GB1568658A

GB1568658A - Bearing retainer assembly

Info

Publication number: GB1568658A
Application number: GB16959/78A
Authority: GB
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1977-07-28
Filing date: 1978-04-28
Publication date: 1980-06-04
Also published as: BR7804187A; MY8200166A; IT1096842B; JPS5425350A; CA1082273A; FR2398919B1; IT7825187A0; FR2398919A1

Description

(54) BEARING RETAINER ASSEMBLY (71) We, CATERPILLAR TRACTOR Co., a corporation organized and existing under the laws of the State of California, United States of America, of 100 N. E. Adams Street, Peoria, Illinois 61629, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to bearing assemblies for, by way only of example, the final drives of tractors and trucks, and particularly to improvements in existing arrangements for preloading such bearings.

Tractors are extensively used in the earth movin industry and typically include right and lem final drives for transmitting power from the engine or motive power means to the right and left track assemblies or wheels. Each final drive typically includes a drive sprocket or wheel journaled to a cross shaft. The shafts are supported by a plurality of bearings which include an arrangement or means for preloading the bearing supporting each shaft in the assembly, which Supports each shaft and sprocket with respect to its support housing. Also included is a retaining ring which abuts a reaction hub of an associated planetary gear assembly, which in turn bears on a bearing.

Our Patent Speciflcation No. 1,483,164 disdoses an improved arrangement for preloading bearings which eliminates many of the problems experienced with the prior art arrangements. The improved preloading arrangement includes a plurality of pins which extend through holes or bores in a reaction hub of an associated planetary gear assembly. Opposite ends of the pins contact a bearing cone on the one hand and a loading ring on the other.

While the described arrangement has proved to be effective in accomplishing its stated objective of preloading the bearings, some problems have been engendered. The problems are due to the fact that the bearing cones are galled or gouged by the associated pins moving in relation to the cones during use. The cones rotate slowly under a load and cause a misalignment of the pins.

The pins, which are typically of harder material than the cones, then gouge into the softer material of the cones. This of course results in unwanted downtime for replacement of the bearings.

In accordance with the present invention, a bearing assembly includes a bearing; preloading means for preloading the bearing and comprising a reaction hub of an associated planetary gear assembly, the hub having a plurality of pins extending through bores therein; axially movable retaining means provided between the bearing and the preloading means for transmitting force from the preloading means to the bearing, the retaining means being a generally ringshaped retainer, one end of which contacts the bearing and the other end of which is contacted by the pins; and mounting means on the retainer and the reaction hub whereby the retainer is non-rotatable relatively to the reaction hub.

The retainer is preferably of a hardened material. The pins passing through the forces are transmitted through the rethe, preferably, planar end faces of the retainer and the thus generated preload forces are transmiteted through the retainer to the bearing cone which is in con tacting relation with a, preferably, planar, opposite face of the retainer.

In this manner, gouging and galling of the bearing cone is eliminaled. The mounting means may comprise splines on the inner periphery of the retainer which mate with accommodation grooves in mounting structure such as a first hub. The reaction hub may be similarly splined to the first hub. In this manner, relative rotation between the retainer and the pins is thereby prevented while axial movement is permitted. This effectively eliminates the probe lem of cocking of the pins and relative movement between the pin and its contacting surface A drive train incorporating an example of a bearing assembly in accordance with the invention is illustrated in the accompanying drawings, in which:- Figure 1 is an axial section; Figure 2 is an enlarged cross-sectional view of a portion of the final drive; and Figure 3 is a view of the retainer ring partly broken away and in partial crosssection in order to illustrate details of the retainer.

Figure 1 shows a single final drive unit wherein power from an engine (not shown) is transmitted through a shaft 10 from a drive mechanism including transmission, steering clutches, and brakes, etc. (also not shown). Power from shaft 10 enters a doublefl planetary drive train including a first sun gear 12 fixed on the end of the shaft. Sun gear 12, in turn, drives a plurality of: first planet gears one of which is shown at 14. The first planet gears are supported by a first planet carrier 16 so that the first planets 14 are also in mesh with a circumscribing ring gear 18. First planet carrier 16 is, in turn, in mesh with a second sun gear 20. The second sun gear 20, in turn, drives a plurality of second planet gears, one of which is shown at 22. The second planet gears are, in turn, supported by a second planet carrier 24. Second planet gears 22 are also in mesh with ring gear 18* Second planet carrier 24 is secured to a housing 26 by means of a plurality of bolts, one of which is shown at 28. Housing 26 is rotatably supported by means of bearings 30 and 32 on a first hub 34. First hub 34 is, in turn. secured to the vehicle main frame (not shown) by bolt means (not shown).

A second, reaction, hub 36 is provided within housing 26 for the purpose of preventing; rotation of ring gear 18. This is done by -having the outer diameter portion of the second hub in mesh with the internal gear teeth 38 of ring gear 18 and the inner diameter portion thereof splined as gener ally showii at 40 to first hub 34, as will be hereinafter more fully described On the outer periphery of housing 26, a drive - sprocket 42 is there secured by a plurality of bolts, one of which is shown at 44. - The bolts secure the drive sprocket 42 to a-radially projecting annular flange 46 of housing 26. The drive sprocket meshes with the conventional track links, one of whidh is shown at 48, which are secured to and fohí! a part of an endless articulated trá-ck tafifig shoes, one of which is shown at OI"''In'"overall operation, rotation of shaft 10 rotates housing 26 and thereby drive sprocket 42 through the above-described double planetary drive train.

As best seen in FIG. 2, second hub 36 is retained on spline 40 which is intermediate the second hub and first hub 34 by means of a preloading ring 52. Ring 52 is secured to the end of hub 34 by a plurality of bolts 54 as best seen in FIG. 3. As seen in FIGS. 2 and 3, the second or reaction hub 36 has a plurality of axially oriented holes or bores 56 therein. Inserted within the bores are a plurality of pins 58.

In the arrangement shown, sixteen pins are fitted within sixteen corresponding bores, equally spaced around a hole circle. The pins are of a length sufficient to extend beyond their bores on opposite sides of the reaction hub.

An annular or ring-shaped retainer 60 is located intermediate bearing 62 and preloading arrangement 64 so as to comprise a bearing retainer system 66 therewith. The bearing retainer 60 includes a pair of planar side faces 68, 70, which contact respectively cone 72 of bearing 62 and pins 58.

Preloading is accomplished by securing ring 52 on hub 34 by means of bolts 54.

Ring 52 forces pins 58 against the side face 70 of retainer 60, which in turn forces side face 68 against cone 72. This results in force being transmitted through cone or outer race 73 of bearing 62 by way of housing 26 to outer race 74 of bearing 76 and thereby to inner race 78. In this manner, force is transmitted so as to preload both bearings. The desired preload force is achieved by setting and maintaining the proper length of pins 58.

More particularly, the distance X between shoulders 80, 82 of bearings 72, 76, and the distance Y between the outer end of the hub 34 and the shoulder 84 on hub 34 for the inner race 78 of bearing 76 is closely tolerated to ensure the proper preload on both bearings imparted by pins 58 of controlled length L. The width W of the reaction hub through which pins 58 pass is slightly less than the length L of the pins.

which permits a slight radial movement of the hub within the tolerance of the spline connection 40. However, since retainer 60 contains a plurality of splines 86 on its inner periphery in accommodating grooves, the relative movement between pins 58 and the retainer 60 is also slight. In any event, the pins do not contact inner race or bearing cone 72, so that galling and gouging which might otherwise occur is eliminated. It may also be noted that the pins are of a slightly smaller diameter than the diameter of the holes 56, which prevents transfer of torque between the pins and the hub within the tolerance of the spline connection as the hub moves radially.

Claims

WHAT WE CLAIM IS:-

1. A bearing assembly including a bearing; mounting means for the bearing; preloading means for preloading the bearing and comprising a reaction hub of an associated planetary gear assembly, the hub having a plurality of pins extending through bores therein; axially movable retaining means provided between the bearing and the preloading means for transmitting force from the preloading means to the bearing, the retaining means being a generally ring shaped retainer, one end of which contacts the bearing and the other end of which is contacted by the pins; and mounting means on the retainer and the reaction hub whereby the retainer is non-rotatable relatively to the reaction hub.

2. An assembly according to claim 1, wherein the retainer has substantially planar and end surfaces.

3. An assembly according to claim 1 or claim 2, wherein the mounting means on the retainer comprise splines on the inner periphery of the retainer.

4. An assembly according to any one of the preceding claims, wherein the retainer is of a material harder than the material of the bearing so as to protect the bearing from galling.

5. An assembly according to any one of the preceding claims, further comprising a first hub on a shaft; and a housing rotatably mounted on the first hub by the bearing; splines connecting the radially innermost portion of the reaction hub to the first hub; and a preloading ring mounted on the first hub; the pins transmitting a preloading force from the preloading ring to the bearing via the retainer.

6. An assembly according to claim 5, wherein the reaction hub is loosely located between the retainer and the preloading ring.

7. An assembly according to claim 5 or claim 6, wherein the pins pass through the bores in the reaction hub with a clearance.

8. A drive train incorporating an assembly according to any one of claims 5 to 7, and further comprising a planetary gear assembly, through which the housing is driven from the shaft, and which takes a reaction from the reaction hub.

9. An assembly according to claim 1, substantially as described with reference to the accompanying drawings.