Load compensator for height adjustable table

• US 20060130713A1
• Filed: 12/16/2005
• Published: 06/22/2006
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Steelcase Incorporated
• Original Assignee: Steelcase Development Corporation (Steelcase Incorporated)
• Inventors: Heidmann, Kurt, Andres, Todd, Jones, David K.
• Granted Patent: US 8,091,841 B2
• Time in Patent Office: Days
• US Class Current: 108/106
• CPC Class Codes: A47B 13/023 with a central column
• CPC Class Codes: A47B 2013/024 being assembled to a base
• CPC Class Codes: A47B 2200/0051 Telescopic
• CPC Class Codes: A47B 2200/0052 with two telescopic parts
• CPC Class Codes: A47B 9/00 Tables with tops of variable height lecterns with variable height A47B19/06; school forms or desks with variable height A47B39/02, A47B41/02; seats with variable height A47C3/20
• CPC Class Codes: A47B 9/02 with balancing device, e.g. by springs, by weight
• CPC Class Codes: A47B 9/12 with flexible height-adjusting means, e.g. rope, chain
• CPC Class Codes: A47B 9/20 Telescopic guides

Abstract

A force adjustment assembly for use within a telescoping subassembly that includes a first elongated member and a second elongated member that is supported by the first elongated member for sliding motion along an extension axis, the subassembly further including a force equalizer assembly that includes a strand having first and second ends that are supported by the second and first elongated members, respectively, the adjustment assembly comprising a preloader supported by at least one of the first and second elongated members and supporting at least a portion of the strand, the preloader applying a preload force via the strand when the second elongated member is in a fully extended position and an adjuster for adjusting the preload force applied by the preloader.

Claims

1. An assembly for adjusting the position of a first guide member, the assembly comprising:

a second guide member forming a channel, the first guide member positioned within the channel for sliding movement along an adjustment axis;

a threaded shaft mounted at least partially within the channel for rotation about the adjustment axis;

a nut threadably receiving the shaft and supported by the first guide member; and

a lever member supported by the first guide member and including at least a first nut engaging member;

wherein the lever member restricts rotation of the nut with respect to the first guide member during at least a portion of travel of the first guide member within the channel and allows nut rotation in at least a first direction with respect to the first guide member when the first guide member is in at least a first position.

2. The assembly of claim 1 wherein the first guide member is capable of assuming positions within the channel between and including a maximum preload force position and a minimum preload force position, the lever member restricting rotation of the nut with respect to the first guide member when the first guide member position is between the maximum and minimum preload force positions and allowing the nut to rotate in at least one direction when the first guide member is in one of the maximum and minimum preload force positions, the maximum preload force position being the first position of the first guide member.

3. The assembly of claim 2 wherein the nut is supported within the first guide member by bearings.

4. The assembly of claim 3 wherein the bearings include radial bearings and thrust bearings.

5. The assembly of claim 4 wherein the radial bearings include first and second radial bearings and the thrust bearings include first and second thrust bearings.

6. The assembly of claim 1 wherein the nut includes a first set of radially extending teeth that travel along a first circular path as the nut rotates and the lever member includes at least a first nut engaging member, at least a portion of the first nut engaging member located within the first circular path when the lever member restricts nut rotation in the first direction, the first nut engaging member outside the first circular path when the first guide member is in the maximum preload force position and the lever member allows the nut to rotate in the first direction.

7. The assembly of claim 6 wherein the first guide member is capable of assuming positions within the channel between and including a maximum preload force position and a minimum preload force position, the assembly including at least a first bearing surface linked to and stationary with respect to the second guide member, when the first guide member is in the maximum preload force position, the lever engaging the first bearing surface and sliding into a first lever position in which the first nut engaging member is outside the first circular path, the maximum preload force position being the first position of the first guide member.

8. The assembly of claim 7 wherein lever member includes at least a second nut engaging member, at least a portion of the second nut engaging member located within the circular path when the lever member is in the first lever position to restrict nut rotation in a second direction opposite the first direction.

9. The assembly of claim 8 wherein the nut includes a second set of radially extending teeth that travel along a second circular path as the nut rotates and wherein the at least a portion of the second nut engaging member is located within the second circular path when the lever member is in the first lever position.

10. The assembly of claim 1 wherein the lever member allows nut rotation in at least a second direction with respect to the first guide member and opposite the first direction when the first guide member is in at least a second position.

11. The assembly of claim 10 wherein the nut includes a first set of radially extending teeth that travel along a first circular path as the nut rotates and the lever member includes at least a first nut engaging member, at least a portion of the first nut engaging member located within the first circular path when the lever member restricts nut rotation in the first direction, the first nut engaging member outside the first circular path when the first guide member is in a first position and the lever member allows the nut to rotate in the first direction and wherein the nut includes a second set of radially extending teeth that travel along a second circular path as the nut rotates and the lever member includes at least a second nut engaging member, at least a portion of the second nut engaging member located within the second circular path when the lever member restricts nut rotation in a second direction, the second nut engaging member outside the second circular path when the first guide member is in a second position and the lever member allows the nut to rotate in the second direction.

12. The assembly of claim 11 wherein the first guide member is capable of assuming positions within the channel between and including a maximum preload force position and a minimum preload force position, the assembly including at least first and second bearing surfaces linked to and stationary with respect to the second guide member, when the first guide member is in the maximum preload force position, the lever engaging the first bearing surface and sliding into a first lever position in which the first nut engaging member is outside the first circular path and, when the first guide member is in the minimum preload force position, the lever engaging the second bearing surface and sliding into a second lever position in which the second nut engaging member is outside the second circular path.

13. The assembly of claim 12 wherein each of the teeth includes a ramped surface and a generally oppositely facing radial surface.

14. The assembly of claim 13 wherein the ramped surfaces of each tooth in the first set of teeth all slope in a first direction and the ramped surfaces of the each tooth in the second set of teeth slope in a second direction that is opposite the first direction when the nut is axially viewed.

15. The assembly of claim 14 wherein each of the first and second nut engaging members forms a ramped surface and a generally oppositely facing flat surface and, wherein, when at least a portion of one of the nut engaging members is located within one of the circular paths, the engaging member ramped surface is adjacent and faces a ramped surface of an adjacent tooth while the engaging member flat surface is adjacent and faces a radial surface of an adjacent tooth.

16. The assembly of claim 12 further including at least a first biaser that biases the lever member into an intermediate position between the maximum and minimum preload force positions when the lever member is separated from the first and second bearing surfaces, the first and second nut engaging members within the first and second circular paths, respectively, when the lever member is in the intermediate position.

17. The assembly of claim 16 wherein the at least a first biaser includes first and second compression springs.

18. The assembly of claim 17 further including first and second spring bearing surfaces linked to and stationary with respect to the first guide member, the first and second springs contacting the first and second spring bearing surfaces, respectively.

19. The assembly of claim 18 wherein the lever member includes first and second spring engaging members, the first spring sandwiched between the first spring bearing surface and the first spring engaging member and the second spring sandwiched between the second spring bearing surface and the second spring engaging member.

20. The assembly of claim 11 wherein each of the first and second sets of teeth circumscribe the circumference of the nut, each tooth is substantially aligned with and extends parallel to the adjustment axis and wherein the nut forms a recessed circumferential space between the first and second sets or teeth.

21. The assembly of claim 20 wherein when either of the first and second nut engaging members disengages the nut, at least a portion of the disengaging member is located within the recessed circumferential space.

22. The assembly of claim 1 for use in a telescoping assembly including a first elongated member and a second elongated member that is supported by the first elongated member for movement along an extension axis that is substantially parallel to the adjustment axis, the second guide member supported by the second elongated member.

23. The assembly of claim 22 further including a counterbalance force apparatus that includes a strand having first and second ends that are linked to the first and second elongated members, respectively, wherein an intermediate portion of the strand is linked to the first guide member.

24. The assembly of claim 23 wherein the counterbalance force apparatus includes a spring and wherein the second end of the strand is linked to the second elongated member via the strand.

25. The assembly of claim 24 further including a snail cam pulley and an adjustment pulley, the adjustment pulley supported by the first guide member and the snail cam pulley supported by the second elongated member, the strand passing over each of the snail cam pulley and the adjustment pulley.

26. The assembly of claim 25 further including a power law pulley that is supported by the second elongated member, the strand passing over the power law pulley.

27. The assembly of claim 1 further including an indicator linked to the first guide member for indicating the position of the first guide member with respect to the second guide member.

28. The assembly of claim 27 wherein the indicator includes an elongated indicator member that includes first and second ends and that is supported at the first end at a pivot point by the second guide member, wherein an intermediate portion of the indicator member is in communication with the first guide member which forces the second end of the indicator member to move as the first guide member moves along the channel.

29. The assembly of claim 28 wherein the guide member forces the indicator to pivot about the pivot point as the first guide member moves along the channel.

30. An assembly for adjusting the position of a first guide member, the assembly comprising:

a second guide member forming a channel, the first guide member positioned within the channel for sliding movement along an adjustment axis;

a threaded shaft mounted at least partially within the channel for rotation about the adjustment axis;

a nut threadably receiving the shaft and supported by the first guide member; and

a lever member supported by the first guide member;

wherein the lever member restricts rotation of the nut with respect to the first guide member during at least a portion of travel of the first guide member within the channel, allows nut rotation in a first direction and restricts rotation in a second direction opposite the first direction with respect to the first guide member when the first guide member is in at least a first position along the channel and allows nut rotation in the second direction and restricts rotation in the first direction when the first guide member is in at least a second position along the channel.

31. The assembly of claim 30 wherein the first guide member is capable of assuming positions within the channel between and including a maximum preload force position and a minimum preload force position and wherein the first and second first guide member positions are the maximum and minimum preload force positions.

32. The assembly of claim 31 wherein the nut includes a first set of radially extending teeth that travel along a first circular path as the nut rotates and the lever member includes at least a first nut engaging member, at least a portion of the first nut engaging member located within the first circular path when the lever member restricts nut rotation in the first direction, the first nut engaging member outside the first circular path when the first guide member is in the maximum preload force position and the lever member allows the nut to rotate in the first direction and wherein the nut includes a second set of radially extending teeth that travel along a second circular path as the nut rotates and the lever member includes at least a second nut engaging member, at least a portion of the second nut engaging member located within the second circular path when the lever member restricts nut rotation in a second direction, the second nut engaging member outside the second circular path when the first guide member is in the minimum preload force position and the lever member allows the nut to rotate in the second direction.

33. The assembly of claim 32 wherein each of the teeth includes a ramped surface and a generally oppositely facing radial surface.

34. The assembly of claim 33 wherein the ramped surfaces of each tooth in the first set of teeth all slope in a first direction and the ramped surfaces of the each tooth in the second set of teeth slope in a second direction that is opposite the first direction when the nut is axially viewed.

35. The assembly of claim 34 wherein each of the first and second nut engaging members forms a ramped surface and a generally oppositely facing flat surface and, wherein, when at least a portion of one of the nut engaging members is located within one of the circular paths, the engaging member ramped surface is adjacent and faces a ramped surface of an adjacent tooth while the engaging member flat surface is adjacent and faces a radial surface of an adjacent tooth.

36. The assembly of claim 30 further including at least a first biaser that biases the lever member into an intermediate position between the maximum and minimum preload force positions when the lever member is separated from the first and second bearing surfaces, the first and second nut engaging members within the first and second circular paths, respectively, when the lever member is in the intermediate position.

37. The assembly of claim 36 wherein the at least a first biaser includes first and second compression springs.

38. A support assembly, the assembly comprising:

a first elongated member having a length dimension parallel to a substantially vertical extension axis;

a second elongated member supported by the first member for sliding motion along the extension axis between at least an extended position and a retracted position;

a spring that generates a variable spring force that depends at least in part on the degree of spring loading, the spring having first and second ends;

an equalizer assembly including a strand having first and second ends, the first end linked to the second end of the spring and a second end linked to the first member, the force equalizer assembly and spring applying a force between the first and second members tending to drive the elongated members into the extended position wherein the applied force is substantially constant irrespective of the position of the second elongated member with respect to the first elongated member;

a preloader supporting at least a portion of the strand, the preloader applying a preload force via the strand to the spring when the second elongated member is in a fully extended position; and

an adjuster for adjusting the preload force applied by the preloader.

39. The apparatus of claim 38 further including a sensor supported by at least one of the first and second elongated members for determining and issuing a signal when the preload applied by the preloader is outside a specific range of a load on the second elongated member.

40. The apparatus of claim 39 wherein the adjuster modifies the preload applied by the preloader when a signal is received from the sensor.

41. The apparatus of claim 40 wherein the adjuster includes a motor.

42. The apparatus of claim 38 wherein the preloader includes a power law pulley and wherein the strand is also supported at least in part by the power law pulley.

43. The apparatus of claim 42 wherein the preloader includes an adjustment pulley having a channel of constant radius that is mounted for rotation to an adjustment shaft, the strand supported at least in part by the adjustment pulley, the adjustment pulley adjustably mounted within the cavity so that the relative position of the adjustment pulley to the spiral cam pulley is modifiable to alter the preload force on the spring.

44. The apparatus of claim 43 wherein the strand extends from the first strand end, about the spiral cam pulley, from the spiral cam pulley to the adjustment pulley, from the adjustment pulley to the power law pulley and from the power law pulley to the second end of the spring.

45. The apparatus of claim 38 wherein a table top is mounted to the second elongated member.

46. The assembly of claim 38 wherein the spring and equalizer assembly together tend to drive the second elongated member into the extended position.

47. The apparatus of claim 38 wherein the preloader also includes an adjustment pulley having a channel of constant radius that is mounted for rotation to an adjustment shaft, the strand supported at least in part by the adjustment pulley, the adjustment pulley adjustably mounted within the cavity so that the relative position of the adjustment pulley to the spiral cam pulley is modifiable to alter the preload force on the spring.

48. The apparatus of claim 47 wherein the preloader further includes an adjustment assembly including at least a first adjustment member and an adjustment drive, the adjustment pulley supported by the first adjustment member, the first adjustment member supported by the drive and the drive supported by the second elongated member, the drive operable to move the first adjustment member along an adjustment trajectory to modify the relative position of the adjustment pulley to the spiral cam pulley to alter the preload force on the spring.

49. The apparatus of claim 48 wherein the preloader further includes a first guide member supported by the second elongated member, the first adjustment member includes a second guide member and forms one of a threaded shaft and a threaded channel, the drive includes a second adjustment member that forms the other of a threaded shaft and a threaded channel wherein, the second guide member is received by the first guide member to facilitate sliding movement along the adjustment trajectory and the threaded shaft is threadably receivable within the threaded channel such that when the second adjustment member is rotated, the first adjustment member moves along the trajectory thereby changing the relative position of the adjustment pulley with respect to the second elongated member.

50. The apparatus of claim 49 wherein the adjuster includes an adjustment coupler and wherein the second adjustment member is supported by the adjustment coupler.

51. The apparatus of claim 50 wherein the adjustment coupler is supported by the second elongated member for rotation about an adjustment axis and includes a first coupling surface and wherein the drive includes a second coupling surface that contacts the first coupling surface wherein the second coupling surface moves with the first coupling surface when the force therebetween is below a coupling threshold level.

52. The apparatus of claim 51 wherein at least one of the first and second coupling surfaces is formed of bronze.

53. The apparatus of claim 50 wherein the adjustment coupler includes a first beveled gear and wherein the adjuster further includes a second beveled gear that mates with the first beveled gear such that the first beveled gear rotates when the second beveled gear is rotated, the second beveled gear formed about a gear axis and including a distal end configured to mate with an adjustment tool.

54. The apparatus of claim 38 wherein the adjuster includes a first coupling surface and the preloader includes a second coupling surface that contacts the first coupling surface to form a friction contact wherein, when the first coupling surface moves, a force is applied via the friction contact to the second coupling surface tending to move second coupling surface to adjust the preloader force.

55. The apparatus of claim 38 further including a force indicator linked to the preloader, the force indicator indicating the level of preload force applied to the spring via the preloader.

56. The assembly of claim 38 wherein the preloader is capable of applying a maximum preload force and a minimum preload force, the assembly further including a clutch mechanism that links the adjuster to the preloader when the preload force applied is within the range between the maximum and minimum forces and de-links the adjuster from the preloader when the preload force is either the maximum or the minimum preload force.

57. The assembly of claim 56 wherein the adjuster includes a threaded shaft and a nut, the preloader includes a first guide member and the clutch includes a lever member supported by the first guide member that restricts rotation of the nut when the preload force is within the maximum and minimum range and that allows the nut to rotate in a first direction and in a second direction when the maximum and minimum preload forces are applied, respectively.

58. The assembly of claim 57 further including a second guide member that forms at least one channel, the first guide member engaging the channel to slide there along, the first guide member supported by the nut.

59. The assembly of claim 58 wherein the lever member includes first and second nut engaging members where each of the nut engaging members forms a ramped surface and a substantially oppositely facing flat surface, the ramped surfaces of the first and second nut engaging members substantially facing in opposite directions.

60. The assembly of claim 59 wherein the nut forms a plurality of radially extending teeth that travel along a circular path as the nut rotates wherein at least a portion of the first nut engaging member is within the circular path when the preloader applies the minimum preload force and is outside the circular path when the preloader applies the maximum preload force and at least a portion of the second nut engaging member is within the circular path when the preloader applied the maximum preload force and is outside the circular path when the preloader applies the minimum preload force.

61. The assembly of claim 60 wherein the lever member is in an intermediate position with portions of both the first and second nut engaging members within the circular path when the preload force applied is between the maximum and minimum preload forces.

90. The assembly of claim 38 wherein the first end of the spring is supported by and stationary with respect to the second elongated member and wherein the preloader is supported by at least one of the first and second elongated members.

62. A force adjustment assembly for use within a telescoping subassembly that includes a first elongated member and a second elongated member that is supported by the first elongated member for sliding motion along an extension axis, the subassembly further including a force equalizer assembly that includes a strand having first and second ends that are supported by the second and first elongated members, respectively, the adjustment assembly comprising:

a preloader supporting at least a portion of the strand, the preloader applying a preload force via the strand when the second elongated member is in a fully extended position; and

an adjuster for adjusting the preload force applied by the preloader.

63. The assembly of claim 62 wherein the preloader includes a power law pulley and wherein the strand is also supported at least in part by the power law pulley.

64. The assembly of claim 63 wherein the preloader also includes an adjustment pulley, the strand supported at least in part by the adjustment pulley, the adjustment pulley supported by the second elongated member so that the position of the pulley with respect to the second elongated member is adjustable to alter the preload force.

65. The assembly of claim 62 wherein the preloader also includes an adjustment pulley, the strand supported at least in part by the adjustment pulley, the adjustment pulley supported by the second elongated member so that the position of the pulley with respect to the second elongated member is adjustable to alter the preload force.

66. The assembly of claim 62 wherein the preloader includes an adjustment assembly including at least a first adjustment member and an adjustment drive, the adjustment pulley supported by the first adjustment member, the first adjustment member supported by the drive and the drive supported by the second elongated member, the drive operable to move the first adjustment member along an adjustment trajectory to modify the relative position of the adjustment pulley to the second elongated member to alter the preload force.

67. The assembly of claim 66 wherein the first adjustment member includes a first guide member and forms one of a threaded shaft and a threaded channel, the preloader further includes a second guide member supported by the second elongated member, the drive includes a second adjustment member that forms the other of a threaded shaft and a threaded channel wherein, the first guide member is received by the second guide member to facilitate sliding movement along the adjustment trajectory and the threaded shaft threadably receivable within the threaded channel such that when the second adjustment member is rotated, the first adjustment member moves along the adjustment trajectory thereby changing the relative position of the adjustment pulley with respect to the second elongated member.

68. The assembly of claim 67 wherein the adjuster includes an adjustment coupler and wherein the second adjustment member is supported by the adjustment coupler.

69. The assembly of claim 68 wherein the adjustment coupler is supported by the second elongated member for rotation about an adjustment axis and includes a first coupling surface, the drive includes a second coupling surface that contacts the first coupling surface and wherein the second coupling surface moves with the first coupling surface when the force therebetween is below a coupling threshold level.

70. The assembly of claim 69 wherein at least one of the first and second coupling surfaces is formed of bronze.

71. The assembly of claim 70 wherein the coefficient of friction between the first and second coupling surfaces is between 0.05 and 0.5.

72. The assembly of claim 69 wherein the adjustment coupler includes a first beveled gear and wherein the adjuster further includes a second beveled gear that mates with the first beveled gear such that the first beveled gear rotates when the second beveled gear is rotated, the second beveled gear formed about a gear axis and including a distal end formed to mate with an adjustment tool.

73. The assembly of claim 62 wherein the adjuster includes a first coupling surface and the preloader includes a second coupling surface that contacts the first coupling surface to form a friction contact wherein, when the first coupling surface moves, a force is applied via the friction contact to the second coupling surface tending to move second coupling surface to adjust the preloader force.

74. The assembly of claim 62 further including a force indicator linked to the preloader, the force indicator indicating the level of preload force applied to the spring via the preloader.

75. The assembly of claim 74 wherein the indicator includes an elongated indicator member that is mounted at a pivot point to the preloader to pivot about the pivot point.

76. The assembly of claim 75 wherein the preloader includes a first guide member that moves along an adjustment axis as the preload force is modified and the indicator includes an elongated indicator member supported at a first end for pivotal motion by the second elongated member and in communication with at least a portion of the first guide member such that the second end of the elongated member moves as the first guide member moves along the adjustment axis.

77. The assembly of claim 76 wherein the adjuster includes a member that forms an adjustment tool engaging structure at a distal end and the indicator includes a visible portion that moves with the indicator member, the visible portion positioned proximate the engaging structure.

78. The assembly of claim 62 wherein the preloader is capable of applying a preload force within a range between a maximum preload force and a minimum preload force, the assembly further including a clutch mechanism that couples the adjuster to the preloader when the preload force applied is within the range and de-couples the adjuster from the preloader when the applied force is outside the range.

79. The assembly of claim 78 wherein the adjuster includes a threaded shaft and a nut, the preloader includes a first guide member and a pulley supported by the guide member and the clutch includes a lever member supported by the first guide member, the lever member restraining the nut when the preload force is within the range and allowing the nut to rotate in at least a first direction when the maximum preload force is applied by the preloader.

80. The assembly of claim 79 wherein the lever member also allows the nut to rotate in a second direction opposite the first direction when the minimum preload force is applied by the preloader.

81. The assembly of claim 79 wherein the nut is supported within the first guide member by thrust and radial bearings.

82. The assembly of claim 79 wherein the nut includes a first set of radially extending teeth that travel along a first circular path as the nut rotates and the lever member includes at least a first nut engaging member, at least a portion of the first nut engaging member located within the first circular path when the lever member restricts nut rotation in the first direction, the first nut engaging member outside the first circular path when the first guide member is in the maximum preload force position and the lever member allows the nut to rotate in the first direction.

83. The assembly of claim 82 wherein the nut includes a second set of radially extending teeth that travel along a second circular path as the nut rotates and the lever member includes at least a second nut engaging member, at least a portion of the second nut engaging member located within the second circular path when the lever member restricts nut rotation in a second direction, the second nut engaging member outside the second circular path when the first guide member is in the minimum preload force position and the lever member allows the nut to rotate in the second direction.

84. The assembly of claim 83 wherein each of the teeth includes a ramped surface and a generally oppositely facing radial surface.

85. The assembly of claim 84 wherein the ramped surfaces of the first portion of teeth all slope in a first direction and the ramped surfaces of the second portion of teeth slope in a second direction that is opposite the first direction when the nut is axially viewed.

86. The assembly of claim 85 wherein each of the first and second nut engaging members forms a ramped surface and a generally oppositely facing flat surface and, wherein, when one of the nut engaging members is located at least partially within one of the tooth paths, the engaging member ramped surface is adjacent a ramped surface of an adjacent tooth while the engaging member flat surface is adjacent a radial surface of another adjacent tooth.

87. The assembly of claim 62 wherein preloader includes a first adjustment member, an adjustment pulley and an adjustment drive, the adjuster is linked to the first adjustment drive, the pulley is linked to the first adjustment member and the first adjustment member is linked to the adjustment drive.

88. The assembly of claim 87 wherein the first adjustment member is linked to the adjustment drive via a clutch.

91. The assembly of claim 62 wherein the preloader is supported by at least one of the first and second elongated members.

89. A force adjustment assembly for use within a telescoping subassembly that includes a first elongated member and a second elongated member that is supported by the first elongated member for sliding motion along an extension axis, the subassembly further including a force equalizer assembly that includes a strand having first and second ends that are supported by the second and first elongated members, respectively, the adjustment assembly comprising:

a preloader supporting at least a portion of the strand, the preloader applying a preload force via the strand when the second elongated member is in a fully extended position;

an adjuster for adjusting the preload force applied by the preloader; and

a clutch between the adjuster and the preloader for, when the force between the adjuster and the preloader exceeds a threshold level, allowing the adjuster to slip with respect to the preloader.

92. The assembly of claim 89 wherein the preloader is supported by at least one of the first and second elongated members.