Patent US3815631A successfully refreshed from Google Patents.
US3815631A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic control valve
Assignee: International Motors LLC
•
Filing: 1973-05-01
•
Granted: 1974-06-11
•
Expires: 1993-05-01
Abstract
Abstract A closed centre hydraulic control system for a track-laying vehicle comprises a pair of spool valves and a pair of variable relief valves. Each spool valve controls the supply of hydraulic fluid to the clutch and brake cylinders associated with a respective one of the tracks of the vehicle and is operable in three positions: a first position in which the brake is disengaged and the clutch is engaged, a second position in which the clutch is disengaged and the brake is disengaged, and a third position in which the clutch is disengaged and the brake is fully engaged. Movement of the spool valves from the second to the third positions is effective to increase progressively the pressure at which the relief valve relieves hydraulic fluid supplied to the associated brake cylinder, so that the brakes are progressively engaged during the movement of the spool valve from the second position to the third position.
Inventors
- 👤 D Shaw
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:56
CPC Classifications
B; B62; B62D; B62D11/00; B62D11/02; B62D11/06; B62D11/08; B60; B60T; B60T15/00; B60T15/02; B60T15/04; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/8667; Y10T137/86694; Y10T137/86702; Y10T137/87169; Y10T137/87233; Y10T137/87241
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
175 words
A control assembly for the steering system of a track-laying vehicle comprising a housing, a pair of spool valves and a pair of variable relief valves located within said housing, a supply port, an exhaust port and four outlet ports defined in said housing, two of said outlet ports being associated with each spool valve, each spool valve being reciprocable in said housing between a first position in which one of said associated outlet ports is connected to said supply port and said other associated outlet port is connected to said exhaust port, and second and third positions in both of which positions the said one outlet port is connected to the exhaust port, and the said other outlet port is connected with the supply port and, through one of said variable relief valves, with said exhaust port, movement of said spool valve from said second position to said third position being effective to increase the pressure at which said variable relief valve effects communication of the said other outlet port with said exhaust port.
Claim 2
Dependent Claim
175 words
A control assembly for the steering system of a track-laying vehicle comprising a housing, a pair of spool valves and a pair of variable relief valves located within said housing, a supply port, an exhaust port and four outlet ports defined in said housing, two of said outlet ports being associated with each spool valve, each spool valve being reciprocable in said housing between a first position in which one of said associated outlet ports is connected to said supply port and said other associated outlet port is connected to said exhaust port, and second and third positions in both of which positions the said one outlet port is connected to the exhaust port, and the said other outlet port is connected with the supply port and, through one of said variable relief valves, with said exhaust port, movement of said spool valve from said second position to said third position being effective to increase the pressure at which said variable relief valve effects communication of the said other outlet port with said exhaust port.
Claim 3
Dependent Claim
78 words
A control assembly according to claim 1 wherein each variable relief valve comprises a valve member, a valve seat defining an aperture through which the communication between the said other outlet port and the exhaust port is established, a compression spring biasing said valve member into said valve seat, the compression of the spring being increased by the spool valve associated with the relief valve during movement of the spool valve from the second to the third position.
Claim 4
Dependent Claim
39 words
A control assembly according to claim 1 including means defining a metering orifice, the supply port being placed in communication with the said other outlet port and, through the relief valve, with the exhaust port via said metering orifice.
Claim 5
Dependent Claim
32 words
A control assembly according to claim 1 wherein said housing defines a common return gallery through which said variable relief valves effect communication of the said other ports with said exhaust port.
References Cited (Backward Citations)
US3734129A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |