Abstract:
A pump suitable for use with contamination-sensitive fluids such as food products or pharmaceutical fluids includes an outer casing containing an internal cavity, the outer casing having an enlarged opening on one end, a second opening on an opposite end, a first inlet port and a first outlet port. The internal cavity has pumping parts disposed substantially within the cavity, the pumping parts comprising end blocks each having a drive and idler shaft support, a drive shaft and an idler shaft, a plurality of pumping wheels, and a center block with an internal cavity defining a pumping chamber. The enlarged opening of the outer casing is sealed by an end cap, an elastomeric seal and a quickly removable industry-standard clamp. The second opening of the outer casing is provided for the drive shaft and is sealed by an elastomeric shaft seal. The pumping wheels are rotationally active with, but not axially retained, on respective support shafts and are substantially free to slide on their respective axes.

Description:
FIELD OF THE INVENTION 
   The invention relates to a pump designed for pumping materials over a wide range of viscosities and is particularly advantageous when pumping contamination-sensitive fluids. More particularly, the invention also extends to a pump which can be mounted at any convenient rotary angle that is substantially coaxial with the drive shaft. 
   The invention also relates to a pump which essentially contains no threaded fasteners. 
   The invention further extends to a pump where the internal functioning components are substantially free to find the position of least communication with the pumping wheels that are disposed substantially in the pumping chamber. 
   BACKGROUND OF THE INVENTION 
   Gear pumps enjoy wide acceptance in many fluid pumping applications. To drive a gear pump, it suffices to impart rotary movement to one of the pumping wheels through the drive shaft and coupling connecting to a prime mover, such as an electric motor. The rotary motion will be transmitted to the idler shaft through the arrangement of meshing projections disposed on the pumping wheels and the engaging surface between the pumping wheels and both shafts. In many instances where such pumps are used, it may be desirable to orient the inlet and outlet ports on the pump casing to suit a wide variety of product handling configurations where the product supply reservoir may be positioned in a variety of locations along some vertical axis with respect to the actual position of the pump. Typical configurations would include placement of the reservoir above or below the pump as the situation dictates. 
   When pumping contamination-sensitive fluids such as food products or pharmaceutical fluids, it is also commonly required to disassemble, clean and reassemble the pump on a daily, if not more, basis. A pump that can be quickly dismantled, easily cleaned and rapidly brought back into service would present itself as being particularly advantageous. Functioning surfaces that are in contact and move relative to each other tend to produce unwanted particulates abraded from those surfaces. It is desirable to minimize the production of unwanted particulates, and as such, a pump whose functioning components are able to find the position of least communication with each other within the pump would be advantageous. 
   Where possible, it would also be advantageous to substantially transfer various abrasion producing forces to a member exterior to the pump casing. It is also desirable to have a gear pump with a limited number of ingress points to minimize possibilities for contamination of the sensitive fluids that are typically handled in food and pharmaceutical packaging environments. 
   A functioning gear pump must contain certain elemental features. These features can be present in a wide variety of configurations that may reflect the application, cost considerations and experience of the designer. In most gear pump designs, there is typically a need for one or more pumping wheels, a means for transferring rotational forces from a prime mover to at least one pumping wheel, a means for providing support and a guide for at least one shaft on which at least one pumping wheel is disposed, a means for maintaining a separation between the fluid being pumped and outside contaminants, a means for keeping the various members assembled and a means for maintaining a preferred alignment of the functioning members. 
   Conventional so-called gear pumps in existence typically handle the required internal functions in a wide variety of ways. However, they tend to include the need for threaded fasteners, integrally applied to hold the various pump components in a preferred relationship to each other. This method of construction where through bolts or threaded rods go through various machine members is often referred to as ‘tie-rod’ assembly, and is quite common in pneumatic and hydraulic cylinder assembly where one or more threaded rods are used to effect end cap retention on a cylinder. 
   An example of this kind of pump with ‘tie-rod’ construction would be the ‘Steripump’, which is sold by Nova Packaging Systems, 7 New Lancaster Road. Leominster, Mass. 01453. This pump features a plurality of stacked wafers that include end blocks, end caps and a member disposing a gear chamber. The assembly is held together with three threaded fasteners that go through the various wafers that make up the pump assembly. The issues associated with this mode of construction include a plurality of exposed circumferential gaps between the wafers that require the need for multiple o-ring face seals between adjacent wafers. The wafers themselves each require three openings for the passage of the threaded fasteners. With this type of construction there are associated assembly, disassembly and cleaning issues. If there is a deviation from the intended geometry of the pump components, tie-rod construction may inadvertently force pump members to possibly attain a location within the bolted-together stack of components which may not be the location of least communication between the members. As well, a further result of possible misalignment of the pumping chamber with respect to the pumping wheels would be friction that may tend to abrade one or more of the surfaces in contact to produce unwanted particles from those surfaces. Those particles would undesirably mix with the fluid being pumped. 
   One of the goals of the current invention is to minimize the production of particles abraded from the working surfaces of the pumping components. 
   Conventional gear pump bodies are typically mounted to the prime mover in a restricted single orientation that may limit the possible configurations of the inlet and outlet ports. 
   It is a further goal of this invention to allow the user to conveniently orient the pump housing to suit the configuration requirements of the fluid pumping situation at hand. 
   Once again, referencing the ‘Steripump’ from Nova Packaging Systems, that particular gear pump can be mounted in only the configuration that is arranged by the factory at the time of ordering the pump. One arrangement offered in their ‘Fillit’ machine offers a substantially bottom inlet port and another model, the ‘Power Fillit’ offers a substantially top inlet port. Modification of the factory-supplied arrangement by the user to suit a different supply reservoir arrangement would require extensive and impractical modifications to the host machine. 
   U.S. Pat. No. 5,755,566 Marsillo, et al. entitled ‘Self Driving Fluid Pump’, discloses an innovative pumping wheel configuration disposed in an arrangement of parts substantially held together by a ‘tie-rod’ arrangement of bolts. From the ‘Description of Preferred Embodiments’ in U.S. Pat. No. 5,755,566 we read: “The housing  12  includes a central portion  22  that is integrally formed with the inlet port  13  and with the outlet port  16 . A top cover  24  and the bottom cover  26  are mounted on respective sides of the central section  22  by using suitable fasteners such as bolts  27 . The top cover  24  differs from the bottom cover  26  by the provision of an aperture to accommodate the rotary shaft  18 . This arrangement allows the pump  10  to be easily disassembled, simply by removing the bolts  27  in order to gain access to the internal mechanism for cleaning or maintenance.” 
   Swiftpack-King, Swiftpack House, 3 Arden Road, Arden Forest Industrial Estate, Alcester, Warwickshire, UK., offers their ‘King’ pump which features a similar threaded tie rod construction, this time with 2 threaded rods on either end of a member disposing a gear chamber through which the threaded rods do not pass. The member disposing the gear chamber is however rigidly maintained by tie rod assembly at some potentially variable location between the end blocks that are positioned on either side of the member disposing the gear chamber and pressed against the member disposing the gear chamber. This method of assembly may force the member disposing the gear chamber into a non-minimal cooperation with other members of the functioning gear pump assembly. The ‘King’ pump as well features pumping wheels that are pinned to their support shafts. In addition to previously mentioned issues with this construction, the pinned construction arrangement may present itself as a potential cleaning issue as there may be a requirement in some pumping applications to disassemble the pumping wheels for thorough cleaning during product change-overs and end of run conditions. A gear pump with fewer seals would also be advantageous and would constitute a significant improvement in terms of reducing potential leaks and possible ingress of unwanted materials. The prime mover side retaining end block of the ‘King’ pump assembly is threaded in two locations and the front end plate has clearance holes for passing the threaded tie rods. The two end caps each require o-ring face seals to prevent leakage and to reduce ingress of unwanted contaminants. This pump also features removable inlet and outlet port assemblies which require additional seals for containment of pumped liquid. Finally there is the drive shaft seal. In total, this pump requires five elastomeric seals for normal operation. As elastomeric seals are selected to be compatible with the chemical characteristics of the fluid products being pumped, it is necessary to have available an assortment of elastomeric seals molded from various compounds as each situation dictates. 
   Conventional gear pumps typically feature some alignment mechanism such as one or more alignment pins or reference marks, to ensure a preferred functioning alignment of the various required pump elements. This can be a source of error and damage when incorrectly assembling the pumps for preferred operation. The alignment pins require corresponding recesses. Both pins and recesses can be quite small. The pins can be easily lost or misplaced. The recesses are also an issue when it comes to cleaning or servicing the pump. It is a further goal of the current invention to provide a pump assembly where a single alignment element, an extended bushing, acting in communication with a receiving recess disposed in the pump body and coaxial with the drive shaft opening, is substantially the only alignment mechanism required to ensure that the pump has been assembled in the preferred manner. 
   OBJECTIVE AND STATEMENT OF THE INVENTION 
   An object of the present invention is to provide a pump that overcomes or at least alleviates the deficiencies associated with prior art devices. 
   A further object of the present invention is to provide a pump with increased suitability for use with contamination-sensitive fluids as may be encountered in the pharmaceutical or food processing industries. 
   A further object of the present invention is to provide a pump that can be oriented in any rotational position about the axis of the drive shaft to easily adapt to any required orientation of the inlet and outlet ports. 
   A further object of the present invention is simplified construction where the operational parts of the pump are encased inside a separate containment vessel, a sealable chamber that has a minimum number of openings and requirements for seals. 
   A further object of the present invention is to provide a gear pump that does not require threaded fasteners for assembly and operation. 
   A further object of the present invention is to provide a gear pump where certain internal members are able to find their position of least communication to reduce internal friction that may lower production of unwanted particles. 
   A further object of the present invention is to have a gear pump where the preferred alignment of the various members is not dependent on extra members not central to the actual functioning of the gear pump, such as added alignment pins or reference marks. 
   As embodied and broadly described herein, the invention provides a pump comprising: a casing having an internal cavity where the casing acts as a containment vessel, a protected functional pumping assembly separated from outside variables such as unwanted contaminants, a plurality of internal sections whose relationship is to provide the substantial functionality of a gear pump, an arrangement on the exterior of the pump casing substantially coaxial with the drive shaft, that permits mounting and running the pump with any rotational orientation of the main pump body along the axis of the drive shaft, an extended drive shaft support wear bushing that acts as an alignment mechanism to preferably maintain at least one of the internal functioning pump components in a preferred axis to the pump casing, a first inlet port on the pump casing for admitting fluid into the pump casing, a first outlet port on pump casing for discharging fluid from the internal pumping chamber member, a second inlet port on the internal pump chamber member to permit fluids to enter pumping chamber, a second outlet port on internal pumping chamber for discharging pumped fluid from pumping chamber, a first and second pumping wheels mounted for rotation in the pumping chamber about spaced apart rotation axes, each pumping wheel including a set of angularly spaced projections located in a generally common plane, the set of projections of one pumping wheel being in a condition of mesh with the set of projections of the other pumping wheel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Detailed descriptions of preferred embodiments of the invention are provided herein with reference to the following drawings, in which: 
       FIG. 1  is a side elevation view of an assembled pump in accordance with the invention. It illustrates the relative positions of the components disposed within the cavity of the pump body and the rotary union arrangement between the gear pump casing and the docking plate that receives the pump casing at any rotational angle about an axis substantially along the drive shaft axis. 
       FIG. 2  is an exploded view of the pump with the internal components shown along their functioning axes. 
       FIG. 3  is a view of the drive shaft member and idler shaft member illustrating the sliding and engaging mechanism for the pumping wheels. 
       FIG. 4  is an exploded view of the pump casing and the end block support closest to the drive shaft opening disposed in the pump casing. The drawing illustrates the communication between the extended bushing disposed in the first end block and the receiving recess in the pump casing for a section of protruding extended bushing for substantially maintaining the alignment of the first end block within the pump housing. 
       FIG. 5  illustrates the communication of the pump drive shaft to the bearings of the prime mover and how the motor output shaft and pump drive shaft are fully inserted into the coupling to provide a close communication between members. 
   

   In the drawings, preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention. It should also be pointed out that the pump can be used for transporting materials other than contamination sensitive substances without departing from the spirit of the invention. 
   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring now to the drawings,  FIG. 1  illustrates a pump constructed in accordance with the present invention that is particularly well suited for pumping contamination sensitive fluids.  FIG. 1  further illustrates a housing  11 , preferably made of stainless steel to be compatible with regulations concerning the handling of products intended for human consumption. The pump housing  11 , substantially acting as a containment vessel for the pump members  18 - 35  disposed within pump housing  11  and substantially disposing first end block  23 , middle block  25 , second end block  24  and first rotary union  46  disposed on the pump casing  11 . Second receiving rotary union  47  is disposed on the docking plate  44 . It is possible to implement the mounting of rotary union  46  at any rotational position to receiving rotary union  47  and then secure the assembly in the preferred orientation with an industry standard circumferential clamp  48  that draws the two halves of the rotary union close enough to prevent relative movement between members  46  and  47  until it is desired to loosen clamp  48  and re-orient the pump casing  11  with respect to the docking plate  44 . 
     FIG. 1  also illustrates the extended bushing  18 , being received by recess  38  in the pump casing  11 , extended bushing  18  acting to substantially maintain end block  23  and any members cooperating with end block  23  in a preferred parallel alignment with the axis  15  of drive shaft  27 . 
     FIG. 2  illustrates an exploded view of the pump designated generally by numeral  10  which includes a housing  11 . From the pump housing  11  projects an inlet port  12  for admitting material into the pump casing  11 , and an outlet port  13 , for discharging pumped material. 
     FIG. 2  further illustrates the cooperation between drive shaft  27 , drive shaft axis  15 , idler shaft  22 , idler shaft axis  29 , with the first end block  23  and second end block  24  is substantially sufficient to maintain the internal members of the pump members  18 - 35  in a preferred functional alignment and for first end block  23 , second end block  24  and middle block  25  to rotate about the drive axis  15  within the available pump cavity  17  to find their position of least communication. This technique eliminates the need for separate alignment means which may include independent alignment pins or alignment reference marks disposed on various pump members and allows for a substantial degree of cooperative self-positioning of the functional members within the pump housing about the drive shaft axis  15 . 
   Protruding from pump casing  11 , through drive shaft opening  37 , is drive shaft  27 , that is supported and guided by the extended bushing  18  disposed in first end block  23  and by wear bushing  28 , disposed in end block  24 . 
   Disposed on drive shaft  27 , is a first pumping wheel  20 , which through intermeshing means provides a rotational force to idler pumping wheel  21 . 
   Disposed on the drive shaft  27  is a suitable coupling  43  for connection to an electric motor (not shown in the drawings). The electric motor is provided to impart rotary movement to the drive shaft  27  in order to drive the internal pumping mechanism as it will be described below. 
     FIG. 2  further illustrates that middle block  25  disposing gear chamber  31  and inner chamber surface  32 . Other than being disposed in the pump body cavity, middle block  25  cooperates with, but is not attached to any members of the pump members  18 - 35 . The free floating nature of the middle block  25  permits block  25  to self-orient and attain a least co-operational position within pump  10 , thereby achieving a substantially lower level of rotary resistance than that of a more movement restricted middle member  25  that may have been incorrectly positioned and locked into a non-preferable location as may be effected in other ‘non-floating’ designs. The rotary resistance becoming a source of unwanted abrasion of the members that are in intimate contact and contributing to the unwanted production of particles abraded from the surfaces in contact. 
   The first inlet port  12  disposed on the pump casing  11  is in cooperation with the second inlet port  33  disposed in the middle member  25 . The first outlet port  13  disposed on the pump casing  11  is in cooperation with the second outlet port  34  disposed in the middle member  25 . Thus, the second inlet port  33  on the middle member  25  admits fluid into pumping chamber  31  for purposes of being pumped by pumping wheels  20 ,  21  around the internal surface  32  of the pumping chamber  31 , to the second outlet port  34  disposed in the middle member  25 . 
   Re-meshing of the pumping wheels  20 ,  21  substantially near second outlet port  34  serves to squeeze the transferring product out of the interprojection spaces  35   n  between the pumping wheel projections  30   n.    
   Since the first inlet port  12  on the pump casing  11  cooperates with the second inlet port  33  and the first outlet port  13  on the pump casing  11  cooperates with the second outlet port  34  disposed in middle member  25 , fluids are eventually transferred from the first inlet port  12  on the pump casing  11  to the first outlet port  13  on the pump casing  11  when pump  10  is in preferred operation. 
     FIG. 2  also illustrates the relationship of the circumferential clamp  45  acting to draw end cap flange  50  disposed on end cap  41  closer to the pump casing clamping flange  49  disposed on the open side of the pump casing  11 , compressing elastomeric seal  36  interposed between end cap flange  50  and pump casing clamping flange  49 . This clamping action effects to substantially seal pump  10  from unwanted outside contaminants and leaks from within pump  10 . Shaft seal  42  completes the sealing requirements for pump  10  by presenting itself as a resilient interface between the rotating drive shaft  27  and the pump casing  11 . 
   Pumping wheel  20  and pumping wheel  21  are substantially identical, the only difference arises from their disposed locations. Pumping wheel  20  is driven substantially from the prime mover, and idler pumping wheel  21  is in turn driven from drive pumping wheel  20 . This is a substantial outcome of the two pumping wheels  20 ,  21  being in a cooperative mesh arrangement. 
     FIG. 3  illustrates the cooperation of the drive shaft  27  with first pumping wheel  20 . As can be seen, a section of drive shaft  27   a , disposes a hexagonal engaging surface with bore  20   a  of drive pumping wheel  20 . Thus drive shaft  27  can impart a rotary movement to drive pumping wheel  20  as well as pumping wheel  20  being able to substantially slide along hexagonal section  27   a  disposed on drive shaft  27 . Most polygon surfaces effected about axis  15  of drive shaft  27  may be able to provide driving and sliding ability to pumping wheel  20 , however, polygons disposing less than about 6 sides clearly require sharper pumping wheel bore angles in the receiving bore  20   a  of pumping wheel  20  that may concentrate drive forces in a fewer number of internal corners in bore  20   a  of pumping wheel  20 , leading to premature failure of the integrity of drive pumping wheel  20 . 
   Symmetrical shapes disposing more than 6 sides may tend to eventually round off the internal bore  20   a  of the pumping wheel due to the required driving forces, eventually leading to loss of engagement between drive shaft  27  and pumping wheel  20 . 
     FIG. 3  also illustrates cooperation of idler shaft  22  with second (idler) pumping wheel  21 . The operation and logic behind the functioning of this assembly is consistent with that of drive shaft  27  and drive shaft pumping wheel  20 . 
     FIG. 4  illustrates wear bushing  19  and extended bushing  18  disposed in end block  23 . Recess  38  in pump casing  11  is substantially coaxial with drive shaft opening  37  and acts to receive a portion of extended bushing  18  means to effect substantial alignment between functioning members  18 - 35  disposed in pump cavity  17  and drive shaft axis  15 . 
     FIG. 5  illustrates the cooperation of pump drive shaft  27  to support bearings of the prime mover. It illustrates the communication of pump drive shaft  27  to the bearings of the prime mover and how the motor output shaft and pump drive shaft  27  are fully inserted into the coupling  43  to provide a close communication between the members. The support bearings in many electric motors are of the ball bearing type where a group of hardened metal balls arranged in a circular configuration substantially maintained within dual races provide support for the operating shaft of an electric motor. In addition to providing support for the rotating shaft in the motor, this type of bearing is able to withstand substantial thrust loading along the axis of its rotation. 
     FIG. 5 , illustrates how forces axial with the pump drive shaft  27  are transferred to the ball bearings of the electric motor instead of to surfaces within the pump which may contribute to the generation of unwanted particulates from those surfaces. 
   Hexagonal section  27   a  disposed on drive shaft  27  contributes by being able to slidably engage pumping wheel  20  as shown in  FIG. 3  and still be able to slightly move along its axis of rotation to maintain a preferred communication with the bearings of the electric motor. 
   Pump  10  comprises a casing  11  having a first inlet port  12  and a first outlet port  13  through which a fluid can be transferred. A mounting arrangement  46 - 48  for casing  11  permits infinite rotational orientation of pump casing  11  about the axis  15  of the drive shaft  27 . Pump  10  features an internal cavity  17  disposed in casing  11 , internal cavity  17  carrying an arrangement of pumping components  18 - 35  to be described hereinafter that cooperate with first inlet port  12  and first outlet port  13  of casing  11  to move fluid through pump  10 . Pumping components within internal cavity  17  comprise a middle block  25 , at least one pumping wheel  20 , at least one shaft  27  and at least two end blocks  23 ,  24 , the function of each component  18 - 35  also fully described hereinafter. Middle block  25  includes a second internal inlet port  33  in communication with first inlet port  12  and substantially along the same axis  14  as first inlet port  12  for further admitting fluid into pumping chamber  31 , a second internal outlet port  34  disposed in middle block  25  in communication with first outlet port  13  substantially along the same axis  39  as first outlet port  13  for discharging fluid from pumping chamber  31  through first outlet port  13  of pump casing  11 . Extended shaft bushing  18  maintains drive shaft  27  in a preferred axis of rotation. Functional alignment of components  18 - 35  disposed within pump casing  11  is substantially maintained by drive shaft  27  and idler shaft  22  that are rotationally supported within end blocks  23 ,  24 . Idler shaft  22  is disposed completely internally within cavity  17  and rotates freely in bushings  26 ,  19 , wear bushing  19  disposed in first block  23  and bushing  26  disposed in second block  24 . Shafts  27 ,  22  carry one or more pumping wheels  20 ,  21  slidably mounted and engaged for rotation about separate axes  15 ,  29 , pumping wheels  20 ,  21  having a plurality of angularly spaced projections  30 - 30   n , slidably engaging an internal peripheral surface  32  of pumping chamber  31  thereby defining interprojection pockets  35 - 35   n  therebetween wherein interprojecting pockets  35 - 35   n  capture fluid therein for transporting fluid through pumping chamber  31  between second internal inlet port  33  and second internal outlet port  34  thus transporting fluid through pump casing  11  from first inlet port  12  to first outlet port  13 . Pumping wheel  20  has an internal bore  20   a  configured to mate with external surface  27   a  of drive shaft  27  and be slidably engaged therewith. Likewise, pumping wheel  21  has an internal bore  21   a  conforming to, and slidably engaged upon an exterior surface  22   a  of idler shaft  22 . Though external surfaces  22   a ,  27   a  and internal bores  21   a ,  22   a  are shown in  FIG. 3  as polygonal, it is fully within the scope of this invention to provide for other configurations for mating, yet rotationally engaging surfaces  21   a / 22   a  and  20   a / 27   a . Pump casing  11  has a first opening  16  therein allowing for removal of components  18 - 35  and a second opening  37  through which protrudes one end  27   b  of drive shaft  27  for rotary engagement via coupler  43  to prime mover to provide rotational momentum to pumping wheels  20  and through intermeshing means, pumping wheel  21 . Drive shaft  27  is supported in bushing  28  in second block  24  and passes through extended bushing  18  in first block  23 . 
   Middle block  25  that contains pumping chamber  31  is not affixed to either block  23 ,  24  nor to casing  11  of pump  10  and is therefore free to slightly move about inside the pump cavity  17  automatically attaining a location that best suits the particular location of pumping wheels  20 ,  21  insofar as finding a position of least contact with pumping wheels  20 ,  21  that are disposed in pumping chamber  31 . Pump  10  preferably has a single industry-standard clamp  45  which retains end cap  41  to casing  11  with elastomeric seal  36  therebetween that substantially seals pump casing  11  from both leaks and ingress of unwanted outside contaminants. Pump casing  11  of pump  10  can be mounted for normal operation in any rotational orientation about axis  15  of drive shaft  27 . No threaded fasteners, as commonly used in prior art pumps, are required to maintain pump  10  in a preferred configuration suitable for pumping. Pumping wheels  20 ,  21  are substantially slidably engaged along axes  15 ,  29  of their respective support shafts  27 ,  22  while being rotationally active therewith. Pump  10  further includes a coupling  43  mounted to drive shaft  27  for connecting drive shaft  27  to a prime mover. 
   Preferably, first and second pumping wheels  20 ,  21  are mounted on separate shafts  27 ,  22 , at least one of shafts  27 ,  22  projecting outside pump casing  11 . It should be readily apparent to those skilled in the art that the inherent symmetry of middle block  25  is conducive to the safe placement and operation of middle block  25  within the pump cavity  17 , in more than one orientation. Thus, middle block  25  is reversible upon assembly into cavity  17  where either face may be contiguous with block  23  and/or pumping wheel  20  disposed in cavity  31 . Furthermore, it should be abundantly apparent that internal functioning components such as pumping wheels  20 ,  21 , support shafts  22 ,  27 , end blocks  23 ,  24  and middle block  25  are free to substantially float within pump cavity  17  so as to find the location of least resistance during preferred operation of the pump. 
   The above description of preferred embodiments should not be interpreted in any limiting manner since variations and refinements are possible which are within the spirit and scope of the present invention. The scope of the invention is defined in the appended claims and their equivalents.