Wheel substitutes for land vehicles – Wheel on top of upper track run
Patent
1980-11-19
1982-11-30
Scherbel, David A.
Wheel substitutes for land vehicles
Wheel on top of upper track run
305 28, 305 31, 474134, 474135, B67D 5510
Patent
active
043613632
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates generally to crawler track assemblies for track-type vehicles and more particularly to idler recoil devices for crawler track assemblies.
2. Background Art
A great problem faced by those who design crawler track roller frames relates to the near certainty that foreign objects, such as tree limbs and rocks, will be drawn between an idler, roller or drive sprocket of the crawler track assembly and the corresponding endless chain link assembly. This causes an increase in the effective path length for the endless chain link assembly which places the substantially inelastic chain link assembly in increased tension occasionally resulting in damage. If the position of each idler and sprocket which guide and support the track chain is perfectly fixed any foreign object trapped between the endless chain link assembly and a corresponding idler, roller or drive sprocket will result in the occurrence of one of the following three events: (1) the foreign object will be sufficiently small that the increase in endless chain link assembly length it causes is less than the slack available in the endless chain; (2) the foreign object will be crushed until it is sufficiently small to cause an increase in path length less than the available slack; or (3) the foreign object will not be sufficiently small or sufficiently crushed and the resulting strain on the endless track chain link assembly will either damage the endless track chain assembly or some part of the frame.
A related problem is that track-type vehicles, being frequently used on rough terrain, are apt to run up against obstacles with the front and the back of their crawler tracks. This can place a tremendous compressional or shear loading on the components of the roller frame, most typically an idler, in contact with the point of impact and the associated portion of the frame. If this transient loading is not in some way dampened, the structural parts subjected to this loading will be required to be of significantly greater strength and, consequently, of greater cost than would otherwise be necessary.
The most commonly attempted solution to these difficulties has been to resiliently mount the fore and/or aft idlers. Typical are the fluid shock absorber systems of Purcell et al in U.S. Pat. No. 3,841,424 issued Oct. 15, 1974; the torsion bar shock absorber system of Garman described in U.S. Pat. No. 3,768,878 issued Oct. 30, 1973; the ribbon spring shock absorber system of Heaslet set forth in U.S. Pat. No. 2,315,421 issued on Mar. 30, 1943; and the coil spring system used by Meisel as described in U.S. Pat. No. 4,149,757 issued Apr. 17, 1979. Yet another solution, utilizing a compressible pad, is set forth in U.S. Pat. No. 3,938,606 to Yancey, issued Feb. 17, 1976.
While all of the aforementioned schemes are to some extent effective, a recoil device of reduced weight, complexity, and cost and of greater mechanical advantage, with simpler maintenance requirements would be further advantageous.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, a roller frame of a crawler track-type vehicle has an idler recoil device with an idler connected to a link which itself is pivotally connected by a central point thereon to one end of the roller frame. The idler is rotatably connected to said idler link and is outwardly biased by a compressible pad in such a manner that the idler moves inward so as to relieve endless track chain assembly tension once the tension reaches some preselected minimum value. The recoilable idler also has shock absorbing capabilities to mitigate the effects of transient ground loadings and functions in a load sharing manner with an adjacent roller assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic side elevational view of an embodiment of the present invention;
FIG. 2 is a partial diagrammatic top plan view corresponding to FIG. 1 with the endless track chain as
REFERENCES:
patent: 2315421 (1943-03-01), Heaslet
patent: 3332725 (1967-07-01), Reinsma
patent: 3768878 (1973-10-01), Garman
patent: 3826325 (1974-06-01), Purcell et al.
patent: 3841424 (1974-10-01), Purcell et al.
patent: 3901563 (1975-08-01), Day
patent: 3938606 (1976-02-01), Yancey
Caterpillar Tractor Co.
Phillips Richard F.
Scherbel David A.
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