Seal guard for crawler

A final drive seal guard for a track-type tractor including a base component adapted to be stationarily fixed to the tractor and to surround a portion of a spindle housing of the final drive, a sprocket component adapted to be carried on and surround a portion of a sprocket hub of the final drive that rotates about an axis, and an intermediate component adapted to be bolted over the exterior of one of said base and sprocket components and surround portions of both of said base and sprocket components, the intermediate component and another of said base or sprocket components being mutually arranged to form a radially extending sealing gap at a potential path of debris into the guard at a location free of a relatively long axial gap upstream in said potential path.

BACKGROUND OF THE INVENTION

The invention relates to final drive seal guards for track-type tractors.

PRIOR ART

Track-type tractors or “crawlers” when operating in landfills, especially, are prone to accumulate debris around a seal between a stationary spindle housing and a rotating sprocket hub driving the track. The debris, particularly cable, wire and the like, can be drawn into the seal area and cause the seal to fail, leading to expensive repairs. Debris, additionally, can accumulate around the seal area and cause destructive abrasion as well as unnecessary power consumption and excessive drive component wear.

U.S. Pat. Nos. 6,231,136, 6,293,631, and 7,946,661 disclose examples of prior art seal guards particularly useful in adverse environments such as in landfills. The guards disclosed in these patents have demonstrated significant improvement in the operation of tractors in landfill applications. Modifications of some of these guards in attempts to improve their effectiveness have met with limited success. For example, encircling the cylindrical groove sealing area of the guard of U.S. Pat. Nos. 6,231,136 and 6,293,631 with axially extending cylindrical half-sleeves, radially bolted to the guard exterior has demonstrated a tendency of debris to migrate into primarily axially extending clearances or gaps. Axially telescoped guard components of the prior art, if distorted by random impacts during service for example, can be difficult or nearly impossible to separate and/or reassemble.

SUMMARY OF THE INVENTION

The guard of the present invention has improved sealing performance and serviceability obtained with primary outer guard elements that provide an initial radially extending sealing gap and that are radially installed and retained. The radial sealing gap between rotating and non-rotating parts of the seal guard has a reduced tendency to accumulate and/or be abraded by debris.

An outer component part of the guard proper is installed radially on a guard base component. This feature allows the outer component part to be drawn against the base component with radially oriented mounting bolts. If the outer component part is distorted during service it is not ordinarily difficult to remove for repair or replacement. If not perfectly repaired to the original configuration, the outer component part can be readily forcibly drawn into an operable installed position by tightening of the mounting bolts.

In the disclosed preferred embodiments, the guard has three annular components each of which is or can be diametrically split. A stationary or base component is fixed to the tractor frame, a rotating component is fixed to the sprocket hub and an intermediate cover component bridging over the base and rotating components is fixed to the base component. Ideally, the intermediate cover component has counterbored holes for receiving and protecting the heads of associated mounting bolts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 1-3, a first embodiment of a seal guard10is illustrated. It will be understood that the following descriptions are of guards at one machine side and that the guard for the opposite machine side is symmetrical about a vertical plane. The illustrated guard10is suitable for use on Caterpillar® Models D5-D11 and, for example, a D6XE.LGP. The guard10for each machine side comprises three annular components11-13, each of the components preferably being diametrally split to enable the guard10to be installed while the respective final drive remains assembled. The components are preferably fabricated as unitary cast steel parts. The component or base11on the left inFIGS. 1-3comprises two generally semi-circular parts11A,11B. The base parts11A,11B each include a cylindrical wall16having an external or radially stepped-out rim17providing increased thickness and a radially extending internal flange18both essentially co-extensive with the arcuate length of the wall16. Integral with the wall16and flange18are a plurality of axially oriented angularly spaced apertured bosses or lugs19.

The external rim17has a plurality of circumferentially or angularly spaced internally tapped radially oriented holes21. In the illustrated case, the holes are arranged in axially spaced pairs as explained below.

Axially away from the base component11, the guard10includes a sprocket side component12, hereafter sprocket component, formed of two semi-circular parts12A,12B of essentially the same construction. The sprocket component part12A,12B includes a semi-cylindrical wall22with a radially outwardly extending mounting flange23, a radially inwardly extending stiffening flange24and a radially outward sealing flange25distal from the mounting flange23. Preferably, the flanges23,25are each continuous along the arcuate extent of the respective wall22. Regularly spaced, axially oriented holes28are provided in the mounting flange23.

An intermediate component13bridges over the base and sprocket components and comprises semicircular two parts13A,13B. An intermediate part13A,13B has a semi-cylindrical wall31preferably with an inwardly projecting peripheral rim32adjacent one end. The wall31and rim32are formed with arcuately spaced, radially oriented counterbores33which, as shown, can be somewhat oval shaped.

A plane36between a spindle housing37and sprocket hub38is sealed by a mechanical seal, sometimes known in the industry as a duo cone seal developed by Caterpillar® within the spindle housing37and sprocket hub38. The seal is susceptible to damage when wire or like material winds around this zone and is drawn into the seal. A damaged seal can lead to catastrophic failure of internal parts of the final drive. The spindle housing37and sprocket hub38including their internal components are sometimes referred to as the final drive of a track-type tractor, it being understood that these assemblies ordinarily exist on the left and right sides of a tractor. The guard10reduces the risk of seal failure by excluding debris from the seal area or zone between the spindle housing37and sprocket hub38. The non-rotating spindle housing37has a peripheral flange41bolted to the tractor frame. The sprocket hub38is rotationally supported on the spindle housing37.

Axially oriented holes48in the base component11match up with a limited number of the spindle hub mounting holes and associated internally threaded holes in the tractor frame.

The guard10is assembled around the final drive by bolting the base component11on the tractor frame. Bolts47are assembled through the holes48alignable with certain of the factory bolt holes existing in the spindle housing flange41and tractor frame. The original factory bolts at these matching hole centers are previously removed and the base component is fixed in place on the frame with longer bolts assembled through the holes48in the bosses19. It will be understood that the internal flange18is spaced from the adjacent edge of the base component and coplanar faces of the bosses19to bridge, with clearance, over the heads of original bolts remaining in place and retaining the spindle housing in place.

The sprocket component12is fixed to a rotating flange51of the sprocket hub38with substitute bolts52assembled in holes28in the mounting flange23, sprocket hub38and sprocket segments53.

With the base and sprocket components11,12in place, the intermediate component13is assembled on the base component with radially oriented bolts60received in the counterbored or milled holes33in the intermediate component and the threaded holes21in the base component parts11A,11B. The inboard or outboard base component holes21are selected depending on the final drive width of the model tractor on which the guard is installed.

The intermediate component13effectively closes off the space surrounding the separation plane36and associated internal seal between the spindle housing37and sprocket hub38. The radially outward extending sealing flange25of the sprocket component12and inwardly extending flange34of the intermediate component establish a relatively narrow sealing gap70in a generally radial plane. This gap70can initially range between a rubbing fit of essentially zero clearance to about 1/16 inch. The radial length of the gap70is longer than the axial length or width of a gap between the flange34and wall22.

Note that reference to axial and radial directions are with respect to the axis of rotation of the sprocket hub indicated at40.

The track of the tractor is indicated at54.

Preferably, joints between the half parts of the base11and intermediate component13are offset by 90 degrees as indicated inFIG. 2.

Referring toFIGS. 4 and 5, there is shown a second embodiment of the inventive guard76useful with Caterpillar® Models D5K and D6K, for example. As with the embodiment of the guard10previously described, the guard comprises three components: a base component77, a sprocket component78and an intermediate component79. These components are symmetrically replicated for installation on the final drive of an opposite side of a tractor. In this second embodiment, the base and intermediate components77,79each comprise two semicircular parts77A,77B and79A,79B while the sprocket component78is a unitary annulus or ring.

The base component parts77A,77B each has a semi-cylindrical wall81and a radially outwardly extending integral rim82on an outboard end. The rim82has radially oriented internally threaded holes83. A plurality of angularly spaced integral tabs84extend radially inwardly from the wall81. The tabs84have axial holes86that align with bolt holes in a flange88of a spindle housing89.

The sprocket component78includes a short cylindrical wall91and an integral radially outwardly extending flange92.

The intermediate component parts79A,79B each have a semi-cylindrical wall93. At one end, the wall93has an integral radially inwardly directed rim94with an inside radius substantially the same as the outside radius of the base rim82and angularly spaced counter-sunk radially oriented holes or slots96alignable with the threaded holes83. At the opposite end, the wall93has an integral radially inwardly directed flange97with an inside radius slightly larger than the outside diameter of the sprocket component wall91.

The guard76is installed on the final drive on each side of a tractor. Installation is accomplished by removing the sprocket hub, designated98, from the spindle housing89. The base component parts77A,77B are preferably installed after removal of the sprocket hub98, there being greater working space at this time, although this step can be done prior to removal of the sprocket hub. The base component77is fixed to the tractor by removing certain ones of the factory spindle hub mounting bolts, aligning the tab holes86with the hub flange holes and assembling substitute longer bolts into the tab holes, spindle hub flange holes and threaded holes in the tractor frame. While the base component77is described as being diametrally split, it may be provided as a one-piece annular unit.

The sprocket component78is stitch welded on the inner side of the sprocket hub98with the flange92away from the sprocket hub. Care is taken to assure that the sprocket component78is concentric with the axis or center of the sprocket hub98.

With the base component part77A,77B bolted on the spindle flange88and the sprocket component78welded in place, the sprocket hub is reassembled on a spindle housing. The intermediate component parts79A,79B are assembled over the base and sprocket components77,78. The intermediate component parts79A,79B are fixed on the base component77A,77B, preferably with no gaps and with their joints 90 degrees out of alignment with the joints of the base component parts, with radially oriented bolts99assembled in the counterbored holes or slots96and threaded radial holes83.

The various parts of the guard are proportioned so that the inwardly extending radial flange97of the intermediate component parts79A,79B form a small sealing gap100in a radial plane with the outwardly extending radial flange92of the sprocket component78. The sealing gap100can initially range from a rubbing fit of zero clearance to about 1/16 inch. An axially extending gap101between the intermediate component flange97and the sprocket component wall91can range between a slight rubbing fit to a gap of about 1/16 inch. As shown, the axial length of the gap101is less than the radial length of the radial sealing gap100.

Both of the above-described guards10,76have improved resistance to the ingress of debris. Each provide a radial sealing gap without an appreciable upstream, axially oriented gap of equal or greater length in a path for debris migrating into the guard interior. It has been found that gaps of appreciable axial length particularly at the beginning of a path into the guard are prone to accumulate debris which accelerates abrasive wear and enlarges the transverse section or size of the axially oriented gap thereby losing effectiveness in excluding debris.

The disclosed guards if distorted by impact during use are easier to disassembly than prior art arrangements where the parts are axially telescoped within one another. Still further, the outer guard components,13,79, if distorted in use, can be removed and brought back to shape and reinstalled. The radially oriented bolts60and99greatly assist in reinstallation even if the components are slightly misshapen because tightening the bolts tends to draw the components into registration. Moreover, the countersunk holes or slots which receive the heads of the bolts60,99eliminates the tendency in prior art guards of debris, particularly wire or other strands of material, to be snagged by a bolt head and precipitate the build-up of debris on a guard.

While the invention has been shown and described with respect to particular embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.