Patent Publication Number: US-2020298287-A1

Title: Mobile surface maintenance machine with an onboard pressure washer

Description:
RELATED MATTER 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/822,811, filed Mar. 23, 2019, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present application discloses embodiments of pressure washers and, in particular, embodiments of surface maintenance machines with pressure washers. 
     BACKGROUND 
     Surface maintenance machines can perform maintenance tasks such as sweeping, scrubbing, and polishing (burnishing) a surface. The number of maintenance tasks that a surface maintenance machine is capable of performing can increase the number of components and power consumption requirements of the surface maintenance machine. Thus, while it can be advantageous to have a surface maintenance machine that can perform a variety of maintenance tasks, current surface maintenance machines may be confined in the number of maintenance tasks capable of being performed due to weight and efficiency constraints associated with enabling such tasks. 
     SUMMARY 
     Embodiments disclosed herein can provide a pressure washer that efficiently utilizes resources available at a surface maintenance machine. Such embodiments can allow a mobile surface maintenance machine to incorporate such a pressure washer while maintaining weight, power, size, and other efficiency considerations for the surface maintenance machine. 
     One embodiment includes a mobile surface maintenance machine. This mobile surface maintenance machine embodiment includes a mobile body, a solution tank for containing a supply of a cleaning fluid, wheels for supporting and transporting the mobile body, one or more surface maintenance tools at the mobile body, an output channel, an electric power source, a first electric motor, and a pressure washer. The output channel is fluidly connected to the solution tank. The output channel provides a fluid channel to carry cleaning fluid from the solution tank to a surface on which the one or more surface maintenance tools perform surface maintenance. The electric power source is at the mobile body and includes one or more batteries. The first electric motor is powered by the electric power source. The first electric motor is configured to actuate the one or more surface maintenance tools. The pressure washer includes a spray wand, a pressure pump, and a second electric motor. The spray wand terminates in a nozzle to dispense the cleaning fluid therethrough. The pressure pump is fluidly coupled to the spray wand and to the solution tank. The pressure pump is positioned upstream of the spray wand to supply the cleaning fluid from the solution tank to the spray wand. The pressure pump is configured to pressurize the cleaning fluid supplied to the spray wand. The second electric motor is operatively coupled to and configured to drive the pressure pump. The second electric motor is configured to receive electric power from the electric power source and is commonly powered by the electric power source that provides power to the first electric motor. The second electric motor is separate from the first electric motor. 
     In a further embodiment of this mobile surface maintenance machine, the first electric motor can be one or more electric motors, and the one or more electric motors can be configured to generate torque to rotate the wheels of the surface maintenance machine. 
     In a further embodiment of this mobile surface maintenance machine, the pressure pump can be coupled to the solution tank via a feed pump or via a gravity feed arrangement. 
     In a further embodiment of this mobile surface maintenance machine, the mobile surface maintenance machine can include a motor controller in operative communication with the electric power source and the second electric motor. In one such embodiment, the motor controller can be configured to convert a DC input signal from the electric power source and convert the DC signal to a DC output signal and supply the DC output signal to the second electric motor. In such embodiment, the motor controller can be configured to convert the DC input signal from the electric power source to the DC output signal without converting the DC input signal to an AC signal. 
     In a further embodiment of this mobile surface maintenance machine, the second electric motor can be a totally enclosed non-ventilated type electric motor. 
     In a further embodiment of this mobile surface maintenance machine, the second electric motor can include a motor housing. The motor housing can be liquid-proof to restrict ingress of liquid into the second electric motor. 
     In a further embodiment of this mobile surface maintenance machine, the pressure pump can be configured to pressurize the cleaning fluid to a pressure of at least 1000 psi. For example, the pressure pump can be configured to pressurize the cleaning fluid to a pressure of at least 1000 psi and to enable a cleaning fluid output from the spray wand at a flow rate of two gallons per minute. In another embodiment, the pressure pump can be configured to pressurize the cleaning fluid to a pressure of at least 2000 psi. For example, the pressure pump is configured to pressure the cleaning fluid to a pressure of at least 2000 psi and to enable a cleaning fluid output from the spray wand at a flow rate of two gallons per minute. 
     An additional embodiment includes a pressure washer coupled to a mobile surface maintenance machine. This pressure washer embodiment includes a spray wand, a pressure pump, a feed pump, an electric motor, and a motor controller. The spray wand terminates in a nozzle to dispense a cleaning fluid therethrough. The pressure pump is fluidly coupled to the spray wand and positioned upstream of the spray wand to supply the cleaning fluid to the spray wand. The feed pump is positioned within the mobile surface maintenance machine. The feed pump is fluidly coupled to and located upstream of the pressure pump. The pressure pump receives the cleaning fluid from the feed pump at a first pressure and pressurizes the received cleaning fluid to a second pressure that is greater than the first pressure. The electric motor is operatively coupled to and configured to drive the pressure pump. The electric motor is configured to receive electric power from an electric power source positioned within the mobile surface maintenance machine. The motor controller is in operative communication with each of the electric motor and the pressure pump. The motor controller is operatively coupled with the pressure pump, and the motor controller receives signals indicative of one or more operating conditions of the surface maintenance machine and indicative of one or more operation conditions of the electric motor or the pressure pump. The motor controller is configured to receive current from the electric power source and supply or stop supplying current to initiate or stop, respectively, operation of the electric motor based on the one or more operating conditions of the surface maintenance machine and the one or more operating conditions of the electric motor or the pressure pump. The supplying of current to initiate operation of the electric motor to drive the pressure pump is configured to provide cleaning fluid to the spray wand at the second pressure. 
     In a further embodiment of this pressure washer, the pressure pump and the electric motor are each mounted on a single drive shaft, such that the pressure pump is directly coupled to the electric motor. 
     In a further embodiment of this pressure washer, the motor controller is configured to supply current to the electric motor when at least one of the following conditions are satisfied: if onboard sensors indicate that the mobile surface maintenance machine has the cleaning fluid in a solution tank, if the pressure pump is receiving the cleaning fluid from the feed pump, and if the pressure pump is operational. 
     In a further embodiment of this pressure washer, the motor controller is configured to stop supplying current to the electric motor when at least one of the following conditions are satisfied: if onboard sensors indicate that the mobile surface maintenance machine is being propelled, if the solution tank is empty, if the electric motor is overheating, and if the mobile surface maintenance machine has been stopped in an emergency. 
     In a further embodiment of this pressure washer, the motor controller is housed at a housing, and the housing is configured to dissipate heat from surfaces of the motor controller. In one such embodiment, the housing of the motor controller is in fluid communication with the feed pump and is positioned downstream thereof, such that the cleaning fluid from the feed pump passes through the housing of the motor controller, thereby cooling the motor controller. 
     In a further embodiment of this pressure washer, the electric power source includes one or more batteries, and the motor controller is electrically coupled to the one or more batteries. 
     Another pressure washer embodiment is coupled to a mobile surface maintenance machine. This pressure washer embodiment includes a spray wand, a pressure pump, an electric motor, and a motor controller. The spray wand terminates in a nozzle to dispense a cleaning fluid therethrough. The pressure pump is fluidly coupled to the spray wand and positioned upstream of the spray wand to supply the cleaning fluid received from a fluid source from within the mobile surface maintenance machine. The electric motor is operatively coupled to the pressure pump and configured to drive the pressure pump. The electric motor is configured to receive electric power from an electric power source positioned within the mobile surface maintenance machine. The motor controller is in operative communication with each of the electric power source, the electric motor and the pressure pump, and the motor controller is operatively coupled with the pressure pump. The motor controller is configured to: receive signals from the mobile surface maintenance machine indicative of one or more operating conditions of the mobile surface maintenance machine, receive signals indicative of one or more operating conditions of the electric motor and the pressure pump respectively, determine whether the one or more operating conditions of the mobile surface maintenance machine indicate that the one or more operating conditions of the mobile surface maintenance machine are configured to permit operation of the pressure washer, determine whether one or more operating conditions of the electric motor and the pressure pump indicate that the one or more operating conditions of the electric motor and the pressure pump are configured to permit operation of the pressure washer, and send an output signal to the electric motor. Upon receipt of the output signal from the motor controller, the electric motor receives electric power from the electric power source and drives the pressure pump. 
     In a further embodiment of this pressure washer, the fluid source is a solution tank, and the pressure pump is fluidly coupled to the solution tank and a feed pump. Each of the solution tank and the feed pump can be positioned within the mobile surface maintenance machine. 
     In a further embodiment of this pressure washer, the motor controller is operatively coupled to a pressure switch positioned upstream of the pressure pump. The motor controller is configured to receive a first electrical signal from the pressure switch indicative of fluid being received by the pressure pump from the fluid tank and via the feed pump. In one such example, the motor controller is configured to send the output signal including a second electrical signal to the electric motor if the motor controller determines that the first electrical signal received from the pressure switch indicates that the fluid is received by pressure pump from the fluid tank via the feed pump. Upon receipt of the second electrical signal, the electric motor receives electric power from the electric power source and drives the pressure pump. 
     In a further embodiment of this pressure washer, the motor controller is operatively coupled to a temperature sensor operatively coupled to the electric motor. The motor controller is configured to receive a third electrical signal from the temperature sensor indicative of the temperature of the electric motor to determine if the electric motor is overheating. In one such example, the motor controller is configured to send the output signal including a fourth electrical signal to the electric motor if the motor controller determines that the first electrical signal received from the pressure switch indicates that the fluid is received by pressure pump from the solution tank via the feed pump. Upon receipt of the fourth electrical signal, the electric motor stops receiving electric power from the electric power source and thereby stops driving the pressure pump. In a further example, the motor controller is operatively coupled to a temperature sensor operatively coupled to the electric motor. Here, the motor controller is configured to receive a third electrical signal from the temperature sensor indicative of the temperature of the electric motor to determine if the electric motor is overheating. 
     In a further embodiment of this pressure washer, the motor controller is configured to send the output signal comprising a fourth electrical signal to the electric motor if the motor controller determines that the second electrical signal received from the temperature sensor indicates that the electric motor is overheating. 
     In a further embodiment of this pressure washer, the motor controller is in operative communication with one or more onboard sensors of the mobile surface maintenance machine, to receive electrical signals indicative of at least one of the following: whether the mobile surface maintenance machine is propelling, if the fluid source is empty, if the mobile surface maintenance machine has a pressure washer, and if the mobile surface maintenance machine has been stopped in an emergency stop. 
     In a further embodiment of this pressure washer, the motor controller is configured to send a fifth electrical signal to the electric motor if the motor controller determines that: the pressure pump is receiving the cleaning fluid, the motor temperature is less than preset temperature maximum, or the pressure pump is operational. 
     Another embodiment includes a mobile surface maintenance machine. In this embodiment, the mobile surface maintenance includes a body, wheels for supporting the body for movement over a surface, a fluid source, an electric power source positioned at (e.g., within) the body, a fluid source positioned at (e.g., within) the body, a feed pump, and a pressure washer. The feed pump is in fluid communication with and positioned downstream of the fluid source, and the feed pump is configured to pressurize the fluid in the fluid source to a first pressure. The pressure washer is positioned on an exterior of the body. The pressure washer includes a spray wand terminating in a nozzle to dispense a cleaning fluid therethrough, a pressure pump, an electric motor, and a motor controller. The pressure pump is fluidly coupled to the spray wand and positioned upstream of the spray wand to supply the cleaning fluid to the spray wand. The pressure pump is fluidly coupled to and located downstream of the feed pump, and the pressure pump configured to pressurize fluid received from the feed pump to a second pressure that is greater than the first pressure. The electric motor is operatively coupled to and configured to drive the pressure pump. The electric motor is configured to receive electric power from, and positioned within, the mobile surface maintenance machine. The motor controller is in operative communication with each of the electric motor and the pressure pump, and the motor controller is operatively coupled with the pressure pump. The motor controller is configured to receive current from the electric power source and supply or stop supplying current to initiate or stop, respectively, operation of the electric motor based on one or more operating conditions of the surface maintenance machine and one or more operating conditions of the electric motor and the pressure pump. 
     In a further embodiment of this mobile surface maintenance machine, an entirety of the pressure washer is positioned to the exterior of an outer surface the body. 
     In a further embodiment of this mobile surface maintenance machine, the pressure washer is positioned to the rear of a transverse center plane of the mobile surface maintenance machine. 
     The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective view of a mobile surface maintenance machine (vehicle) according to an embodiment of the present disclosure; 
         FIG. 1B  is a sectional perspective view of the mobile surface maintenance machine of  FIG. 1A  taken along a longitudinal plane through the mobile surface maintenance machine; 
         FIG. 1C  is a perspective view of the mobile surface maintenance machine of  FIG. 1A ; 
         FIG. 1D  is an electrical schematic of certain electrical components according to an embodiment of the present disclosure; 
         FIG. 2  is a perspective view of a pressure washer provided at the surface maintenance machine of  FIGS. 1A-1D  according to an embodiment of the present disclosure; 
         FIG. 3  is a partial interior perspective view of a mobile surface maintenance machine (vehicle) and the pressure washer of  FIGS. 1 and 2 ; 
         FIG. 4  is a schematic that illustrates various components of the pressure washer of  FIG. 2  wherein solid lines indicate fluid coupling, solid lines with arrows indicate flow direction, and dotted lines indicate electrical coupling; 
         FIG. 5  is a perspective view illustrating an electric motor and pressure pump of the pressure washer of  FIG. 2 ; 
         FIG. 6  is a sectional perspective view of a motor controller according to an embodiment of the present disclosure; and 
         FIG. 7  is a control algorithm executed by the motor controller according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1A-1C  are perspective views of an exemplary surface maintenance machine  100  according to an aspect of the invention.  FIG. 1A  is a perspective view of the surface maintenance machine.  FIG. 1B  is a perspective sectional view taken through the longitudinal plane  1 B in  FIG. 1A .  FIG. 1C  is a partial perspective view of the surface maintenance machine in  FIG. 1A . Referring to the illustrated embodiments shown in  FIGS. 1A-1C , the surface maintenance machine  100  is a ride-on machine. During use, an operator may ride the surface maintenance machine  100  in a seated position and sit in the seat in the operator cab  101 . Alternatively, the machine can be a walk-behind or a tow-behind machine. 
     The surface maintenance machine can perform maintenance tasks such as sweeping, scrubbing, polishing (burnishing) a surface. The surface can be a floor surface, pavement, road surface and the like. Embodiments of the surface maintenance machine  100  include components that are supported on a mobile body  102 . The mobile body  102  comprises a frame supported on wheels  103  for travel over a surface, on which a surface maintenance operation is to be performed. The mobile body  102  may include operator controls and a steering control such as a steering wheel  108  such that an operator can turn the steering wheel  108  and control the speed of the surface maintenance machine  100  without having to remove the operator&#39;s hands from the steering wheel  108  using means well-known in the art. Continuing with the illustrated embodiment of  FIGS. 1A-1C , advantageously, controls for steering, propelling, and controlling various operations of the surface maintenance machine  100  can be provided on an operator console  110 . 
     The surface maintenance machine  100  can be powered by batteries  114 . The batteries  114  can be proximate the rear of the surface maintenance machine  100 , or it may instead be located elsewhere, such as within the interior of the surface maintenance machine  100 , supported within a frame, and/or proximate the front of the surface maintenance machine  100 . Alternatively, the surface maintenance machine  100  can be powered by an external electrical source (e.g., a power generator) via an electrical outlet  276  or a fuel cell. 
     The surface maintenance machine  100  includes one or electric motors  112  that are supported on the mobile body  102  and may be located within the interior of the surface maintenance machine  100 . One or more electric motors  112  receive power from batteries  114 . Electric motors  112  supply torque to the surface maintenance machine, including the torque to rotate the wheels  103  in order to propel the surface maintenance machine  100  in a selected direction. Electric motors  112  are one or more electrically powered motors where the mechanical output of the electric motors (e.g., output shaft) provides the torque. 
     The surface maintenance machine  100  includes a maintenance head assembly  116  (sometimes the assembly is referred to as a maintenance head). The maintenance head assembly  116  houses one or more surface maintenance tools  118  such as scrub brushes, sweeping brushes, and polishing, stripping or burnishing pads, and tools for extracting (e.g., dry or wet vacuum tools). For example, the maintenance head assembly  116  is a cleaning head comprising one or more cleaning tools (e.g., sweeping or scrubbing brushes) as surface maintenance tools  118 . Alternatively, the maintenance head assembly  116  is a treatment head comprising one or more treatment tools (e.g., polishing, stripping or buffing pads). Many different types of surface maintenance tools are used to perform one or more maintenance operations on the surface. The maintenance operation can be a dry operation or a wet operation. In a wet operation, fluid, such as cleaning fluid from an on-board solution tank  120 , is supplied to or proximate to the maintenance head assembly  116  where it may be sprayed onto the underlying floor surface. Such maintenance tools include sweeping, scrubbing brushes, wet scrubbing pads, polishing/burnishing and/or buffing pads. Additionally, one or more side brushes for performing sweeping, dry or wet vacuuming, extracting, scrubbing or other operations can be provided. The maintenance head assembly  116  can extend toward a surface on which a maintenance operation is to be performed. For example, the maintenance head assembly  116  can be attached to the base of the surface maintenance machine  100  such that the head can be lowered to an operating position and raised to a traveling position. The maintenance head assembly  116  can be connected to the surface maintenance machine  100  using any known mechanism, such as a suspension and lift mechanism. The torque for the maintenance head may be provided by the one or more electric motors  112 . In an aspect of the invention, different ones of the one or more electric motors provide the torque to propel the machine and provide the torque to actuate components of the maintenance head assembly  116 , such as the one or more surface maintenance tools. 
     Referring to  FIG. 1D , an embodiment of a basic electrical schematic of portions of the surface maintenance machine  100  is shown. As shown, one or more electric motors  112  receive power from batteries  114 , which are batteries in  FIG. 1D . Power may be controlled or regulated via suitable electrical controls, some of which are described herein. Electric motors  112  are operatively connected to one or more of the wheels  103  and/or one or more surface maintenance tools  118 . Electric motors  112  supply torque to the surface maintenance machine, including the torque to rotate the wheels  103  in order to propel the surface maintenance machine  100  in a selected direction. Electric motors  112  supply torque to the maintenance head assembly  116 , in general, and to one or more surface maintenance tools  118 , in particular. Additional components may be inserted between those shown; the electrical schematic merely provides the basic operative connections. 
     Referring back to  FIGS. 1A-1C , in some embodiments, the interior of the surface maintenance machine  100  can include a vacuum system (not shown) for removal of debris from the surface. In such embodiments, the interior can include a on-board solution tank  120  and a fluid recovery tank  122 . The on-board solution tank  120  tank can include a fluid source such as a cleaning or sanitizing fluid that can be applied to the surface during treating operations. In advantageous embodiments, the cleaning or sanitizing fluid can be water. The fluid recovery tank  122  holds recovered fluid that has been applied to the surface and soiled. The interior of the surface maintenance machine  100  can include passageways (not shown) for passage of debris and dirty liquid. In some such cases, the vacuum system can be fluidly coupled to the fluid recovery tank  122  for drawing dirt, debris or soiled liquid from the surface. The vacuum system may comprise a vacuum-assisted squeegee mounted to extend from a lower rearward portion of surface maintenance machine  100 . Fluid, for example, clean liquid, which may be mixed with a detergent, can be dispensed from the on-board solution tank  120  to the floor beneath surface maintenance machine  100 , in proximity to the scrubbing brushes, and soiled scrubbing fluid is drawn by the squeegee centrally, after which it is suctioned via a recovery hose into the fluid recovery tank  122 . Surface maintenance machine  100  can also include a feedback control system to operate these and other elements of surface maintenance machine  100 , according to apparatus and methods which are known to those skilled in the art. 
     In alternative embodiments, the surface maintenance machine  100  may be combination sweeper and scrubber machines. In such embodiments, in addition to the elements describe above, the surface maintenance machine  100  may either be an air sweeper-scrubber or a mechanical sweeper-scrubber. Such a surface maintenance machine  100  can also include sweeping brushes (e.g., rotary broom) extending toward a surface (e.g., from the underside of the surface maintenance machine  100 ), with the sweeping brushes designed to direct dirt and debris into a hopper. In the cases of an air sweeper-scrubber, the surface maintenance machine  100  can also include a vacuum system for suctioning dirt and debris from the surface  120 . In still other embodiments, the surface maintenance machine  100  may be a sweeper. In such embodiments, the surface maintenance machine  100  may include the elements as described above for a sweeper and scrubber surface maintenance machine  100 , but would not include the scrubbing elements such as scrubbers, squeegees and fluid storage tanks (for detergent, recovered fluid and clean liquid). 
     With continued reference to  FIGS. 1A-1C , the mobile surface maintenance machine can be provided with an on-board pressure washer  200 . The pressure washer may be operated to pressure wash an area, for instance, by manually applying pressurized cleaning fluid (e.g., water). For example, the mobile surface maintenance machine may operate upon a surface and treat a surface. During, before or after maintenance of the surface, an operator may drive the mobile surface maintenance machine to a target area, and stop the machine from propelling, and optionally, stop the machine from performing maintenance operation. The operator may then engage the pressure washer to apply pressurized cleaning fluid and wash an area. In some embodiments, the pressure washer can be useful for pressure washing areas that may not be adequately maintained by the surface maintenance machine (e.g., floors that have oil stains). Alternatively, the pressure washer can be useful for washing areas that may not be easily accessible by the surface maintenance machine (e.g., walls, corners, recesses, stairs, etc.). Any use of the pressure washer to apply pressurized cleaning fluid and wash an area can be contemplated, and the use of the disclosed embodiments of the pressure washer is not limited to the examples listed herein. 
     With continued reference to  FIG. 2 , components of the pressure washer can be positioned on an exterior of the body for ease of access by an operator. According to some such embodiments, the pressure washer can be positioned to a rear of a transverse center plane  204  of the machine. In this embodiment, the rear can be opposite to a forward direction  208  of travel of the machine. In the illustrated embodiment, the pressure washer is positioned on a body panel to the rear of the operator cab, however, other locations thereof are contemplated. 
     In further advantageous embodiments, an entirety of the pressure washer (with the exception of one or more of fluid hoses, couplings, electrical wires and connectors) may be positioned on and supported by an exterior surface  210  of the machine. Such embodiments may permit the pressure washer to be located on existing machines (e.g., as a retrofit) without having to reposition or repackage other components of the surface maintenance machine. In the illustrated embodiment, the exterior surface  210  is a top surface of the machine. Alternatively, other surfaces (e.g., lateral surfaces, rear surfaces or other suitable locations) can support the pressure washer. Alternatively, only certain portions of the pressure washer may be positioned on an exterior surface  210  of the machine. 
     As seen in  FIG. 2 , the pressure washer includes a spray wand  220 . The spray wand  220  can be rested in a holster  222  when not in use. Holster  222  may be placed in any convenient location relative to the machine. The spray wand  220  terminates in a nozzle  224  that can dispense the cleaning fluid therethrough. Accordingly, as may be appreciated, the spray wand  220  can include fluid passageways that may be in fluid communication with the nozzle  224 . The fluid passageways can also be in fluid communication with other components of the pressure washer (to be described), and indirectly be in fluid communication with the fluid tank so as to receive cleaning fluid therefrom. The spray wand  220  can include a trigger  226  located opposite to the nozzle  224 . The trigger  226  can be actuated (e.g., by an operator&#39;s thumb and/or fingers) to enable cleaning fluid from the fluid tank to flow (via components of the pressure washer) and through fluid passageways, ultimately exiting the spray wand  220  via the nozzle  224 . The dimensions of the spray wand  220  and the nozzle  224  can be chosen so as to provide a desired pressure for pressure washing operations. A hose  228  may couple to the spray wand  220  near the trigger  226  to move the spray wand  220  to a location away from the machine and engage the trigger  226  to perform a pressure washer. 
     As will be described further below, in advantageous aspects, the pressure washer can be powered by the batteries  114  of the mobile surface maintenance machine. Further, as mentioned above, the pressure washer can use cleaning fluid from the on-board fluid tank. Accordingly, the pressure washer can be fluidly coupled to the on-board fluid tank and a feed pump  232  of the surface maintenance machines.  FIG. 3  illustrates a partial perspective view of the pressure washer. In  FIG. 3 , exterior housing  264  of the pressure washer have been removed to facilitate ease of visualization of components of the pressure washer. As seen in  FIG. 3 , the pressure washer can receive fluid from the on-board fluid tank (best seen in  FIGS. 1A-1C ) via an interior flow channel  230 . In one example, the interior flow channel  230  can be in the form of a hose or a tube.  FIG. 3  also illustrates two output flow channels  278 ,  280  from the feed pump  232 . Output channel  278 , which again may be a hose, feeds cleaning fluid from on-board solution tank  120  to the maintenance head assembly  116  or to a location proximate a surface maintenance tool of the maintenance head assembly  116 . The maintenance head assembly  116  and/or its surface maintenance tool may then provide surface maintenance on a wet floor. Output channel  280 , which again may be a hose, feeds cleaning fluid from the same on-board solution tank  120  towards the pressure washer. 
     With continued reference to  FIG. 3 , the machine can include a feed pump  232  fluidly coupled to the fluid tank. Since feed pump  232  may be a smaller pump, feed pump  232  includes both an electric motor and a feed pump within the same housing. Of course, feed pump  232  may also have an electric motor located outside the housing for the pump. The electric motor can be in electrical communication (e.g., via electric wires) with an batteries  114  (e.g., one or more of the vehicle battery). Alternatively, the electric power source can be an external power source. With reference to  FIG. 3 , the electric motor within feed pump  232  can thus receive electric power from the batteries  114  and may receive cleaning fluid (e.g., water, either alone or in combination with detergent, sanitizer, and the like) from the fluid tank and may pressurize the cleaning fluid to a first pressure. In one aspect of the invention, the feed pump  232  can be replaced with a gravity feed system. That is, if the on-board solution tank  120  is located higher on the machine than the maintenance head assembly  116  and the intake of the pressure washer, then a gravity feed arrangement where gravity is used to supply cleaning fluid from the on-board solution tank  120  may be used to feed cleaning fluid under a lower pressure (e.g., 10 psi) instead of an active pump, such as feed pump  232 . 
     Referring back to the basic electrical schematic of  FIG. 1D , feed pump  232  receives power from batteries  114  via suitable electrical controls that may control or regulate the power to the feed pump  232 . The feed pump  232  then supplies cleaning fluid to the floor and/or, as discussed below, to a pressure pump. The cleaning fluid can be applied to the floor at one or more locations, including the floor surface on which the surface maintenance tools  118  perform surface maintenance (e.g., floor areas scrubbed by scrub brushes). Additional components may be inserted between those shown; the electrical schematic merely provides the basic operative connections to the feed pump  232 . 
     As seen from  FIG. 3 , the on-board solution tank  120  can have one or more onboard sensors ( 233 , best seen in  FIG. 4 ) to verify operation of the fluid tank and/or the feed pump  232 . For instance, in one example, as seen in  FIG. 3 , a fluid tank level sensor  234  can be coupled to the fluid tank, and can monitor the amount of cleaning fluid remaining in the on-board solution tank  120 . The fluid tank level sensor  234  can be in operative communication with the operator console  110  (shown in  FIGS. 1A-1C ) to provide an indication (e.g., as a visual graphical icon on a display in the operator console  110 ) of the level of fluid remaining the fluid tank  120 . The fluid tank level sensor  234  can also indicate if the level of fluid remaining in the on-board solution tank  120  is below a predetermined volume. Further, the fluid tank level sensor  234  can provide an indication (e.g., an electrical signal output, a visual graphical icon on the operator console  110 , audible alarm, and the like) if the on-board solution tank  120  is empty. 
     In additional or alternative embodiments, a feed pump sensor may be coupled to the feed pump  232  to monitor the operation of the feed pump  232 . In an example, the feed pump sensor may monitor pressure of the feed pump  232 , and provide indication of whether the feed pump  232  is in operation. In advantageous aspects, the feed pump sensor  238  may be the same component that may monitor a pressure of a pressure pump  240  (to be described). Alternatively, the feed pump sensor may include other types of sensors that may monitor other quantities of the feed pump  232 , and provide an indication of whether the feed pump is in operation. For instance, the feed pump sensor  238  can provide an indication (e.g., an electrical signal output, a visual graphical icon on the operator console  110 , audible alarm, and the like) if the feed pump  232  is operating. The feed pump sensor  238  can also provide another indication (e.g., an electrical signal output, a visual graphical icon on the operator console  110 , audible alarm, and the like) if the feed pump  232  is not operating. Such embodiments may permit operation of the pressure washer only under certain permissible operating conditions so as to reduce the chances of damage to components of the pressure washer (e.g., if fluid line stops supplying fluid to the pressure pump due to a disconnected hose, and the like). Such embodiments may also permit the use of available resources (e.g., cleaning fluid, electric power from the batteries  114 ) on the mobile surface maintenance machine efficiently. 
     As seen in  FIG. 3 , the pressure washer can include a pressure pump  240 .  FIG. 4  is a schematic that illustrates the positioning of the pressure pump  240  along with associated components of the pressure washer. As seen therefrom, the pressure pump  240  can be fluidly coupled (e.g., via one or more fluid fittings, such as hose barbs, clamps, or other types of fluid connectors) to the spray wand  220  and positioned upstream thereof to supply the cleaning fluid to the spray wand  220 . The pressure pump  240  can be fluidly coupled to and located downstream of the feed pump  232 . The pressure pump  240  can pressurize the cleaning fluid received from the feed pump  232  at a first pressure to a second pressure, the second pressure being greater than the first pressure. Low pressure feeds are typically pressured to about 45 psi. In certain embodiments, the second pressure can be greater than about 1000 psi. In some embodiments, the second pressure can be greater than 2500 psi. The flow rate of the cleaning fluid at these second pressures can be greater than 1 gallon a minute. In some embodiments, the flow rate is greater than 1.5 gallons a minute and may be greater than 2 gallons per minute. 
     In certain embodiments, the pressure pump  240  can be a piston pump that can also be electrically powered by the batteries  114 , as will be described further below. In an embodiment, the pressure pump  240  can generally operate at constant speeds and be powered by an electric motor that rotates at a constant rate of rotation. In some such cases, the pressure pump  240  may deliver a generally constant volumetric flow rate of the cleaning fluid to the spray wand  220 . Alternatively, in other embodiments, the pressure pump  240  can operate at variable speeds and/or provide a variable volumetric flow rate of the cleaning fluid to the spray wand  220 . 
     Referring to  FIGS. 3 and 4 , in advantageous aspects, the pressure washer can include a pressure sensor positioned in fluid communication with the pressure pump  240 . In certain advantageous aspects, the pressure sensor can be the feed pump sensor  238 . The feed pump sensor  238  can measure pressure in the fluid line that couples the pressure pump  240  with the feed pump  232  and to determine whether the pressure pump  240  is receiving the cleaning fluid from the feed pump  232  at acceptable pressures, as further described below. In advantageous embodiments, the feed pump sensor  238  can provide an additional indication of whether the feed pump  232  is supplying cleaning fluid to the pressure pump  240  and ensure that the flow lines connecting the feed pump  232  to the pressure pump  240  are not occluded. 
     The feed pump sensor  238  can, in some cases be a pressure switch  244  that can include electrical circuitry that can be in operative communication with the operator console  110  to provide an indication (e.g., as a visual graphical icon on a display in the operator console  110 , an electrical signal etc.) of the pressure measured by the feed pump sensor  238 . In certain advantageous aspects, the pressure switch  244  can be in electrical communication with the pressure pump  240 , and if the pressure measured by the feed pump sensor  238  is less than a first predetermined pressure, the pressure switch  244  can fluidly and/or electrically communicate with the pressure pump  240  and stop the operation of the pressure pump  240 . Such embodiments can advantageously reduce the chances of damage of the pressure pump  240 , for instance, as a result of running “dry.” 
     With continued reference to  FIGS. 3 and 4 , in one exemplary embodiment, the first valve  246  can be an unloader valve. In such embodiments, if the pressure in spray wand is greater than a second predetermined pressure, the first valve  246  can be actuated to redirect any cleaning fluid in the fluid line back to the fluid tank, and thereby reduce the risk of overpressuring the spray wand (e.g., inadvertent release of the trigger of the spray wand when not in use) and/or damage to the pressure pump  240 . 
     In additional or alternative aspects, as described above, the pressure switch  244  can also be in electrical communication with electric motor (as will be described further below), and stop the operation of the pressure pump  240  (e.g., by sending a signal to a control algorithm as will be described below) such that the pressure pump  240  may not be operated until it receives cleaning fluid at appropriate pressures. 
     Alternatively, the feed pump sensor  238  can be a pressure transducer. In such embodiments, some or all of the functionalities described above with respect to the pressure switch  244  may be performed by the pressure transducer. Additional electrical components, such as switches can be provided in such cases to shut off operation of the pressure pump  240  in the event that the measured pressure upstream of the pressure pump  240  is less than the first predetermined pressure. 
     In certain optional embodiments, as seen in  FIGS. 3 and 4 , the pressure washer also includes additional fluid components such as valves or pressure regulators that can reduce the chances of the cleaning fluid from being overpressurized. As seen from  FIGS. 3 and 4 , the pressure washer can include a second valve  248 . The second valve  248  can be in fluid communication with the pressure pump  240 . The second valve  248  can vent and/or redirect fluid back to the fluid tank in the event of the pressure in the fluid line (as measured by the feed pump sensor  238 ) exceeding the second predetermined pressure. 
     As seen from  FIGS. 3 and 4 , an electric motor  250  can be operatively coupled to and configured to drive the pressure pump  240 . The electric motor  250  can receive electric power from the batteries  114  positioned within the mobile surface maintenance machine. Accordingly, one or more electrical cables  252  can operatively connect and/or establish operative communication between the batteries  114  and the electric motor  250 . Advantageously, the electric motor  250  may be a dedicated motor and separate from other electric motors that drive other components (e.g., wheel, surface maintenance tools) of the surface maintenance machine. The surface maintenance machine may, however, have a common electric power source (array of batteries) to power all the electric motors on the machine, including the electric motor  250 . 
     In an embodiment, the electric motor  250  can be a brushed or brushless, totally enclosed non-ventilated DC motor. In some such embodiments, the electric motor may have a motor housing that is liquid proof to reduce the chances of liquid ingress. Such a liquid proof motor prolongs the lifespan of the electric motor if it is positioned on and supported by an exterior surface  210  of the machine, as described above, such as on the top surface of the machine. At such a location, the electric motor  250  is likely to be sprayed with cleaning fluid. Alternatively, other types of electric motors that can provide motive power (e.g., torque) to drive the electric pump can be contemplated without loss of functionality. In another aspect, a liquid-cooled motor is used as the electric motor  250 . In one aspect, a fan-cooled motor is used as the electric motor  250 . The fan-cooled motor may be located on an exterior surface  210  of the machine, as described above, or in an interior location of the machine. In some such designs, baffles or other obstructions may be added to help deflect liquids and prevent them from contacting the fan-cooled motor. 
     With continued reference to  FIG. 3 , in an embodiment, the pressure pump  240  and the electric motor  250  may be directly coupled so as to efficiently package components of the pressure washer. Accordingly, a direct coupling between the pressure pump  240  and the electric motor  250  may be established through a drive shaft  254 , as shown in  FIG. 5 . As seen therefrom, the electric motor  250  has a drive shaft  254  that may be directly coupled to the pressure pump  240 . Couplings (e.g., flanges with fasteners as shown in  FIG. 5 ) may provide a frictional connection between the pressure pump  240  and the electric motor  250 . In some such embodiments, the drive shaft  254  may optionally be keyed to facilitate ease of assembly and positioning of the pressure pump  240  to the electric motor  250 . 
     In certain embodiments, the electric motor  250  can draw a current of between about 50 amperes and about 100 amperes (e.g., about 85 amperes). Further, in some such embodiments, the electric power source (e.g., batteries  114  or external power source) may have a voltage output between 30 volts and about 40 volts (e.g., about 35 volts). The electric motor  250  may, in some embodiments have a power rating of between about 2 horsepower and about 10 horsepower (e.g., about 6 horsepower). In some such embodiments, the electric motor  250  may receive electric power when a certain set of operating parameters are met, so as to optimize usage of the onboard resources (e.g., electric power and cleaning fluid). For instance, the electric motor  250  may receive electric power when the batteries  114  is not providing power to propel the mobile surface maintenance machine, and/or to perform one or more operations. Such embodiments may advantageously ensure that the amount of power available from the batteries  114  is sufficient to meet the power requirements of the electric motor  250 . 
     As best seen in  FIG. 4 , according to some aspects a temperature sensor  256  may be in operative communication with the electric motor  250 . In some embodiments, the temperature sensor  256  may be mounted on to a component of the electric motor  250  (e.g., directly on to the windings, on the motor housing  264 , and the like). The temperature sensor  256  may measure the temperature of the electric motor  250  during operation, and the measured temperature can be used to determine whether the electric motor  250  is being overheated according to an embodiment of the present disclosure. 
     In alternative or additional embodiments, the electric motor  250  can be operatively coupled to (e.g., by wired connection) to a current sensor. The current sensor may monitor the amount of current drawn by the electric motor  250 . The measured current can be used to determine whether the electric motor  250  is being overheated according to additional or alternative embodiments of the present disclosure. 
     As seen from  FIGS. 3 and 4 , the pressure washer can include a motor controller  260  that can be in operative communication with one or more components of the pressure washer. In the illustrated embodiment, for instance, the motor controller  260  is in operative communication with each of the electric motor  250  and the pressure pump  240 . Referring again to  FIG. 1D , motor controller  260  is shown in operative communication with the electric motor  250 , pressure pump  240 , and batteries  114 . Additionally, or alternatively, the motor controller  260  may also be in direct operative communication with the batteries  114 . As shown, pressure pump  240  receives cleaning fluid from feed pump  232 . Additional components may be inserted between those shown; the electrical schematic merely provides the basic operative connections to the pressure pump  240 . 
     Additionally, or alternatively, the motor controller  260  may also be in direct operative communication with the batteries  114 . Additionally, the motor controller  260  may be in operative communication with one or more onboard sensors  233 , such as the fluid tank level sensor  234  coupled to the fluid tank that monitors the amount of cleaning fluid remaining in the fluid tank. The motor controller  260  may be in operative communication with the feed pump sensor  238  that can monitor the operation of the feed pump  232 . Further, the motor controller  260  may also be in operative communication with the feed pump sensor  238  that can measure pressure in the fluid line that couples the pressure pump  240  to the feed pump  232 . In addition, the motor controller  260  may also be in communication with the temperature sensor  256  or current sensor that can monitor motor temperature or current draw to determine whether the electric motor  250  is being overheated. 
     In aspects of the present disclosure, operative communication between the motor controller  260  and one or more of the electric motor  250 , the pressure pump  240 , the batteries  114  and the sensors described herein may be direct (e.g., by electrical wires) or indirect (e.g., no direct electrical coupling between sensors and motor controller  260 ) connection with each other. 
     In some embodiments, the motor controller  260  can be a permanent magnet motor controller  260  with a power rating capable of handling the current drawn by the motor. In some embodiments, the electric motor  250  may draw between about 85 amperes and about 90 amperes, as described previously. Accordingly, in such embodiments, the permanent magnet motor controller  260  may have a power rating of at least twice the current drawn by the motor. In one embodiment, the motor controller  260  may have a power rating of about 200 amperes. 
     Referring back to  FIG. 4 , the motor controller  260  is housed on a housing  264 . In certain advantageous embodiments, the housing  264  can dissipate heat from surfaces of the motor controller  260 . Accordingly, in certain aspects, the housing  264  can include (e.g., be fabricated from) a material that has a generally high thermal conductivity so as to rapidly dissipate heat from surfaces of the motor controller  260 . In one example, the housing  264  can include (e.g., be fabricated from) aluminum. Materials having thermal conductivity generally in the same order of magnitude as aluminum are also contemplated. 
     In additional or alternative aspects, the motor controller  260  can be cooled by directing the cooling fluid through a flow passage  268  therethrough. Accordingly, in such embodiments, the motor controller  260  can be in fluid communication with the feed pump  232  to receive cleaning fluid therefrom which can cool the motor controller  260 .  FIG. 6  is a sectional perspective view of the housing  264  of the motor controller  260 . As seen therefrom, the housing  264  comprises a flow passage  268  extending through the housing  264 . The flow passage  268  can be a “through-passage” and can extend substantially along an entire dimension (e.g., length, width, thickness and the like) of the housing  264 . In the illustrated embodiment, the flow passage  268  extends lengthwise along the housing  264 . 
     With continued reference to  FIG. 6 , the flow passage  268  can have an inlet  272  and an outlet  276 . The inlet  272  can be fluidly coupled (e.g., via hose  280  and barb fittings  282 ), to the feed pump  232 . The inlet  272  of the flow passage  268  can be positioned downstream thereof, such that the cleaning fluid from the feed pump  232  passes through the inlet  272  of the flow passage  268 , enters the flow passage  268  and passes through the housing  264 . The outlet  276  of the flow passage  268  can be in fluid communication with the pressure pump  240  and/or components such as pressure sensors, etc. Accordingly, the cleaning fluid (e.g., pressurized water) can flow through the housing  264  of the motor controller  260  prior to entering the pressure pump  240 , thereby cooling the motor controller  260 . 
     In advantageous aspects, the motor controller  260  can be a programmable motor controller  260 , a programmable computer such as a microprocessor, a programmable logic controller, and the like, and can include (and/or be in communication with) on-board or remote non-transitory storage media for storing instructions in the form of algorithms and/or data. The controller can also be application specific integrated circuits (ASICs), microcontrollers, microprocessors, field-programmable gate arrays (FPGAs), or any other appropriate structure capable of receiving and processing data, as well as, circuitry distributed across a network to receive and process data and control system operation as described herein from a remote location. In aspects of the present disclosure, the motor controller  260  may receive electrical signals from one or more sensors described herein and can execute one or more control algorithms disclosed herein to initiate supply of electric power or stop supply of electric power to the electric motor  250 . 
     In certain aspects of the disclosure, the motor controller  260  can regulate the supply of electric power to the electric motor  250 . Accordingly, the motor controller  260  can be configured to receive current from the batteries  114  and supply or stop supplying current to initiate or stop operation of the electric motor  250  respectively, based on one or more operating conditions of the surface maintenance machine and/or one or more operating conditions of the electric motor  250  and the pressure pump  240  according to control algorithms. 
     As noted, the regulation and/or start and stop of current flow to the electric motor  250  can be provided by the motor controller  260 . In one embodiment, the motor controller  260  may convert a DC input signal from the batteries  114  to a DC output signal to drive the electric motor  250 . Advantageously, the motor controller  260  may not convert the DC input signal to an AC signal and instead may directly convert the DC input signal to a DC output signal, unlike conventional power circuits in surface maintenance machines, thereby improving power conversion efficiency. In some embodiments, the motor controller  260  may generate DC output signals in the form of pulse width modulated (PWM) signals to provide current flow over a desired duty cycle (e.g., 50%, 75%, etc.) Such embodiments may advantageously provide control of motor parameters (e.g., including speed) via the PWM signals. Moreover, in instances where the DC voltage provided by the power source fluctuates, such as where the power source is provided by batteries, the motor controller  260  may modify the duty cycle of its PWM output in order to try and provide an effective output voltage that remains consistent. The consistent effective output voltage from motor controller therefore controls the speed of the electric motor  250  to a generally constant speed. 
     As described previously, aspects of the present disclosure may also include a control algorithm  300  to determine whether the motor controller  260  can start or stop supply of electric current to the electric motor  250 .  FIG. 7  shows a non-limiting exemplary embodiment that can be executed by the motor controller  260 . At step  302 , the motor controller  260  can receive one or more sensor inputs.  FIG. 7  provides a non-exhaustive list of sensors, one or more of which may be provided on the vehicle or on the pressure washer. For example, the vehicle may include a sensor (e.g., an optical encoder, accelerometer, and the like) that may send a signal to the motor controller  260  to indicate whether the vehicle is in motion and/or performing a surface maintenance operation. Additionally or alternatively, the vehicle may have a vehicle computer that controls operation of the vehicle that can be in operative communication with the motor controller  260  to provide information indicative of whether or not the vehicle is propelling, or if the vehicle is performing a surface maintenance operation or if the vehicle is stopped, whether the vehicle is in an emergency stop. 
     Further, additional sensors, such as a fluid tank level sensor  234  measuring of a level of cleaning fluid in the cleaning fluid tank, and a feed pump sensor  238  measuring of operation of the feed pump  232  may send electrical signals to the motor controller  260  indicative of the level of cleaning fluid in the cleaning fluid tank, and operation of the feed pump  232 . Additionally, the feed pump sensor  238  of the pressure washer and the temperature sensor  256  of the electric motor  250  can also communicate with the motor controller  260  by sending one or more electrical sensors indicative of whether the cleaning fluid is at adequate pressure to run the pressure pump  240  and whether the electric motor  250  is overheating, respectively. The motor controller  260  may use the sensor inputs to decide whether to enable operation of the electric motor  250  by supplying electric power from the power electric source. Additional or alternative embodiments may provide sensors or circuits to determine whether the battery has enough stored energy to complete a pressure washing operation. Additional or alternative embodiments may also include sensors or circuits to determine if the motor controller (in addition to or instead of the motor) is overheating and/or if there is an under-voltage or an over-voltage condition. 
     With continued reference to  FIG. 7 , the motor controller  260  can receive signals from the mobile surface maintenance machine indicative of one or more operating conditions of the mobile surface maintenance machine. The motor controller  260  can also receive signals indicative of one or more operating conditions of the electric motor  250  and the pressure pump  240  respectively. The motor controller  260  can determine whether the one or more operating conditions of the mobile surface maintenance machine indicate that the one or more operating conditions of the mobile surface maintenance machine are configured to permit operation of the pressure washer. Further, the motor controller  260  can also determine whether one or more operating conditions of the electric motor  250  and the pressure pump  240  indicate that the one or more operating conditions of the electric motor  250  and the pressure pump  240  are configured to permit operation of the pressure washer. 
     Accordingly, at step  304  the motor controller  260  determines, based on signals received from the vehicle computer or one or more sensors, whether the machine has an onboard pressure washer. At step  306 , the motor controller  260  can determine, based on signals received from the vehicle computer or one or more sensors whether the vehicle is propelling and/or performing a surface maintenance operation. At step  308 , the motor controller  260  can determine, based on signals received from the vehicle computer or one or more sensors, whether the vehicle is stopped in an emergency stop. At step  310 , the motor controller  260  can determine, based on signals received from the fluid tank level sensor  234 , whether the fluid tank is empty. At step  312 , the motor controller  260  can determine, based on signals received from the feed pump sensor  238 , whether the feed pump  232  is operational. 
     In alternative or additional embodiments, steps  302  to  312  may be performed by a vehicle controller. At optional step  314 , an enable signal may be generated by the vehicle controller and sent to the motor controller  260 , when one or more of the following conditions are met: if the onboard sensors indicate that the mobile surface maintenance machine is not being propelled or not performing a surface maintenance operation, if the vehicle is not parked in an emergency stop, if the solution tank is not empty, if the feed pump  232  is operating. At optional step  318 , an enable signal may not be sent to the motor controller  260 , when one or more of the following conditions are met: if the onboard sensors indicate that the mobile surface maintenance machine is being propelled, or performing a surface maintenance operation, or if the vehicle is parked in an emergency stop, if the solution tank is empty, if the feed pump  232  is not operating. 
     Continuing with the exemplary algorithm of  FIG. 7 , at step  320 , the motor controller  260  can determine, based on signals received from the feed pump sensor  238 , whether the pressure pump  240  receives the cleaning fluid at an adequate pressure upstream thereof. At step  322 , the motor controller  260  can determine, based on signals received from the temperature sensor  256 , whether the electric motor  250  is overheating. The motor controller  260  can start supplying at step  324  current to the electric motor  250  when one or more of the following conditions are satisfied: if the onboard sensors indicate that the mobile surface maintenance machine is not being propelled, or if the machine is not performing a surface maintenance operation, or if the vehicle is not parked in an emergency stop, if the solution tank is not empty, if the feed pump  232  is operating, if the pressure pump  240  receives cleaning fluid at adequate pressures, and optionally, if an enable signal is received (e.g., at step  314 ). At step  328 , the motor can controller stop supplying current to the electric motor  250  when one or more of the following conditions are satisfied: if the onboard sensors indicate that the mobile surface maintenance machine is being propelled (and/or performing a surface maintenance operation), or if the machine is performing a surface maintenance operation, or if the vehicle is parked in an emergency stop, if the solution tank is empty, if the feed pump  232  is not operating and optionally, if an enable signal is not received (e.g., at step  318 ). 
     Optionally, the motor controller  260  can send an output signal to the electric motor  250 , whereby, upon receipt of the output signal from the motor controller  260 , the electric motor  250  receives electric power from the batteries  114  and drives the pressure pump  240 . The output signal can be in the form of modulated signals (e.g., pulse width modulated signals) and can regulate (e.g., duty-cycle) current supply to the electric motor  250 . Upon receipt of the signal, the electric motor  250  may generate torque and drive the pressure pump  240 , thereby generating pressurized cleaning fluid to be dispensed through the spray wand  220  for a pressure washing operation. 
     Embodiments of the present disclosure provide one or more advantages. In certain embodiments, an entirety of the pressure washer (with the exception of fluid hoses, couplings, and electrical wires and connectors) may be positioned on and supported by an exterior surface  210  of the machine and may use resources already available on existing surface maintenance machines. Such embodiments may permit the pressure washer to be located on existing machines (e.g., as a retrofit) without having to reposition or repackage other components of the surface maintenance machine. Further, control algorithms according to exemplary embodiments of the present disclosure ensure that the amount of available resources (e.g., electrical power and cleaning fluid) is optimally used.