US3752266A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid pressure braking systems
Assignee: Whitnash PLC
•
Filing: 1971-01-13
•
Granted: 1973-08-14
•
Expires: 1991-01-13
Abstract
Abstract A vehicle braking system comprising internal shoe drum brakes of the two-leading shoe type for each wheel. Each front brake is operated by two wheel cylinders. Each rear brake is operated by a wheel cylinder at one end of the brake shoes and by a wedge-type mechanical expander at the other end. A first liquid accumulator is connected through a pedal operated valve to the wheel brake wheel cylinders and to one of the wheel cylinders of each front brake. A second liquid accumulator is connected through the pedal operated valve to the other front brake wheel cylinders and through a manually operable valve also to motor cylinders for the expanders. A third liquid accumulator is connected through the manually operable valve to said motor cylinders. The piston of each motor cylinder is urged in the brake applying direction by a spring acting through a plunger. Normally liquid pressure from the third accumulator acts on the plungers in opposition to the springs so that, for service braking, the expanders are operated by liquid supplied by operation of the pedal operated valve. For parking purposes, the manually operable valve is operated to cut off the supply of liquid from the third accumulator so that the expanders act to apply the rear brakes either due to the action of the spring, or due to the action of liquid pressure supplied by the pedal operated valve which liquid pressure is directed also by the manually operable valve to act on the plunger in opposition to the spring.
Inventors
- 👤 L Chouings
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:07
CPC Classifications
F; F16; F16D; F16D65/00; F16D65/14; F16D65/16; F16D65/22; B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T13/141; B60T13/22; F16D2125/00; F16D2125/18; F16D2125/58; F16D2125/66
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
281 words
A fluid pressure braking system for a vehicle including, on at least one wheel of the vehicle, an internal shoe drum brake having a drum and two brake shoes, two fluid pressure operated expanding devices for applying the shoes of said brake to said brake drum, one said expanding device acting between one pair of ends of said brake shoes and the other expanding device acting between the other pair of adjacent ends oF said brake shoes, and two separate fluid pressure systems each for operating a respective one of said two expanding devices, means for operating both said fluid pressure systems simultaneously to apply said brake as a two leading shoe brake, said one expanding device comprising members actuated by fluid pressure in one said fluid pressure system to apply the brake shoes to the drum and the said other expanding device including mechanical expanding means to apply the brake shoes to the drum, spring means operative to exert a force on said mechanical applying means to apply the brake shoes to the drum, a first piston associated with said mechanical expanding means in which fluid pressure in the other of said fluid pressure systems acts to actuate said mechanical expanding means, a second piston associated with said spring means, valve means for controlling the application of fluid pressure to said second piston and normally connecting said piston to a source of fluid pressure so that said fluid pressure acts on said second piston to prevent said spring means from applying the brake, said valve means being operatIve to release the fluid pressure acting in said second piston to allow the brake to be applied for parking by the spring.
Claim 2
Dependent Claim
281 words
A fluid pressure braking system for a vehicle including, on at least one wheel of the vehicle, an internal shoe drum brake having a drum and two brake shoes, two fluid pressure operated expanding devices for applying the shoes of said brake to said brake drum, one said expanding device acting between one pair of ends of said brake shoes and the other expanding device acting between the other pair of adjacent ends oF said brake shoes, and two separate fluid pressure systems each for operating a respective one of said two expanding devices, means for operating both said fluid pressure systems simultaneously to apply said brake as a two leading shoe brake, said one expanding device comprising members actuated by fluid pressure in one said fluid pressure system to apply the brake shoes to the drum and the said other expanding device including mechanical expanding means to apply the brake shoes to the drum, spring means operative to exert a force on said mechanical applying means to apply the brake shoes to the drum, a first piston associated with said mechanical expanding means in which fluid pressure in the other of said fluid pressure systems acts to actuate said mechanical expanding means, a second piston associated with said spring means, valve means for controlling the application of fluid pressure to said second piston and normally connecting said piston to a source of fluid pressure so that said fluid pressure acts on said second piston to prevent said spring means from applying the brake, said valve means being operatIve to release the fluid pressure acting in said second piston to allow the brake to be applied for parking by the spring.
Claim 3
Dependent Claim
43 words
A fluid pressure braking system according to claim 1, wherein a valve operated by a parking control member is arranged to release fluid pressure from said additional fluid pressure means only when pressure is also relieved in both of the fluid pressure systems.
Claim 4
Dependent Claim
78 words
A fluid pressure braking system according to claim 1 wherein the mechanical expanding means are operated by a piston assembly including a first piston on which fluid pressure in said other fluid pressure system acts to operate the expanding means and a second piston on which the spring means acts to operate the expanding means, the additional fluid pressure means including said second piston and means for applying fluid pressure to said second piston to oppose the spring.
Claim 5
Dependent Claim
126 words
A fluid pressure braking system accordig to claim 3 wherein a valve operated by a parking control member is arranged to release fluid pressure from said additional fluid pressure means only when pressure is also relieved in both of the fluid pressure systems, and including a manually operable valve for controlling the additional fluid pressure means, said manually operated valve being operable to connect a cylinder, in which fluid pressure acts on said second piston, selectivley to a source of fluid pressure independent of both of said fluid pressure systems and to the said other one of said fluid pressure systems so that fluid pressure acting therein is controlled in common with fluid pressure operating the shoe expanding means operated by fluid pressure in that system.
Claim 6
Dependent Claim
19 words
A fluid pressure braking system according to claim 1, wherein the fluid employed in the system is a liquid.
References Cited (Backward Citations)
US2064575A
Cited
US2154636A
Cited
US2155030A
Cited
US2418666A
Cited
US3417843A
Cited
US3463276A
Cited
US3513946A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |