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US3727628A
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Underspeed valve hydrostatic control system
Assignee: Caterpillar Inc
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Filing: 1970-08-31
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Granted: 1973-04-17
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Expires: 1990-08-31
Abstract
Abstract A hydrostatic control system including an underspeed valve which may be used to control the displacement of hydraulic pumps and motors by differential pressure generating means. The underspeed valve has a valve spool which is actuated by a pressure proportional to engine speed, a pressure responsive to a demand speed, and a preset spring biasing pressure.
Inventors
- 👤 C Habiger
- 👤 D Hopkins
- 👤 G Johnson
- 👤 F Winters
- 👤 W Norick
- 👤 Zandt R Van
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:54
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/465; F15; F15B; F15B11/00; F15B11/02; F15B11/04; F15B11/05; Y; Y10; Y10T; Y10T137/00; Y10T137/2496; Y10T137/2514; Y10T137/2521; Y10T137/2524; Y10T137/2559; Y10T137/2574; Y10T137/2579; Y10T137/2587
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
314 words
A valve comprising a body, a spool located within a bore in the body, means biasing said spool to a first position against one end of the body, at least one fluid inlet in said body communicating the exterior of said body with said spool, at least one fluid outlet communicating the exterior of said body with said spool at a point on said spool removed from the point of communication of said at least one fluid inlet, a first chamber located entirely within the other end of said spool, means communicating said first chamber with said at least one fluid inlet, a first piston reaction means in said first chamber for causing said spool to be motivated toward the one end of said body, a second chamber located entirely within the one end of said spool for selective communication with said at least one fluid inlet, a second piston reaction means in said second chamber for causing said spool to be motivated toward the other end of said body, means on said spool closing off communication between said at least one fluid inlet and said at least one fluid outlet when said spool is in said first position as well as in a second position against said other end of said body, said means on said spool intercommunicating said at least one fluid inlet with said at least one fluid outlet when said spool is in a position intermediate said first and second positions, a second fluid inlet in said one end of said body and in communication with said one end of said valve spool to motivate said valve spool toward said other end of said body, and a third fluid inlet in said other end of said body and in communication with said other end of said valve spool to motivate said valve spool toward said one end of said body.
Claim 2
Dependent Claim
314 words
A valve comprising a body, a spool located within a bore in the body, means biasing said spool to a first position against one end of the body, at least one fluid inlet in said body communicating the exterior of said body with said spool, at least one fluid outlet communicating the exterior of said body with said spool at a point on said spool removed from the point of communication of said at least one fluid inlet, a first chamber located entirely within the other end of said spool, means communicating said first chamber with said at least one fluid inlet, a first piston reaction means in said first chamber for causing said spool to be motivated toward the one end of said body, a second chamber located entirely within the one end of said spool for selective communication with said at least one fluid inlet, a second piston reaction means in said second chamber for causing said spool to be motivated toward the other end of said body, means on said spool closing off communication between said at least one fluid inlet and said at least one fluid outlet when said spool is in said first position as well as in a second position against said other end of said body, said means on said spool intercommunicating said at least one fluid inlet with said at least one fluid outlet when said spool is in a position intermediate said first and second positions, a second fluid inlet in said one end of said body and in communication with said one end of said valve spool to motivate said valve spool toward said other end of said body, and a third fluid inlet in said other end of said body and in communication with said other end of said valve spool to motivate said valve spool toward said one end of said body.
Claim 3
Dependent Claim
63 words
The invention of claim 1 further including means for generating a first fluid pressure, means for generating a pressure differential from said first fluid pressure so as to produce a second fluid pressure, means communicating said first fluid pressure with said second fluid inlet, and means communicating said second fluid pressure with said at least one fluid inlet and said third fluid inlet.
Claim 4
Dependent Claim
14 words
The invention of claim 2 wherein said pressure differential generating means comprises an orifice.
Claim 5
Dependent Claim
69 words
The invention of claim 1 further including means generating a first fluid pressure, means for generating a pressure differential from said first fluid pressure so as to produce second and third fluid pressUres, means communicating said first fluid pressure with said second fluid inlet, means communicating said second fluid pressure with said at least one fluid inlet, and means communicating said third fluid pressure with said third fluid inlet.
Claim 6
Dependent Claim
66 words
The invention of claim 4 wherein said at least one fluid inlet comprises fourth and fifth fluid inlets positioned so as to motivate said spool in opposite directions, means communicating said second fluid pressure with said fourth fluid inlet, and speed control valve means for variably intercommunicating said fourth and fifth inlets so as to provide a variable pressure differential between said fourth and fifth inlets.
Claim 7
Dependent Claim
15 words
The invention of claim 4 wherein said means generating a pressure differential comprises a venturi.
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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) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |