Boots – shoes – and leggings
Patent
1980-05-07
1982-08-10
Smith, Jerry
Boots, shoes, and leggings
180197, 303 96, 361238, G06F 1520, B60T 810
Patent
active
043441394
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to vehicle drive systems of the type having spaced apart drive wheels which are driven through a differential from a common power source and, more particularly, to a method and apparatus for controlling slip between the differentially driven wheels due to a loss of traction at one wheel by discrete proportional applications of braking force to the wheel with the lesser traction.
2. Background Art
It is well known that the standard vehicle having spaced apart drive wheels or wheel-sets which are powered by a single engine through a differential drive experiences difficulties when one of the two differentially driven wheels loses traction. Conditions which give rise to a loss of traction exist commonly in construction sites and other off-road locations as well as on normal roads during wet, snowy or icy weather. A truck or automobile having one of two differentially driven wheel-sets on ice and the other on ground providing good traction is often unable to move due to the fact that the action of the differential drive system directs all power to the wheel having no traction. The result is a slip condition wherein the wheel without traction rotates at twice its normal speed relative to the drive shaft and the wheel with traction remains stationary.
To alleviate the slip or loss of traction condition, various mechanical anti-spin devices have been developed and put into commercial use. Such devices, however, can produce an abrupt transfer of all driving power to the wheel or wheel set having traction. This abrupt and full power transfer can create such mechanical stresses as to shorten the useful life of the drive train and/or cause catastrophic failure. In addition, mechanical anti-spin units often fail to accommodate the wheel speed differential which arises during normal turning of the vehicle and hence give rise to excessive tire wear due to drag effect.
An alternative approach to the slip problem due to loss of traction in differentially driven vehicles involves the provision of separately actuable drive wheel brakes whereby the operator can selectively apply a braking force to the spinning or slipping wheel thus to effect a balancing of power as between the slipping and nonslipping wheels; i.e., the application of the braking force to the slipping wheel simulates increased rolling resistance and results in a more even distribution of power as between the two differentially driven wheels. Systems of this type are common on farm vehicles but are not believed to be practical on large transport or off-road vehicles such as trucks and road graders.
More sophisticated approaches to slip control using the selectively actuable wheel brake systems are known in the prior art. These systems include a speed sensor disposed on or adjacent each of the differentially driven wheels for generating speed signals, means for comparing the two signals to develop a slip signal and selectively operated solenoid means or solenoid operated valves to actuate either the left or right wheel brake when a slip condition is detected. One such system is disclosed in the U.S. Patent to Devlin, No. 4,066,300 issued Jan. 3, 1978. Another such system is disclosed in the U.S. Patent to Eger, Jr. et al, No. 3,025,772 issued Mar. 20, 1962. Both the Devlin and Eger, Jr. et al systems involve abrupt application and release of brake forces to the slipping wheel. This approach, unless utilized with very light braking forces, and at low speeds, can be detrimental to operator control of the vehicle unless the operator is given an opportunity to participate in the overall actuation of the slip control system.
The present invention is directed to overcoming the problems of the prior art and to provide an improved vehicle slip control system.
DISCLOSURE OF THE INVENTION
In one aspect of the invention an apparatus is provided for automatically balancing the power transfer between two differentially driven vehicle wheels when one of the wheels loses traction, by applying a proportionally varying
REFERENCES:
patent: 3780346 (1973-12-01), Gagnon
patent: 3802529 (1974-04-01), Burckhardt et al.
patent: 3825306 (1974-07-01), Fink
patent: 3893535 (1975-07-01), Burckhardt et al.
patent: 3941203 (1976-03-01), Leconte
patent: 4066300 (1978-01-01), Devlin
patent: 4260199 (1981-04-01), Reinecke
Miller Robert G.
Myers Allen D.
Phelps Weldon L.
Sieving Alfred W.
Caterpillar Tractor Co.
Smith Jerry
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