Patent Application
20160176455
This disclosure generally relates to track-type machines and, more specifically, relates to idler yoke assemblies for track-type machines.
Track-type machines, such as track-type tractors, excavators, bulldozers, track loaders and skid-steer loaders, are used in a variety of applications. Generally speaking, these machines have an operator station, a power source, an undercarriage and a pair of track systems laterally flanking the machine. Each track system includes a track roller frame positioned along a lengthwise-extending direction of the track-type machine and a drive sprocket that is rotatably driven by the power source. In one design, the drive sprocket is located at one end the track roller frame. In another design, known as a high drive system, the drive sprocket is positioned above and toward one end of the frame.
Each track system also includes one or more idler wheels. If the drive sprocket is located at one end of the track roller frame, the idler wheel is positioned at an opposite end of the frame. If the drive sprocket is positioned above and towards one end of the track roller frame, the track system includes idler wheels positioned at each end of the frame. Further, such track systems typically include one or more upper and/or lower rollers. These rollers are located along the lengthwise-extending axis of the track roller frame between the sprocket and the one or more idler wheels. Such track systems also include an endless track that circumscribes the drive sprocket, the one or more idler wheels, and the rollers. The endless track is rotatably engaged with the drive sprocket and transfers the energy of the power source to the ground to thereby provide locomotion to the track-type machine.
Maintaining proper tension on the endless track is important to the operation of track-type machines. Therefore, at least one of the one or more idler wheels may move relative to the track roller frame in a direction generally along the lengthwise-extending axis of the track roller frame. This movement is possible due to at least one of the one or more idler wheels being supported by a yoke that is engaged with the track roller frame by a key and keyway system. This key and keyway system, however, may be susceptible to wear, such as at the interface between the key and keyway.
One attempt to reduce the wear experienced between components is disclosed in U.S. Pat. No. 4,042,117 (the '117 patent). The '117 patent is directed to a wear plate for use in a connection assembly for coupling railway cars together. More specifically, when railway cars are coupled together and in motion, the cars move towards and away from each other, and the connection assembly is provided to take up and allow for such slack. The '117 patent does so by providing a shank that slides with a sill, with a coupler extending from the shank for connection to an adjacent railcar. The slack in such assembly is limited by a draft key that is positioned in a slot extending through the shank and sill. Given the weight of the coupler, when the shank slides within the sill, the shank is biased upwardly against the sill, thereby causing the draft key to frictionally engage an upper surface of the slot. Over time, this causes wear and deterioration of the sill. The '117 patent therefore provides a wear plate on the upper surface.
While arguably effective for its specific purpose, the '117 patent is related to railway cars and in no way to track-type machines. Moreover, a track-type machine and its associated track systems are subjected to external forces significantly different from rail cars. For example, while rail cars ride along a predefined railway with little deviation in horizontal angle, track-type machines are typically employed in earth-moving operations which subject them to terrain that is dynamic and more challenging. In addition, the loads experienced by a track-type tractor are more extreme and intermittent than the typically smooth course traversed by a railcar. The nature of the work performed by track-type tractors can also cause the track systems to be subjected to loads coming from practically every angle, thereby potentially causing wear on multiple surfaces of the key and keyway system.
The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems associated with the prior art.
In accordance with one aspect of the present disclosure, an idler yoke assembly for a track system of a track-type machine is disclosed. The idler yoke assembly includes a yoke configured to support an idler wheel of the track system and be operatively coupled with a tensioning member of the track system. The yoke further includes a first arm having a first keyway. A wear strip is secured to the first keyway with the wear strip being configured for sliding engagement with a key of the track system as the yoke moves relative to the track system.
In accordance with another aspect of the present disclosure, a track-system for a track type machine is disclosed. The track-system includes a track roller frame and a tensioning member operatively coupled with the track roller frame. The track-system further includes a yoke operatively coupled with the tensioning member. The yoke has a first arm, a second arm spaced apart from the first arm, with the first arm including a first keyway and the second arm including a second keyway. An idler wheel is rotatably disposed between the first arm and the second arm.
In accordance with another aspect of the present disclosure, a method of operating an idler yoke assembly of a track system is disclosed, wherein the idler yoke assembly includes a key and a yoke having a keyway. In a first step, a first wear strip is secured to a first surface of the keyway. Next, a second wear strip is secured to a second surface of the keyway. The key is then slid within the keyway with the key engaging the first and second wear strips.
These and other aspects and features of the present disclosure will be more readily understood when read in conjunction with the accompanying drawings.
Referring now to the drawings, and with specific reference to
Referring to
In addition, the track system 20 includes one or more upper rollers 30 operatively secured to and upwardly extending from the track roller frame 22. Opposite the one or more upper rollers 30, the track system 20 further includes one or more lower rollers 32 operatively secured to the track roller frame 22. Further, the track system 22 includes one or more idler wheels 34, 36. If the drive sprocket 26 is located at the first end 28 of the track roller frame 22 as depicted in
Further, the track system 22 also includes an endless track 38. The endless track 38 circumscribes the drive sprocket 26, the upper rollers 30, the lower rollers 32 and the first idler wheel 34. Similarly, in a high drive system where the drive sprocket 26 is located above the track roller frame 22 towards the first end 28 of the track roller frame 22 as illustrated in
Turning now to
Referring now to
In light of this, the present disclosure significantly improves upon the prior art by, among other things, providing replaceable wear strips on the keyways 49 and 50. More specifically, a first wear strip 53 may be secured into the first keyway 49. The first wear strip 53 is configured for sliding engagement with the key 51 of the track system 20 as the yoke 42 moves relative to the track roller frame 22 of the track system 20, as shown best in
In addition, more than one wear strip may be provided in each keyway. As opposed to rail and other applications subjected only to wear on an upper surface or the like, the keyways of a track-type tractor are subjected to frictional wear in many locations and from many directions. Accordingly, the first keyway 49 may further include a first upper ledge 54 and a first lower ledge 56, with the first wear strip 53 secured to either the first upper ledge 54 or the first lower ledge 56, and a second wear strip 58 secured to the other ledge. In the embodiment of
The second arm 47 and second keyway 50 may be similarly provided with wear strips. More specifically, a third wear strip 64 may be secured into the second keyway 50, as shown best in
Referring now to
Turning now to
With regard to choice of materials, the wear strip 53 may be made from any number of different materials including, but not limited to, materials which are the same or different from the material from which the yoke 42 is manufactured.
The wear strip 53 may be designed so that its lifespan coincides with a service life of the track system 20. If the body 92 lacks appropriate thickness, or the material chosen to make the wear strip 53 lacks suitable hardness, the strip 53 may be worn through by the time the track system 20 is serviced. Such a situation may lead to undesirable wear on the yoke 42. On the other hand, if the thickness of the body 92 is too great to begin with, the strip 53 may fail to wear a suitable amount by the time the track system 20 is to be serviced. In such a circumstance, the idler wheel 34 may become overly worn, thereby inhibiting machine performance. Correspondingly, the thickness of the wear strip 53 may be greater than or equal to about eight (8) millimeters and less than or equal to about sixteen (16) millimeters, although such dimensions are simply exemplary. In some embodiments, the thickness of the wear strip 53 may be greater than or equal to about ten (10) millimeters and less than or equal to about fourteen (14) millimeters. In these or other embodiments, the thickness of the wear strip 53 may be about, or equal to, twelve (12) millimeters. Other dimensions are certainly possible. As an appropriate hardness is also of import, in one exemplary embodiment, the hardness level of the material is less than or about equal to Rockwell C53. Other hardness levels are certainly possible.
The wear strip 53 may further include a wear zone 98 that extends along a mid-section 99 of the body 92. The wear zone 98 is the portion of the wear strip 53 is in contact with the first key 51 or the second key 52 as the yoke 42 moves relative to the track roller frame 22 of the track system 20.
The wear strip 53 may be secured to the first keyway 49 or the second keyway 50 by any number of different methods including, but not limited to, welding, brazing or the like. Alternatively, the wear strip 53 may be secured to the keyways 49, 50 by a chemical material, such as an adhesive. Another choice for securing the wear strip 53 to the keyways 49, 50 is through mechanical fastening. In such an embodiment, the wear strip 53 may include one or more threaded holes 100. Such threaded holes 100 may be located outside the wear zone 98 towards the first end 88 and second end 90 of the wear strip 53, or such holes 100 may be located inside the wear zone 98. Such threaded holes 100 may be through-holes or blind holes. Furthermore, threaded bolts 102 may be used to attach the wear strip 53 to its respective keyway 49, 50 as depicted in
Referring now to
In operation, the first key 51 and second key 52 of the key assemblies 104, 106 are supported by the track roller frame 22. Each key 51, 52 extends through the track roller frame 22 of the track system 20 and is received in a channel 112 between its respective wear strips 53, 58 and 64, 72 in its respective keyway 49, 50. The keys 51, 52 therefore slidably support the yoke 42 of the idler yoke assembly 40. The yoke 42 in turn rotatably supports the first idler wheel 34 by the partial bores 74, 76, the shaft 78 and the couplers 84. The underside 73 of the endless track 38 is engaged with and supported by the first idler wheel 34.
Under normal conditions, the tensioning member 44 biases the first idler wheel 34 towards the end of the track roller frame 22 opposite the first end 28. In the event the endless track 38 collides with an object, or otherwise encounters inconsistent resistance, the yoke 42 moves relative to the track roller frame 22 towards the first end 28 along the interface between the keys 51, 52 and the wear strips 53, 58, 64, 72. Then, after the collision subsides, or the obstruction is otherwise overcome, the tensioning member 44 moves the yoke 42 away from the first end 28 along interface between the keys 51, 52 and the wear strips 53, 58, 64, 72.
Referring next to
In operation, an idler yoke assembly having wear strips can find use in many industrial applications, such as in a track system of a track-type machine. More specifically, the idler yoke assembly with wear strips finds use in the track systems of track-type machines utilizing a key and keyway system to support the movement of a yoke relative to a track roller frame.
Generally, the track systems of track-type machines include the track roller frame and a sprocket located at one end of the track roller frame. Each system also includes one or more upper or lower rollers located along the track roller frame and an idler wheel located at an end of the track roller frame opposite the sprocket. The idler wheel is supported by an idler yoke assembly. The idler yoke assembly includes a yoke that is operatively coupled to a tensioning member of the track system. The yoke further includes a first arm and a second arm spaced apart from the first arm. The first and second arms each include keyways that are slidably engaged with a key of the track system.
During use, the track system may collide with an object, or otherwise encounter inconsistent resistance. In response, the yoke moves relative to the track roller frame along the surface between the keys and the keyways. Then, after the collision ends or the resistance is overcome, the tensioning member moves the yoke relative to the track roller frame towards a normal position along the surface between the keys and keyways. As repeated movement of the keyways relative to the keys deteriorates the surface of the keyways associated with the prior art, the present disclosure sets forth apparatus and methods which greatly abate such deterioration.
More specifically, to better sustain the life of the yoke, the present disclosure secures wear strips to one or more surfaces of the yoke keyways. For example, the wear strips may be secured to the upper ledges and lower ledges of the yoke keyways. Since the keys of the track system are received in the channels between the wear strips, when the track system collides with an object or otherwise encounters inconsistent resistance, the yoke moves relative to the track system with the keys frictionally engaging the wear strips as opposed to the keyways themselves. After repeated movement of the keyways relative to the keys, the wear strips may be removed and replaced, rather than requiring the entire yoke to be replaced, refurbished or remanufactured as is the case with the prior art. In so doing, considerable expense is avoided, and the serviceable life of the yoke assembly is enhanced.
The above description is meant to be representative only, and thus modifications may be made to the embodiments described herein without departing from the scope of the disclosure. Thus, these modifications fall within the scope of present disclosure and are intended to fall within the appended claims.
