US3908374A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic drive arrangement
Assignee: Caterpillar Inc
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Filing: 1974-08-28
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Granted: 1975-09-30
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Expires: 1994-08-28
Abstract
Abstract A hydrostatic drive arrangement for a vehicle providing synchronized rotation of a pair of output drive shafts including a pair of transmissions each having a closed loop hydraulic system hydraulically interconnecting a variable displacement pump and a hydraulic motor, and a pressure responsive hydraulic synchronizing valve disposed between the hydraulic systems and normally open to permit restricted interflow of fluid between the hydraulic systems with the valve being responsive to fluid pressure in one of the hydraulic systems to block flow therethrough when the fluid pressure in the one hydraulic system exceeds a predetermined value.
Inventors
- 👤 Cyril W Habiger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:19
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/4078; F15; F15B; F15B11/00; F15B11/16; F15B11/22; F16H61/44; F16H61/456; Y; Y10; Y10T; Y10T137/00; Y10T137/2496; Y10T137/2559; Y10T137/2574; Y10T137/2605; Y10T137/2617
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
124 words
A hydrostatic drive arrangement for a vehicle providing synchronized rotation of a pair of output drive shafts, comprising; a pair of variable speed hydrostatic transmissions each of which has a positive displacement pump, a hydraulic motor, and a closed loop hydraulic system interconnecting said pump and said motor for communicating fluid therebetween; and hydraulic synchronizing means interconnected between said hydraulic systems of said transmissions normally permitting interflow of fluid between said hydraulic systems for synchronizing the output speeds of said transmission when the fluid pressure in said hydraulic systems is below a predetermined value, said synchronizing means being responsive to fluid pressures in said hydraulic systems to block interflow therebetween when the fluid pressure in one of said hydraulic systems exceeds said predetermined value.
Claim 2
Dependent Claim
124 words
A hydrostatic drive arrangement for a vehicle providing synchronized rotation of a pair of output drive shafts, comprising; a pair of variable speed hydrostatic transmissions each of which has a positive displacement pump, a hydraulic motor, and a closed loop hydraulic system interconnecting said pump and said motor for communicating fluid therebetween; and hydraulic synchronizing means interconnected between said hydraulic systems of said transmissions normally permitting interflow of fluid between said hydraulic systems for synchronizing the output speeds of said transmission when the fluid pressure in said hydraulic systems is below a predetermined value, said synchronizing means being responsive to fluid pressures in said hydraulic systems to block interflow therebetween when the fluid pressure in one of said hydraulic systems exceeds said predetermined value.
Claim 3
Dependent Claim
48 words
The hydrostatic drive arrangement of claim 1 wherein said synchronizing means includes a synchronizing valve having means providing a passage therethrough, a valve member operatively associated with said passage, and a spring resiliently urging saiD valve member to an open position permitting fluid flow through the synchronizing valve.
Claim 4
Dependent Claim
65 words
The hydrostatic drive arrangment of claim 2 wherein said synchronizing valve includes means providing an auxiliary flow path for transmitting fluid under pressure from said one hydraulic system to said valve member for moving it to a closed position against the bias of said spring for blocking fluid flow through said passage when the fluid pressure in said one hydraulic system exceeds said predetermined value.
Claim 5
Dependent Claim
32 words
The hydrostatic drive system of claim 3 wherein said passage means includes a bore formed in said valve and a pair of ports individually communicating said bore with said closed hydraulic systems.
Claim 6
Dependent Claim
44 words
The hydrostatic drive arrangement of claim 4 wherein said valve member is a valve spool slidably disposed in said bore and having an annular groove formed therein, said valve spool forming an actuating chamber in said bore in communication with said auxiliary flow path.
Claim 7
Dependent Claim
59 words
The hydrostatic drive arrangement of claim 5 wherein said auxiliary flow path communicates with both of said hydraulic systems, and includes shuttle check valve means responsive to fluid pressure in said one hydraulic system for communicating said one hydraulic system with said chamber and blocking fluid flow through said auxiliary flow path to the other of said hydraulic systems.
Claim 8
Dependent Claim
78 words
The hydrostatic drive arrangement of claim 6 wherein each of said closed hydraulic systems includes a pair of conduits individually interconnecting said pump and said motor, said pump being a variable displacement, overcenter reversible flow pump for selectively transmitting fluid through one of said conduits, and a shuttle check valve disposed between said conduits is parallel with said motor and responsive to fluid pressure in said one conduit for communicating said one conduit with said hydraulic synchronizing means.
References Cited (Backward Citations)
US2941609A
Cited
US3795109A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |