US3588286A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control systems for hydraulic pumps
Assignee: ZF International UK Ltd
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Filing: 1969-06-20
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Granted: 1971-06-28
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Expires: 1989-06-20
Abstract
Abstract A CONTROL SYSTEM FOR AN HYDRAULIC POSITIVE DISPLACEMENTTYPE PUMP COMPRISING A PISTON IN A CYLINDER, THE PISTON BEING CONNECTED TO THE SWASHPLATE OF THE PUMP, A SPOOL IN A BORE IN THE PISTON AND PASSAGE MEANS WHEREBY FLUID CAN REACH OPPOSITE ENDS OF THE PISTON TO CAUSE IT TO MOVE TO CONTROL THE INCLINATION OF THE PUMP SWASHPLATE, THE POSITION OF THE SPOOL CONTROLLING THE FLOW THROUGH THE PASSAGES, AND A SPRING ACTING BETWEEN THE PISTON AND THE SPOOL AND MEANS INCLUDING SYSTEM OF ROLLERS AND SLOTS FOR VARYING THE FORCE EXERTED BY THE SPRING UPON THE SPOOL IN ACCORDANCE WITH THE POSITION OF THE PISTON IN THE CYLINDER.
Inventors
- 👤 Robert T J Skinner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:05
CPC Classifications
F; F04; F04B; F04B1/00; F04B1/12; F04B1/26; F04B1/30; F04B1/32; F04B1/324; F04B49/00; F04B49/08
Claims Analysis
Total Claims: 0
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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) | 1974-06-27 | 1974-12-27 | 1975-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-27 | 1978-12-27 | 1979-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-27 | 1982-12-27 | 1983-06-28 | $7700.00 | Window Closed / Lapsed |