Wheel substitutes for land vehicles – Wheel on top of upper track run
Patent
1980-08-29
1982-07-13
Scherbel, David A.
Wheel substitutes for land vehicles
Wheel on top of upper track run
305 27, 305 28, B62D 5510, B62D 5530
Patent
active
043391567
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates generally to track-type tractor undercarriages and more particularly to a means for resiliently mounting on a track-type vehicle with a suspended undercarriage the rear idler and an adjacent track roller such that both are bogied adding softness to the rear of the vehicle to reduce undercarriage loads and improve the ride for the operator.
2. Background Art
Most land vehicles utilize either wheels or crawler tracks for the purpose of supporting the frame of the vehicle above the ground and for converting power into motion. Crawler tracks, which typically have a relatively great area of ground contact, are fairly rugged and can be designed to substantially conform to depressions and other irregularities in the ground. They are most commonly chosen for vehicles which will be operating where conditions are severe: deep snow, battlefields, marshy areas, heavy construction, etc.
Typically, crawler tracks include a front and a rear idler, which are freely turning wheels around which a track chain is placed; several freely turning rollers mounted between the idlers, which serve to transfer the weight of the vehicle to the ground by limiting the upward movement of the track; a track drive sprocket which serves to convert power from the engine into motion of the tracks and hence of the vehicle; and, a roller frame upon which the idlers and rollers are mounted. In some designs the drive sprocket is located at the extreme rear of the crawler track replacing one of the idlers.
The technology of crawler tractors has advanced to the point where they are reasonably reliable, durable and efficient. However, there is much yet to be done toward improving the ability of crawler undercarriage systems to absorb mechanical shocks and equalizing the pressure exerted upon the ground by each incremental length of the track in contact with it. Advancement in these areas will serve to increase the rate at which the vehicles can travel, this being currently limited in most cases by the amount of mechanical shock the vehicle and its operator can absorb. It will also serve to improve the vehicle performance in mud and other conditions where poor weight distribution across the track can result in the vehicle becoming unduly mired in the surface across which it travels.
In crawler track undercarriage systems mechanical shock is generally dealt with in two manners. The more obvious is through use of traditional shock absorbers in one form or another. In U.S. Pat. No. 1,836,446, issued Dec. 15, 1931, Christie details a system in which the rollers are rotatably mounted on an end of a connecting member another end of which is rotatably connected to the roller frame, the freedom of movement of the member and hence the roller being limited by a coil spring. A related system, using a resilient pad placed between the connecting member and a mechanical stop, is described in U.S. Pat. No. 3,774,708 issued to Purcell et al on Nov. 27, 1973. Holt, in U.S. Pat. No. 1,317,651, issued Sept. 30, 1919, teaches a similar system involving leaf springs. A combination of a leaf spring suspension for the roller-roller frame mounting and the encasement of each roller axle in a resilient material is set forth in U.S. Pat. No. 1,547,053 issued to Kegresse on July 21, 1925.
A second commonly used system for lessening the amount of shock transferred from the crawler tracks to the remainder of the vehicle is by use of some load transfer mechanism. In its simplest form this is achieved by rotatably connecting two or more rollers to a rigid member known as a bogie which is itself pivotally connected to the roller frame. When an undercarriage with bogie-mounted rollers passes over a bump, a rock for example, the bogie is caused to rotate allowing the track to deflect upward at the point overlying the rock while forcing that part of the track under the other roller connected to the bogie to move downward. In this manner the pressure exerted upon the ground by the track is reduced at points where a crawler undercarr
REFERENCES:
patent: 2315421 (1943-03-01), Heaslet
patent: 2467947 (1949-04-01), Skelton
patent: 3826325 (1974-07-01), Purcell et al.
patent: 4230378 (1980-10-01), Purcell et al.
Caterpillar Tractor Co.
Phillips Richard F.
Scherbel David A.
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