Patent Application
20070057575
The present disclosure relates generally to track-type work machines, and relates more particularly to a track-type work machine having a vertical idler adjuster.
Track type work machines are in widespread use in construction, mining, forestry, and similar industries. In particular, bulldozers, cranes and pavers are commonly seen track type work machines along roads, freeways and at construction sites. “Tracks” rather than wheels are typically used on work machines operating in environments where creating sufficient traction with conventional tires is problematic or impossible. Rather than rolling across a work surface on wheels, track type work machines utilize one or more tracks extending about a plurality of rolling elements. Such tracks are typically made up of a loop of coupled metal links having outer sides that engage the ground or work surface, and inner sides travelling about the rolling elements, which can include various drive rollers, support rollers, tensioners and “idlers.”
An idler in a track type work machine is a rolling element that passively rolls against the inner side of the track, and can have a plurality of teeth much like a gear wheel that engage against the bushings joining the track links. The idler is typically positioned at an opposite end of the track roller frame to a drive wheel or sprocket, and supports that end of the track during operation. Rollers are typically positioned between the idler and the sprocket, and support the inner side of the track opposite the ground.
Over the course of work machine operation, the various moving parts of the track assembly can undergo significant wear. The track links, rollers, idlers and drive sprockets can all experience wear from the nearly constant metal-to-metal contact. For example, the idler can include grooves or pockets separating the teeth. A phenomenon known in the art as “tooth root wear” describes deepening of these pockets over time due to repetitive engagement and disengagement with the track, which in turn wears due to its corresponding engagement against the idler. A horizontal plane, located at the bottom of the idler, and intersecting bushings in the track can be defined as the idler plane. As the idler and bushings wear, the idler plane can actually migrate. The rollers will also tend to wear down as they operate against the track links over time. The “roller plane” may be thought of as a horizontal plane located at the bottom of the rollers, and intersecting bushings in the track. In a manner similar to the idler plane, wear of the track links and rollers can actually cause the roller plane to migrate.
In many common work machines, the idlers, rollers and track links have traditionally been made of similar materials, for example steel, and thus the various elements have a tendency to wear at approximately the same rate. Accordingly, the relative distance between the roller plane and idler plane remains roughly the same over the course of many hours of operation. In the past, servicing of the work machine and replacement of the idlers, rollers and in some instances track links would take place at predetermined intervals, based generally on similar wear rates of the same.
In an attempt to prolong the life of certain of the work machine components, in recent years designers have begun to employ rotating bushings connecting side by side track links, and toothed idlers running on the rotating bushings. The wear rate of rotating bushings is relatively slow, as the rotating bushings can roll into and out of engagement with the other components rather than sliding. The rate of migration/translation of the idler plane is a function primarily of tooth root wear and rotating bushing wear, whereas the rate of migration/translation of the roller plane is a function primarily of roller wear and track link wear. Tooth root wear and rotating bushing wear tends to be slower than roller and link wear, and consequently the rate of change in the position of the idler plane tends to be slower than the rate of change in the position of the roller plane.
Where the rate of change in position of the roller plane outpaces the rate of change in the idler plane, the relative separation of the respective planes can change over time. For many work machine operations, it is desirable to maintain the roller plane and idler plane substantially at constant positions relative to one another. For example, if the idler plane lies at an inappropriate position relative to the roller plane, the ride, blade control or work surface finish can be compromised in certain operations.
The present disclosure is directed to one or more of the problems or shortcomings set forth above.
In one aspect, the present disclosure provides a track-type work machine including a roller frame, and an idler mounted proximate an end of the roller frame. The idler includes an idler shaft, and at least one support block supporting the idler shaft. One or both of the idler shaft and the at least one support block include a plurality of assembly orientations corresponding to different idler heights relative to the roller frame.
In another aspect, the present disclosure provides an idler mounting apparatus for a track-type work machine. The idler mounting apparatus includes a roller frame, an idler yoke disposed proximate an end of the roller frame, and a rotatable idler supported in the idler yoke, the rotatable idler including an idler shaft. First and second support blocks are provided and support the idler shaft. At least one of the idler shaft and the first and second support blocks includes a plurality of assembly orientations corresponding to a plurality of vertical idler positions relative to the roller frame.
In still another aspect, the present disclosure provides a method of vertically adjusting a rotatable idler in a track-type work machine. The method includes the steps of relieving pressure on the idler, and re-orienting at least one of an idler shaft and at least one support block supporting the idler shaft. The step of re-orienting vertically repositions the idler shaft relative to a roller frame of the work machine, the method further including the step of returning pressure to the idler.
a is a perspective view of one component of the vertical idler adjuster of
b is a perspective view of a second component of the vertical idler adjuster of
a is a perspective view of a third component of the vertical idler adjuster of
b is a perspective view of a fourth component of the vertical idler adjuster of
c is a side diagrammatic view of the components of
Referring to
Turning to
Vertical idler adjuster 132 preferably includes first and second support blocks 140 disposed at opposite ends of idler shaft 119 and coupled with idler yoke 134. In a preferred embodiment, a retainer hook 150 is positioned on each side of idler shaft 119 and slidably couples the same with roller frame 130. Each of support blocks 140 includes an eccentric aperture 142 within which the respective ends of idler shaft 119 are positioned. Support blocks 140 are positionable in at least a first assembly orientation, as shown in
Turning to
Support blocks 340 are preferably outer blocks, and are coupled with inner blocks 360 via a plurality of removable fasteners 350. Each of support blocks 340 further includes an eccentric aperture 351 that supports an end of idler shaft 319. Vertical idler adjuster 332 preferably has a plurality of assembly orientations, including that shown in
Turning to
Vertical idler adjuster 432 preferably includes a positioning block 436 coupled with an idler yoke 434. Positioning block 436 slides in between top and bottom rails of a track roller frame 430. Front 438b, and rear 438a support blocks are preferably coupled via block 438a with positioning block 436. Blocks 438a and 438b support an end of idler shaft 419 in an eccentric aperture 451, defined in part by each of blocks 438a and 438b. Idler 418 is mounted on idler shaft 419 in a conventional manner, and its position relative to roller frame 430 can be adjusted by placing vertical idler adjuster 432 in a selected one of a plurality of assembly orientations. A horizontal plane extending through idler shaft 419, identified as Plane O, represents a vertical position of the axis of rotation of idler 418 relative to roller frame 430. Adjustment of vertical idler adjuster 432 can adjust the relative position of Plane O with respect to roller frame 430.
a illustrates rear support block 438a, including a plurality of mounting apertures 439 disposed therein for coupling the same with positioning block 436. Rear block 438a further preferably includes a lip or wall 441 positionable about an end of idler shaft 419 when supported therein.
a and 7b illustrate perspective views of opposite ends of positioning block 436, including mounting apertures 437 in a first end thereof, and mounting apertures 435 in a second end thereof. Mounting apertures 435 and 437 provide for coupling of positioning block 436 to idler yoke 434 and rear support block 438a, respectively.
The embodiment of
Turning now to
Referring to the drawing Figures generally, work machine 10 will over the course of a period of operation experience wear of various components, including track 14 and rollers 20. Accordingly, after a certain time, idler plane I may lie in a position relative to roller plane R that differs from its desired position. To continue working within desired specifications, it will be desirable to vertically adjust the position of idler plane I relative to roller plane R, restoring the same to the desired relative positions, typically by raising idler 18, 118, 218, 318, 418 relative to roller frame 30, 130, 230, 330, 430. Idler adjuster 32, 132, 232, 332, 432 is used to vertically adjust idler 18, 118, 218, 318, 418 to compensate for a faster rate of change in the position of roller plane R than in idler plane I. Each of the embodiments herein includes a plurality of assembly orientations corresponding to different vertical heights of the respective idler and idler plane. Preferably, the various idler adjuster components may be re-positioned from one angular orientation about the respective idler rotation axis to at least a second angular orientation.
Idler plane translation is a function of bushing and tooth root wear, whereas roller plane translation is a function of roller and link wear. In earlier designs, using non-rotating bushings, the translation of the work machine's idler plane was faster. With the advent of rotating bushings idler plane translation in many systems has slowed while translation of the roller plane continues at approximately the same rate. In some instances, the translation rate of roller plane R may be about five times the translation rate of idler plane I. For example, where roller plane R translates 10 mm, idler plane I may translate only about 2 mm, a difference of about 8 mm. In certain applications, an 8 mm departure, or less, from specifications in the relative positions of planes R and I can affect operation.
Referring in particular to
Once hook retainers 150 are removed, support blocks 140 are removed, inverted, and repositioned about idler shaft 119. Idler 118 can generally be jacked to its desired vertical position once hook retainers 150 are removed, however, this step can take place following, or prior to removal and inverting of support blocks 140. Inverting support blocks 140 vertically repositions eccentric apertures 142 relative to roller frame 130. Thus, once support blocks 140 are inverted, idler 118 may be returned to rest on roller frame 130 at its adjusted vertical position and hook retainers 150 repositioned.
It should be appreciated that the relative position of eccentric apertures 142 in support blocks 140 might be selected based on a projected service schedule of work machine 10. In other words, the degree of “eccentricity” of apertures 142 can be selected based on an estimated number of operating hours of work machine 10 and an estimated wear rate of the respective track components. For example, if it is estimated that idler 118 will need to be vertically adjusted a certain vertical distance after a certain number of operating hours, apertures 142 can be offset from a center of the respective support block 140 a corresponding distance. In this manner, designers can set the vertical idler adjustment schedule to coincide with other service tasks. Similar considerations apply to all of the vertical idler adjuster embodiments disclosed herein.
Turning to
Although vertical idler adjuster 232 is described in the context of a single hex 222, and rotation/adjustment of idler 218 from only one side thereof, those skilled in the art will appreciate that embodiments are possible, and may even be preferred, wherein mirror-image vertically offset shafts 219 and hexes 222 are disposed on both sides of idler 218.
Referring to
Referring to
Front and rear support blocks 438a and 438b can also be inverted relative to roller frame 430 and, accordingly, can provide two more possible vertical idler positions by repositioning eccentric aperture 451. Vertical idler adjuster 432 can thus be used to incrementally raise or lower idler 418 by re-configuring positioning block 436 and front and rear support blocks 438a and 438b among their various assembly orientations.
By selecting offset coupling means, for example, including one or both of apertures 435 and 437 of positioning block 436, and apertures 439 of rear support block 438a, multiple assembly orientations can be created. Embodiments are contemplated wherein the degree of eccentricity of aperture 451, and the degree of vertical offset of the various mounting apertures are all selected to provide assembly orientations to incrementally raise or lower idler 418 as desired. For example, inverting either one of positioning block 436, or support blocks 438a and 438b, might raise idler 418 the same height, thus providing for at least two equal vertical adjustments. In contrast, inverting positioning block 436, or alternatively support blocks 438a and 438b, might provide different vertical height adjustments of idler 418, for example, an initial relatively large adjustment, and one or more subsequent, relatively fine adjustments.
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the intended spirit and scope of the present disclosure. For example, while the above description is primarily concerned with raising an idler height to compensate for wear, some applications might call for decreasing a relative idler height, to which the presently disclosed embodiments are well suited. Further, although several of the embodiments are discussed in the context of having only two assembly orientations, additional orientations might be possible. For example, rather than simply inverting support blocks 140 and 340, they might be rotated 90 degrees to provide a more moderate vertical adjustment than that available by inverting the same. Other aspects, features and advantages will be apparent upon an examination of the attached drawing figures and appended claims.
