Patent Publication Number: US-8529222-B2

Title: Surface pump assembly having a thrust chamber with a telescoping shaft

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional application Ser. No. 61/175,706 filed May 5, 2009, and entitled “A Surface Pump Assembly Having a Thrust Chamber with a Telescoping Shaft,” which is hereby incorporated herein by reference in its entirety for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     This disclosure relates generally to a thrust chamber for a centrifugal pump. More particularly, the disclosure relates to a telescoping shaft for the thrust chamber. 
     One type of surface pump commonly used to inject large volumes of liquid into a well is a centrifugal pump. A typical, conventional centrifugal surface pump  10  is illustrated by  FIG. 1 . Surface pump  10  is supported on a skid  15 , and has a housing  20  with an inlet end  25  and a discharge end  30 . Inlet end  25  is fluidicly coupled to an intake chamber  35 . Liquid to be pressurized by pump  10  is supplied to inlet end  25  of pump  10  through intake chamber  35 . Liquid that has been pressurized by pump  10  is exhausted from pump  10  through discharge end  30 . 
     Pump  10  further includes a shaft  40  and a motor  50  operable to rotor shaft  40 . Shaft  40  extends through housing  20  and a number of stages disposed therebetween. Each stage of pump  10  includes an impeller and a diffuser disposed within housing  20  about shaft  40 . When shaft  40  rotates, velocity is imparted to liquid passing through pump  10  by the impellers. Interaction of the liquid with the diffusers converts the velocity to pressure. Thus, the liquid is pressurized as it passes through the multiple stages of pump  10 . 
     In reaction to the pressure increase of the liquid, axial thrust is transferred to shaft  40  by the impellers. The thrust load is transferred along shaft  40  to bearings disposed within thrust chamber  45 . Thrust chamber  45  further includes one or more mechanical seals disposed about shaft  40  proximate the locations where shaft  40  passes into and out of thrust chamber  45 . These mechanical seals prevent the loss of fluid contained within thrust chamber  45  for lubricating and cooling the bearings. 
     During the life of a surface pump assembly, such as the one described above, the mechanical seal(s) experiences wear and must be replaced regularly, for example, every two years. Bearings in the thrust chamber also experience wear and must be rebuilt or replaced. Such maintenance operations often require the connections to the pump be disconnected and the pump physically moved to enable removal and replacement of the mechanical seal, bearings, or thrust chamber. Consequently, these operations can require a day or more of downtime to perform the necessary maintenance procedure. 
     Accordingly, there is a need for apparatus that enables quicker removal and replacement of the mechanical seal, bearings, or thrust chamber. It would be particularly desirable if the apparatus enabled access to the mechanical seal or thrust chamber without the necessity to disconnect and move the pump. 
     SUMMARY OF THE PREFERRED EMBODIMENTS 
     A thrust chamber for a surface pump assembly is disclosed. In some embodiments, the thrust chamber has a telescoping shaft with a rotatable shaft member, an adjusting nut, and a sleeve. The adjusting nut is threadably disposed about the shaft member and moveable axially relative to the shaft member by rotation. The sleeve is translatably disposed about the shaft member. 
     In some embodiments, the surface pump assembly includes a pump having a pump shaft, a thrust chamber having a telescoping shaft extending therein, and a motor coupled to the telescoping shaft and operable to rotate the telescoping shaft. The telescoping shaft includes a shaft member and a first sleeve disposed thereabout. The first sleeve is moveable relative to the shaft member between a first position, wherein the first sleeve is coupled to the pump shaft, and a second position, wherein the first sleeve is disengaged from the pump shaft. 
     Some methods for servicing the thrust chamber include disposing a first sleeve about a shaft member, wherein the first sleeve is coupled to a pump shaft and the shaft member is coupled to a motor, disengaging the first sleeve from the pump shaft, and moving a seal assembly from a first position, wherein the seal assembly is inaccessible, to a second position, wherein the seal assembly is accessible. 
     Thus, embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior thrust chambers. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiment, and by referring to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of the disclosed embodiments, reference will now be made to the accompanying drawings in which: 
         FIG. 1  is schematic view of conventional pump assembly; 
         FIG. 2  is a schematic representation of a pump assembly having a thrust chamber with a telescoping shaft in accordance with the principles disclosed herein; 
         FIG. 3  is a cross-sectional view of the thrust chamber of  FIG. 2  with an embodiment of a telescoping shaft shown in two positions, the upper half of the telescoping shaft engaged with the pump shaft and the lower half of the telescoping shaft disengaged from the pump shaft; 
         FIG. 4  is a cross-sectional view of the pump shaft interlocked within the seal sleeve; 
         FIG. 5  is a cross-sectional view of the thrust chamber of  FIG. 2  with another embodiment of a telescoping shaft; 
         FIG. 6  is a perspective, exploded view of the telescoping shaft of  FIG. 5 ; and 
         FIGS. 7A through 7D  are schematic views of the telescoping shaft of  FIG. 5 , illustrating assembly and installation of the telescoping shaft. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS 
     The following description is directed to exemplary embodiments of thrust chamber for a surface pump assembly having a centrifugal pump. The embodiment disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. One skilled in the art will understand that the following description has broad application, and that the discussion is meant only to be exemplary of the described embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. Moreover, the drawing figures are not necessarily to scale. Certain features and components described herein may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in interest of clarity and conciseness. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. Further, the terms “axial” and “axially” generally mean along or parallel to a central or longitudinal axis. The terms “radial” and “radially” generally mean perpendicular to the central or longitudinal axis, while the terms “azimuth” and “azimuthally” generally mean perpendicular to both the central or longitudinal axis and a radial axis normal to the central longitudinal axis. As used herein, these terms are consistent with their commonly understood meanings with regard to a cylindrical coordinate system. 
     Referring now to  FIG. 2 , there is shown a surface pump assembly with a thrust chamber having a telescoping shaft in accordance with the principles disclosed herein. Surface pump assembly  100  includes a centrifugal pump  105 , an intake chamber  110 , a thrust chamber  115 , and a motor  120  connected in series and mounted on a skid  125 . Pump  105  has a housing  140  with an inlet end  130  and a discharge end  135 . Inlet end  130  is fluidicly coupled to, meaning in fluid communication with, intake chamber  110 . Liquid to be pressurized by pump  105  is supplied to inlet end  130  of pump  105  through intake chamber  110 . Liquid that has been pressurized by pump  105  is exhausted from pump  105  through discharge end  135 . 
     Pump  105  further includes a rotatable shaft  145  extending through housing  140  and a number of stages  150  disposed within housing  140  about shaft  145 . Shaft  145  of pump  105  extends from housing  140  through intake chamber  110  to thrust chamber  115 . Each stage  150  of pump  105  includes an impeller  155  and a diffuser  160  disposed within housing  140  about shaft  145 . When shaft  145  rotates, velocity is imparted to liquid passing through pump  105  by impellers  155 . Interaction of the liquid with diffusers  160  converts the velocity to pressure. Thus, the liquid is pressurized as it passes through multiple stages  150  of pump  105 . In reaction to the pressure increase of the liquid, axial thrust is transferred to shaft  145  by impellers  155 . 
     Referring next to  FIG. 3 , thrust chamber  115  includes a housing  165  disposed about a rotatable telescoping shaft  170 . A telescoping shaft in accordance with the principles disclosed herein, including shaft  170 , derives its name from its ability to extend and to retract within thrust chamber housing  165 .  FIG. 3  illustrates telescoping shaft  170  in both its extended and retracted configurations. In  FIG. 3 , the upper half  172  of shaft  170  is shown retracted, and the lower half  174  of shaft  170  is shown extended toward pump shaft  145 . When telescoping shaft  170  is retracted, shaft  170  is disconnected from pump shaft  145 . Alternatively, when telescoping shaft  170  is extended, shaft  170  may be coupled to pump shaft  145 . 
     Thrust chamber housing  165  includes a pump end  175  and a motor end  180 . Pump end  175  of thrust chamber housing  165  is configured to enable coupling of pump shaft  145  with telescoping shaft  170  of thrust chamber  115  when shaft  170  is extended, as illustrated in  FIG. 3  by the lower half  174  of shaft  170 . In the embodiment shown in  FIG. 3 , pump end  175  of housing  165  has an opening  185  through which pump shaft  145  and telescoping shaft  170  extend to engage. Motor end  180  of thrust chamber housing  165  includes an opening  190  through which telescoping shaft  170  extends to couple with motor  120  ( FIG. 2 ). Thus, telescoping shaft  170  enables coupling of pump shaft  145  to motor  120 . 
     Proximate motor end  180  of housing  165 , thrust chamber  115  further includes a bearing assembly  195  having a plurality of bearings  200  which support and enable rotation of telescoping shaft  170 . Fluid is disposed within thrust chamber  115  to lubricate and cool bearings  200 . In some embodiments, including those illustrated by  FIG. 3 , the fluid is oil. 
     To contain the fluid disposed within thrust chamber housing  165 , thrust chamber  115  further includes one or more seal assemblies  205  disposed about telescoping shaft  170 . In the embodiments shown in  FIG. 3 , thrust chamber  115  includes one seal assembly  205  extending into opening  185  of pump end  175  of thrust chamber housing  165 . Seal assembly  205  includes a seal housing  210  with a mechanical seal  215  disposed therein. During operation of pump  105 , seal housing  210  is coupled to the inner surface of thrust chamber housing  165 , such as by bolts. When servicing of thrust chamber  115  is required, such as to replace seal  215 , seal housing  210  may be decoupled from thrust chamber housing  165  to enable access to seal  215 . Mechanical seal  215  is an annular member disposed about shaft  170 . In some embodiments, seal  215  is a Type 1 seal. 
     Telescoping shaft  170  includes a shaft member  230  having a first end  235  that extends through motor end  180  of thrust chamber housing  165  to couple with motor  120 , as previously described, and second end  240  disposed within thrust chamber housing  165 . Telescoping shaft  170  further includes an adjusting nut  245 , a spacer sleeve  250 , and a seal sleeve  255  disposed about shaft member  230  proximate its second end  240 . Adjusting nut  245  threadably engages shaft member  230 . Thus, rotation of nut  245  about shaft member  230  moves nut  245  axially relative to shaft member  230 . 
     Seal sleeve  255  is a tubular member that is slideable or translatable in the axial direction relative to shaft member  230  between two positions, one of engagement with pump shaft  145 , as illustrated by the lower half  174  of shaft  170  in  FIG. 3 , and one of disengagement from pump shaft  145 , as illustrated by the upper half  172  of shaft  170  in this figure. Because seal sleeve  255  is extendable and retractable relative to shaft member  230 , shaft  170  may be described as telescoping. The length of seal sleeve  255  is selected such that when seal sleeve  255  translates or extends to engage pump shaft  145  at one end, the opposite end of seal sleeve  255  does not disengage shaft member  230 . 
     Seal sleeve  255  is configured to couple with pump shaft  145  when extended, as illustrated in  FIG. 3  by the lower half  174  of shaft  170 . When seal sleeve  255  and pump shaft  145  are coupled, rotational loads to seal sleeve  255  are transferred to pump shaft  145 . In the embodiment shown, seal sleeve  255  and pump shaft  145  interlock via plurality of lugs disposed on each to enable transfer of rotational load from seal sleeve  255  to pump shaft  145 . As best viewed in  FIG. 4 , seal sleeve  255  has a plurality of lugs  257  extending radially inward from its inner surface  259 . A recess  261  is formed between each pair of adjacent lugs  257 . Similarly, pump shaft  145  has a plurality of lugs  263  extending radially outward from its outer surface  267 . A recess  269  is formed between each pair of adjacent lugs  263 . When seal sleeve  255  is extended relative to shaft member  230 , seal sleeve  255  receives pump shaft  145  therein with lugs  263  of pump shaft  145  disposed within recesses of seal sleeve  255  and lugs  257  disposed within recesses  269  of pump shaft  145 . Thus, seal sleeve  255  and pump shaft  145  are interlocked and rotational load may be transferred therebetween. 
     Seal assembly  205  proximate pump end  175  of thrust chamber housing  165  is disposed about seal sleeve  255 . When seal housing  210  is decoupled from thrust chamber housing  165  and seal sleeve  255  translates relative to shaft member  230 , seal housing  210  and mechanical seal  215  move with seal sleeve  255 . Thus, translation of seal sleeve  255  toward adjusting nut  245  enables separation of seal housing  210  from thrust chamber housing  165  and allows access to mechanical seal  215 . Subsequent translation of seal sleeve  255  in the opposite direction enables recoupling of seal housing  210  to thrust chamber housing  165  with mechanical seal  215  being disposed in opening  185 . 
     As illustrated by the lower half  174  of telescoping shaft  170  in  FIG. 3 , spacer sleeve  250  is a tubular member which may be coupled between adjusting nut  245  and seal sleeve  255 . When so installed, spacer sleeve  250  enables the transfer of axial load from seal sleeve  255  to shaft member  230 . Also, spacer sleeve  250  enables seal sleeve  255  to remain coupled to pump shaft  145 . 
     During operation of pump  105 , liquid to be pressurized by pump  105  is supplied through intake chamber  110  to inlet end  130  of pump  105 . Motor  120  rotates telescoping shaft  170  of thrust chamber  115  and pump shaft  145  coupled thereto. As pump shaft  145  rotates, liquid passing through pump  105  is pressurized. The thrust load imparted to pump shaft  145  in reaction to the liquid pressurization is transferred from pump shaft  145  along telescoping shaft  170  to bearings  200  within thrust chamber  115 . In particular, the axial load imparted from pump shaft  145  is transferred along seal sleeve  255 , spacer sleeve  250 , adjusting nut  245 , and shaft member  230  to bearings  200 . Liquid contained within thrust chamber housing  165  by seal assemblies  205  lubricates and cools bearings  200  as telescoping shaft  170  rotates. 
     Over time, mechanical seal  215  may wear and require replacement. When such maintenance operations become necessary, pump  105  is turned off, and seal housing  210  is decoupled from thrust chamber housing  165 . Telescoping shaft  170  is then retracted to disengage or decouple from pump shaft  145 . To disengage telescoping shaft  170  from pump shaft  145 , spacer sleeve  250  is decoupled from adjusting nut  245  and seal sleeve  255 , and seal sleeve  255  is translated along shaft member  230  toward adjusting nut  245 , as illustrated by the upper half  172  of shaft  170  in  FIG. 3 . Translation of seal sleeve  255  toward adjusting nut  245  enables seal sleeve  255  to disengage pump shaft  145 . Because sealing housing  210  has been decoupled from thrust chamber housing  165 , seal housing  210  and mechanical seal  215  translate with seal sleeve  255  toward adjusting nut  245 , enabling access to mechanical seal  215 . Seal  215  may then be serviced, including inspection, repair, and/or replacement of seal  215 . 
     After replacement of mechanical seal  215 , telescoping shaft  170  is extended to again engage pump shaft  145  and to reassemble seal housing  210  with new mechanical seal  215  disposed therein. Seal sleeve  255  is translated to engage pump shaft  145 . Translation of seal sleeve  255  returns seal housing  220  of seal assembly  205  to engagement with thrust chamber housing  165 , enabling these components to be again coupled with mechanical seal  215  disposed within opening  185 . Spacer sleeve  250  is then coupled between adjusting nut  245  and seal sleeve  255  to enable load transfer between shaft member  230  of telescoping shaft  170  and pump shaft  145 . Operation of pump  105  may then resume. 
     Also over time, bearings  200  may wear and need to be rebuilt or replaced. When this becomes necessary, pump  105  is turned off, and telescoping shaft  170  is retracted to disengage pump shaft  145 , as described above. Thrust chamber  115  may then be disconnected from motor  120  and removed from pump assembly  100  to enable bearings  200  to be replaced or rebuilt. After servicing to bearings  200  is complete, thrust chamber  115  is then repositioned between motor  120  and intake chamber  110 , and reconnected to motor  120 . Telescoping shaft  170  of thrust chamber  115  is then extended to again engage pump shaft  145  and to reassemble seal housing  210 , both as described above. Operation of pump  105  may then resume. 
     Turning now to  FIG. 5 , an alternative embodiment of a telescoping shaft for thrust chamber  115  is shown. Telescoping shaft  300  includes a shaft member  305  having a first end  235  ( FIG. 3 ) that extends through motor end  180  of thrust chamber housing  165  to couple with motor  120 , as previously described, and second end  315  disposed within thrust chamber housing  165 . Proceeding from right to left in  FIG. 5 , telescoping shaft  300  further includes a coupling pilot  320 , a coupling shaft  325 , a coupling spacer  330 , a thrust chamber half coupling  335 , a pump half coupling  340 , and a seal sleeve  345 . 
     Seal sleeve  345  is a tubular member having two ends  350 ,  355  and configured to receive pump shaft  145  therethrough. When telescoping shaft  300  is installed between thrust chamber  115  and pump  105 , as shown, pump shaft  145  is received within seal sleeve  345  with end  350  of seal sleeve  345  abutting a shoulder  360  formed on the outer surface of pump shaft  145 . End  355  of seal sleeve  345  has a recessed portion  365 . 
     Pump half coupling  340  is an annular ring-shaped member having two ends  370 ,  375  and a plurality of axially or longitudinally extending splines  380  disposed on its inner surface, as best viewed in  FIG. 6 . Referring to both  FIGS. 5 and 6 , end  370  of pump half coupling  340  is configured to be received within recessed portion  365  of seal sleeve  345 , such that pump half coupling  340  seats against seal sleeve  345 . End  375  of pump half coupling  340  is flanged with a plurality of recesses  385  formed along its periphery. Splines  380  are configured to interlock with mating splines  410  formed on the outer surface of pump shaft  145  to couple pump half coupling  340  and pump shaft  145  when telescoping shaft  300  is installed between thrust chamber  115  and pump  105 . When splines  380 ,  410  are interlocked, rotational loads to pump half coupling  340  are transferred to pump shaft  145 . 
     Thrust chamber half coupling  335  is tubular member with two flanged ends  390 ,  395  and a plurality of axially or longitudinally extending splines  400  disposed along its inner surface. Flanged end  390  has a plurality of axially extending lugs  405 . When telescoping shaft  300  is installed between thrust chamber  115  and pump  105 , each lug  405  of flanged end  390  of thrust chamber half coupling  335  is received within a recess  385  of flanged end  375  of pump half coupling  340  such that these half couplings  335 ,  340  are coupled. When coupled, rotational loads to thrust chamber half coupling  335  are transferred to pump half coupling  340  via interlocked lugs  405  and recesses  385 . Flanged end  395  has a plurality of axially extending throughbores  415  disposed about its periphery. 
     Coupling spacer  330  is a tubular member having a flanged end  420  with a plurality of axially extending threaded bores  425  and a plurality of threads  430  formed over a portion of its inner surface. Threaded bores  425  of coupling spacer  330  align with throughbores  415  of thrust chamber half coupling  335  to enable coupling of these components  330 ,  335  via a threaded bolt  435  inserted through each pair of aligned bores  415 ,  425 . 
     Coupling shaft  325  is a cylindrical member having a plurality of splines  440  disposed about its outer surface proximate one end  445 . Splines  440  are configured to interlock with splines  400  of thrust chamber half coupling  335  when end  445  of coupling shaft  325  is inserted through coupling spacer  330  into thrust chamber half coupling  335 , as shown. Coupling shaft  325  further includes a plurality of threads  450  disposed on its outer surface proximate its midsection and a plurality of circumferentially spaced bores  455  disposed on its outer surface and axially displaced from threads  450 . Threads  450  are configured to rotatably engage threads  430  of coupling spacer  330  when coupling shaft  325  is inserted within coupling spacer  330 , as shown. Bores  455  are each configured to receive a rod, wherein a torque load applied to the rod enables relative rotation of coupling shaft  320  and coupling spacer  330 , such that coupling spacer  330  threads onto or unthreads from coupling  330 . 
     At an end  460 , coupling shaft  325  further includes a circular recess  465  and a plurality of ribs  470  extending radially from recess  465  and axially from end  460 . End  315  of shaft member  305  includes a circular recess  475  and a plurality of recesses (not shown) extending radially from recess  475 . When telescoping shaft  300  is installed between pump shaft  145  and motor  120 , as shown, end  460  of coupling shaft  325  abuts end  315  of shaft member  305  such that circular recesses  465 ,  475  align, and each recess of shaft member  305  aligns with and receives therein a rib  470  of coupling shaft  325 . Coupling pilot  320  is a cylindrically shaped member configured to be received within aligned circular recesses  465 ,  475 . Engagement of ribs  470  of coupling shaft  325  with recesses of shaft member  305  in this manner enables shaft member  305  and coupling shaft  325  to be coupled. When coupled, rotational loads to shaft member  305  are transferred to coupling shaft  325 . 
     During operation of pump  105 , liquid to be pressurized by pump  105  is supplied through intake chamber  110  to inlet end  130  of pump  105 . Motor  120  rotates telescoping shaft  300  of thrust chamber  115  and pump shaft  145  coupled thereto. As pump shaft  145  rotates, liquid passing through pump  105  is pressurized. The thrust load imparted to pump shaft  145  in reaction to the liquid pressurization is transferred from pump shaft  145  along telescoping shaft  300  to bearings  200  within thrust chamber  115 . Liquid contained within thrust chamber housing  165  by seal assemblies  205  lubricates and cools bearings  200  as telescoping shaft  300  rotates. 
     Over time, mechanical seal  215  ( FIG. 5 ) may wear and require replacement. When such maintenance operations become necessary, pump  105  is turned off, and telescoping shaft  300  is decoupled from pump shaft  145 . To disengage telescoping shaft  300  from pump shaft  145 , bolts  435  coupled between thrust chamber half coupling  335  and coupling spacer  330  are removed. A rod is inserted into one of bores  455  on the outer surface of coupling shaft  325 . A torque load is applied to the rod to prevent rotation of coupling shaft  325  while coupling spacer  330  is rotated relative to coupling shaft  325  toward shaft member  305 . When coupling spacer  330  has translated axially toward shaft member  305  and away from pump half coupling  340  a sufficient distance, lugs  405  of thrust chamber half coupling  335  disengage recesses  385  of pump half coupling  340 , and thrust chamber half coupling  335  is free to move relative to pump half coupling  340 . 
     Coupling spacer  330  is further threaded toward shaft member  305  to enable additional clearance between thrust chamber half coupling  335  and pump half coupling  340 . The additional clearance enables coupling shaft  325 , with coupling spacer  330  and thrust chamber half coupling  335 , to be moved relative to shaft member  305  to disengage ribs  470  of coupling shaft  325  from the mating recesses on shaft member  305 . Coupling spacer  330 , thrust chamber half coupling  335 , and coupling shaft  325  may then be removed from thrust chamber  115  to enable access to and replacement of mechanical seal  215 . 
     After replacement of mechanical seal  215 , coupling spacer  330 , thrust chamber half coupling  335 , and coupling shaft  325  are reinstalled within thrust chamber  115 . Bolts  435  are recoupled between thrust chamber half coupling  335  and coupling spacer  330 . Coupling spacer  330 , thrust chamber half coupling  335 , and coupling shaft  325  are axially aligned between pump half coupling  340  and shaft member  305 , as illustrated by  FIGS. 7A and 7B . Coupling spacer  330 , thrust chamber half coupling  335 , and coupling shaft  325  are then translated toward shaft member  305  to enable ribs  470  of coupling shaft  325  to seat within the mating recesses on shaft member  305 , as illustrated by  FIG. 7C . The rod is then reinserted within a bore  455  on the outer surface of coupling shaft  325  to prevent rotation of coupling shaft  325 , while coupling spacer  330  is rotated about coupling shaft  325  until lugs  405  of thrust chamber half coupling  335  are again seated within recesses  385  of pump half coupling  340 , as shown in  FIG. 7D . Additional torque may be applied to coupling spacer  330  to ensure secure engagement of telescoping shaft  300  between pump shaft  145  and motor  120 . Operation of pump  105  may then resume. 
     Also over time, bearings  200  may wear and need to be rebuilt or replaced. When this becomes necessary, pump  105  is turned off. Thrust chamber half coupling  335 , coupling spacer  330 , and coupling shaft  325  may then be removed in a manner described above. Next, pump half coupling  340  and seal sleeve  345  are disengaged from pump shaft  145  and removed. Finally, thrust chamber  115  is disconnected from motor  120  and removed from pump assembly  100  to enable bearings  200  to be replaced or rebuilt. 
     After servicing to bearings  200  is complete, thrust chamber  115  is then repositioned between motor  120  and intake chamber  110 , and reconnected to motor  120 . Telescoping shaft  300  of thrust chamber  115  is reinstalled to again engage pump shaft  145 . Seal sleeve  345  is installed over pump shaft  145 , and pump half coupling  340  is seated within recessed portion  365  of seal sleeve  345 . Thrust chamber half coupling  335 , coupling spacer  330 , and coupling shaft  325  may then be reinstalled in a manner described above. Operation of pump  105  may then resume. 
     Servicing of certain conventional thrust chambers typically requires decoupling of multiple pump connections and displacement or relocation of the pump to enable sufficient clearance to access the mechanical seal or thrust chamber. Due to the telescoping ability of shafts  170 ,  300  of thrust chamber  115  disclosed herein, movement of pump  105  is not required to access either mechanical seal  215  or thrust chamber  115 . Consequently, telescoping shafts  170 ,  300  of thrust chamber  115  enables quicker replacement of mechanical seal  215  or servicing to bearings  200  of thrust chamber  115 , and therefore less down time. 
     While various embodiments have been showed and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings herein. The embodiments herein are exemplary only, and are not limiting. Many variations and modifications of the apparatus disclosed herein are possible and within the scope of the invention. Accordingly, the scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.