US3777857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic braking system for vehicles
Assignee: Girling Ltd
•
Filing: 1971-07-29
•
Granted: 1973-12-11
•
Expires: 1991-07-29
Abstract
Abstract In a fluid-pressure operated braking system for vehicles incorporating internal shoe-drum brakes the brake shoes are separated to apply the brake by a wedge actuated by pistons arranged in tandem in a cylinder and individually acted upon by pressure fluid derived from separate sources under manual control.
Inventors
- 👤 M Hughes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 05:54
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/24; B60T13/26; B60T13/38; F; F16; F16D; F16D65/00; F16D65/14; F16D65/16; F16D65/22; F16D2125/00; F16D2125/18; F16D2125/58; F16D2125/66
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
89 words
A fluid-pressure-operated braking system for vehicles incorporating internal shoe-drum brakes wherein the brake shoes are separated at at least one end by a wedge actuated by a piston-rod carrying two axially spaced pistons working in a cylinder on opposite sides of a stationary partition in the cylinder through which the piston-rod passes and with which it is in sliding and sealing engagement, the piston-rod and piston assembly being loaded by a spring urging it inwardly in a direction to apply the said spring being located in sAid fourth space.
Claim 2
Dependent Claim
89 words
A fluid-pressure-operated braking system for vehicles incorporating internal shoe-drum brakes wherein the brake shoes are separated at at least one end by a wedge actuated by a piston-rod carrying two axially spaced pistons working in a cylinder on opposite sides of a stationary partition in the cylinder through which the piston-rod passes and with which it is in sliding and sealing engagement, the piston-rod and piston assembly being loaded by a spring urging it inwardly in a direction to apply the said spring being located in sAid fourth space.
Claim 3
Dependent Claim
62 words
A braking system as in claim 5 wherein fluid pressure is normally maintained in the first and third spaces to urge the piston-rod and piston assembly outwardly against the action of the spring and retain it in that position, the supply of pressure fluid to the two spaces being derived from two separate sources under the control of a manually operated valve.
Claim 4
Dependent Claim
72 words
A braking system as in claim 1 wherein, for normal service braking, pressure fluid is supplied from two separate sources under the control of a foot-operated valve to the second and fourth spaces in the cylinder to urge the piston-rod and piston assembly inwardly to apply the brake, the first and third spaces being simultaneously exhausted to a reservoir at atmospheric pressure whereby the spring assists in the application of the brake.
Claim 5
Dependent Claim
63 words
A braking system as in claim 1 wherein, for parking or emergency braking, the first and third spaces in the cylinder are exhausted to a reservoir at atmospheric pressure by a manually operated valve whereby the piston-rod and piston assembly is urged inwardly by the spring to apply the brake and hold it applied until the first and third spaces are again pressurised.
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) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |