Patent US3841714A successfully refreshed from Google Patents.
US3841714A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Parking brake control
Assignee: MIDBRAKE Corp
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Filing: 1973-05-02
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Granted: 1974-10-15
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Expires: 1993-05-02
Abstract
Abstract A parking brake control valve and system including a spring applied brake actuator which is released by air, the control valve receiving air from the service brake reservoir and being manually controlled to deliver air to the actuator to release the brakes or to exhaust air from the actuator to apply the brakes. The control valve is automatically operated in response to pressure below a predetermined minimum in the service brake system to apply the parking brakes. In the event of automatic application of the parking brake actuator, the control valve may be manually maintained in a parking brake release position for emergency operation of the vehicle.
Inventors
- 👤 F Schultz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:18
CPC Classifications
B; B60; B60T; B60T15/00; B60T15/02; B60T15/04; B60T15/041; B60T13/00; B60T13/10; B60T13/24; B60T13/26; B60T13/38
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
317 words
A parking brake control valve comprising a housing, a first inlet port adatped for connection to a first source of air under pressure, a second inlet port adatped for connection to a second of air under pressure, a pressure outlet port adapted for communication with a parking brake, an exhaust port open to the atmosphere, a valve control means slidable in said housing between a brake applied position and a brake released position and including a first control valve closing said first inlet port to said pressure outlet port when said control means is in said brake applied position and opening said first inlet port to said outlet port when said control means is in said brake released position, a second control valve closing said second inlet port to said outlet port and opening the latter to said exhaust port when said control means is in said brake applied position and closing said exhaust port and opening said second inlet port to said outlet port when said control means is in said brake released position, said valve control means including a piston is said housing between said inlet ports and separating said inlet ports from each other, biasing means urging said control means to said brake applied position, said valve control means being movable from brake released to brake applied position in response to the presence of pressure at said first inlet port and at one side of said piston below a predetermined minimum and being manually movable against the action of said biasing means to a brake released position when the pressure at the other side of said piston is below a predetermined minimum, and check valve means between said outlet port and said second inlet port preventing communication therebetween when said control means is in a brake released position and the pressure at said second inlet port is less than at said first inlet port.
Claim 2
Dependent Claim
317 words
A parking brake control valve comprising a housing, a first inlet port adatped for connection to a first source of air under pressure, a second inlet port adatped for connection to a second of air under pressure, a pressure outlet port adapted for communication with a parking brake, an exhaust port open to the atmosphere, a valve control means slidable in said housing between a brake applied position and a brake released position and including a first control valve closing said first inlet port to said pressure outlet port when said control means is in said brake applied position and opening said first inlet port to said outlet port when said control means is in said brake released position, a second control valve closing said second inlet port to said outlet port and opening the latter to said exhaust port when said control means is in said brake applied position and closing said exhaust port and opening said second inlet port to said outlet port when said control means is in said brake released position, said valve control means including a piston is said housing between said inlet ports and separating said inlet ports from each other, biasing means urging said control means to said brake applied position, said valve control means being movable from brake released to brake applied position in response to the presence of pressure at said first inlet port and at one side of said piston below a predetermined minimum and being manually movable against the action of said biasing means to a brake released position when the pressure at the other side of said piston is below a predetermined minimum, and check valve means between said outlet port and said second inlet port preventing communication therebetween when said control means is in a brake released position and the pressure at said second inlet port is less than at said first inlet port.
Claim 3
Dependent Claim
65 words
A parking brake control valve as set forth in claim 1 in which said second valve presents a pressure responsive surface when said control means is in said brake released position, said surface being responsive to pressure at said pressure outlet port in excess of said predetermined minimum to maintain said control means in said brake released position against the action of said biasing means.
Claim 4
Dependent Claim
39 words
A parking brake control valve as set forth in claim 2 in which said check valve means is closed in response to pressure acting on said pressure responsive surface in excess of the pressure at said second inlet port.
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) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |