Work vehicle oscillation system

A work vehicle comprises a front frame, a rear frame, an oscillation frame, a slew bearing, and a rolling-element bearing. The slew bearing and the rolling-element bearing allow oscillation between the oscillation frame and the rear frame about a fore-aft axis.

FIELD OF THE DISCLOSURE

The present disclosure relates to oscillation about a fore-aft axis between the front and rear sections of a work vehicle, such as an articulated dump truck.

BACKGROUND OF THE DISCLOSURE

There are articulated dump trucks which have a front section and a rear section. The front section has the operator's station, and the rear section has a dump body for carrying a payload therein. The front and rear sections are articulated to one another. An oscillation system of the truck allows oscillation between the front and rear sections about a fore-aft axis of the truck to accommodate lateral terrain variations between the front and rear sections.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, there is provided a work vehicle. The work vehicle comprises a front frame, a rear frame, an oscillation frame, a slew bearing, and a rolling-element bearing. The oscillation frame is articulated to the front frame allowing relative pivotal movement between the front frame and the oscillation and rear frames about an articulation axis. The rolling-element bearing is rearward of the slew bearing relative to a fore-aft axis of the work vehicle. The slew bearing and the rolling-element bearing are coupled to the oscillation frame and the rear frame allowing oscillation between the oscillation frame and the rear frame about the fore-aft axis. The rolling-element bearing may improve the useful life of the slew bearing by unloading some of a moment on the slew bearing.

The above and other features will become apparent from the following description and the attached drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring toFIG. 1, there is shown a work vehicle10configured, for example, as an articulated dump truck. As such, the vehicle10may have a front section12and a rear section14. The front and rear sections12,14may be articulated to one another for relative pivotal movement therebetween about an articulation axis15. The rear section14may have an oscillation system16allowing oscillation between the front and rear sections12,14about a fore-aft or oscillation axis18of the vehicle10to accommodate lateral terrain variations between the front and rear sections12,14.

The front section12may be the power head of the vehicle10and may have a front frame20. The operator's station and the engine may be included in the front section12and mounted to the front frame20.

The rear section14may have a rear frame22and a dump body configured to carry material therein. The dump body may be pivoted to the rear frame22. A lift cylinder on each side of the dump body may be coupled to the rear frame22and the dump body to tip the dump body to unload material from the dump body. The rear section14has two rear wheels on each side of the vehicle10, the two wheels on each side coupled in tandem, the two tandems pivotable about a tandem axis23.

Referring toFIGS. 2 and 3, the oscillation system16may include an oscillation frame24, a slew bearing26, and a rolling-element bearing28spaced axially apart from the slew bearing26relative to the fore-aft axis18. The oscillation frame24may be articulated to the front frame20allowing relative pivotal movement between the front frame20and the oscillation and rear frames24,22about the articulation axis15. The slew bearing26and the rolling-element bearing28may be coupled to the oscillation frame24and the rear frame22allowing oscillation between the oscillation frame24and the rear frame22about the fore-aft axis18. The rolling-element bearing26may be rearward of the slew bearing26relative to the fore-aft axis18to unload some of the radial component of the moment on the slew bearing26to improve the useful life of the slew bearing26.

The oscillation frame24has a front connector portion30and a rear tubular portion32. The connector portion30and the front frame20are articulated to one another to provide an articulation joint for relative pivotal movement between the front and rear sections12,14about the articulation axis15. A driveline33extends through the interior of the tubular portion32and is mounted within the tubular portion32with a front bearing76and a rear bearing78(e.g., each a ball bearing) for relative rotation between the driveline33and the oscillation frame24. The slew bearing26and the rolling-element bearing28surround the tubular portion32of the oscillation frame24. The oscillation frame24may be constructed, for example, as a casting made, for example, of ductile iron.

The vehicle10has a left steering cylinder and a right steering cylinder, which are coupled to the front frame20and the connector portion30to cause such relative pivotal movement for steering of the vehicle10. By putting the steering cylinders between the front frame20and the oscillation frame24instead of between the rear frame22and the oscillation frame24, the hydraulic lines to the steering cylinders do not have to cross the articulation joint, avoiding potential damages to the lines in such a case.

The slew bearing26may have a radially outer race34, a radially inner race36, rollers38(e.g., right circular cylinder in shape), and a pair of annular seals40. The outer race34may be fastened to a first cross wall41of a front cross structure of the rear frame22with fasteners (e.g., bolts with respective washers and nuts), the first cross wall having a main cross plate and an annular plate coupled (e.g., welded) to the main plate (the plates made, for example, of high strength low alloy steel). The inner race36may be fastened to the connector portion30of the oscillation frame24with fasteners (e.g., bolts with respective washers). The rollers38are positioned radially between the outer and inner races34,36and joined by a cage. Rotation axes of adjacent rollers40may be angled cross-wise relative to one another at an exemplary angle of 45 degrees; as such, the slew bearing26may be a cross roller slew bearing.

The seals40may be positioned on opposite sides of the rollers40to inhibit ingress of relatively small debris into the bearing26. One of the seals40may mate with an annular groove of the inner race36so as to be mounted thereto, and the other seal40may mate with an annular groove of the outer race34so as to be mounted thereto. The seals40may be made, for example, of polyurethane.

Referring toFIGS. 2A,2B,3, and4, a split-ring seal42may contact the oscillation frame24and the slew bearing26so as to establish a sealed connection therebetween. The seal42may contact the oscillation frame24, the inner race36, and the outer race34so as to establish the sealed connection therebetween. The seal42acts as a first line of defense that inhibits ingress of relatively large debris from entering the bearing26.

Opposite ends of the seal42may be fastened together with a fastener. As shown, for example, inFIG. 2a, the fastener may include a bolt80extending through a boss82of a first end of the seal42and a boss82of a second end of the seal42, a nut84threaded onto the bolt80, and two washers86, one associated with the bolt head and the other associated with the nut84. The fastener may be tightened by tightening of the nut84onto the bolt80(which may also be referred to as a cap screw).

The bolt80may have a (partially threaded) breakaway section90and may therefore be relatively long, providing a lead-in portion for receipt of the nut84onto the bolt80. During installation of the seal42, the nut84is advanced onto the breakaway section90and then onto the main threaded section of the bolt80, stretching the seal42. Once the seal42is installed, the breakaway section90may interfere with performance of the seal in that the breakaway section90may catch on nuts of the fasteners used to fasten the outer race34to the frame22and not allow free relative rotation between the seal42and the outer race34of the slew bearing26. As such, after the fastener has been tightened, the breakaway section90may be broken off at a reduced-diameter frangible portion of the bolt80, reducing the length of the bolt80.

Tightening of the fastener may pressurize a ring88of the seal42onto the oscillation frame24against the slew bearing26. As the ring88is pressurized, a first radially inner surface92of the ring88may slide radially inwardly against the oscillation frame24until the ring88nests at the interface between the oscillation frame24and the inner race36of the slew bearing26with the first radially inner surface92in contact with the oscillation frame24, a second radially inner surface94in contact with a radially outer surface of the inner race36of the slew bearing26, and a lip96of the ring88in contact with an axially forwardly facing surface of the outer race34of the slew bearing26. InFIG. 3, the radially inner surfaces92,94of the seal42are drawn relatively thick to indicate that they would be in contact with the oscillation frame24and the inner race36, respectively. In actual use, the ring88would be positioned slightly radially inwardly and axially rearwardly from where shown to establish such contact and loading of the lip96against the outer race34, and the seal42may be modified in size slightly to effect such contact.

Referring toFIGS. 2 and 3, a guard44may extend over the slew bearing26to deflect debris (e.g., debris that may fall from the dump body) from the seal42which could otherwise grind against the seal42during oscillation. The guard44may be mounted to the oscillation frame24. The guard44may have a connector portion46and a deflector portion48. The connector portion46may have two tabs50extending in laterally opposite directions relative to the fore-aft axis18. Each tab50may be fastened to the connector portion30of the oscillation frame24with a fastener including a bolt and washers, the bolt extending through a washer above the tab50, the tab50, and a number of washers (e.g., three) positioned between the tab50and the connector portion30of the oscillation frame24and acting as shims. The deflector portion48may have two deflector wings52extending in laterally opposite directions relative to the fore-aft axis18over the slew bearing26.

The guard44may have a top plate52and a rear plate54coupled (e.g., welded) to a rear edge of the top plate52(the plates52,54made, for example, of high strength low alloy steel). The top plate52may provide the tabs50and a top portion of the wings52, and the rear plate56may provide a rear portion of the wings52.

The front cross-structure may have a second cross wall58and a bearing housing60. The second cross wall58may be rearward of the first cross wall41, and may have a main cross plate and an annular plate coupled (e.g., welded) to that main plate (the plates made, for example, of high strength low alloy steel). The bearing housing60, made, for example, of gray iron, may be fastened to the second cross wall58with fasteners in the form of, for example, bolts and washers, each bolt extending through a respective washer and the main and annular plates of the second cross wall58into the bearing housing60.

A protective tube61may surround the tubular portion32of the oscillation housing24to keep dirt and water out of the oscillation system and provide strength for the rear frame22. The protective tube61may be coupled (e.g., welded) to the main plate of the first cross wall41and the annular plate of the second cross wall58. To form the protective tube61, a rectangular plate (made, for example, of high strength low alloy steel) may be rolled into a tubular shape and the ends of the plate may be chamfered to provide a weld groove that receives a weld.

The rolling-element bearing28is positioned radially between the bearing housing60and the tubular portion32of the oscillation housing24relative to the fore-aft axis18. The rolling-element bearing28may have a radially outer race62, a radially inner race64, rolling elements66, and a pair of annular seals68. The outer race62may be pressed into the bearing housing60. The inner race64may be lightly pressed onto the tubular portion32of the oscillation housing24. The rolling elements66may be positioned radially between the outer and inner races62,64. The rolling elements66may be rollers, and, as such, the bearing28may be a roller bearing, such roller bearing avoiding shimming.

The first and second seals68may be positioned on axially opposite sides of the rolling-element bearing28relative to the fore-aft axis18to inhibit ingress of debris into the bearing28. Each of the first and second seals68may contact the tubular portion32of the oscillation frame24and the rear frame22so as to establish a sealed connection therebetween. Each seal68is positioned on the tubular portion32. The forward first seal68mates with a groove in the bearing housing60so as to be mounted thereto, and the rearward second seal68mates with a groove defined between the annular plate of the second cross wall58and the main plate of the second cross wall58so as to be mounted to that groove. Each seal68may include a sealing element (made, for example, of polyurethane) and an O-ring (made, for example, of rubber), the sealing element having a lip against the tubular portion32of the oscillation frame24, the O-ring spring-loading the sealing element since the inside diameter of the sealing element is relatively large. For ease of illustration, each seal68(i.e., the sealing element and the O-ring) is shown in its relaxed (undeflected) condition, although one of ordinary skill in the art would recognize that it would be deflected in use.

Referring toFIG. 4, the rolling-element bearing28may improve the useful life of the slew bearing26by unloading some of a moment on the slew bearing26. The center of gravity of the rear section14is forward of the tandem axis23, tending to tip the rear section14forward. The articulation joint counteracts this tendency, applying a moment67to the oscillation frame24about the intersection of the fore-aft axis18and the articulation axis15. This moment is taken up by the slew bearing26and the rolling-element bearing28, with axial and radial forces69,70on the upper portion of the slew bearing26, an axial force72on the lower portion of the slew bearing26, and a radial force74on the rolling-element bearing28. The rolling-element bearing28thus unloads some of the moment67on the slew bearing26.

For ease of illustration, no welds and threads have been shown, but are to be understood.