Patent Publication Number: US-9835183-B2

Title: Actuator with central torque member

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates generally to actuators, and more particularly, to fluid-powered rotary actuators in which axial movement of a piston results in relative rotational movement between a body and a shaft. 
     Description of the Related Art 
     Rotary helical splined actuators have been employed in the past to achieve the advantage of high-torque output from a simple linear piston-and-cylinder drive arrangement. The actuator typically uses a cylindrical body with an elongated rotary shaft extending coaxially within the body, with an end portion of the shaft typically providing rotational output drive and the body held stationary, although in some applications the rotational output drive may be provided by the body with the shaft held stationary. An elongated annular piston sleeve has a sleeve portion splined to cooperate with corresponding splines on the inward wall of the body sidewall and on the outward wall of the shaft. The splines may be formed directly on the inward wall of the body sidewall or one a ring gear formed on or connected to the body sidewall. The piston sleeve is reciprocally mounted within the body and has a piston head portion for the application of fluid pressure to one or the other opposing sides thereof to produce axial movement of the piston sleeve. 
     As the piston sleeve linearly reciprocates in an axial direction within the body, outer helical splines of the sleeve portion engage helical splines on the inward wall of the body sidewall to cause rotation of the sleeve portion. The resulting linear and rotational movement of the sleeve portion is transmitted through inner helical splines of the sleeve portion to helical splines on the outward wall of the shaft to cause the shaft to rotate relative to the body. Bearings are typically supplied to rotatably support one or both ends of the shaft relative to the body. 
     Reducing the length and weight of fluid-powered rotary actuators and increasing their durability are an almost always present challenge. As is reducing the cost of the actuator. 
     It will be therefore be appreciated that there has long been a significant need for fluid-powered actuators that have a reduced length and are lighter in weight, and are less expensive to manufacture. The present invention fulfills these needs and further provides other related advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a cross-sectional side elevational view of a fluid-powered rotary actuator embodying the present invention, shown taken substantially along the line A-A of  FIG. 2 . 
         FIG. 2  is an end elevational view of the actuator of  FIG. 1 . 
         FIG. 3  is a cross-sectional side elevational view of a second embodiment of the fluid-powered rotary actuator of  FIG. 1 . 
         FIG. 4  is a cross-sectional side elevational view of a third embodiment of the fluid-powered rotary actuator of  FIG. 1 . 
         FIG. 5  is a cross-sectional side elevational view of a fourth embodiment of the fluid-powered rotary actuator of  FIG. 1 . 
         FIG. 6  is an end elevational view of the actuator of  FIG. 5 . 
         FIG. 7  is a cross-sectional side elevational view of a fifth embodiment of the fluid-powered rotary actuator of  FIG. 1 . 
         FIG. 8  is a perspective view of the actuator of  FIG. 7 . 
         FIG. 9  is a side elevational view of the actuator of  FIG. 7 . 
         FIG. 10  is an end elevational view of the actuator of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in the drawings for purposes of illustration, a first embodiment of the invention is embodied in a fluid-powered rotary actuator  10  is shown in  FIGS. 1 and 2 . The rotary actuator  10  has an elongated housing or body  12  with a body sidewall  14  and first and second body ends  16  and  18 , respectively. The body sidewall  14  has a first body end sidewall portion  15 A toward the first body end  16 , a second body end sidewall portion  15 B toward the second body end  18 , and a mid-body sidewall portion  15 C located about midway between the first and second body ends  16  and  18 . 
     A circumferentially extending first body shoulder  14 A of the body sidewall  14  is located axially inward from the first body end  16  at the first body end sidewall portion  15 A, and is axially outward facing toward the first body end  16 . A circumferentially extending second body shoulder  14 B of the body sidewall  14  is located axially inward from the first body end  16  at the mid-body sidewall portion  15 C, and is axially facing toward the second body end  18 . The body further includes an axially outward circumferentially extending first body end wall  15 D located at the first body end  16  and an axially outward circumferentially extending second body end wall  15 E located at the second body end  18 . 
     A rotary drive or output shaft  20  is coaxially positioned at least partially within the body  12  and supported for rotation relative to the body about a longitudinal axis  21  of the body sidewall  14 . The shaft  20  has a shaft first end portion  20 A located toward the first body end  16  and the first body sidewall portion  15 A, with a circumferentially extending shaft flange portion  22  positioned axially outward of the body  12  at the first body end and extending radially outward of an inward portion of the body sidewall portion  15 A. The shaft  20  has an elongated shaft portion  24  coaxially positioned within the body  12  and having an open ended cylindrical in cross-section shape, interior chamber  20 B with an opening  20 C at its end toward the second body end  18 . The shaft portion  24  extends from the shaft flange portion  22  at the first body end  16  partially along length of the body  12  toward the second body end  18 , and terminates at the mid-body sidewall portion  15 C, whereat an annular shaft second end portion  20 D is located and defines the opening  20 C. The shaft second end portion  20 D has an inward annular wall portion  20 E with inward grooves, illustrated as splines S 1 , extending over at least a portion of its longitudinal length. 
     A circumferentially extending shoulder  25  of the shaft portion  24  at the shaft first end portion  20 A is located axially inward from the first body end  16 , and is axially inward facing toward the second body end  18 . The shoulder  25  is in face-to-face juxtaposition with the first body end shoulder  14 A, with a circumferentially extending thrust bearing  26  positioned therebetween to limit axial movement of the shaft  20  toward the second body end  18 . 
     The shaft flange portion  22  has a plurality of circumferentially arranged apertures  28  (only two being illustrated in  FIG. 1 ) for attaching the shaft  20  to a structure (not shown) to which the rotational drive of the actuator  10  is to be transmitted by the powered rotation of the shaft, such as by using bolts (not shown). 
     An exclusion seal  30  and a pressure seal  32  are disposed between the periphery of the shaft first end portion  20 A and the first body end sidewall portion  15 A to provide a fluid-tight seal and containment seal therebetween. It is noted that each of the seals  30  and  32  is positioned in a circumferentially extending groove in the inward wall of the first body end sidewall portion  15 A; however, as shown in a subsequently described embodiment (see  FIG. 5 ), the grooves for the seals  30  and  32  may alternatively be provided in the outward wall of the shaft first end portion  20 A. A bearing  34  is positioned between the shaft first end portion  20 A and the first body end sidewall portion  15 A, in the area between the pressure seal  32  and the first body end shoulder  14 A, to facilitate sliding rotary motion and radial load transfer between the shaft first end portion  20 A and the first body end sidewall portion  15 A. 
     The shaft second end portion  20 D has a threaded outward annular wall portion  20 F. The shaft  20  includes a ring member  36  with a threaded inward annular wall portion  38  which is threadably received on the threaded outward annular wall portion  20 F of the shaft second end portion  20 D. The ring member  36  is mounted to the shaft second end portion  20 D for rotational movement therewith as the shaft  20  rotates during fluid-powered operation of the actuator  10 . The ring member  36  has a circumferentially extending shoulder  40  axially facing toward the first body end  16 , and located in face-to-face juxtaposition with second body shoulder  14 B, with a circumferentially extending thrust bearing  42  therebetween to limit axial movement of the shaft  20  toward the first body end  16 . In an alternative embodiment not illustrated, the ring member  36  may be formed as an integral portion of the shaft  20 , or be attached to the shaft second end portion  20 D by other than a threaded connection such as by threaded fasteners, pins or retaining rings. A bearing  44  is positioned between the ring member  36  and the mid-body sidewall portion  15 C to facilitate sliding rotary motion and radial load transfer between the ring member  36  of the shaft  20  and the mid-body sidewall portion  15 C. 
     The actuator  10  further includes a torque member  50 . The torque member  50  has a circumferentially extending torque member flange portion  52 , an end flange, positioned axially outward of the body  12  at the second body end  18 . The torque member flange portion  52  has a plurality of circumferentially arranged apertures  54  (only two being illustrated in  FIG. 1 ) for attaching the torque member  50  to the body  12 . A plurality of bolts  56  extend through the apertures  54  and are each threadably received in one of a plurality of circumferentially arranged apertures  58  in the second body end wall  15 E located at the second body end  18 , which are arranged to correspond in position with the apertures  54  in the torque member flange portion  52 . The bolts  56  prevent rotational movement and axial movement of the torque member flange portion  52  relative to the body  12  during fluid-powered operation of the actuator  10 . It is noted that the torque member flange portion  52  in alternative embodiments not shown may be welded, pinned or otherwise attached to the second body end sidewall portion  15 B toward the second body end  18 . 
     The torque member  50  further has an elongated torque member central portion  60  coaxially positioned within the body  12  with a fixed end portion  62  attached to the torque member flange portion  52  at the second body end  18 . The torque member flange portion  52  serves as a connection member connecting the torque member central portion  60  and hence the torque member  50  to the body  12  at the second body end  18 , as described above. The torque member central portion  60  extends partially along the longitudinal axis  21  of the body sidewall  14  toward the first body end  16 , from the torque member flange portion  52  at the second body end  18 , partially along the length of the body toward the first body end  16 , and terminates at about the mid-body sidewall portion  15 C and the inward end of the shaft second end portion  20 D, whereat a free end portion  64  is located. The torque member central portion  60  has an outward wall portion  66  with outward grooves, illustrated as splines S 2 , extending over at least a substantial portion of its axial length. 
     The torque member flange portion  52  and the torque member central portion  60  are formed as an integral portion of the torque member  50 . Since the torque member flange portion  52  is attached to the body  12  in a manner to prevent rotational movement and axial movement of the torque member flange portion relative to the body  12  during fluid-powered operation of the actuator  10 , the attachment of the torque central member portion  60  to the torque member flange portion  52  prevents rotational movement and axial movement of the torque member central portion  60  relative to the body  12  during fluid-powered operation of the actuator  10 . In an alternative embodiment not illustrated, the torque member flange portion  52  and the torque member central portion  60  may be formed as separate parts connected together in a manner to prevent rotational movement and axial movement of the torque member central portion  60  relative to the body  12  during fluid-powered operation of the actuator  10 . 
     The actuator  10  has an annular force-converting piston sleeve  70  coaxially and reciprocally mounted within the body  12  coaxially with the shaft  20  for movement from a first end position toward the first body end  16  and a second end position toward the second body end  18 . The piston sleeve  70  has an annular piston head portion  72  toward the second body end  18  and an annular sleeve portion  74  rigidly attached to the piston head portion and extending therefrom toward the first body end  16 . The piston head portion  72  carries seals  72 A to provide a fluid tight seal between the piston head portion and an inward wall  73  of an annular chamber  75  of the body  12  toward the second body end  18  within which the piston head portion  72  reciprocates as the piston sleeve  70  reciprocates between its first end position and second end position during fluid-powered operation of the actuator. The piston sleeve  70  has an elongated cylindrical in cross-section shape, interior piston sleeve chamber  76  positioned therewithin in coaxial alignment with the axis  21  of the body sidewall  14 . The interior piston sleeve chamber  76  has a closed end wall  78  at an end  80  toward the first body end  16 , and an opening  82  at an end  84  toward the second body end  18 , which provides the opening  82  in the axially outward end of the piston head portion  72 . 
     The sleeve portion  74  of the piston sleeve  70  is sized to extend through the opening  20 C of the shaft portion  24  of the shaft  20  and into the interior chamber  20 B of the shaft portion  24 . The sleeve portion  74  has outward grooves, illustrated as splines S 3 , extending over at least a substantial portion of its axial length which slidably mesh with the inward splines S 1  of the annular shaft second end portion  20 D of the shaft  20  as the piston sleeve  70  reciprocates between its first end position and second end position during fluid-powered operation of the actuator. 
     The elongated torque member central portion  60  is sized to extend through the opening  82  in the piston head portion  72  of the piston sleeve  70  and into the interior piston sleeve chamber  76  of the piston sleeve. The piston sleeve chamber  76  has an inward wall  86  with inward grooves, illustrated as splines S 4 , extending over at least a portion of its axial length toward the second body  18  which slidably mesh with outward splines S 2  of the torque member central portion  60  as the piston sleeve  70  reciprocates between its first end position and second end position during fluid-powered operation of the actuator. 
     In the illustrated embodiment of  FIG. 1 , the first set of inter-meshing splines S 1  and S 3  are helical with the same slope, and the second set of inter-meshing splines S 2  and S 4  are helical with the same slope, although the slopes of the first and second sets need not be the same and it is customary for the first set to be of opposite hand than the second set. Further, both of the first and second sets on inter-meshing splines need not be helical and in some instances the one set is straight and the other is helical. It should be understood that while splines are shown in the drawings and described herein, the principle of the invention is applicable to any form of linear-to-rotary motion conversion means, such as balls or rollers, or other means such as where the shaft second end portion  20 D of the shaft  20  and the sleeve portion  74  have cooperating torque transmission surfaces and the torque member central portion  60  and the inward wall  86  of the piston sleeve chamber  76  have cooperating torque transmission surfaces which transform axial motion of the piston sleeve  70  into relative rotational movement between the body  12  and the shaft  20 . The torque transmission surfaces may be non-circular cross-sectional shapes. 
     The body  12  of the actuator  10  may be mounted to another structure  90  in a variety of manners. In the illustrated embodiment of  FIG. 1 , the body  12  has mounting projections  92  with threaded apertures  94  which receive bolts  96  to fasten the body  12  to the structure  90 . 
     As will be readily understood, reciprocation of the piston head portion  72  within the annular chamber  75  of the body  12  as the piston sleeve  70  reciprocates between its first end position and second end position during fluid-powered operation of the actuator, occurs when hydraulic fluid, such as oil, air or any other suitable fluid, under pressure selectively enters through one or the other of a first port P 1  extending through the mid-body sidewall portion  15 C which is in fluid communication with a fluid-tight compartment portion  75 A of the annular chamber  75  to a side of the piston head portion toward the first body end  16 , or through a second port P 2  extending through the second body end sidewall portion  15 B which is in fluid communication with a fluid-tight compartment portion  75 B of the annular chamber  75  to a side of the piston head portion toward the second body end  18 . As the piston head portion  72  linearly reciprocates in an axial direction within the body  12 , the inward helical splines S 4  of the piston sleeve chamber  76  engage or mesh with the outward helical splines S 2  of the torque member central portion  60  to cause rotation of the piston sleeve  70 . Since the torque member central portion  60  is prevented from rotating relative to the body  12  during fluid-powered operation of the actuator  10 , as described above, the linear and rotational movement of the piston sleeve  70  is transmitted through the outward helical splines S 3  of the sleeve portion  74  of the piston sleeve to the inward helical splines S 1  of the annular shaft second end portion  20 D of shaft  20  to cause the shaft  20  to rotate. The smooth inward wall  73  of the annular chamber  75  has sufficient axial length to accommodate the full end-to-end reciprocating stroke travel of the piston head portion  72  to allow reciprocation of the piston sleeve  70  between its first end position and second end position during fluid-powered operation of the actuator. Axial movement of the shaft  20  is restricted, as described above, so the shaft cannot move in the axial direction. As such, all axial movement of the piston sleeve  70  is converted into rotational movement of the shaft  20 . Depending on the slope and direction of turn of the various helical splines, there may be provided a summing of the rotary output of the shaft  20 . 
     The application of fluid pressure to the first port P 1  produces axial movement of the piston sleeve  70  toward the second body end  18 . The application of fluid pressure to the second port P 2  produces axial movement of the piston sleeve  70  toward the first body end  16 . The rotary actuator  10  provides relative rotational movement between the body  12  and shaft  20  through the conversion of linear movement of the piston sleeve  70  into rotational movement of the shaft, in a manner well known in the art. The shaft  20  is selectively rotated by the application of fluid pressure to one or the other of the first port P 1  or the second port P 2 , and the rotation is transmitted to the structure (not shown) to which the shaft flange portion  22  is attached. If the shaft flange portion  22  is attached to a stationary structure, then the mounting projections  92  of the body  12  may be attached to the structure  90  for the body to transmit the rotational force of the actuator  10  to the structure  90 . When hydraulic fluid under pressure is applied to the first port P 1  the piston head portion  72  will move axially within the annular chamber  75  toward the second body end  18  and produce one of clockwise or counterclockwise rotation of the shaft  20 , and when hydraulic fluid under pressure is applied to the second port P 2  the piston head portion  72  will move axially within the annular chamber  75  toward the first body end  16  and produce the other of clockwise or counterclockwise rotation of the shaft  20 . 
     While the piston sleeve  70  is described as having a piston sleeve, the effective piston head surface area is the full circular area with a diameter equal to the diameter of the interior bore of the body  12  wherein the piston head portion  72  reciprocates. This is because the shaft  20  does not extend through the piston sleeve  70 , either the piston head portion  72  or the closed end wall  78  of the interior piston sleeve chamber  76 , and the torque member central portion  60  does not extend through the closed end wall  78 , hence the effective piston head surface area is not limited as in actuators where the shaft passes through the piston sleeve and hence reduces the effective piston head surface area to which pressurized hydraulic fluid is applied when applied through either the first or second ports P 1  or P 2 . 
     It is noted that with conventional rotary actuators the piston sleeve has a sleeve portion splined to cooperate with corresponding splines formed directly on the inward wall of the body sidewall or on a ring gear directly connected to the inward wall of the body sidewall, and transmits all the operating torque to a portion of the body sidewall at an intermediate location between the opposite ends of the body as the piston sleeve reciprocates between its first end position and second end position during fluid-powered operation of the actuator. Whereas with the present invention using the torque member  50 , the operating torque of the actuator  10  is transmitted during fluid-powered operation of the actuator by the piston sleeve portion  74  of the piston sleeve  70  to the rather stout torque member central portion  60  located on the axis  21  of the actuator, interior of the annular piston sleeve, and transfers that torque via the torque member flange  52  to the second body end  18  of the body, rather than to the surface of the mid-body sidewall portion  15 C. This eliminates the body torque transmission surface from the bore of actuator body and allows restraining of the axial movement of the shaft without a large diameter shaft which extends out both ends of the body, thus reducing the mass and increasing the area for the pressurized fluid to act on the piston head portion of the piston sleeve. It also allows a shaft mounting flange which extends outward of the body. This configuration enables a shorter and lighter actuator to be constructed to provide a short, light and cost effective product having a shaft mounting surface which extends outward of the body interior at the first body end  16 . 
     It is further noted that the radial location of the transmission of torque between the splines S 4  of the sleeve portion  74  and the splines S 2  of the torque member  50  is located radially inward from the radial location of the transmission of the torque between the splines S 3  of the sleeve portion  74  and the splines S 1  of the shaft  20 . 
     A second embodiment of the fluid-powered rotary actuator  10  of the present invention is shown in  FIG. 3 . The actuator of this second embodiment has substantially the same basic design as the first embodiment so only the more significant difference will be described and the same reference numbering will be used for the same or similar component of the actuator. 
     The actuator  10  of this second embodiment is shown attached to a saddle or “C”-shaped attachment frame  100 , which is positioned outward of the body  12 . The attachment frame  100  has a first end leg  100 A at the first body end  16  and a second end leg  100 B at the second body end  18 , with a mid-portion member  100 C spanning between the first and second end legs. The first end leg  100 A is rigidly attached to the shaft flange portion  22  at the first body end  16  for rotation with the shaft  20  relative to the body  12 , with the first end leg being spaced axially apart from the first body end. The first end leg  100 A abuts against an outward end face of the shaft flange portion  22  and is bolted thereto by a plurality of circumferentially arranged bolts  102  (only two being illustrated in  FIG. 3 ) which extend through the apertures  28 . 
     The attachment frame  100  is used to transmit the rotational drive of the actuator  10  to a structure (not shown) to which the attachment frame is connected or of which the attachment frame is an integral part. The attachment frame  100  has the rotational drive of the shaft  20  transmitted thereto so as to provide the torque needed, e.g., to a mining drill mounting platform (or another tool) for tilting the drill (or other tool) to which the attachment frame is connected to a desired lateral tilt angle and holding the drill (or other tool) in that position while the drill (or other tool) performs the desired work. The attachment frame  100  is limited in axial movement relative to the body  12 . 
     The first end leg  100 A and the second end leg  100 B of the attachment frame  100  extend radially beyond the body sidewall  14  and the mid-portion member  100 C extends between the first and second end legs and is rigidly attached to both, and extends generally parallel to the body sidewall  14  at a position spaced away from the body sidewall. The mid-portion member  100 C of the attachment frame  100  is configured to be rigidly attached to the structure to which the rotational drive of the actuator  10  is to be transmitted. 
     The second end leg  100 B of the attachment frame  100  is axially spaced apart outward of the torque member flange portion  52 , and has an aperture  104  within which is a bearing  106 . In this second embodiment of the actuator  10 , the torque member  50  further includes a stub shaft  108  attached to the torque member flange portion  52  and projecting axially outward in coaxial alignment with the axis  21  of the body sidewall  14 . The stub shaft  108  is rotatably supported by the bearing  106  such that the second end leg  100 B of the attachment frame  100  rotates freely relative to the torque member  50  but yet is supported by the torque member. 
     A third embodiment of the fluid-powered rotary actuator  10  of the present invention is shown in  FIG. 4 . The actuator of this third embodiment has substantially the same basic design as the first and second embodiments so only the more significant difference will be described and the same reference numbering will be used for the same or similar component of the actuator. 
     The shaft  20  of the actuator  10  of the this third embodiment includes a central shaft member or shaft rod  110  in coaxial alignment with the axis  21  of the body sidewall  14 . A rod first end portion  112  of the rod  110  is connected to an axially inward end of the shaft first end portion  20 A at the first body end  16  for rotation with the shaft first end portion  20 A, and extends coaxially within the body  12  toward the second body end  18  through an aperture  114  in the end wall  78  of the interior piston sleeve chamber  76  and through an axially extending open ended interior chamber  116  of the torque member  50 , and terminates in a rod second end portion  118  positioned axially outward beyond the torque member flange portion  52 . The rod  110  is rotatably disposed in the aperture  114  in the end wall  78  of the interior piston sleeve chamber  76  and in the interior chamber  116  of the torque member  50 , and rotates freely relative to both. Seals  120  and  122  are provided, respectively, to prevent passage of fluid between the rod  110  and the aperture  114  and an exit opening  124  of the interior piston sleeve chamber  76  in the torque member flange portion  52 . 
     The rod second end portion  118  is received in the aperture  104  of the second end leg  100 B of the attachment frame  100 . In this embodiment the rod second end portion  118  rotates with the second end leg  1108  and also is supported by the torque member flange portion  52  of the torque member  50 . 
     A fourth embodiment of the fluid-powered rotary actuator  10  of the present invention is shown in  FIGS. 5 and 6 . The actuator of this fourth embodiment has substantially the same basic design as the first and second embodiments so only the more significant difference will be described and the same reference numbering will be used for the same or similar component of the actuator. 
     The actuator  10  of the this fourth embodiment is configured for mounting the torque member flange portion  52  (connection member) of the torque member  50  to the structure  90  (i.e., the support structure for the actuator), rather than using mounting projections  92  of the body  12  as shown in the embodiments described above. In such manner, the operating torque of the actuator  10  is transmitted during fluid-powered operation of the actuator by the piston sleeve portion  74  of the piston sleeve  70  to the torque member central portion  60  located on the axis  21  of the actuator, interior of the annular piston sleeve, which transfers that torque via the torque member flange  52  directly to the structure  90  to which the actuator is mounted, rather than to the second body end  18  of the body  12  or any other portion of the body or body sidewall  14 , thereby relieving the body of the requirement to handle the substantial torque resulting during fluid-powered operation of the actuator. This is accomplished by sizing the diameter of the torque member flange portion  52  to extend radially outward beyond the second body end wall  15 E located at the second body end  18  to define a circumferentially extending attachment portion  126  which projects sufficiently outward beyond the second body end wall  15 E to accommodate a plurality of circumferentially arranged apertures  128  (only two being illustrated in  FIG. 5 ) for attaching the torque member flange portion  52  to the structure  90 . A plurality of bolts  130  extend through the apertures  128  and are each threadably received in one of a plurality of circumferentially arranged apertures  132  in the structure  90 , which are arranged to correspond in position with the apertures  128  in the torque member flange portion  52 . Alternatively, the structure  90  may be provided with apertures  133  aligned with the apertures  54  of the torque member flange portion  54 , and the bolts  56  used to attach the torque member flange portion  52  to the body  12  at the second body end  18  may be used to also attach the torque member flange portion  52  to the structure  90 , with the bolts lengthened to accommodate for the thickness of the structure  90 . Yet a second alternative manner of attaching the torque member flange portion  52  to the structure  90  is to provide the structure with a plurality of apertures  133 A, shown radially inwardly located relative to the bolts  56 , with a plurality of bolts  135  extend through the apertures  133 A and each threadably received in one of a plurality of apertures  1338  in the torque member flange portion  52 , which are arranged to correspond in position with the apertures  133 A. 
     The shaft  20  of the actuator  10  of this fourth embodiment has a shaft flange portion  22  which does not extend radially outward of the inward portion of the body sidewall portion  15 A. Further, the apertures  28  for attaching the shaft  20  to a structure are located axially inward of inward portion of the body sidewall portion  15 A. The shaft  20  further includes a shaft rod  134  in coaxial alignment with the axis  21  of the body sidewall  14 . A rod first end portion  136  of the rod  134  is rigidly connected to an axially inward end of the shaft first end portion  20 A at the first body end  16  for rotation with the shaft first end portion  20 A, and extends coaxially within the body  12  toward the second body end  18  through an aperture  138  in the end wall  78  of the interior piston sleeve chamber  76 , and terminates in a rod second end portion  140  positioned within interior piston sleeve chamber  76 , axially inward of the free end portion  64  of the torque member central portion  60 . The rod  134  is rotatably disposed in the aperture  138  in the end wall  78  of the interior piston sleeve chamber  76 , and rotates freely relative to the torque member  50 . A seal  142  is provided to prevent passage of fluid between the rod  134  and the aperture  138 . 
     The locations of the first port P 1  and the second port P 2  are changed to be in the shaft first end portion  20 A, rather than in the mid-body sidewall portion  15 C and the second body end sidewall portion  15 B as with the embodiments described above. The first port P 1  extends through the shaft first end portion  20 A of the shaft  20 , located toward the first body end  16 , and is in fluid communication with the interior chamber  20 B of the shaft portion  24 , which is in fluid communication with the fluid-tight compartment portion  75 A of the annular chamber  75  to a side of the piston head portion toward the first body end  16 . The second port P 2  extends through the shaft first end portion  20 A of the shaft  20 , located toward the first body end  16 , and is in fluid communication with the interior piston sleeve chamber  76  of the piston sleeve  70  via a channel  144  axially extending through the rod  134  and terminating at the rod second end portion  140  positioned within the interior piston sleeve chamber  76 , which is in fluid communication with the fluid-tight compartment portion  75 B of the annular chamber  75  to a side of the piston head portion toward the second body end  18 . It is understood that great flexibility exists to alter the locations of the first port P 1  which supplies fluid to the fluid-tight compartment portion  75 A of the annular chamber  75  and the second port P 2  which supplies fluid to the fluid-tight compartment portion  75 B of the annular chamber  75 . Minor construction changes can be made to relocate the first and second ports P 1  and P 2  without departing from the spirit of the invention, whether the ports are in or attached to the body  12 , the shaft  20  or the torque member  50 . 
     It is to be understood that features and aspects of any one of the disclosed embodiments of the fluid-powered rotary actuator  10  may be used in others of the disclosed embodiments, alone or in combination with other features and aspects of different ones of the disclosed embodiments. 
     A fifth embodiment of the fluid-powered rotary actuator  10  of the present invention is shown in  FIGS. 7-10 . The actuator of this fifth embodiment has substantially the same basic design as the first embodiment so only the more significant difference will be described and the same reference numbering will be used for the same or similar component of the actuator. 
     The body  12  of the actuator  10  of the this fifth embodiment is design to have a shorter overall length. The body sidewall  14  and the shaft  20  are shortened. This is partly achieved by not using the body shoulders  14 A and  14 B or the ring member  36  to limit the axial movement of the shaft  20  within the body  20 , as will be described below. 
     Also, in this fifth embodiment, the shaft  20  does not use the circumferentially extending shaft flange portion  22  positioned axially outward of the body  12  at the first body end for the location of the plurality of circumferentially arranged apertures  28  for attachment of the shaft to a structure to which the rotational drive of the actuator  10  is to be transmitted by the powered rotation of the shaft. Instead, the apertures  28  are located in a central shaft end wall portion  150 . The shaft  20  has a shoulder portion  152  which extends circumferentially about the central shaft end wall portion  150  and is located axially inward of the central shaft end wall portion. 
     The torque member central portion  60  in this fifth embodiment extends along the longitudinal axis  21  of the body sidewall  14  to the shaft first end portion  20 A at the first body end  16  and has its free end portion  64  adjacent to a recessed portion of an inward surface  154  of the central shaft end wall portion  150  to limit the axial movement of the shaft  20  within the body  12  toward the second body end  18 . A thrust bearing  155  is positioned between the free end portion  64  of the torque member central portion  60  and the recessed portion of the inward surface  154  of the central shaft end wall portion  150 . The free end portion  64  does not inhibit rotation of the shaft  20 . 
     To reach the central shaft end wall portion  150 , the free end portion  64  of the torque member central portion  60  passes through a central aperture  156  in the end wall  78  of the interior piston sleeve chamber  76 . A seal  158  is provided to prevent passage of fluid between the free end portion  64  and the wall of the central aperture  156 . The piston sleeve  70  is free to both move axially and rotate relative to at least one of the torque member  50  or the shaft  20 . 
     An end cap  160  is position at the first body end  16  and has a central aperture  162  into which the central shaft end wall portion  150  projects. A seal  164  is provided to prevent passage of fluid between the central shaft end wall portion  150  and the wall of the central aperture  162 . The first body end sidewall portion  15 A of the body sidewall  14  has a threaded outward wall portion  166 . The end cap  160  has a threaded inward wall portion  160 A which is threadably received on the threaded outward wall portion  166  of the first body end sidewall portion  15 A. An annular thrust bearing  168  is positioned between an inward wall (i.e., cap stop wall portion) of the end cap  160  and the shoulder portion  152  of the shaft  20  to facilitate sliding rotary motion. The end cap  160  limits movement of the shaft  20  within the body  20  toward the first body end. Bearings  170  and  172  are positioned between the inward wall of the sidewall  15 A and the outward wall of the shaft  20  to transfer radial loads between the body  20  and the shaft. 
     The actuator  10  of the fifth embodiment is not illustrated with any particular mounting members by which the body  12  may be mounted to another structure either for support by the structure or for rotation of the structure. It may use the mounting projections  92  illustrated for the embodiment of  FIG. 1 , or any other manner of attachment. 
     This fifth embodiment utilizes first and second ports P 1  and P 2 , as does the embodiment of  FIG. 1 , to cause movement of the piston sleeve  70 , however, they are not illustrated in the drawings for the fifth embodiment. The fluid-powered operation of the actuator  10  of the fifth embodiment is the same as with the embodiment of  FIG. 1 . 
     It should be understood that the sliding bearings described above and shown in the drawings for all embodiments may be eliminated or replaced with rolling element type bearings. 
     It will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.