Patent US3851473A successfully refreshed from Google Patents.
US3851473A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brake application control devices
Assignee: Whitnash PLC
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Filing: 1973-06-07
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Granted: 1974-12-03
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Expires: 1993-06-07
Abstract
Abstract A dual line liquid pressure braking system includes a master cylinder device in which the driver operable pedal acts upon the master cylinder piston through the spool of a spool valve which controls the connection of a group of brake operating master cylinders to either a liquid pressure accumulator or to a reservoir. Liquid displaced from the master cylinder bore by movement of the master cylinder piston is fed to another group of brake operating motor cylinders.
Inventors
- 👤 W Bainbridge
- 👤 D Parsons
- 👤 H Hodkinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:44
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T13/142; B60T13/145; B60T13/146
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
214 words
A master cylinder device comprising a body, a bore in the body, a freely floating master cylinder piston in the bore, and control valve means arranged to apply fluid under pressure from a remote fluid pressure supply source to the master cylinder piston to move the master cylinder piston within the bore, wherein the control valve means include a valve spool slidable in the bore, first second and third ports in the wall of the bore, and a space in the bore between the valve spool and the piston, the valve spool being arranged to place the first port in communication with a selected one of the second and third ports dependent upon the position of the valve spool within the bore, the first port also being in communication with said space, said valve spool being tubular with a through bore, with a rod in said through bore, first resilient means urging the tubular valve spool away from the master cylinder piston and second resilient means arranged so that brake applying movement is imparted to the rod and is imparted to said valve spool via said second resilient means and, if fluid pressure is not available in said space to move said master cylinder piston, said rod imparts brake applying movement to the piston.
Claim 2
Dependent Claim
214 words
A master cylinder device comprising a body, a bore in the body, a freely floating master cylinder piston in the bore, and control valve means arranged to apply fluid under pressure from a remote fluid pressure supply source to the master cylinder piston to move the master cylinder piston within the bore, wherein the control valve means include a valve spool slidable in the bore, first second and third ports in the wall of the bore, and a space in the bore between the valve spool and the piston, the valve spool being arranged to place the first port in communication with a selected one of the second and third ports dependent upon the position of the valve spool within the bore, the first port also being in communication with said space, said valve spool being tubular with a through bore, with a rod in said through bore, first resilient means urging the tubular valve spool away from the master cylinder piston and second resilient means arranged so that brake applying movement is imparted to the rod and is imparted to said valve spool via said second resilient means and, if fluid pressure is not available in said space to move said master cylinder piston, said rod imparts brake applying movement to the piston.
Claim 3
Dependent Claim
30 words
A master cylinder device according to claim 1, wherein the valve spool is arranged so as to place said first port in communication with said third port via said space.
Claim 4
Dependent Claim
32 words
A master cylinder device according to claim 1, wherein said first port communicates with said space via a non-return valve which prevents flow of fluid from said space towards said first port.
Claim 5
Dependent Claim
36 words
A master cylinder device according to claim 1, wherein said first port and said space are placed in communication with the selected one of said second and third ports via passage means in said valve spool.
Claim 6
Dependent Claim
19 words
A master cylinder device according to claim 1, wherein the second resilient means comprises a pad of elastomeric material.
Claim 7
Dependent Claim
78 words
The master cylinder device of 1 including a slave cylinder device and conduit means connecting the master cylinder device to the slave cylinder device so that liquid displaced from the master cylinder by movement therein of a master cylinder piston is transmitted to the slave cylinder causing movement of a slave cylinder piston in the slave cylinder, said second port being connected to a liquid reservoir and said third port being connected to a source of liquid pressure.
Claim 8
Dependent Claim
78 words
The master cylinder device of 1 including a slave cylinder device and conduit means connecting the master cylinder device to the slave cylinder device so that liquid displaced from the master cylinder by movement therein of a master cylinder piston is transmitted to the slave cylinder causing movement of a slave cylinder piston in the slave cylinder, said second port being connected to a liquid reservoir and said third port being connected to a source of liquid pressure.
Claim 9
Dependent Claim
31 words
The master cylinder device of claim 6, wherein the slave cylinder is one brake operating motor cylinder and said first port is in conduit communication with another brake operating motor cylinder.
Claim 10
Dependent Claim
27 words
The master cylinder device of claim 6 for operating a friction clutch, wherein the first port of the motor cylinder device to the conduit means is closed.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |