Fluid-power device with rollers

• US 4,838,103 A
• Filed: 01/20/1987
• Issued: 06/13/1989
• Est. Priority Date: 07/03/1986
• Status: Expired due to Fees

• Current Assignee: 1994 Weyer Family Limited Partnership
• Original Assignee: Paul P. Weyer
• Inventors: Weyer, Paul P.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Anchell, Scott
• Application Number:
  US07/006,007
• Time in Patent Office: 875 Days
• Field of Search: 74/89.15, 74/424.8 B, 74/424.8 C, 74/424.8 R, 74/441, 74/458, 74/459, 92/2, 92/31, 92/33, 92/, 277/136, 277/137, 277/DIG. 7, 277/DIG. 9, 384/504, 403/355, 403/356, 403/359
• US Class Current: 74/424.92
• CPC Class Codes: F15B 15/068 the motor being of the helical type
• CPC Class Codes: F16H 25/2266 arranged substantially in parallel to the screw shaft axis planetary rollers F16H25/2252
• CPC Class Codes: Y10T 74/19795 Parallel to shaft
• CPC Class Codes: Y10T 74/19902 Screw and nut

Abstract

A fluid-powered actuator having a body with interior helical grooves, an output shaft with exterior helical grooves, a first set of rollers in rolling engagement with only the body grooves and axially skewed at an angle corresponding to the lead angle of the body grooves, a second set of rollers in rolling engagement with only the output shaft grooves and axially skewed at a skew angle corresponding to the lead angle of the output shaft grooves, and an axially reciprocating piston sleeve mounted within the body and retaining the rollers in fixed axial and circumferential position relative to the piston sleeve during powered operation of the device. In several embodiments, the first and second sets of rollers are axially spaced apart.

Claims

1. A fluid-power device, comprising:

a body;

an axially extending drive member supported for movement relative to said body and connectable to an external device, one of said body or said drive member having a plurality of helical grooves with ridges therebetween formed on a surface portion thereof and having an axial pitch and a lead angle with a left-hand or right-hand turn;

a plurality of rollers, each having at least one circumferential ridge;

an axially reciprocating member reciprocally mounted within said body, said reciprocating member rotatably retaining said rollers in fixed axial and circumferential position relative to said reciprocating member during powered operation of the fluid-power device, said rollers being retained by said reciprocating member in circumferentially distributed arrangement in seated rolling engagement with said grooved surface portion for transmitting force between said reciprocating member and the one of said body or said drive member having said grooved surface portion, each ridge of said rollers being positioned for rolling travel in the corresponding grooves of said grooved surface portion, said rollers being retained by said reciprocating member in an axially skewed position relative to said body or drive member with which engaged, such that the angle of skew corresponds to said hand turn of said engaged helical groove so as to improve angular alignment of said roller ridges with said engaged helical grooves of said grooved surface portion;

means for transmitting torque between said reciprocating member and the other of said body or said drive member; and

at least one piston mounted for reciprocal movement and operatively engaging said reciprocating member.

2. The device of claim 1 wherein said rollers have a skew angle generally corresponding to said lead angle of said helical grooves.

3. The device of claim 1 wherein said rollers are circumferentially spaced apart with substantially equal inter-roller spacing therebetween, and the number of helical grooves of said grooved surface portion is equal to about the sum of an integer number plus 0.5, times the number of said rollers.

4. The device of claim 1 wherein the number of said helical grooves of said grooved surface portion is equal to about the sum of an integer number plus 0.5, times the number of equally spaced circumferentially adjacent positions for rollers for engagement therewith.

5. The device of claim 4 wherein circumferentially adjacent ones of said rollers are axially offset relative to each other by about 0.5 times the axial spacing between said roller ridges.

6. The device of claim 1 wherein said rollers are axially positioned in generally coplanar relation and the number of helical grooves of said grooved surface portion is an integer multiple of the number of equally spaced circumferentially adjacent positions for rollers for engagement therewith.

7. The device of claim 1 wherein said reciprocating member includes a plurality of spindles each rotatably and coaxially retaining at least one roller of said rollers and positioned adjacent to said grooved surface portion, said spindles being circumferentially distributed about said grooved surface portion to position said rollers in seated rolling engagement therewith, said spindles retaining said rollers against axial movement relative thereto and in said axially skewed position, said spindles being retained by said reciprocating member to prevent axial movement of said spindles relative to said reciprocating member during powered operation of the fluid-power device.

8. The device of claim 7 wherein said rollers each have a longitudinally extending substantially coaxial roller bore therethrough rotatably receiving one of said spindles, said axial bore being defined by an interior sidewall, corresponding ones of said roller bore sidewalls and spindles having integrally formed thereon a plurality of confronting and corresponding ball races defining a plurality of ball channels extending circumferentially thereabout, and the fluid-power device further includes a plurality of balls seated in said ball channels to restrict axial movement of said rollers relative to said spindles while permitting free rotation of said rollers on said spindles.

9. The device of claim 8 wherein each of said rollers is defined by a plurality of rings disposed on one of said spindles, each of said rings having a radially outward facing surface portion shaped to form in combination with the other of said plurality of rings said roller ridges.

10. The device of claim 7 wherein each of said spindles is supported at one end by a cantilever support arm rigidly attached thereto, and said reciprocating member includes a sleeve portion having a plurality of circumferentially spaced apart bore holes formed in an end portion thereof, each said bore hole sized to receive one of said support arms, said support arms being disposed in said sleeve bore hoes with said spindles supported thereon and positioned axially beyond said end portion of said sleeve portion.

11. The device of claim 10 wherein said support arm and spindle for each of said rollers are attached together in coaxial relation to form a substantially straight, elongated member, and said sleeve bore holes are formed in said reciprocating member sleeve portion at a bore hole skew angle corresponding to said roller skew angle.

12. The device of claim 10 wherein said support arm and spindle for each of said rollers are attached together in eccentric relation to form an angled member with said spindle angled relative to said support arm by an angle corresponding to said roller skew angle, and said sleeve bore holes are formed in said reciprocating member sleeve portion in substantially parallel axial alignment with the one of said body or said drive member having said grooved surface portion.

13. The device of claim 7 wherein each of said spindles is supported between first and second support arms, and said reciprocating member includes at least one recess with at least one of said rollers positioned therein and projecting radially beyond said reciprocating member to rollingly engage said grooved surface portion, said recess having a pair of opposed and axially spaced apart wall portions with each of said wall portions supporting one or the other of said first and second support arms.

14. The device of claim 13 wherein said first and second support arms for each spindle are coaxial, and said support arms and spindle for each said roller are attached together in coaxial relation.

15. The device of claim 14 further including a coaxial pair of bore holes sized to receive said first and second support arms, with said pair of bore holes having one bore hole in one of said wall portions and the other bore hole in the other of said wall portions at a bore hole skew angle corresponding to said roller skew angle, said first and second support arms for each said spindle being disposed in said pair of bore holes.

16. The device of claim 14 wherein said first and second support arms extend outward from said spindle beyond said wall portions of said recess and are rigidly fastened to said reciprocating member with a selected axial angular orientation.

17. The device of claim 13 wherein said first and second support arms are coaxial, and said support arms and spindle for each said roller are attached together in eccentric relation with said spindle angled relative to said first and second support arms at an angle corresponding to said roller skew angle, and further including a pair of bore holes sized to receive said first and second support arms, with each pair of said bore holes having one bore hole in one of said wall portions and the other bore hole in the other of said wall portions in substantially parallel axial alignment with the one of said body or said drive member having said grooved surface portion.

18. The device of claim 13 wherein said recess is a transverse open-ended slot in an end portion of said reciprocating member.

19. The device of claim 13 wherein said recess is a window extending transversely fully through said reciprocating member.

20. The device of claim 13 wherein said reciprocating member includes a plurality of said recesses circumferentially spaced apart.

21. The device of claim 13 wherein said recess is a circumferentially extending recess opening toward the one of said body or said drive member having said grooved surface portion, and said rollers are disposed in said recess and circumferentially spaced apart from each other.

22. The device of claim 7 wherein at least one of said spindles is selectively and adjustably axially movable relative to said reciprocating member, and the fluid-power device further includes adjustment means for selectively and adjustably axially moving said movable spindle in an axial direction within at least a limited range to axially move said roller rotatably retained on said movable spindle to eliminate backlash resulting from said roller coacting with said grooved surface portion as said piston moves from one axial direction to the other within said body as it reciprocates.

23. The device of claim 22 wherein said movable spindle is supported by at least one support arm, said support arm and movable spindle being attached together in eccentric relation with said spindle angled relative to said support arm at an angle corresponding to said roller skew angle, said support arm being disposed on an axis in substantial parallel axial alignment with the one of said body or said drive member having said grooved surface portion and rotatably supporting said movable spindle for selective and adjustable eccentric movement about said axis, and wherein said adjustment means includes control means for selectively and adjustably rotating said supported movable spindle about said axis to produce eccentric movement of said roller retained thereon, whereby rotation of said supported movable spindle and said roller retained thereon produces movement of said roller in said axial direction for elimination of backlash.

24. The device of claim 23 wherein said control means includes a member selectively extendable to engage a portion of said supported movable spindle at a position offset from said axis to apply an adjustment torque thereon to rotate said supported movable spindle eccentrically about said axis.

25. The device of claim 24 wherein said engagement portion of said supported movable spindle is an engagement surface oriented at an oblique angle relative to said axis and said extendable member is supported by said reciprocating member for selective extension relative to said reciprocating member to engage said inclined engagement surface.

26. The device of claim 24 including a plurality of said supported movable spindles, each positioned circumferentially adjacent to the other and each having both said engagement portion to be engaged by said extendable member of the next adjacent spindle to one side thereof and said extendable member to engage said engagement portion of the next adjacent spindle to the other side.

27. The device of claim 1 wherein circumferentially adjacent one of said rollers are axially offset relative to each other.

28. The device of claim 27 further including spacer means for holding said axially offset circumferentially adjacent ones of said rollers at a fixed axial offset position relative to the other ones of said rollers.

29. A fluid-power device, comprising:

a body having a plurality of helical grooves with ridges therebetween formed on an inward facing surface portion thereof, said body helical grooves having a first axial pitch and a first lead angle with a first left-hand or right-hand turn;

an axially extending drive member supported for movement relative to said body and connectable to an external device, said drive member having a plurality of helical grooves with ridges therebetween formed on an outward facing surface portion thereof positioned within said body, said drive member grooves having a second axial pitch and a second lead angle with a second left-hand or right-hand turn;

a first plurality of elongated rollers having circumferential grooves with ridges therebetween;

a second plurality of elongated rollers having circumferential grooves with ridges therebetween;

an axially reciprocating member reciprocally mounted within said body, said reciprocating member rotatably retaining said first and second pluralities of rollers in fixed axial and circumferential position relative to said reciprocating member during powered operation of the fluid-power device, said reciprocating member retaining said first plurality of rollers in circumferentially distributed arrangement in seated rolling engagement with said grooved body inward surface portion and retaining said second plurality of rollers in circumferentially distributed arrangement in seated rolling engagement with said grooved drive member outward surface position for transmitting force between said body, drive member and reciprocating member, each ridge of said first plurality of rollers being positioned for rolling travel in the corresponding grooves of said body and out of engagement with said grooves of said drive member, and each ridge of said second plurality of rollers being positioned for rolling travel in the corresponding grooves of said drive member and out of engagement with said grooves of said body, at least said first or second pluralities of rollers being retained by said reciprocating member in an axially skewed position relative to the one of said body or drive member with which engaged, such that the angle of skew corresponds to said first or second hand turn of said engaged body or drive member helical grooves so as to improve angular alignment of said roller ridges with said engaged body or drive member helical grooves; and

at least one piston mounted for reciprocal movement and operatively engaging said reciprocating member.

30. The device of claim 29 wherein said axially skewed first or second plurality of rollers have an axial pitch corresponding to said first or second axial pitch of said body or drive member helical grooves with which engaged.

31. The device of claim 29 wherein said first plurality of rollers are axially positioned toward one end of said reciprocating member axially spaced away from said grooved drive member outward surface portion, and said second plurality of rollers are axially positioned toward an opposite end of said reciprocating member axially spaced away from said grooved body inward surface portion.

32. The device of claim 31 wherein said grooved body inward surface portion and said grooved drive member outward surface portion are axially spaced apart and substantially not axially overlapping.

33. The device of claim 29 wherein said first and second pluralities of rollers are in fixed radial position relative to said reciprocating member with said first plurality of rollers being radially positioned spaced outward of said grooved drive member outward surface portion and with said second plurality of rollers being radially positioned spaced inward of said grooved body inward surface portion.

34. The device of claim 33 wherein said first and second pluralities of rollers are positioned in generally circumferentially aligned arrangement with the other, with rollers of said first and second pluralities of being positioned circumferentially adjacent each other.

35. The device of claim 29 wherein at least said first plurality of rollers have an axial pitch corresponding to said first axial pitch and are angularly skewed at an angle generally corresponding to said first lead angle, or said second plurality of rollers have an axial pitch corresponding to said second axial pitch and are angularly skewed at an angle generally corresponding to said second lead angle.

36. The device of claim 29 wherein said axially skewed first or second plurality of rollers are skewed at an angle substantially equal to said first or second lead angle of said body or drive member helical grooves with which engaged.

37. The device of claim 29 wherein said first plurality of rollers are rotatably attached to said reciprocating member toward one end portion thereof, and said second plurality of rollers are rotatably attached to said reciprocating member at an opposite end portion thereof axially spaced apart from said first plurality of rollers.

38. The device of claim 37 wherein said first plurality of rollers are positioned axially outward of a first end of said reciprocating member toward one end of said body, and said second plurality of rollers are positioned axially outward of a second end of said reciprocating member toward an opposite end of said body.

39. The device of claim 29 wherein at least said first or second pluralities of rollers are circumferentially spaced apart with substantially equal inter-roller spacing therebetween, and the number of corresponding grooves of said plurality of body or drive member helical grooves is equal to about the sum of an integer number plus 0.5, times the number of said first or second pluralities of rollers.

40. The device of claim 29 wherein at least the number of said plurality of drive member helical grooves or the number of said plurality of body helical grooves is equal to about the sum of an integer number plus 0.5, times the number of equally spaced circumferentially adjacent positions for rollers for engagement therewith.

41. The device of claim 40 wherein at least circumferentially adjacent ones of said first plurality of rollers are axially offset relative to each other by about 0.5 times the axial spacing between said roller ridges of said first plurality of rollers, or circumferentially adjacent ones of said second plurality of rollers are axially offset relative to each other by about 0.5 times the axial spacing between said roller ridges of said second plurality of rollers.

42. The device of claim 29 wherein at least said first or second pluralities of rollers are axially positioned in generally coplanar relation, and the number of corresponding grooves of said plurality of body or drive member helical grooves is an integer multiple of the number of equally spaced circumferentially adjacent positions for rollers for engagement therewith.

43. The device of claim 29 wherein said reciprocating member includes a first plurality of spindles each rotatably and coaxially retaining at least one roller of said first plurality of rollers and positioned adjacent to said grooved body surface portion, said first plurality of spindles being circumferentially distributed about said grooved body surface portion to position said rollers of said first plurality of roller in seated rolling engagement with said grooved body surface portion, and a second plurality of spindles each rotatably and coaxially retaining at least one roller of said second plurality of rollers and positioned adjacent to said grooved drive member surface portion, said second plurality of spindles being circumferentially distributed about said grooved drive member surface portion to position said rollers of said second plurality of rollers in seated engagement with said grooved drive member surface portion, said spindles retaining said rollers against axial movement relative thereto and retaining said axially skewed first or second plurality of rollers at said roller skew angle, said spindles being retained by said reciprocating member to prevent axial movement of said spindles relative to said reciprocating member during powered operation of the device.

44. The device of claim 43 wherein said rollers each have a longitudinally extending substantially coaxial roller bore therethrough rotatably receiving one of said spindles, said axial bore being defined by an interior sidewall, corresponding ones of said roller bore sidewalls and spindles having formed thereon a plurality of confronting and corresponding ball races defining a plurality of ball channels extending circumferentially thereabout, and the fluid-power device further includes a plurality of balls seated in said ball channels to restrict axial movement of said rollers relative to said spindles while permitting free rotation of said rollers on said spindles.

45. The device of claim 44 wherein each of said rollers is defined by a plurality of rings disposed on one of said spindles in juxtaposition, each of said rings having a radially outward facing surface portion shaped to form in combination with the other of said plurality of rings said roller grooves and ridges.

46. The device of claim 45 wherein said rings having first and second axially outward oppositely facing sidewalls each with an axially outward opening circumferential ball groove formed thereon, said first and second sidewall ball grooves being axially spaced apart so that said ring ball grooves on adjacent first and second ring sidewalls of adjacent pairs of said rings define one of said roller ball races.

47. The device of claim 43 wherein each of said spindles is supported at one end by a cantilever support arm rigidly attached thereto, and said reciprocating member includes a sleeve portion having a first plurality of circumferentially spaced apart bore holes formed in a first end portion thereof and a second plurality of circumferentially spaced apart bore holes formed in an opposite second end portion thereof, each said bore hole being sized to receive one of said support arms, said support arms being disposed in said bore holes with said first and second pluralities of spindles supported thereon and positioned axially beyond said first and second end portions of said sleeve portion, respectively.

48. The device of claim 47 wherein said support arm and spindle for each of said axially skewed first or second plurality of rollers are attached together in coaxial relation to form a substantially straight, elongated member, and said bore holes for said axially skewed first or second plurality of rollers are formed in said first or second end portion of said sleeve portion at a bore hole skew angle corresponding to said roller skew angle.

49. The device of claim 47 wherein said support arm and spindle for each of said axially skewed first or second plurality of rollers are attached together in eccentric relation to form an angled member with said spindle angled relative to said support arm by an angle corresponding to said roller skew angle, and said bore holes are formed in said first or second end portion of said sleeve portion in substantially parallel axial alignment with the one of said body or said drive member with which said axially skewed first or second plurality of rollers are engaged.

50. The device of claim 43 wherein each of said spindles is supported between first and second support arms.

51. The device of claim 50 wherein said reciprocating member includes a first plurality of recesses with at least one of said rollers of said first plurality of rollers positioned therein and projecting radially outward beyond said reciprocating member to rollingly engage said grooved body inward surface portion, and includes a second plurality of recesses with at least one of said rollers of said second plurality of rollers positioned therein and projecting radially inward beyond said reciprocating member to rollingly engage said grooved drive member outward surface portion, each said recess having a pair of opposed and axially spaced apart wall portions with each said wall portions supporting one or the other of said first or second support arms for said roller positioned therein.

52. The device of claim 51 wherein said recesses of said first and second pluralities of recesses are in substantially circumferential alignment.

53. The device of claim 51 wherein said first and second support arms extend outward from said spindle beyond said wall portions of said recess and are rigidly fastened to said reciprocating member with a selected axial angular orientation.

54. The device of claim 51 wherein each of said first and second pluralities of recesses is a window extending transversely fully through said reciprocating member

55. The device of claim 51 wherein each of said first and second pluralities of recesses is a transverse open-ended slot in an end portion of said reciprocating member.

56. The device of claim 51 wherein said first and second support arms for each spindle are coaxial, and said support arms and spindle for each said roller are attached together in coaxial relation.

57. The device of claim 56 further including a coaxial pair of bore holes for each of said first and second pluralities of recesses sized to receive said first and second support arms for said roller positioned in said recess, with said pairs of bore holes for said axially skewed first or second plurality of rollers having one bore hole in one of said wall portions and the other bore hole in the other of said wall portions at a bore hole skew angle corresponding to said roller skew angle for said axially skewed first or second plurality of rollers, said first and second support arms for each said spindle being disposed in said pair of bore holes.

58. The device of claim 50 wherein said reciprocating member includes a first circumferentially extending recess opening radially toward said body and having said first plurality of rollers disposed therein circumferentially spaced apart from each other, said first plurality of rollers projecting radially outward beyond said reciprocating member to rollingly engage said grooved body inward surface portion, and includes a second circumferentially extending recess opening radially inward toward said drive member and having said second plurality of rollers disposed therein circumferentially spaced apart from each other, said second plurality of rollers projecting radially inward beyond said reciprocating member to rollingly engage said grooved drive member outward surface portion.

59. The device of claim 50 wherein said first and second support arms are coaxial, and said support arms and spindle for each said roller of said axially skewed first or second plurality of rollers are attached together in eccentric relation with said spindle angled relative to said first and second support arms at an angle corresponding to said roller skew angle.

60. The device of claim 59 further including a plurality of pairs of bore holes sized to receive said first and second support arms, with each pair of said bore holes having one bore hole in one wall portion of a recess of said reciprocating member and the other bore hole in another opposed and axially spaced apart wall portion of said recess, each said pair of said bore holes being in substantially parallel axial alignment with the one of said body or drive member engaged by said axially skewed first or second plurality of rollers.

61. The device of claim 43 wherein said spindles of at least said first or second plurality of spindles are selectively and adjustably axially movable relative to said reciprocating member, and the fluid-power device further includes adjustment means for selectively and adjustably axially moving said movable spindles in an axial direction within at least a limited range to axially move said rollers rotatably retained thereon to eliminate backlash resulting from said rollers coacting with said body or drive member helical grooves as said piston moves from one axial direction to the other within said body as it reciprocates.

62. The device of claim 61 wherein said spindles of said first and second plurality of spindles are selectively and adjustably axially movable with respect to said reciprocating member, with said movable spindles of said first plurality of spindles and said movable spindles of said second plurality of spindles being movable in opposite axial directions to eliminate backlash.

63. The device of claim 61 wherein said movable spindles are eccentrically rotatable to axially move the contact points of said rollers retained thereon with the corresponding grooves of said body or drive member.

64. The device of claim 61 wherein each of said movable spindles retaining one of said axially skewed first or second plurality of rollers is supported by at least one support arm, said support arm and said movable spindle being attached together in eccentric relation with said spindle angled relative to said support arm at an angle corresponding to said roller skew angle, said support arm being disposed on an axis in substantial parallel axial alignment with said body and rotatably supporting said movable spindle for selective and adjustable eccentric movement about said axis, and wherein said adjustment means includes control means for selectively and adjustably rotating sad supported movable spindle about said axis to produce eccentric movement of said roller retained thereon, whereby rotation of said supported movable spindle and said roller retained thereon produces movement of said roller in said axial direction for elimination of backlash.

65. The device of claim 64 wherein said control means includes a member selectively extendable to engage a portion of said supported movable spindle at a position offset from said axis to apply an adjustment torque thereon to rotate said supported movable spindle eccentrically about said axis.

66. The device of claim 65 wherein said engagement portion of said supported movable spindle is an engagement surface oriented at an oblique angle relative to said axis and said extendable member is supported by said reciprocating member for selective extension relative to said reciprocating member to engage said inclined engagement surface.

67. The device of claim 65 wherein said supported movable spindles are positioned circumferentially adjacent to each other and each has both said engagement portion to be engaged by said extendable member of the next adjacent spindle to one side thereof and said extendable member to engage said engagement portion of the next adjacent spindle to the other side.

68. The device of claim 29 wherein circumferentially adjacent ones of said first or second plurality of rollers are positioned axially offset relative to each other.

69. The device of claim 68 wherein circumferentially adjacent ones of said spindles corresponding to said axially offset circumferentially adjacent rollers are positioned axially offset relative to each other.

70. The device of claim 69 wherein said axially offset circumferentially adjacent spindles includes spacer means for holding said axially offset spindles at a fixed axial offset position relative to the other ones of said spindles.

71. The device of claim 29 wherein said reciprocating member includes a plurality of spindles each rotatably and coaxially retaining at least one roller of said axially skewed first or second plurality of rollers and being positioned adjacent to the corresponding one of said grooved body or drive member surface portion, said spindles being circumferentially distributed about said grooved body or drive member surface portion to position said rollers of said axially skewed first or second plurality of rollers retained thereon in seated rolling engagement with the corresponding one of said grooved body or drive member surface portion, said spindles retaining said rollers against axial movement relative thereto and at said roller skew angle, said spindles being retained by said reciprocating member to prevent axial movement of said spindles relative to said reciprocating member during powered operation of the fluid-power device.

72. The device of claim 71 wherein said spindles are selectively and adjustably axially movable relative to said reciprocating member, and the fluid-power device further includes adjustment means for selectively and adjustably axially moving said movable spindles in an axial direction within at least a limited range to axially move said rollers rotatably retained on said movable spindles to eliminate backlash resulting from said rollers coacting with said body or drive member helical grooves as said piston moves from one axial direction to the other within said body as it reciprocates.

73. The device of claim 72 wherein said movable spindles are eccentrically rotatable by said adjustment means to axially move the contact points of said rollers retained thereon with the corresponding grooves of said body or drive member.

74. The device of claim 72 wherein each of said movable spindles retaining one of said rollers of said axially skewed first or second plurality rollers is supported by at least one support arm, said support arm and said movable spindle being attached together in eccentric relation with said spindle angled relative to said support arm at an angle corresponding to said roller skew angle, said support arm being aligned on an axis in substantial parallel axial alignment with said body and rotatably supporting said movable spindle for selective and adjustable eccentric movement about said axis, and wherein said adjustment means includes control means for selectively and adjustably rotating said supported movable spindle about said axis to produce eccentric movement of said roller retained thereon, whereby rotation of said supported movable spindle and said roller retained thereon produces movement of said roller in said axial direction for elimination of backlash.

75. A fluid-power device, comprising:

a body;

an axially extending drive member supported for movement relative to said body and connectable to an external device, one of said body or said drive member having a plurality of helical grooves formed on a surface portion thereof positioned within said body, said grooves having an axial pitch and a lead angle with a left-hand or right-hand turn;

a plurality of rollers, each having at least one circumferential ridge and being rotatably supported by a spindle, each said spindle being supported between first and second support arms;

an axially reciprocating member reciprocally mounted within said body, said reciprocating member supportably retaining first and second support arms in fixed axial and circumferential position relative to said reciprocating member during powered operation of the fluid-power device, with said rollers in seated rolling engagement with said grooves for transmitting force between said reciprocating member and said grooved one of said body or drive member, said ridges of said rollers being positioned for rolling travel in the corresponding helical grooves;

means for transmitting torque between said reciprocating member and the other of said body of drive member; and

at least one piston mounted for reciprocal movement and operatively engaging said reciprocating member.

76. The device of claim 75 wherein said spindles retain said rollers in an axially skewed position relative to said body or drive member with which engaged, such that the angle of skew corresponds to said hand turn of said engaged body or drive member helical grooves to improve angular alignment of said roller ridges with said engaged body or drive member helical grooves.

77. The device of claim 76 wherein said rollers are coaxially retained by said spindles and said spindles are circumferentially distributed about said grooved body or drive member surface portion with which said rollers are engaged, and wherein said first and second support arms and said spindle therebetween are attached together in eccentric relation with said spindle angles relative to said support arms at an angle corresponding to said roller skew angle, said first and second support arms are coaxially extending along an axial in substantial parallel alignment with said body and rotatably support said spindle for selective and adjustable eccentric rotational movement about said axis, and the fluid-power device further includes means for selectively and adjustably rotating said spindle about said axis to produce eccentric movement of said roller retained thereon, with said eccentric movement producing a component of movement of said roller in an axial direction relative to said body or drive member surface portion with which said roller is engaged for elimination of backlash.

78. A fluid-power device, comprising:

a body;

an axially extending drive member supported for movement relative to said body and connectable to an external device, one of said body or said drive member having a plurality of helical grooves with ridges therebetween formed on a surface portion thereof positioned within said body;

an axially reciprocating member reciprocally mounted within said body;

a plurality of rollers having circumferential grooves with ridges therebetween;

a plurality of cantilever spindles having a free, unattached first end portion extending into a circumferential space adjacent to said grooved surface portion and circumferentially distributed thereabout, said spindle free end portions each having at least one of said rollers coaxially and rotatably retained thereon and retained against axial movement relative to said spindles, each said spindle having a second end portion attached to said reciprocating member to support said first end portion in cantilevered manner and to prevent axial and circumferential movement of said spindle, said reciprocating member retaining said spindle free first end portions and said rollers rotatable retained thereon in fixed axial and circumferential position relative to said reciprocating member during powered operation of the fluid-power device, said rollers on said spindles being retained by said reciprocating member in circumferentially distributed arrangement in seated rolling engagement with said grooved surface portion for transmitting force between said reciprocating member and the one of said body or said drive member having said grooved surface portion, each ridge of said rollers being positioned for rolling travel in the corresponding grooves of said grooved surface portion;

an annular spindle support plate having a central opening through which said drive member extends and a plurality of circumferentially distributed spindle openings, each said spindle opening receiving one of said spindle free first end portions therethrough and providing support thereto against lateral forces on said spindles, said support plate being attached to said spindles for travel therewith during powered operation of the fluid-power device;

means for transmitting torque between said reciprocating member and the other of said body or said drive member; and

at least one piston mounted for reciprocal movement and operatively engaging said reciprocating member.

79. A fluid-power device, comprising:

a body;

an axially extending drive member supported for movement relative to said body and connectable to an external device, one of said body or said drive member having a plurality of helical grooves with ridges therebetween formed on a surface portion thereof positioned within said body;

an axially reciprocating member reciprocally mounted within said body;

a plurality of rollers having circumferential grooves with ridges therebetween, each being defined by a plurality of annular rings coaxially aligned and positioned together, each of said rings having a radially outward facing surface portion shaped to form in combination with the other of said plurality of rings said roller grooves and ridges, at least one of said rings further including at least one annular skirt coaxial with said one ring and axially extending therefrom toward the next adjacent one of said rings, whereby said surface portions of said plurality of rings can be axially spaced apart to provide a desired roller pitch;

a plurality of cantilever spindles having a free, unattached first end portion extending into a circumferential space adjacent to said grooved surface portion and circumferentially distributed thereabout, said spindle free end portions each having at least one of said rollers coaxially and rotatably retained thereon and retained against axial movement relative to said spindles, each said spindle having a second end portion attached to said reciprocating member to support said first end portion in cantilevered manner and to prevent axial and circumferential movement of said spindle, said reciprocating member retaining said spindle free first end portions and said rollers rotatable retained thereon in fixed axial and circumferential position relative to said reciprocating member during powered operation of the fluid-power device, said rollers on said spindles being retained by said reciprocating member in circumferentially distributed arrangement in seated rolling engagement with said grooved surface portion for transmitting force between said reciprocating member and the one of said body or said drive member having said grooved surface portion, each ridge of said rollers being positioned for rolling travel in the corresponding grooves of said grooved surface portion;

means for transmitting torque between said reciprocating member and the other of said body or said drive member; and

at least one piston mounted for reciprocal movement and operatively engaging said reciprocating member.

80. The device of claim 79 where each said ring includes annular first and second skirts, one of said first or second skirts extending axially to each side thereof, and said first and second skirts each have an axially outward opening circumferential ball groove formed thereon.

81. The device of claim 80 wherein said first and second skirt ball grooves are axially spaced apart so that one of said skirt ball grooves corresponds to and cooperates with one of said skirt ball grooves of an adjacent one of said rings to define a roller ball race to receive a ball.

82. The device of claim 79 wherein said rollers retained on said spindles each have a longitudinally extending substantially coaxial roller bore therethrough rotatably receiving one of said spindles, said axial bore being defined by an interior sidewall, corresponding ones of said roller bore sidewalls and spindles having formed thereon a plurality of confronting and corresponding ball races defining a plurality of ball channels extending circumferentially thereabout, and the fluid-power device further includes a plurality of balls seated in said ball channels to restrict axial movement of said rollers relative to said spindles while permitting free rotation of said rollers on said spindles.

83. A fluid-power device, comprising:

a body;

an axially extending drive member supported for movement relative to said body and connectable to an external device, one of said body or said drive member having at least one helical groove formed on a surface portion thereof positioned within said body;

at least one roller having at least one circumferential ridge;

an axially reciprocating member reciprocally mounted within said body, said reciprocating member rotatably retaining said roller in fixed axial and circumferential position relative to said reciprocating member during powered operation of the fluid-power device with said roller in seated rolling engagement with said grooved surface portion for transmitting force between said reciprocating member and the one of said body or said drive member having said grooved surface portion, said ridge of said roller being positioned for rolling travel in said helical groove of said grooved surface portion;

means for transmitting torque between said reciprocating member and the other of said body or said drive member; and

at least one piston mounted for reciprocal movement and operatively engaging said reciprocating member.

84. The device of claim 83 wherein said at least one groove includes a plurality of helical grooves with ridges therebetween and said at least one roller includes a plurality of rollers with each ridge of said rollers being positioned for rolling travel in one of said helical grooves, and wherein the number of said plurality of helical grooves is an integer multiple of the number of equally spaced circumferentially adjacent positions for roller for engagement therewith.

85. The device of claim 83 wherein said at least one groove includes a plurality of helical grooves with ridges therebetween and said at least one roller includes a plurality of rollers with each ridge of said rollers being positioned for rolling travel in one of said helical grooves, and wherein said reciprocating member includes a plurality of spindles extending into a circumferential space adjacent to said grooved surface portion and circumferentially distributed thereabout, said spindles each having at least one of said rollers coaxially and rotatably retained thereon and retained against axial movement relative to said spindles, said spindles being retained by said reciprocating member to prevent axial movement of said spindles relative to said reciprocating member during powered operation of the fluid-power device.

86. The device of claim 85 wherein said rollers retained on said spindles each have a longitudinally extending substantially coaxial roller bore therethrough rotatably receiving one of said spindles, said axial bore being defined by an interior sidewall, corresponding one of said roller bore sidewalls and spindles having integrally formed thereon a plurality of confronting and corresponding ball races defining a plurality of ball channels extending circumferentially thereabout, and the fluid-power device further includes a plurality of balls seated in said ball channels to restrict axial movement of said rollers relative to said spindles while permitting free rotation of said rollers on said spindles.

87. The device of claim 85 wherein said plurality of spindles each has an attached end portion connected to said reciprocating member and a free end portion positioned in said circumferential space, said spindle free end portions being circumferentially distributed within said circumferential space, said spindles each having at least one of said rollers coaxially and rotatably retained on said free end portion to provide a cantilevered support and retained against axial movement relative to said free end portion.

88. The device of claim 83 wherein said at least one groove includes a plurality of helical grooves with ridges therebetween and said at least one roller has a plurality of said circumferential ridges with a groove between adjacent pairs pairs of said ridges, and is defined by a plurality of annular rings coaxially aligned and positioned together on a spindle, each of said rings having a radially outward facing surface portion shaped to form in combination with the other of said plurality of rings said roller grooves and ridges.

89. The device of claim 88 wherein at least one of said rings further includes at least one annular skirt coaxial with said one ring and axially extending therefrom toward the next adjacent one of said rings, whereby said surface portions of said plurality of rings can be axially spaced apart to provide a desired roller pitch.

90. The device of claim 88 where each said ring includes annular first and second skirts, one of said first or second skirts extending to each side thereof.

91. The device of claim 90 wherein said first and second skirts each have an axially outward opening circumferential ball groove formed thereon, and said first and second skirt ball grooves are axially spaced apart so that one of said skirt ball grooves corresponds to and cooperates with one of said skirt ball grooves of an adjacent one of said rings to define a roller ball race to receive a ball.

92. The device of claim 83 wherein said helical groove of said grooved surface portion of said body or said drive member has an axial pitch and a lead angle with a left-hand or right-hand turn, and wherein said at least one roller is retained by said reciprocating member in axially skewed position relative to said body or drive member with which engaged, such that the angle of skew corresponds to said hand turn of said engaged helical groove to improve angular alignment of said roller ridge with said engaged helical groove of said grooved surface portion.

93. The device of claim 92 wherein said roller has a skew angle generally corresponding to said lead angle of said helical groove.