Patent US3581498A successfully refreshed from Google Patents.
US3581498A
Expired / Lapsed
US
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Hydrostatic transmission
Assignee: Individual
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Filing: 1969-04-25
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Granted: 1971-06-01
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Expires: 1989-04-25
Abstract
Abstract A hydrostatic transmission for a machine tool. The transmission includes a pump driven by a prime mover, a motor for the machine tool driven by the pump, relief valves for ''''shorting out'''' exceedingly high pressures, and a bypass conduit extending between the high- and low-pressure sides of the system. A pilotoperated valve in the bypass conduit is adapted to be opened when the pump displacement is reduced to a predetermined low value to equalize the pressure on opposite sides of the motor and thereby cause the motor to stop.
Inventors
- 👤 Sylvester R Cudnohufsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:00
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/4043
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
158 words
In a hydrostatic transmission of the type including a pump and motor hydraulically coupled in a closed circuit with the pump outlet connected to the motor inlet to define the high-pressure side of the circuit and the motor outlet connected with the pump inlet to define the low-pressure side of the circuit, that improvement which comprises, a bypass conduit extending between and interconnecting the high- and low-pressure sides of said circuit, hydraulically actuated valve means in said bypass conduit for controlling the flow through said conduit, said valve means being pilot operated by the pressure on one side of the circuit, said valve means when closed preventing flow through said bypass conduit, and means for selectively directing pressure from said one side of the circuit to said valve means for opening said valve means to establish free communication between the high- and low-pressure sides of the circuit and thereby equalize the pressure on opposite sides of the motor.
Claim 2
Dependent Claim
158 words
In a hydrostatic transmission of the type including a pump and motor hydraulically coupled in a closed circuit with the pump outlet connected to the motor inlet to define the high-pressure side of the circuit and the motor outlet connected with the pump inlet to define the low-pressure side of the circuit, that improvement which comprises, a bypass conduit extending between and interconnecting the high- and low-pressure sides of said circuit, hydraulically actuated valve means in said bypass conduit for controlling the flow through said conduit, said valve means being pilot operated by the pressure on one side of the circuit, said valve means when closed preventing flow through said bypass conduit, and means for selectively directing pressure from said one side of the circuit to said valve means for opening said valve means to establish free communication between the high- and low-pressure sides of the circuit and thereby equalize the pressure on opposite sides of the motor.
Claim 3
Dependent Claim
23 words
A hydrostatic transmission as called for in claim 1 wherein said valve means is pilot operated from the low-pressure side of said circuit.
Claim 4
Dependent Claim
94 words
A hydrostatic transmission as called for in claim 1 wherein said pump is of the variable displacement type and includes adjustable means for varying the displacement thereof, said valve means normally preventing flow in said bypass conduit, said valve opening means comprising a second valve connecting said pilot-operated valve means for pilot operation by the pressure on the low-pressure side of the circuit, and means operatively connecting said second valve and said adjustable means for actuating said second valve in response to adjustment of the displacement of the pump to a predetermined low value.
Claim 5
Dependent Claim
49 words
A hydrostatic transmission as called for in claim 1 wherein said means for opening said valve means comprise a second valve adapted, when actuated, to connect the low-pressure side of the circuit with said pilot-operated valve means to thereby open the latter, and means for actuating the second valve.
Claim 6
Dependent Claim
67 words
A hydrostatic transmission as called for in claim 4 including means for varying the output of the pump, said means for actuating said second valve comprising means operatively connecting said output-varying means and said second valve to interconnect said pilot-operated valve means with the low-pressure side of the system when the output-varying means are actuated to reduce the output of the pump to a predetermined low value.
Claim 7
Dependent Claim
53 words
A hydrostatic transmission as called for in claim 1 wherein said valve-opening means comprises a conduit extending from said valve means to the low-pressure side of said circuit, and valve means in said last-mentioned conduit for permitting and blocking flow through said last-mentioned conduit to control the operation of the pilot-operated valve means.
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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |