Method and apparatus for preloading the outer race of a tapered roller bearing in a vehicle axle differential

[0002] This invention relates in general to automotive differentials, including a differential carrier rotatably supporting a differential case bearing assembly mounted in the carrier. Typically, a conventional differential has a pinion shaft supported by a pair of axially spaced tapered roller bearings. A second pair of tapered roller bearings support the differential case. It is common practice to preload the inner races of each pair of tapered roller bearings by an axial compressive force.

[0003] Preloading the inner races of tapered roller bearings, is illustrated in U.S. Pat. No. 6,062,737 issued May 16, 2000, to James E. Thienes for “Wheel Hub Retention Apparatus”, by threading a compression member on the shaft against the inner race of one of the bearings.

[0004] Another arrangement is illustrated in U.S. Pat. No. 5,535,517 issued Jul. 16, 1996, to John E. Rode for “Bearing Setting Procedure and Apparatus”, for preloading tapered roller bearings using a collapsible spacer between the inner races of the two bearings.

[0005] U.S. Pat. No. 5,624,345 issued Apr. 29, 1997, to John T. Graft and Richard E. Cleveland, for “Apparatus for Preloading Axle Differential Bearings and Method of Assembling a Differential”, discloses a load deflection member acting on the bearing assembly to maintain a constant predetermined bearing preload to accommodate wear of the drive gears and the bearing assembly.

[0006] The broad purpose of the present invention is to provide a means for adjustably preloading the outer races of a pair of axially spaced tapered roller bearings by providing a pair of threadably connected sleeves. The outer races of both bearings are preloaded by rotating one of the sleeves. The method permits precise preloading of the bearings to accommodate the manufacturing tolerances of the particular axle, the gear arrangement and the geometry of the differential bearings.

[0007] The new design simplifies carrier manufacture by allowing a single tool pass to form all necessary bore surfaces for each of the pinion and differential bores. This should significantly reduce machining costs and improve quality.

[0008] The new design allows the pinion to be pre-assembled without selectable spacer shims or collapsible spacers, further reducing the cost of manufacturing.

[0009] The pinion bearing preload drag can be verified prior to installation with the carrier.

[0010] The cartridge assemblies can be made of a material that is suitable to support the loading stresses generated by the threaded features, while the carrier is made from a relatively light or soft material, i.e. aluminum, plastic, composite or similar.

[0011] The new differential bearing cartridge design eliminates the need for bearing caps that are required in traditional designs.

[0012] Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description.

[0013] The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views, and in which:

[0014] FIG. 1 is a cross-sectional view of a vehicle differential illustrating the invention; and

[0015] FIG. 2 is a view of a pair of sleeves preloading a pair of enclosed tapered roller bearings on the pinion shaft of the differential.

[0016] Referring to the drawings, FIG. 1, illustrates a vehicle differential which includes a differential housing (carrier) 10, on the underside of a vehicle (not shown). The differential includes a pinion shaft 12 upon which a power input pinion gear 14 is typically formed. Pinion gear 14 meshes with a ring gear 16 which in turn is secured to a ring gear flange 18 associated with a differential rotor or case 19. Differential case 19 along with ring gear 16 are rotated in the stationary housing 10 by means of pinion gear 14. The rotary motion of the differential case is imparted to drive axles 20 and 22 and wheels (not shown) of the vehicle. Each of the drive axles is coupled to an output beveled gear set 24 permitting the two axles to be driven at different speeds.

[0017] A plurality of planetary gears 26 mesh with the output gear set 24 to transfer power. Drive axles 20 and 22 are rotatably supported in the housing by means of a pair of tapered roller bearing assemblies generally indicated at 28 and 30.

[0018] Pinion shaft 12 is supported by a pair of axially spaced tapered roller bearings generally indicated at 32 and 34. Roller bearing 32 includes an inner race 36 seated against a shoulder 38 carried on the pinion shaft. Roller bearing 34 has an inner race 40 seated against an annular shoulder 42 on the pinion shaft.

[0019] The outer end of the shaft is threaded at 44. A nut 46, carried on the threaded end 44 of the shaft, engages inner race 40 to secure it against axial motion with respect to the pinion shaft.

[0020] Roller bearing 32 has an outer race 48. Roller bearing 34 has an outer race 50. Both bearings 32 and 34 permit the pinion shaft to rotate about an axis 52.

[0021] A pair of adjustment sleeves 56 and 58 are mounted on outer races 48 and 50, respectively. Sleeve 56 has a threaded section 60 disposed around the axis of the shaft. Sleeve 58 has a threaded section 62 threadably engaged with threaded section 60. The two sleeves are axially movable with respect to one another by rotating one of the sleeves with respect to the other.

[0022] Serrated external structure sleeves 63aand 63bon 56 and 58 prevent rotation of the sleeves upon installation into the carrier 10.

[0023] Sleeve 56 has a shoulder 64 engaging the inner face of outer race 48. Sleeve 58 has an annular shoulder 66 engaging the inner face of outer race 50. Sleeve 56 is slidably mounted in a cylindrical surface 70 of the housing, while sleeve 58 is slidably disposed in a cylindrical surface 72 of the housing. The arrangement is such that by threadably rotating one of the sleeves with respect to the other, the two sleeves apply an adjustable tensile preload against outer races 48 and 50 of the two bearings.

[0024] Still referring to FIG. 1, tapered roller bearing 30 includes an inner race 78 and an outer race 80. The inner race is seated against a shoulder 82 of case 19. A pair of adjustable sleeves 84 and 86 are mounted in the housing. Sleeve 86 is fixed against axial motion, about the axis of rotation 88 of drive axle 20, and has threaded means 90 threadably engaging complementary threads 92 of sleeve 84. Sleeve 84 engages the outer face 96 of outer race 80, that is, the face adjacent the narrow end of roller means 98. Serrations on sleeves 86 and 86aprevent rotation of the housings upon installation into carrier 10. The arrangement is such that by rotating sleeve 84, a desired axial preload is applied to outer race 80. Sleeves 84 and 84aare mechanically locked to prevent rotation once differential bearing preload and ring gear lash has been established.

[0025] Tapered roller bearing 28, mounted on drive axle 22, is preloaded in a similar fashion by parts designated with an “a” that are similar to the corresponding components used for preloading roller bearing assembly 30.

[0026] After the pinion cartridge is assembled to the carrier, nut 46 allows the pinion drag to be monitored without a yoke 102 or companion flange (not shown) in place thereby removing the influence of seal 104 drag.

[0027] Proper pinion gear position is set using a single spacer 100. The external configuration of this spacer allows it to be changed without disturbing the pinion bearing preload.

[0028] Sleeves 56, 58, 84 and 84aphysically support and contain the bearing races 48, 50 and 80 and 80ato insure movement when threadably adjusted. Bearing races 48, 50 and 80 and 80aare typically press fit to carrier 10 to prevent rotation of the race during operation. This interference prevents the proper setting of the bearing position with conventional adjuster nut assemblies.

[0029] Pinion seal 104 is installed after the assembly of the pinion cartridge to reduce the likelihood of damage to the seal.

[0030] Separated cartridge assemblies generated by the assembly of sleeves 56, 58 and 84, 86 and 84a,86aallow the use of dissimilar materials between the cartridges and the carrier without the loss of bearing retention caused by thermal growth differences between the materials.

[0031] By adjusting sleeves 84 and 84aseparately or in tandem, the proper lash may be set between the ring gear 16 and the pinion gear 14.