Wheel substitutes for land vehicles – With means for tensioning track by moving at least one endwheel – Condition responsive
Reexamination Certificate
1999-12-16
2002-03-12
Stormer, Russell D. (Department: 3617)
Wheel substitutes for land vehicles
With means for tensioning track by moving at least one endwheel
Condition responsive
C305S143000, C305S145000
Reexamination Certificate
active
06354678
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to a drive track chain of a work machine, and more particularly to an apparatus and method for adjusting tension of a drive track chain of a work machine which utilizes a sensor for sensing position of an undercarriage component.
BACKGROUND OF THE INVENTION
A work machine, such as a track-type tractor or excavator, is typically supported and propelled by a pair of undercarriage assemblies, each one of which includes an endless drive track chain having a plurality of interconnected articulating components or links. The undercarriage assembly typically also includes a drive sprocket and one or more idler wheels, around each of which the drive track chain is advanced.
During operation of the work machine, it is necessary to maintain tension on the drive track chain in order to keep the chain from derailing from the drive sprocket and/or the idler rollers. In order to maintain tension on the drive track chain, a tension adjustment mechanism such as a hydraulic cylinder or coiled spring is often included in heretofore designed undercarriages. In particular, the cylinder or coiled spring urges the front idler roller in a direction away from the rear idler roller (or rear drive sprocket in the case of an excavator) thereby creating tension on the track chain.
Over a period of time, a number of the components associated with the undercarriage assembly, such as the links and bushings of the drive track chain and even the idler rollers themselves, begin to wear thereby creating slack in the drive track chain. In order to remove the slack from the drive track chain, it is necessary to increase the tension of the track chain. Such an increase in the tension is generally accomplished by manually injecting or otherwise inserting a material, such as grease, into the tension adjustment mechanism associated with the undercarriage assembly.
The use of such tension adjustment mechanisms has a number of drawbacks associated therewith. For example, manual injection of grease into the slack adjustment mechanism is a labor intensive task which can often lead to a decrease in the efficiency associated with operation of the work machine. Moreover, the drive track chain may inadvertently be operated for a period of time with excessive slack therein. This is true since the drive track chain may be operated with excessive slack from the point in time in which slack is first introduced into the track chain until the point in time in which the tension is manually increased. Such excessive slack may cause irregular wear of a number of the components associated with the undercarriage assembly. Moreover, such excessive slack may also cause the drive track chain to derail during movement of the work machine thereby reducing the efficiency of the work machine due to the delays caused by repair of the undercarriage assembly.
In order to avoid the problems associated with excessive slack in the drive track chain, heretofore designed undercarriage assemblies have been operated with relatively large amounts of tension on the drive track chain. However, operation of the undercarriage assembly with a relatively taut track chain during advancement of the work machine increases the rate at which components associated with the undercarriage assembly wear thereby potentially reducing the useful life of the undercarriage assembly.
Moreover, with particular regard to excavators, it is generally desirable to have the drive track chain relatively taut during performance of a digging or other type of work function in order to prevent the excavator from rolling back and forth within the interior of the drive track chain as a result of recoil forces generated during performance of the digging operation. Hence, a relatively high tension level is typically maintained on the drive track chains of excavators at all times even though it is known that use of such a high tension level increases the rate at which components associated with the undercarriage assembly wear during advancement of the excavator.
What is needed therefore is a track tensioning assembly which overcomes one or more of the above-mentioned drawbacks.
DISCLOSURE OF THE INVENTION
In accordance with a first embodiment of the present invention, there is provided a method of tensioning a drive track chain of an undercarriage assembly. The undercarriage assembly has a first frame member and a second frame member for supporting a body of a work machine. The method includes the step of sensing a position of the first frame member relative to a second frame member and generating a control signal in response thereto. The method further includes the step of adjusting the position of the first frame member relative to the second frame member in response to generation of the control signal.
In accordance with a second embodiment of the present invention, there is provided an undercarriage assembly of a work machine. The undercarriage assembly includes a first undercarriage component and a second undercarriage component which is movable relative to the first undercarriage component. The undercarriage assembly also includes an actuator mechanically coupled to the second undercarriage component so as to move the second undercarriage component relative to the first undercarriage component. The undercarriage assembly further includes a sensor for sensing a linear distance between the first undercarriage component and the second undercarriage component. Moreover, the undercarriage assembly includes a controller which is electrically coupled to the sensor. The controller is configured to (i) communicate with the sensor so as to determine the linear distance between the first undercarriage component and the second undercarriage component, and (ii) operate the actuator so as to move the first undercarriage component relative to the second undercarriage component based on the linear distance between the first undercarriage component and the second undercarriage component.
In accordance with a third embodiment of the present invention, there is provided a work machine. The work machine includes a machine body. The work machine also includes an undercarriage assembly having a frame assembly which supports the machine body. The frame assembly has (i) a first frame member, (ii) a second frame member which is movable relative to the first frame member, and (iii) a fluid cylinder for moving the first frame member relative to the second frame member. The work machine further includes a sensor for sensing position of the first frame member relative to the second frame member. Moreover, the work machine includes a controller which is electrically coupled to the sensor. The controller is configured to (i) communicate with the sensor so as to determine the position of the first frame member relative to the second frame member, and (ii) operate the fluid cylinder so as to move the first frame member relative to the second frame member based on the position of the first frame member relative to the second frame member.
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Bauer Shawn D.
Caterpillar Inc.
Glastetter Calvin E.
Stormer Russell D.
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