US4040673A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid pressure operable brake apparatus with load-compensating means for vehicles with tandem rear axles
Assignee: WABCO WESTINGHOUSE GmbH
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Filing: 1976-10-21
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Granted: 1977-08-09
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Expires: 1996-10-21
Abstract
Abstract Fluid pressure operable brake apparatus for controlling the ratio of braking forces exerted on two rear tandem axles of a vehicle, including a driving axle and a trailing axle, in such manner as to provide compatible synchronous braking effort by taking into account dynamic axle load displacement during braking action and including a stepped-piston relay valve responsive to load conditions of the vehicle for adjusting the ratio of braking forces between the driving axle and the trailing axle accordingly.
Inventors
- 👤 Gerhard Ahaus
- 👤 Siegfried Netzer
- 👤 Hans-Peter Liebig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:30
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/18; B60T8/1812; B60T8/1831; Y; Y10; Y10S; Y10S303/00; Y10S303/02; Y10S303/03
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
355 words
Fluid pressure operable brake apparatus for vehicles having tandem rear axles including a driving axle and a trailing axle and respective brake cylinders therefor, said brake apparatus comprising: a. a first source of fluid under pressure; b. first means for effecting supply of a first braking pressure from said first source to the driving axle brake cylinders at a selected degree; c. second means interposed between said first means and said driving axle brake cylinders for modifying said first braking pressure supplied to said driving axle brake cylinders according to vehicle load; d. a relay valve means being formed therein with a first pressure area, a second pressure area, and a third pressure area, each sealingly isolated form the others, said relay valve means connected in parallel relation to said first means and to said second means and actuable for effecting supply of a second braking pressure therefrom to the trailing axle brake cylinders at a degree of pressure determined by the combined effect of a first actuating pressure from said first means acting on said first pressure area and a second actuating pressure from said second means acting on said third pressure area; e. a second source of fluid at a controlled pressure; and f. third means connected in parallel relation to said first means, to said relay valve means, and to said second source, and including a valve device normally occupying a closed position in which communication between said second source and said relay valve means is cut off, g. said third means being operable responsively to said first actuating pressure at a degree greater than a change-over pressure for effecting operation of said valve device to an open position in which fluid from said second source is communicated to said relay valve means for effecting supply of braking pressure to said trailing axle brake cylinders at a degree determined by the combined effect of said first actuating pressure from said first means acting on said first pressure area, said second actuating pressure from said second means acting on said third pressure area, and said controlled pressure acting on said second pressure area.
Claim 2
Dependent Claim
355 words
Fluid pressure operable brake apparatus for vehicles having tandem rear axles including a driving axle and a trailing axle and respective brake cylinders therefor, said brake apparatus comprising: a. a first source of fluid under pressure; b. first means for effecting supply of a first braking pressure from said first source to the driving axle brake cylinders at a selected degree; c. second means interposed between said first means and said driving axle brake cylinders for modifying said first braking pressure supplied to said driving axle brake cylinders according to vehicle load; d. a relay valve means being formed therein with a first pressure area, a second pressure area, and a third pressure area, each sealingly isolated form the others, said relay valve means connected in parallel relation to said first means and to said second means and actuable for effecting supply of a second braking pressure therefrom to the trailing axle brake cylinders at a degree of pressure determined by the combined effect of a first actuating pressure from said first means acting on said first pressure area and a second actuating pressure from said second means acting on said third pressure area; e. a second source of fluid at a controlled pressure; and f. third means connected in parallel relation to said first means, to said relay valve means, and to said second source, and including a valve device normally occupying a closed position in which communication between said second source and said relay valve means is cut off, g. said third means being operable responsively to said first actuating pressure at a degree greater than a change-over pressure for effecting operation of said valve device to an open position in which fluid from said second source is communicated to said relay valve means for effecting supply of braking pressure to said trailing axle brake cylinders at a degree determined by the combined effect of said first actuating pressure from said first means acting on said first pressure area, said second actuating pressure from said second means acting on said third pressure area, and said controlled pressure acting on said second pressure area.
Claim 3
Dependent Claim
41 words
Fluid pressure operable brake apparatus, as set forth in claim 1, wherein said second means comprises a vehicle load responsive fluid pressure regulator for effecting supply of said first braking pressure at a degree proportional to the degree of vehicle load.
Claim 4
Dependent Claim
124 words
Fluid pressure operable brake apparatus, as set forth in claim 1, wherein said third means comprises: a. a fluid pressure operable electrical switch device connected to said first means and including a switch member interposed in an electrical circuit, said switch member normally occupying an open position in which said circuit is open, said switch device being operable responsively to said first actuating pressure at said degree greater than said change-over pressure for operating said switch member to a closed position in which said circuit is closed; and wherein b. said valve device is provided with a solenoid interposed in said circuit for effecting operation of the valve device to its said closed and open positions upon opening and closing of the circuit, respectively.
Claim 5
Dependent Claim
30 words
Fluid pressure operable brake apparatus, as set forth in claim 1, wherein said relay valve means further comprises a stepped-piston having said first, second, and third pressure areas formed thereon.
Claim 6
Dependent Claim
59 words
Fluid pressure operable brake apparatus, as set forth in claim 4, wherein said relay valve means further comprises a valve unit including a supply valve and an exhaust valve of the self-lapping type for controlling said supply of said second braking pressure to said trailing axle brake cylinders and maintaining the degree of pressure thereof at the established level.
Claim 7
Dependent Claim
39 words
Fluid pressure operable brake apparatus, as set forth in claim 4, wherein said stepped-piston is characterized by a plurality of coaxial annular shoulders of progressively increasing dimensions formed thereon for providing said first, second, and third pressure areas, respectively.
Claim 8
Dependent Claim
27 words
Fluid pressure operable brake apparatus, as set forth in claim 6, wherein said first pressure area is the smallest and said third pressure area is the largest.
Claim 9
Dependent Claim
80 words
Fluid pressure operable brake apparatus, as set forth in claim 7, wherein the dimensions of said first and third pressure areas are predetermined so as to provide, when subjected to said first and second actuating pressures, respectively, a combined effective pressure area for effecting said supply of second braking pressure to the trailing axle at a degree of pressure which produces a braking force thereon less than the braking force effected on the driving axle by said first braking pressure.
Claim 10
Dependent Claim
79 words
Fluid pressure operable braking apparatus, as set forth in claim 8, wherein the dimension of said second pressure area, relative to said first and third pressure areas, is pedetermined so that when said first, third, and second pressure areas are subjected to said first and second actuating pressures and to said controlled pressure, respectively, the braking pressure supplied to and the resulting braking force acting on said trailing axle is substantially equivalent to that acting on the driving axle.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |