pressure of the spray fluid drops sufficiently such that the current provided to motor  12  can cause rotation of rotor  22  and axial displacement of fluid displacement member  16 , such as when the user resumes spraying. Pump  19  thereby returns to the pumping state when the force exerted on the spray fluid overcomes the back pressure of the spray fluid. Controller  15  can be configured to resume current flow according to the pumping state based on the pressure dropping such that motor  12  can rotate. 
     A stall occurs when the driving force on the rotor equals the reaction force of the downstream fluid from one of the fluid displacement member  16  and the suction of fluid upstream of pump  19  when fluid displacement member  16  is in an upstroke. Pump  19  exits the stall when the downstream pressure decreases, such that the forces are no longer in balance and rotor  22  overcomes the forces acting on fluid displacement member  16 . A continuous supply of current to motor  12  during stall provides constant urging of rotor  22 . In some examples, the rotor  22  can be caused to exit the stalled state due to the constant current overcoming the downstream pressure, and not in response to any pressure signal from pressure transducer  101  indicating a drop in pressure. The continuous urging of the rotor  22  ensures that rotor  22  is continuously poised to resume rotating and moving fluid displacement member  16  at the very moment that the fluid starts flowing again, allowing the fluid displacement member  16  to move again. 
     Other spray systems may cease delivery of driving power to the motor when a pressure sensor indicates that the set pressure has been reached. The pressure must drop enough for the pressure sensor to register the drop before a controller resumes supplying current to the motor. This process can lead to a drop in spray pressure just as the user resumes spraying, which is known as deadband. This drop in spray pressure is typically unwanted as it can result in a reduction of the spray fan at the start of spraying and variation in the spray fan. For example, the spray fan varies from the time the trigger is actuated to the time the pressure set point has been reached. In contrast, with constant urging of rotor  22 , the pressure set point is achieved instantly or nearly so upon actuation of the trigger. The motor  12  begins spinning and the pump  19  begins pumping as soon as the downstream flowpath opens, minimizing any potential deadband and providing desired spray pressure when spraying is initiated. 
     Stalling pump  19  in response to spray fluid back pressure provides significant advantages. The user can deadhead pump  19  without damaging the internal components of pump  19 . Controller  15  regulates to the maximum current, causing pump  19  to output a constant pressure. Pump  19  continuously applies pressure to the spray fluid, allowing pump  19  to quickly resume operating and outputting constant pressure when the downstream pressure is relieved. Pulsing the current during a stall reduces heat generated by stator  20  and uses less energy. 
     Motor  12  can remain stalled, while still urging fluid displacement member  16 , for an indefinite period of time. However, if the user fails to use pump  19  for an extended period of time, such as when the user goes to lunch, then power can be saved and less heat can be built up if controller  15  stops power delivery to motor  12 . Controller  15  can sense a stall condition, for example, using motor sensor  102  to detect ceased rotation of rotor  22  and/or based on an amount of current spike experienced and sensed by current sensor  104  when the downstream flowpath initially closes. In some examples, controller  15  can start a timer based on motor  12  entering the stalled state. The timer can be stopped and, in some examples, reset if rotation of rotor  22  is sensed. But after a predetermined amount of time without rotation of the rotor  22 , such as 30 seconds, 5 minutes, 10 minutes, or any other desired temporal threshold, controller  15  can cease delivery of operating power (electrical energy) to motor  12 . Controller  15  can continue to monitor a fluid parameter such as pressure via the fluid sensor  101  while controller  15  has ceased delivery of operating power to the motor  12 . If fluid sensor  101  senses a change in the fluid parameter, such as a pressure drop or flow of fluid, then controller  15  can resume delivery of energy to the motor  12  to rotate rotor  22  and operate as previously described, based on the assumption that the operator has resumed spraying operations. 
     Motor  12  continues to generate heat in a stall condition when current is supplied to provide constant urging of rotor  22 . Heat generation is proportional to current supply over time. In some examples, a temperature sensor can be used to measure a motor temperature or atmospheric temperature adjacent to motor  12 . If a threshold temperature is reached before rotation of rotor  22  has resumed and/or before a predetermined amount of time without rotation has occurred, controller  15  can cease delivery of operating power to motor  12 . In this case, the predetermined period of continued urging is dynamic, based on temperature as opposed to a predetermined period of time. Controlling delivery of operating power to motor  12  during stall based on temperature can account for variations in the environment in which drive system  10  is operated. Both dynamic and static time outs for a stalled motor based on temperature and time, respectively, can prevent overheating and damage to drive system  10 . Controller  15  can resume deliver of energy to motor  12  once fluid sensor  101  senses a change in the fluid parameter, indicating spraying operations have resumed. 
     Controller  15  can reverse the direction of rotation of rotor  22  based on the delivery of electrical energy to motor  12 . For example, controller  15  can cause a rotor  22  to rotate clockwise for a plurality of complete revolutions and then counterclockwise for a plurality of complete revolutions. Regardless of whether the rotor  22  is rotating clockwise or counterclockwise, drive mechanism  14  will still reciprocate the fluid displacement member  16  in the same manner. For example, rotor  22  can rotate clockwise making a plurality of complete revolutions to drive the piston through a first plurality of pumping strokes and can then rotate counterclockwise making a plurality of complete revolutions to drive the piston through a second plurality of pumping strokes. Switching between clockwise and counterclockwise rotation of the rotor  22  can increase wear life on components by providing more uniform wear of parts (e.g., bearings) and can minimize sideloading of fluid displacement member  16 . Reversing the direction of rotation can also be used to troubleshoot problems, such as a locked rotor condition. Reversing the direction of rotation can momentarily release pressure on fluid displacement member  16  to help unstick fluid displacement member  16 . For example, it may be difficult to start motor  12  against pressure. Changing the direction of rotation provides changeover within 90 degrees, allowing for fluid displacement member to encounter the load while moving in an opposite direction and with some momentum to ramrod into the load on the other pump stroke. It is understood that controller  15  can be configured to reverse the direction of rotor  22  rotation based on various operating conditions. 
     Controller  15  can periodically reverse the direction of rotor  22 , such as based on a schedule. For example, after a predetermined amount of time rotating in a first direction, controller  15  can cause the rotor  22  to rotate in a second direction opposite the first direction for the same or a different predetermined amount of time or given amount of time. At the expiration of the amount of time, controller  15  can wait until a stall moment to reverse the direction of rotor  22  so as to not have a reversal of rotor  22  during pumping. Alternatively, controller  15  can time the reversal of rotor  22  rotation based on reversal of the direction to the changeover of fluid displacement member  16  (e.g., fluid displacement member  16  is at the top or bottom of its stroke and reversing direction anyway). 
     Controller  15  can reverse the direction of rotor  22  based on the number of pump cycles. For example, rotor  22  can be reversed based on a predetermined number of complete revolutions of rotor  22  in one direction (e.g., 1000 revolutions) before switching to the other direction for rotating the or another predetermined number and before switching back again. Motor revolutions can be determined for example, by information generated by motor sensor  102 . In some examples, a sensor can be associated with fluid displacement member  16  to sense displacement and count pump cycles. A predetermined number of pump strokes, two of which form a complete pump cycle, may be used instead of motor revolutions. In some examples, the pressure spikes experienced by pressure transducer  101  can be utilized to count pump cycles or strokes. As such, the periodic reversal of rotor  22  can be based on information from motor sensor  102 , pressure transducer  101 , or another sensor of the system. 
     Controller  15  can reverse the direction of rotor  22  based on power to the sprayer having been turned off, such as by actuating the power switch. For example, when the user turns on the sprayer, controller  15  can cause rotor  22  to rotate in a first direction, as needed, until the sprayer is turned off. When the user turns the sprayer on again, controller  15  causes rotor  22  to rotate in the second direction, as needed, until the sprayer is turned off again. This can be continued, switching the direction of rotation of rotor  22  based on turning on and turning off of the sprayer. In some examples, controller  15  can reverse the direction of rotation based on stand-by power being turned off, such as when the sprayer is unplugged. Rotor  22  can thus start up in a new rotational direction each time the sprayer is plugged back in and activated. 
     Controller  15  can monitor a fluid parameter with fluid sensor  101 , and/or can monitor current to motor  12 , and can switch direction of rotation of rotor  22  based on the monitored parameter. For example, if the current draw of the motor  12  exceeds a threshold, which may indicate increased resistance, controller  15  can cause rotor  22  to reverse direction. In some embodiments, controller  15  can cause rotor  22  to reverse direction if rotor  22  stalls while the set pressure has not been reached, indicating an inability to reach pressure. In some embodiments, controller  15  can cause rotor  22  to reverse to rotate in a second direction if rotor  22  is rotating in a first direction and yet is unable to reach the set pressure after a predetermined amount of time, indicating an inefficiency error. 
     Controller  15  can cause rotor  22  to switch direction of rotation if rotor  22  fails to make a complete revolution as indicated, for example, by motor sensor  102 . For example, if rotor  22  completes a partial revolution in a first direction but is unable to complete the full revolution and the actual pressure is less than the target pressure, then this can indicate a locked rotor condition or a jam or other blockage. Controller  15  can cause rotor  22  to rotate in the second direction rotational direction based on such a condition. If rotor  22  is unable to complete a full revolution in the second direction, controller  15  can again cause rotor  22  to reverse direction. This can be repeated until rotor  22  is able to make a full revolution, or for a predetermined period of time, or for a predetermined number of switches, among other options. Controller  15  can be configured to generate an error code based on the rotor  22  failing to rotate when not at pressure and can provide that error information to the user, such as via user interface  17 . In some examples, controller  15  can cause rotor  22  to continue switching between rotational directions, which can cause some pumping depending on the displacement provided by the pump  19 , allowing the system to operate in a partial capacity. 
     During a locked condition where rotor  22  cannot complete a 360-degree rotation, controller  15  can cause rotor  22  to rotate until stopped (due to the blockage/lock) in the first rotational direction and then rotate until stopped (due to the blockage/lock) in the opposite second rotational direction. Controller  15  can continue to reverse rotation until the predetermined switching threshold (e.g., number of direction reversals) is reached, until the locked condition is broken. Controller  15  can be configured to generate an error code based on the rotor  22  failing to rotate when not at pressure and can provide that error information to the user, such as via user interface  17 . If the rotor  22  is able to complete a 360-degree rotation, then controller  15  continues to drive rotation of the rotor  22  to build the actual pressure to the target pressure. The controller  15  thereby resumes operating rotor  22  in the pumping mode if the lock/blockage is overcome. In some examples, controller  15  can cause rotor  22  to continue switching between rotational directions, which can cause some pumping depending on the displacement provided by the pump  19 , allowing the system to operate in a partial capacity. 
     Controller  15  can cause rotor  22  to reverse direction periodically based on a time-based or event-based schedule, for example, based on a calendar, usage time, each time sprayer is turned off or unplugged, number of revolutions, etc. Controller  15  can also cause rotor  22  to reverse direction in response to blockages or inefficiencies in motor operation. For example, controller  15  can cause rotor  22  to reverse direction if rotor  22  is unable to complete a full revolution or if rotor  22  is rotating but is unable to meet the set pressure. 
     During operation, control circuitry  13  can determine, for example, based on pressure sensor  101  or motor sensor  102 , if motor  12  is rotating. If motor  12  is rotating, rotation can continue in the present direction of rotation. If motor  12  is not rotating, controller  15  can determine whether operating power to motor  12  has been ceased (e.g., sprayer has been turned off or unplugged). If operating power to motor  12  has been ceased, controller  15  can cause rotor  22  to change direction of rotation the next time motor  12  is operated. 
     During operation, control circuitry  15  can determine reversal of rotor  22  based on a temporal threshold and/or an event threshold. For example, control circuitry  15  can cause reversal if a predetermined time threshold since the last reversal has been reached (e.g., 15 minutes of operation, 1 hour of operation, 5 hours of operation, or other times)). The predetermined time threshold can be based on time that power is supplied to motor  12  or time that the rotor  22  is actually rotating, among other options. In another example, control circuitry  16  can cause reversal if a predetermined revolution threshold since the last reversal has been reached (e.g., 500 revolutions, 1000 revolutions, 10000 revolutions, or other revolution count. If the temporal and/or event threshold Control circuitry  15  can cause rotor  22  to reverse direction the next time rotor  22  stops and subsequently begins spinning or during spinning of rotor  22 , such as where the revolutions per minute are below a threshold or based on the fluid displacement member  16  being at the end of a stroke. 
     In some examples, control circuitry  15  can stop supplying power to motor based on a predetermined urging time threshold (e.g., 5 seconds, 1 minutes, 5 minutes, or other times of non-use). For example, control circuitry  15  will continue to supply current even when motor  12  is stalled to provide urging on the fluid to maintain pressure and for quick response when spraying resumes. If the predetermined urging time has not been reached, control circuitry  15  can determine if a predetermined maximum temperature has been reached (e.g., temperature of motor or ambient air). If the predetermined maximum temperature has been reached, control circuitry  15  can cease delivery of operating power to motor  12 . If the predetermined temperature has not been reached, control circuitry  15  can continue supplying power to motor  12  to continue the urging until the predetermined urging time or the predetermined temperature is reached. 
     Control circuitry  15  can determine whether the target pressure has been reached, such as based on data from pressure sensor  101 . Control circuitry  15  can determine when rotor  22  is rotating based on data from motor sensor  102 . If rotor  22  is able to rotate but the target pressure has not been reached, control circuitry  15  can cause rotor  22  to reverse rotational direction. If the pressure is lower than the target pressure but rotor is stopped or has low revolutions per minutes (such as below a minimum threshold), controller  15  can cause rotor  22  to reverse a direction of rotation. Controller  15  can cause rotor  22  to continue to reverse direction based on the low target pressure and the operating state of rotor  22  (e.g., speed) to try to overcome the inefficiency, locked rotor, or other blockage. In some examples, controller  15  can provide an error code to the user by user interface  17 , such as based on rotor  22  reversing a set number of times and not breaking the lock/blockage. 
     The examples discussed regarding controller  15  controlling rotation of rotor  22  and current supply to motor  12  are non-limiting examples. Additional, fewer, and/or alternative steps can be taken. For example, drive system  10  can operate with or without constant rotor urging and motor rotation direction can be reversed based any one or more of scheduled (e.g., time-based or event-based) or operating conditions (e.g., blockage). 
     While the pumping assemblies of this disclosure and claims are discussed in the context of a spraying system, it is understood that the pumping assemblies and controls can be utilized in a variety of fluid handing contexts and systems and are not limited to those discussed. Any one or more of the pumping assemblies discussed can be utilized alone or in unison with one or more additional pumps to transfer fluid for any desired purpose, such as location transfer, spraying, metering, application, etc. 
     DISCUSSION OF NON-EXCLUSIVE EXAMPLES 
     The following are non-exclusive descriptions of possible examples of the present invention. 
     A drive system for a reciprocating fluid displacement pump includes an electric motor, a drive, and a fluid displacement member. The motor includes a stator defining an axis and a rotor disposed coaxially around the stator. The drive is directly connected to the rotor to receive a rotational output from the rotor. The fluid displacement member is mechanically coupled to the drive. The drive member converts the rotational output to a linear, reciprocating input to the fluid displacement member. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     The fluid displacement member is mechanically coupled to the drive at an output end of the electric motor. 
     The electric motor further comprises an electrical input end configured to receive electrical power, the electrical input end disposed opposite the output end on the axis. 
     A pump frame mechanically supporting the electric motor. 
     The electric motor is cantilevered from the pump frame. 
     The output end of the electric motor is coupled to the pump frame such that an end of the electric motor disposed opposite the output end is a free end of the cantilevered electric motor. 
     The pump frame is mechanically coupled to each of the rotor and the stator. 
     A coupling member connects the pump frame to an axle of the stator such that the stator is fixed relative to the pump frame. 
     The coupling member is connected to the axle at the free end of the electric motor. 
     The coupling member extends around an exterior of the rotor from the pump frame to the axle. 
     The coupling member includes an axially extending portion that extends from the pump frame across the exterior of the rotor, wherein the axially extending portion is radially separated from the rotor, and a radially extending portion that extends from the axially extending portion to the axle, wherein the radially extending portion is axially separated from the rotor. 
     The rotor is formed from a housing and comprises a permanent magnet array on an inner circumferential face of the housing. 
     The housing extends around three sides of the stator and wherein the housing is rotationally coupled to a pump frame at an output end of the electric motor coupled to the drive. 
     The housing radially overlaps the stator at the output end and radially overlaps the stator at an input end of the electric motor disposed opposite the output end. 
     The stator is fixed to an axle, and wherein the axle extends axially outward from the housing at the input end. 
     A coupling member connects the pump frame to the axle such that the stator is fixed relative to the pump frame. 
     A pump frame supporting the electric motor, wherein the electric motor is supported by the pump frame at an output end of the electric motor coupled to the drive, and a first bearing disposed between the pump frame and the rotor at the output end to support the rotor and allow rotational motion of the rotor with respect to the pump frame. 
     The rotor extends through the pump frame and wherein the rotor is coupled to an inner race of the bearing and the pump frame is coupled to an outer race of the bearing. 
     The pump frame is mechanically coupled to an axle of the stator at an input end opposite the output end, wherein the input end is configured to receive an electrical input. 
     A coupling member extends around an exterior of the rotor from the pump frame to the axle to fix the stator relative to the pump frame. 
     In another example, a method of driving a reciprocating pump includes powering an electric motor to cause rotation of a rotor of the motor, the rotor disposed outside of and around a stator of the motor, receiving a rotational output from the rotor at a drive directly connected to the rotor, translating the rotational output, by the drive, directly to linear, reciprocating motion, and providing, by the drive, a linear reciprocating input to a fluid displacement member connected to the drive to cause the pump rod to pump fluid by reciprocation. 
     The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, additional components, and/or steps: 
     Receiving the rotational output from a first end of the electric motor and providing electrical input to a second end of the electric motor opposite the first end. 
     Mechanically supporting the electric motor with a pump frame disposed at the first end. 
     Rotationally coupling the rotor to the pump frame at the first end, and mechanically fixing the stator to the pump frame at the second end. 
     In yet another example, a fluid displacement apparatus includes an electric motor, a drive, a pump, and a pump frame. The motor includes a stator defining an axis and a rotor disposed around the stator. The drive is connected to the rotor to receive a rotational output from the rotor and convert the rotational output to linear reciprocating motion. The pump includes a piston and a cylinder, the piston receiving the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize both the stator relative to the rotor and the cylinder relative to the piston. 
     The fluid displacement apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     One or more coupling members. The stator includes a first end and a second end opposite the first end, the first end attached to the pump frame while the second end extends away from the pump frame, and the one or more coupling members are attached to the second end of the stator and extend along the exterior of the rotor to connect to the pump frame. 
     One or more wires that extend into the second end of the stator, the one or more wires providing electrical power to operate the stator. 
     In yet another example, a drive system for a reciprocating fluid displacement pump includes an electric motor, a drive, a fluid displacement member, and a support frame. The electric motor includes a stator disposed on an axis and supported by an axle and a rotor disposed coaxially around the stator. The drive is directly connected to the rotor to receive a rotational output from the rotor. The fluid displacement member is mechanically coupled to the drive, wherein the drive is configured to convert the rotational output to a linear, reciprocating input to the fluid displacement member. The support frame is configured to mechanically support the electric motor and the fluid displacement pump, wherein the support frame is mechanically coupled to the stator. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     The support frame is coupled to the rotor at a first end of the electric motor by a first bearing, the first bearing allowing rotation of the rotor within the support frame. 
     The support frame is mechanically coupled to the stator at a second end of the motor axially opposite a first end of the electric motor, wherein the drive is connected to the rotor at the first end. 
     The support frame includes a first frame member at the first end, a second frame member coupled to the stator at the second end, and at least one connecting member connecting the first and second frame members. The at least one connecting member extends across an outer surface of the rotor and is spaced from the rotor to allow rotation of the rotor within the support frame. 
     The second frame member comprises at least one projecting member, wherein the at least one projecting member extends radially outward from the axis such that a distal end of the at least one projecting member is disposed radially outward of the rotor, and wherein the at least one axially-extending member is connected to the at least one projecting member. 
     The electric motor is cantilevered from the first frame member such that the first end is connected to the first frame member and the second end is cantilevered. 
     The second frame member comprises a plurality of projecting members, wherein projecting members of the plurality of projecting members are symmetrically arranged about an axis of the electric motor. 
     The second frame member includes a plurality of projecting members, wherein projecting members of the plurality of projecting members are asymmetrically arranged about the axis. 
     The plurality of projecting members includes one of three projecting members and four projecting members. 
     Projecting members of the plurality of projecting members are arranged in an X-configuration. 
     Projecting members of the plurality of projecting members are arranged in a Y-configuration. 
     The first frame member includes at least one projecting member extending radially outward of the rotor, and wherein the at least one connecting member connects to the at least one projecting member of the first frame member. 
     The first frame member includes a first plurality of projecting members and the second frame comprises a second plurality of projecting members, and wherein a plurality of connecting members connect the first and second pluralities of projecting members. 
     Projecting members of the first plurality of projecting members are axially aligned with projecting members of the second plurality of projecting members. 
     The at least one connecting member is a tie rod. 
     The second frame member is in fixed contact with the axle. 
     The second frame member is supported by the axle and is in contact with an outer radial surface of the axle. 
     The second frame member is in contact with an end face of the axle. 
     A retaining element in fixed contact with the second frame member and a radially inner surface of the axle. 
     The axle is formed of a conducting material to transfer heat from the stator to the second frame member. 
     The second frame member is mechanically coupled to the axle adjacent to a second bearing and wherein the first and second frame members compress the first and second bearings therebetween to preload the first and second bearings. 
     A wave spring washer disposed between the second bearing and the second frame member. 
     A retaining element, wherein the retaining element secures the second frame member to the axle. 
     The retaining element connects to the axle by interfaced threading. 
     A control panel mechanically coupled to the first frame member and the second frame member and partially surrounding the rotor. 
     The first frame member forms a pump frame configured to partially house the fluid displacement member. 
     The support frame includes a plurality of connecting members extending across an exterior of the rotor between a first frame member at a first end of the motor and a second frame member at a second end of the motor, the drive member is connected to the rotor at a first end of the motor, and the support frame is configured to support both torque loads and pump reaction loads. 
     A first subset of the connecting members is positioned to support both torque loads and pump reaction loads. 
     In yet another example, a support frame for a reciprocating fluid displacement pump drive system having an electric motor with an inner stator and an outer rotor includes a first frame member, a second frame member, and at least one connecting member. The second frame member is disposed at an opposite end of the electric motor from the first frame member and separated from the first frame member. The at least one connecting member extends between and connecting the first frame member and the second frame member. The second frame member and the at least one connecting member are configured to at least partially house and to mechanically support the electric motor with the outer rotor. 
     The support frame of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     The first and second frame members each include at least three projecting members, and wherein the connecting members connect projecting members of the first frame member with projecting members of the second frame member. 
     The projecting members of the first frame member are axially aligned with the projecting members of the second frame member. 
     The projecting members of each of the first and second frame members are arranged in one of a Y-configuration and an X-configuration. 
     The connecting members are tie rods. 
     In yet another example, a fluid displacement apparatus includes an electric motor extending along an axis to have a first end and a second end, a drive, a pump, a pump frame, and a motor frame. The electric motor includes a stator extending along the axis and a rotor disposed around the stator and extending along the axis. The drive is connected to the rotor to receive a rotational output from the rotor and convert the rotational output to linear reciprocating motion. The pump includes a piston and a cylinder, the piston receiving the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize the cylinder relative to the piston. The motor frame that stabilizes stator. The motor frame includes a plurality of connecting members that extend from the first end of the motor to the second end of the motor. The plurality of connecting members are arrayed around the rotor. 
     The fluid displacement apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     The motor frame is fixed relative to the pump frame. 
     A first frame member and a second frame member. The first frame member is located on the first end of the motor and the second frame member located on the second end of the motor. Each of the plurality of connecting members extends from the first frame member to the second frame member. 
     The first frame member, the second frame member, and the plurality of connecting members form an exoskeleton around the motor which structurally supports the motor while allowing airflow through exoskeleton and around the rotor. 
     Either of the first frame member and the second frame member is star shaped. 
     In yet another example, a drive system for a reciprocating pump for pumping fluid includes an electric motor and a drive member. The electric motor includes a rotor. The rotor includes an eccentric drive extending from the rotor. The drive member is directly coupled to the eccentric drive and is configured to drive reciprocation of a fluid displacement member. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
     The eccentric drive is directly coupled to the drive member to provide a 1:1 ratio of rotor rotation to pump cycle. 
     The eccentric drive projects axially outward from an end of the rotor and offset from a rotational axis of the rotor. 
     The drive member is coupled to the eccentric drive by a bearing element allowing relative movement between the eccentric drive and the drive member. 
     The eccentric drive is integrally formed with the rotor. 
     The eccentric drive extends into a bore of the rotor and fastened to the rotor. 
     The drive comprises a sleeve and a bolt, wherein the sleeve is received in the bore of the rotor and the bolt is received in the sleeve and threadedly fastened to the rotor. 
     The rotor is disposed coaxially around the stator. 
     The rotor is formed from a housing that extends around the stator, wherein the housing comprises a permanent magnet array on an inner circumferential face. 
     The housing comprises a first cylindrical projection including the eccentric drive. 
     The first cylindrical projection extends in a first axial direction from a front end of the housing, and wherein the housing further comprises a second cylindrical projection, the second cylindrical projecting extending in a second axial direction from the front end of the housing into an axle of the stator. 
     The eccentric drive includes a pin that extends into each of the first cylindrical projection and the second projection. 
     The eccentric drive is formed from a non-ferrous material. 
     The housing further comprises a spacing member, wherein the spacing member extends axially outward from the first cylindrical projection and supports the eccentric drive. 
     The drive system further comprises a pump frame and wherein the first cylindrical projection is coupled to the pump frame by a first bearing, wherein the first bearing allows rotational motion of the rotor with respect to the pump frame. 
     The first cylindrical projection is coupled to the first bearing. 
     The housing extends through the pump frame and wherein the eccentric drive and drive member are positioned axially outward of the first bearing. 
     The eccentric drive and drive member are positioned axially inward of the first bearing. 
     The eccentric drive is integrally formed with the rotor. 
     There are no gears disposed between the rotor and the fluid displacement member. 
     The pump is a double displacement pump. 
     In yet another example, a method of driving a reciprocating pump includes powering an electric motor to cause rotation of a rotor on a rotational axis, providing rotational output of an electric motor directly to a drive member, providing, by the drive member, a linear reciprocating input to a pump rod of the pump, and spraying a fluid from the fluid displacement pump onto a surface. For one revolution of the rotor, the fluid displacement pump proceeds through one pump cycle. 
     The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, additional components, and/or steps: 
     Rotational output is provided through an eccentric drive on the rotor, wherein a position of the eccentric drive is offset from the rotational axis. 
     The eccentric drive is integrally formed with the rotor or extends into the rotor and is secured to the rotor. 
     In yet another example, a pumping system includes and electric motor, a drive member, and a reciprocating pump. The electric motor includes a rotor. The rotor includes an eccentric drive extending from the rotor. The drive member is directly coupled to the eccentric drive. The reciprocating pump includes a fluid displacement member coupled to the drive member and a pump cylinder at least partially housing the fluid displacement member. The drive member is configured to drive reciprocation of the fluid displacement member. 
     The pumping system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The eccentric drive is directly coupled to the drive member to provide a 1:1 ratio of rotor rotation to pump cycle. 
     The eccentric drive projects axially outward from an end of the rotor and offset from a rotational axis of the rotor. 
     The eccentric drive is integrally formed with the rotor or extends into the rotor. 
     The rotor is rotationally coupled to a pump frame by a first bearing and wherein the eccentric drive and drive member are positioned axially inward of the first bearing. 
     The rotor is rotationally coupled to a pump frame by a second bearing and wherein the eccentric drive and drive member are positioned axially outward of the second bearing. 
     The reciprocating pump is a double displacement pump such that the reciprocating pump is configured to output fluid during each of an upstroke and a downstroke of the fluid displacement member. 
     In yet another example, a drive system for a fluid displacement pump includes an electric motor, a drive, a fluid displacement member, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor at a first end of the electric motor. The fluid displacement member is mechanically coupled to the drive, such that the electric motor experiences a pump load generated by reciprocation of the fluid displacement member during pumping. The pump frame is mechanically coupled to the electric motor and configured to support the fluid displacement pump and the electric motor. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     One of the pump frame and the stator is coupled to the rotor at the first end by a first bearing, the first bearing allowing rotational motion of the rotor relative to the one of the pump frame and the stator and supporting a pump load, wherein the pump load is an axial load along an axis of reciprocation of the pump. 
     The pump frame is mechanically coupled to the stator at a rear end of the electric motor opposite the first end. 
     The rotor is disposed coaxially around the stator and wherein the rotor is formed from a housing and a plurality of magnets on an inner circumferential face of the housing. 
     The housing is coupled to an inner race of the first bearing and the pump frame is coupled to an outer race of the first bearing. 
     A second bearing disposed between the rotor and the stator adjacent to the rear end to allow rotational motion of the rotor with respect to the stator, the second bearing positioned to experience pump loads. 
     The rotor is coupled to an outer race of the second bearing and the stator is coupled to an inner race of the second bearing. 
     The rotor is coupled to an inner race of the second bearing and the stator is coupled to an outer race of the second bearing. 
     The rotor extends into an axle of the stator at the first end. 
     A third bearing disposed between the rotor and the axle to allow rotational movement of the rotor with respect to the stator and support the rotor relative to the stator such that an air gap is maintained between the stator and a permanent magnet array disposed on the rotor. 
     The rotor is coupled to an inner race of the third bearing and the axle is coupled to an outer race of the third bearing. 
     The first bearing is positioned at a first radius from a rotational axis of the electric motor and the second bearing is positioned at a second radius from the rotational axis, wherein the first radius is greater than the second radius. 
     The third bearing member is positioned at a third radius from the rotational axis, wherein the third radius is greater than the second radius and less than the first radius. 
     The stator is coupled to the rotor at the first end by the first bearing, and wherein the stator is mechanically fixed to the pump frame at the first end, wherein pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive, the rotor, the first bearing, and the stator. 
     The stator is coupled to the rotor at a rear end opposite the first end of the electric motor by a second bearing, the second bearing allowing rotational motion of the rotor relative to the stator, and wherein pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive, the rotor, the first bearing, the second bearing, and the stator. 
     In yet another example, a drive system for a reciprocating fluid displacement system includes an electric motor, a drive, a fluid displacement member, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor at a first end of the electric motor. The fluid displacement member is mechanically coupled to the drive, wherein the drive converts rotational output from the rotor to linear, reciprocating input to the fluid displacement member. The pump frame is mechanically coupled to the electric motor. The pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive and the rotor. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     A first bearing disposed between the rotor and one of the stator and the pump frame at the first end. The first bearing supports a pump load. The pump load is an axial load along an axis of reciprocation of the pump. 
     Pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive, the rotor, and the first bearing. 
     Pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive, the rotor, the first bearing, and the stator. 
     A second bearing disposed between the rotor and the stator at a rear end of the electric motor opposite the first end, the second bearing positioned to experience pump loads. 
     The pump frame is mechanically fixed to the stator at the rear end and fully separated from the stator at the first end, and wherein pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive, the rotor, the second bearing, and the stator. 
     A third bearing disposed between the rotor and an axle of the stator at the first end to provide rotational movement of the rotor with respect to the stator and to maintain a gap between the stator a plurality of permanent magnets disposed on the rotor, wherein the rotor is coupled to an inner race of the third bearing and the axle is coupled to an outer race of the third bearing. 
     The third bearing is disposed axially between the first bearing and the second bearing. 
     The pump frame is mechanically fixed to the stator at the first end, and wherein pump reaction forces generated by the fluid displacement member during pumping are transmitted to the pump frame via the drive, the rotor, the second bearing, and the stator. 
     The first bearing is positioned at a first radius from a rotational axis of the electric motor and the second bearing is positioned at a second radius from the rotational axis, wherein the first radius is greater than the second radius. 
     In yet another example, a pumping apparatus includes a frame, at least two bearing, an electric motor, a drive, and a pump. The electric motor includes a stator and a rotor configured to output rotational motion. The rotor is supported by the at least two bearings, the at least two bearings supporting rotation of the rotor. The drive is configured to receive the rotational motion and convert the rotational motion into linear reciprocating motion. The pump includes a piston and a cylinder. The piston is configured to receive the linear reciprocating motion to reciprocate within the cylinder through an upstroke and a down stroke. The piston receives a downward reaction force when moving through the up stroke and an upward reaction force when moving through the down stroke. Both of the upward reaction force and the downward reaction force travel through the drive, the rotor, and then to the at least two bearings. 
     The pumping apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The at least two bearings transfer rotational forces associated with rotation of the rotor and both of the upward and downward reaction forces to the frame. 
     In yet another example, a drive system for powering a reciprocating pump for pumping fluid to generate a fluid spray includes an electric motor, an eccentric drive member, and a drive. The electric motor includes a stator and a rotor. The rotor is configured to rotate on a rotational axis. The eccentric drive member extends from the rotor. The drive is coupled to the eccentric driver and is configured to drive reciprocation of a fluid displacement member. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The eccentric drive member is directly coupled to the rotor and to the drive to provide a 1:1 ratio of rotor rotation to pump cycles of the fluid displacement member. 
     The eccentric drive member projects axially outward from an end of the rotor and is radially offset from the rotational axis. 
     The drive is coupled to the eccentric drive member by a bearing allowing relative movement between the eccentric drive member and the drive. 
     The eccentric drive member is integrally formed with the rotor. 
     The eccentric drive member extends into a bore formed in a body of the rotor and is fastened to the rotor within the bore. 
     The eccentric drive member comprises a sleeve and a bolt, wherein the sleeve is received in the bore of the rotor and the bolt is received in the sleeve and threadedly fastened to the rotor. 
     The rotor is formed from a housing that extends around the stator, wherein the housing comprises a permanent magnet array on an inner circumferential face of a body of the housing. 
     The housing comprises a first cylindrical projection extending axially along the rotational axis and including the eccentric drive member. 
     The first cylindrical projection extends in a first axial direction from a first end of the housing, and wherein the housing further comprises a second cylindrical projection, the second cylindrical projection extending in a second axial direction from the first end of the housing into an axle of the stator, the second axial direction opposite the first axial direction. 
     The eccentric drive member includes a pin that extends into each of the first cylindrical projection and the second projection. 
     The eccentric drive member is formed from a non-ferrous material. 
     A pump frame and wherein the first cylindrical projection is coupled to the pump frame. 
     The first cylindrical projection is coupled to the pump frame by a first bearing, wherein the first bearing allows rotational motion of the rotor with respect to the pump frame. 
     The housing extends through the first bearing such that the eccentric drive member and drive are disposed on an axially opposite side of the first bearing from the stator. 
     There are no gears coupling the rotor and the fluid displacement member. 
     In yet another example, a method of driving a reciprocating pump for generating a pressurized fluid spray for spraying onto a surface includes powering an electric motor to cause rotation of a rotor on a rotational axis, providing a rotational output from the rotor to a drive, and providing, by the drive, a linear reciprocating input to a fluid displacement member of the pump to cause reciprocation of the fluid displacement member along a pump axis to pump fluid. The rotor is connected to the fluid displacement member by the drive such that for one revolution of the rotor the fluid displacement pump proceeds through one pump cycle. 
     The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, additional components, and/or steps: 
     Providing the rotational output to the drive by an eccentric drive member coupled to and extending from the rotor, wherein the eccentric driver is configured radially offset from the rotational axis and rotates about the rotational axis. 
     In yet another example, a pumping system for pumping a fluid to generate a pressurized fluid spray includes an electric motor, an eccentric drive member, a drive, and a reciprocating pump. The electric motor includes a stator and a rotor. The rotor is configured to rotate on a rotational axis. The eccentric drive member extends from the rotor. The drive is coupled to the eccentric drive member to receive a rotational output from the rotor. The reciprocating pump includes a fluid displacement member coupled to the drive and a pump cylinder at least partially housing the fluid displacement member. The drive is configured to receive the rotational output from the motor and convert the rotational output into a linear reciprocating motion to drive reciprocation of the fluid displacement member. 
     The pumping system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The eccentric drive member is directly coupled to the rotor and to the drive to provide a 1:1 ratio of rotor rotation to pump cycles of the fluid displacement member. 
     The eccentric driver projects axially outward from an end of the rotor and away from the stator, and wherein the eccentric drive member is radially offset from the rotational axis of the rotor. 
     The eccentric drive member is integrally formed with a body of the rotor. 
     The rotor is rotationally coupled to a pump frame by a first bearing and wherein the eccentric driver and drive member are positioned on an axially opposite side of the first bearing from a permanent magnet array of the rotor. 
     In yet another example, a drive system for a reciprocating fluid displacement pump configured to pump a fluid for spraying of the fluid includes an electric motor, a drive, and a fluid displacement member. The electric motor includes a stator defining an axis, and a rotor disposed coaxially around the stator. The drive is connected to the rotor to receive a rotational output from the rotor. The fluid displacement member is mechanically coupled to the drive. The drive converts the rotational output to a linear, reciprocating input to the fluid displacement member to power pumping by the fluid displacement member. 
     The drive system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The fluid displacement member is mechanically coupled to the drive at a first axial end of the electric motor. 
     The electric motor further comprises a second axial end through which the electric motor is configured to receive electrical power, wherein the second axial end is disposed opposite the first axial end along the axis. 
     A pump frame mechanically supporting the electric motor and the fluid displacement member. 
     The electric motor is cantilevered from the pump frame. 
     The pump frame is mechanically coupled to each of the rotor and the stator. 
     A support member connects the pump frame to an axle of the stator at the second axial end such that the stator is fixed to the pump frame to prevent relative movement of the stator and the pump frame. 
     The support member extends around an exterior of the rotor from the pump frame to the axle. 
     The rotor comprises a housing and a permanent magnet array disposed on an inner circumferential face of the housing. 
     The housing is rotationally coupled to a pump frame at a first axial end of the electric motor, wherein the pump frame supports the fluid displacement member. 
     The stator is fixed to an axle and wherein the housing fully radially overlaps the stator and the axle at the first axial end and at least partially radially overlaps the stator at a second axial end of the electric motor disposed opposite the first end on the axis. 
     The housing includes an opening at the second axial end such that the housing is closed at the first axial end and open at the second axial end. 
     The axle extends axially outward through the opening and beyond the housing at the second axial end. 
     The pump frame is statically connected to a portion of the axle disposed outside of the housing such that the stator is fixed to the pump frame at the second axial end. 
     A pump frame supporting the electric motor, and a first bearing. The electric motor is dynamically supported by the pump frame at a first axial end of the electric motor that is coupled to the drive. The first bearing is disposed between the pump frame and the rotor at the first axial end to support the rotor on the pump frame and allow rotational motion of the rotor with respect to the pump frame. 
     The rotor extends through the pump frame and wherein the rotor is coupled to an inner race of the bearing and the pump frame is coupled to an outer race of the bearing. 
     The pump frame is mechanically coupled to the stator at a second axial end of the electric motor opposite the first axial end. 
     The rotor is formed by a cylindrical body having a first end wall at the first axial rotor end and a second end wall at a second axial rotor end opposite the first axial rotor end, wherein the first wall is closed to fully radially overlap the stator and wherein the second wall includes an opening extending therethrough and aligned on the axis. 
     In yet another example, method of driving a reciprocating pump to pump a fluid to generate a fluid spray for spraying onto a surface includes powering an electric motor to cause rotation of a rotor of the electric motor, the rotor disposed outside of and around a stator of the motor, receiving a rotational output from the rotor at a drive connected to the rotor, translating the rotational output, by the drive, to linear, reciprocating motion, and providing, by the drive, a linear reciprocating input to a fluid displacement member of the pump that is connected to the drive to cause the fluid displacement member to pump the fluid by reciprocation. 
     The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, additional components, and/or steps: 
     Receiving the rotational output from a first axial end of the electric motor and providing an electrical input to the electric motor to power the electric motor through a second axial end of the electric motor disposed opposite the first axial end. 
     Mechanically supporting the electric motor with a pump frame disposed at the first axial end and mechanically supporting the reciprocating pump with the pump frame. 
     Rotationally coupling the rotor to the pump frame at the first axial end and mechanically fixing the stator to the pump frame at the second axial end. 
     In yet another example, fluid displacement apparatus includes an electric motor, a drive, a pump, and a pump frame. The electric motor includes a stator defining an axis and a rotor disposed around the stator to rotate about the stator. The drive is connected to the rotor to receive a rotational output from the rotor and convert the rotational output to a linear reciprocating motion. The pump comprises a piston and a cylinder. The piston receives the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize both the stator relative to the rotor and the cylinder relative to the piston. 
     The fluid displacement apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The pump frame is dynamically coupled to the rotor at a first axial end of the electric motor such that the rotor can move relative to the pump frame and the pump frame is statically coupled to an axle of the stator at a second axial end of the electric motor opposite the first axial end such that the stator is fixed relative to the pump frame. 
     One or more wires that extend into the stator at the second axial end, the one or more wires providing electrical power to operate the stator. 
     In yet another example, a pumping system includes an electric motor, a drive, a pump, and a pump frame. The electric motor includes a stator and a rotor. The stator and rotor are disposed on an axis. The drive is coupled to the rotor to receive a rotational output from the rotor and convert the rotational output to linear reciprocating motion. The pump includes a piston and a cylinder, the piston receiving the linear reciprocating motion from the drive to reciprocate the piston within the cylinder. The cylinder and the stator are connected to the pump frame to stabilize both the stator relative to the rotor and the cylinder relative to the piston. The pumping system can include any of the features of the pumping systems or apparatuses of the preceding paragraphs one or more of any feature referenced herein and/or shown in any one or more of the figures. 
     In yet another example, a sprayer includes an electric motor comprising a stator and a rotor, the rotor configured to output rotational motion; a drive that converts the rotational motion output by the electric motor into linear reciprocating motion; a pump including a piston configured to be linearly reciprocated by the drive; and a controller configured to output electrical energy to the electric motor to control operation of the electric motor. 
     The sprayer of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components: 
     The controller causes the electric motor to reverse rotational direction of the rotor between two modes. In a first mode, the rotor rotates clockwise making a plurality of complete revolutions to drive the piston through a first plurality of pumping strokes. In a second mode, the rotor rotates counterclockwise making a plurality of complete revolutions to drive the piston through a second plurality of pumping strokes. 
     The controller causes the rotor to switch between the first mode and the second mode periodically. 
     The controller causes the rotor to switch between the first mode and the second mode periodically based on a time-based schedule. 
     The controller causes the rotor to switch between the first mode and the second mode based on ceasing supply of electrical energy to the electric motor. 
     The controller causes the electric rotor to switch between the first mode and the second mode based on turning the sprayer on and off. 
     The controller causes the rotor to switch between the first mode and the second mode based on stalling of the rotor. 
     The switch between the first mode and the second mode is based on reaching a locked rotor condition. 
     The controller causes the rotor to switch between the first mode and the second mode based on a rotational speed of the rotor. 
     The controller causes the rotor to switch between the first mode and the second mode based on a parameter of spray fluid measured downstream of the pump. 
     The controller causes the electric rotor to switch between the first mode and the second mode based on the measured parameter not meeting the set pressure within a predetermined period of time even while the piston is reciprocated by the rotor. 
     The parameter is pressure. 
     The controller causes the rotor to switch between the first mode and the second mode based on the measured parameter not meeting a set pressure. 
     The controller causes the electric motor to switch between the first mode and the second mode based on the measured parameter not meeting the set pressure within a predetermined period of time while the piston is reciprocated by the rotor. 
     The controller is configured to deliver driving electric energy to the electric motor when the rotor is stalled due to a resistance of spray fluid applied to the piston at a pressure level and the controller is configured to continue to deliver driving electrical energy to the electric motor so that the rotor is urged forward while the rotor is stalled and so that pressure continues to be applied to the piston through the rotor and the drive and the rotor resumes rotating when spray fluid pressure decreases. 
     The pressure level is set by the user. 
     The rotor resumes rotating when spray fluid pressure decreases below the pressure level. 
     The controller is configured to cease delivering driving electrical energy to the electric motor based on the rotor being stalled for a predetermined period of time. 
     The predetermined period of time is at least five minutes. 
     A fluid sensor configured to monitor a parameter of the spray fluid output by the pump. The controller is configured to monitor the parameter while the controller has ceased delivering driving electrical energy to the electric motor and, based on a change in the parameter, resume delivering electrical energy to the electric motor to rotate the rotor to operate the pump. 
     The controller is configured to cease delivering driving electrical energy to the electric motor based on a sensed temperature of the electric motor or surrounding ambient air. 
     A temperature sensor configured to monitor a temperature of the electric motor and/or surrounding ambient air. 
     The controller causes the electric rotor to switch between the first mode and the second mode based on a parameter of electrical energy being delivered to the motor exceeding a threshold. 
     The parameter is electrical current. 
     The controller causes the electric rotor to switch between the first mode and the second mode based on the measured parameter not meeting the set pressure within a predetermined period of time even while the piston is reciprocated by the rotor. 
     The controller is configured to stall the rotor based on resistance from spray fluid through the rotor. 
     The controller is configured to stall the rotor based on resistance from spray fluid through the rotor at a pressure level. 
     The controller is configured to continue to deliver electrical energy to the electrical motor so that the rotor is urged forward while the rotor is stalled so that pressure continues to be applied to the piston while it is stalled through the rotor and the drive. 
     The controller is configured to continue to deliver electrical energy to the electrical motor so that the rotor is urged forward while the rotor is stalled so that pressure continues to be applied to the piston while it is stalled through the rotor and the drive, and the rotor resumes rotating when spray fluid pressure decreases. 
     The controller is configured to continue to deliver electrical energy to the electrical motor so that the rotor is constantly urged forward while the rotor is stalled so that pressure continues to be applied to the piston while it is stalled through the rotor and the drive and so that the rotor resumes rotating when spray fluid pressure decreases below a pressure level due to the constant urging on the rotor causing the piston to overcome the lower pressure of the spray fluid. 
     While the invention has been described with reference to preferred embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.