US3924712A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic liquid operated and cooled friction brake
Assignee: Self Changing Gears Ltd
•
Filing: 1974-09-27
•
Granted: 1975-12-09
•
Expires: 1994-09-27
Abstract
Abstract An hydraulically operable friction brake wherein the hydraulic liquid also provides the medium for removal of heat during operation, which brake comprises a casing within which are mounted a rotary member and a pressure-operable retarding device arranged and adapted to act upon the rotary member to generate retarding torque, a pump for circulating hydraulic liquid through two separate fluid circuits between the pump and the retarding device, one of the circuits being an actuating circuit arranged and adapted to operate the retarding device; operation of the brake is controlled by a valve device comprising a valve member, a first valve element secured to said member, a second valve element slidable on said member and urged away from the first valve element by a spring so constituting a pressure sensitive device arranged and adapted to control distribution of flow of hydraulic liquid between the two circuits, and a device for equilibrating hydraulic pressure across the valve device.
Inventors
- 👤 Walter Robert Stirling
- 👤 Christopher Robinson Ellis
- 👤 Brian Carol Silvester
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:17
CPC Classifications
F; F16; F16D; F16D65/00; F16D65/78; F16D65/84; F16D65/853; B; B60; B60T; B60T1/00; B60T1/02; B60T1/08; F16D55/00; F16D55/24; F16D55/26; F16D55/36; F16D55/40; F16D57/00; F16D57/06; F16D63/00; F16D2055/0004; F16D2055/0058; F16D2125/00; F16D2125/02; F16D2125/14
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
158 words
An hydraulically operable friction brake of the kind wherein the hydraulic liquid also provides the medium For removing the heat generated during operation of the brake, comprising (i) a casing, (ii) a rotary member mounted in the casing, (iii) a pressure-operable retarding device arranged and adapted to act upon the rotary member to generate retarding torque, (iv) a pump for circulating hydraulic liquid, (v) two separate fluid circuits provided between the pump and the retarding device one being an actuating circuit arranged and adapted to operate the retarding device, and (vi) valve means comprising (a) a valve member, (b) a first valve element secured to said member, (c) a second valve element slidable on said member and urged away from the first valve element by a spring and constituting pressure sensitive means arranged and adapted to control distribution of flow of hydraulic liquid between the two circuits, and (d) means for equilibrating hydraulic pressure across the valve means.
Claim 2
Dependent Claim
158 words
An hydraulically operable friction brake of the kind wherein the hydraulic liquid also provides the medium For removing the heat generated during operation of the brake, comprising (i) a casing, (ii) a rotary member mounted in the casing, (iii) a pressure-operable retarding device arranged and adapted to act upon the rotary member to generate retarding torque, (iv) a pump for circulating hydraulic liquid, (v) two separate fluid circuits provided between the pump and the retarding device one being an actuating circuit arranged and adapted to operate the retarding device, and (vi) valve means comprising (a) a valve member, (b) a first valve element secured to said member, (c) a second valve element slidable on said member and urged away from the first valve element by a spring and constituting pressure sensitive means arranged and adapted to control distribution of flow of hydraulic liquid between the two circuits, and (d) means for equilibrating hydraulic pressure across the valve means.
Claim 3
Dependent Claim
32 words
A friction brake according to claim 1, wherein the means for equilibrating hydraulic pressure comprises a passage in the valve member permitting flow there through of hydraulic liquid in said one circuit.
Claim 4
Dependent Claim
48 words
A friction brake according to claim 1, wherein the means for equilibrating hydraulic pressure comprises a by-pass from the outlet of the pump to a surface of said first valve element remote from the second valve element, wherby the by-pass is opened on actuation of the valve means.
Claim 5
Dependent Claim
37 words
A friction brake according to claim 1, wherein the other of said circuits is in part external of the casing and includes cooling means in the form of at least one heat exchanger mounted on the casing.
Claim 6
Dependent Claim
120 words
A friction brake according to claim 2, wherein the valve means comprises a body member defining a bore, said valve member is in the form of a rod freely passing through said bore, and said first and second valve elements are in the form of pistons which are each a sealing, sliding fit within the bore to define a first space above the first valve element and an intermediate space between said elements, said passage interconnecting the outlet of said pump with said first space, said intermediate space being vented to the interior of the casing wherby hydraulic liquid may be directed from the pump outlet, through the other of said circuits and thereby to the inlet of said pump.
Claim 7
Dependent Claim
61 words
A friction brake according to claim 1, wherein the spring is of a compressive strength such that in operation of the brake the second valve element is capable of movement towards the first valve element to an extent which will maintain substantially constant the pressure in the outlet of the pump over a wide speed range during operation of the brake.
Claim 8
Dependent Claim
56 words
A friction brake according to claim 1, wherin the spring is of a compressive strength such that the second valve element is capable of relatively small movement towards the first valve element whereby the pressure in the outlet of the pump will tend to be proportional to the square of the speed of the rotary member.
Claim 9
Dependent Claim
36 words
A friction brake according to claim 1, including a pressure relief device arranged and adapted to vent into the internal part of said other circuit hydraulic fluid from the external cooling part of predetermined maximum pressure.
Claim 10
Dependent Claim
33 words
A friction brake according to claim 1, including a bellows device arranged and adapted to act upon hydraulic liquid within the casing so as to maintain the hydraulic liquid at a predetermined pressure.
Claim 11
Dependent Claim
52 words
A friction brake according to claim 1, wherein the retarding device includes a piston in the form of an annular bellows and the actuating circuit includes means for supplying hydraulic liquid to the interior of the bellows on actuation of the brake, to expand the bellows and thereby activate the retarding device.
Claim 12
Dependent Claim
31 words
A friction brake according to claim 1, wherein the valve means is actuable by means of a movable actuator rod is sealed to the casing by means including a liquid-tight bellows.
Claim 13
Dependent Claim
53 words
A friction brake according to claim 1, including a thermally sensitive element arranged and adapted To perform a function selected from (a) reducing the hydraulic pressure and (b) causing reduction of the hydraulic pressure, acting on the retarding device during operation of the brake, when the hydraulic liquid attains a predetermined elevated temperature.
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) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |