Patent US6647684B1 successfully refreshed from Google Patents.
US3669147A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power transmission
Assignee: Vickers Inc
•
Filing: 1971-02-18
•
Granted: 1972-06-13
•
Expires: 1991-02-18
Abstract
Abstract A power assisted directional control valve for hydraulic power systems has a sliding spool actuated by a differential piston. A follow-up valve is telescoped within the spool and controls the admission and release of pilot pressure fluid to and from the large side of the actuating piston. To enable the main spool to be shifted in the event of failure of the pilot pressure supply, an auxiliary pilot valve is opened upon overtravel of the normal pilot valve and admits pressure fluid trapped by the main spool to both sides of the actuating piston.
Inventors
- 👤 Robert G Farrell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:00
CPC Classifications
F; F15; F15B; F15B20/00; F15B20/004; F15B13/00; F15B13/02; F15B13/04; F15B13/042; F15B13/043; F15B13/0435; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
136 words
A remotely controlled directional valve comprising a main body, a main spool slidable in the body, porting in the body and grooving on the spool to direct fluid flow forwardly and reversely and to terminate flow to and from a work device, a centering spring for the main spool, means forming an actuating piston for the main spool and having large and small effective areas on its opposing faces, a follow-up pilot valve for admitting and releasing pressure fluid to and from the large side of the actuating piston, and an auxiliary pilot valve normally inoperative and responsive to overtravel of the follow-up pilot valve for admitting pressure fluid trapped by the main valve to the actuating piston, in the event of failure of the main spool to shift when the follow-up pilot valve is shifted.
Claim 2
Dependent Claim
136 words
A remotely controlled directional valve comprising a main body, a main spool slidable in the body, porting in the body and grooving on the spool to direct fluid flow forwardly and reversely and to terminate flow to and from a work device, a centering spring for the main spool, means forming an actuating piston for the main spool and having large and small effective areas on its opposing faces, a follow-up pilot valve for admitting and releasing pressure fluid to and from the large side of the actuating piston, and an auxiliary pilot valve normally inoperative and responsive to overtravel of the follow-up pilot valve for admitting pressure fluid trapped by the main valve to the actuating piston, in the event of failure of the main spool to shift when the follow-up pilot valve is shifted.
Claim 3
Dependent Claim
23 words
A valve as defined in claim 1 wherein the auxiliary pilot valve includes a check valve opening to flow toward the actuating piston.
Claim 4
Dependent Claim
24 words
A valve as defined in claim 1 wherein the auxiliary pilot valve is within the main spool and coaxial with the follow-up pilot valve.
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) | 1975-06-13 | 1975-12-13 | 1976-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-13 | 1979-12-13 | 1980-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-13 | 1983-12-13 | 1984-06-13 | $7700.00 | Window Closed / Lapsed |