Patent US3712758A successfully refreshed from Google Patents.
US3712758A
Expired / Lapsed
US
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Variable displacement pump
Assignee: Navistar International Corp
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Filing: 1970-09-10
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Granted: 1973-01-23
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Expires: 1990-09-10
Abstract
Abstract A pump unit for providing fluid energy having a housing with movable piston unit therein, mechanical means for directing power input to said piston unit, with hydraulic control means for controlling the fluid output from said unit.
Inventors
- 👤 R Lech
- 👤 L Reinbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:00
CPC Classifications
F; F04; F04B; F04B49/00; F04B49/12; F04B49/121; F04B1/00; F04B1/12; F04B1/122; F04B1/124; F04B1/14
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
170 words
A variable displacement pump comprising: a housing having a plurality of cylindrical chambers arranged about an axis and connected to suction and discharge conduits; a cam means rotatable relative to said chambers about said axis; a primary piston having a counterbore reciprocally mounted in each of said chambers; a pumping piston reciprocally mounted in each of said chambers and having a rod extending toward said primary pistons; a head attached to said rod and reciprocally mounted within said counterbore; spring means interposed between said primary piston and said pumping piston for urging said pistons apart; means for introducing fluid to each of said chambers between said pistons; means for selectively controlling the pressure of said fluid; and each of said cylindrical chambers having an enlarged diameter portion and a reduced diameter portion; said primary piston sealingly engaging said enlarged diameter portion and said pumping piston sealingly engaging said reduced diameter pOrtion; whereby fluid pressure within said chamber between said pistons acts to hold said primary piston against said cam means.
Claim 2
Dependent Claim
170 words
A variable displacement pump comprising: a housing having a plurality of cylindrical chambers arranged about an axis and connected to suction and discharge conduits; a cam means rotatable relative to said chambers about said axis; a primary piston having a counterbore reciprocally mounted in each of said chambers; a pumping piston reciprocally mounted in each of said chambers and having a rod extending toward said primary pistons; a head attached to said rod and reciprocally mounted within said counterbore; spring means interposed between said primary piston and said pumping piston for urging said pistons apart; means for introducing fluid to each of said chambers between said pistons; means for selectively controlling the pressure of said fluid; and each of said cylindrical chambers having an enlarged diameter portion and a reduced diameter portion; said primary piston sealingly engaging said enlarged diameter portion and said pumping piston sealingly engaging said reduced diameter pOrtion; whereby fluid pressure within said chamber between said pistons acts to hold said primary piston against said cam means.
Claim 3
Dependent Claim
20 words
An apparatus according to claim 1, wherein retaining means carried by said primary piston retains said head within said counterbore.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |