US3885391A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic braking system
Assignee: Girling Ltd
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Filing: 1973-06-25
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Granted: 1975-05-27
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Expires: 1993-06-25
Abstract
Abstract In a master cylinder assembly transfer chambers in master cylinders are connected by a transfer port or passage, and the transfer chambers are isolated from the pressure spaces of the cylinders by normally closed transfer valves which are adapted to be opened by axial movement of pistons in a brake applying direction. At least one of the master cylinders incorporates pressure relief means defining at least when the transfer valve is closed, a leak path between the transfer chamber of that master cylinder and a reservoir for fluid to compensate for increase in pressure in the chambers due to thermal expansion of the hydraulic fluid.
Inventors
- 👤 Roy Campbell
- 👤 Anthony George Price
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:25
CPC Classifications
B; B60; B60T; B60T11/00; B60T11/10; B60T11/16; B60T11/20; B60T11/21; B62; B62D; B62D11/00; B62D11/02; B62D11/06; B62D11/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
153 words
An hydraulic master cylinder assembly for a vehicle braking system comprising first and second separate master cylinders, each comprising a piston adapted to work in a bore, a pressure space in said bore in front of said piston, means defining a transfer chamber, and a transfer valve which is normally closed and which is opened by movement of said piston in a direction to pressurise hydraulic fluid in said pressure space, wherein said transfer chambers are connected by a transfer passage and at least one of said master cylinders incorporates pressure relief means defining, at least when said transfer valve of said one master cylinder is closed, a leak path between said transfer chamber of that master cylinder and a recuperation port for connection to a reservoir for fluid to permit fluid seepage therebetween to compensate for increase in volume of fluid within said transfer chambers due to thermal expansion of hydraulic fluid.
Claim 2
Dependent Claim
153 words
An hydraulic master cylinder assembly for a vehicle braking system comprising first and second separate master cylinders, each comprising a piston adapted to work in a bore, a pressure space in said bore in front of said piston, means defining a transfer chamber, and a transfer valve which is normally closed and which is opened by movement of said piston in a direction to pressurise hydraulic fluid in said pressure space, wherein said transfer chambers are connected by a transfer passage and at least one of said master cylinders incorporates pressure relief means defining, at least when said transfer valve of said one master cylinder is closed, a leak path between said transfer chamber of that master cylinder and a recuperation port for connection to a reservoir for fluid to permit fluid seepage therebetween to compensate for increase in volume of fluid within said transfer chambers due to thermal expansion of hydraulic fluid.
Claim 3
Dependent Claim
20 words
A master cylinder as claimed in claim 1, wherein each master cylinder incorporates pressure relief means comprising a leak path.
Claim 4
Dependent Claim
21 words
A master cylinder assembly as claimed in claim 1, wherein said leak path incorporates a member of at least permeable material.
Claim 5
Dependent Claim
25 words
A master cylinder assembly as claimed in claim 1, wherein said leak path comprises a clearance between two complementary members in said first master cylinder.
Claim 6
Dependent Claim
41 words
A master cylinder assembly as claimed in claim 4, wherein said clearance is defined between a valve member and a complementary seating with which said valve member engages when subjected to pressure from the transfer chamber of said second master cylinder.
Claim 7
Dependent Claim
33 words
A master cylinder assembly as claimed in claim 5 wherein said valve member comprises a ball and a light compression spring is adapted normally to urge said valve member away from said seating.
Claim 8
Dependent Claim
38 words
A master cylinder assembly as claimed in claim 1, wherein each transfer valve comprises a seating in said piston, and a valve head for engagement with said seating, said pressure relief means being incorporated in said transfer valve.
Claim 9
Dependent Claim
18 words
A master cylinder assembly as claimed in claim 7, wherein the seating is of at least permeable material.
Claim 10
Dependent Claim
87 words
A master cylinder assembly as claimed in claim 7, wherein a rod extends through said seating and said head is carried by said rod, said rod being provided with a by-pass passage which by-passes said seating when said head is in engagement with it, a valve assembly incorporated in said head controlling fluid flow through said by-pass passage, said valve assembly being normally open to provide a leak path and being adapted to close when subjected to pressure in said transfer chamber of the other master cylinder.
Claim 11
Dependent Claim
89 words
A master cylinder assembly as claimed in claim 1, wherein each transfer valve comprises a seating in said piston, a transfer valve head for engagement with said seating, a rod extending through said seating and having a first end carrying said transfer valve head and a second end, and a recuperation valve controlling communication between said recuperation port and said pressure space comprising a rEcuperation seating surrounding said recuperation port, and a recuperation valve head for engagement with said recuperation seating carried by said second end of said rod.
Claim 12
Dependent Claim
23 words
A master cylinder assembly as claimed in claim 10, wherein said pressure relief means is incorporated in at least one of said rods.
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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |