US3650107A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power transmission
Assignee: Vickers Inc
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Filing: 1970-08-12
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Granted: 1972-03-21
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Expires: 1990-08-12
Abstract
Abstract A hydrostatic variable speed and reversible power transmission especially suited for driving mobile equipment has a variable displacement pump with a uni-directional delivery and a variable displacement and reversible hydraulic motor with a single highpressure delivery line. Coordinated control of the pump and the motor is obtained by a manual control lever shiftable in a Ushaped pattern to progressively increase the transmission speed ratio forwardly when moved up one leg of the U and reversely when moved up the other leg of the U. A followup servomotor controls the displacement of the driving motor, utilizing a feedback mechanism which is sensitive only to the magnitude of the motor displacement and not to its direction. A pilot valve responsive to shifting of the control handle from one leg to the other of the U reverses the action of the servovalve upon the displacement varying mechanism of the driving motor, and when in mid position serves as an anti-creep bypass.
Inventors
- 👤 Kenaeth Court
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:07
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/439; Y; Y10; Y10S; Y10S60/00; Y10S60/912
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
149 words
A hydrostatic variable speed and reversible power transmission comprising a uni-directionally driven variable displacement pump, means for controlling the pump to deliver fluid in a single direction only and at selectively variable rates, a single continuous high pressure delivery conduit extending from the pump, a motor of the reversible variable displacement type forming the terminus of the delivery conduit, a return fluid system connected to the motor outlet and to the pump inlet, and a combined displacement and direction control system for the pump and the motor including means for holding the pump at or near zero delivery and the motor at maximum delivery for transmission neutral, and operable to first increase the pump displacement and then reduce the motor displacement to increase the transmission output speed, and means for reversing the operation of the control means upon the motor without reversing the direction of flow through the motor.
Claim 2
Dependent Claim
149 words
A hydrostatic variable speed and reversible power transmission comprising a uni-directionally driven variable displacement pump, means for controlling the pump to deliver fluid in a single direction only and at selectively variable rates, a single continuous high pressure delivery conduit extending from the pump, a motor of the reversible variable displacement type forming the terminus of the delivery conduit, a return fluid system connected to the motor outlet and to the pump inlet, and a combined displacement and direction control system for the pump and the motor including means for holding the pump at or near zero delivery and the motor at maximum delivery for transmission neutral, and operable to first increase the pump displacement and then reduce the motor displacement to increase the transmission output speed, and means for reversing the operation of the control means upon the motor without reversing the direction of flow through the motor.
Claim 3
Dependent Claim
70 words
A transmission as defined in claim 1 wherein the control means includes a single crank, a first link between the crank and the pump, a second link extending, at a large angle from the first link, between the crank and the motor, lost motion connections in each link, and resilient means giving priority of output motion to the first link whenever the crank is moved away from the neutral position.
Claim 4
Dependent Claim
41 words
A transmission as defined in claim 1 wherein the control system includes a followup servomotor for the pump and a followup servomotor for the motor, each servomotor having a range of motion equivalent to shifting between zero and full displacement only.
Claim 5
Dependent Claim
25 words
A transmission as defined in claim 1 which includes a charging pump connected directly to the inlet of the first pump with no intervening valving.
Claim 6
Dependent Claim
26 words
A transmission as defined in claim 1 wherein the return fluid system includes a heat exchanger connected to carry the entire return flow from the motor.
Claim 7
Dependent Claim
26 words
A transmission as defined in claim 1 wherein the return fluid system includes a filter connected to carry the entire return fluid flow from the motor.
Claim 8
Dependent Claim
38 words
A transmission as defined in claim 1 wherein the control system utilizes fluid delivered by the pump to operate the motor control means, whereby the motor is shifted from neutral to full displacement before the motor is driven.
Claim 9
Dependent Claim
24 words
A transmission as defined in claim 1 wherein the control system includes a bypass for the charging pump when the control is in neutral.
Claim 10
Dependent Claim
32 words
A transmission as defined in claim 1 wherein the control system includes a bypass for fluid delivered by the pump at low displacement when the control is in neutral to prevent creep.
Claim 11
Dependent Claim
27 words
A transmission as defined in claim 1 wherein the control system includes a bypass for small reverse flows from the pump when the control is in neutral.
Claim 12
Dependent Claim
65 words
A transmission as defined in claim 1 which includes a single relief valve which opens out of the delivery conduit to the return system and is effective to carry excess fluid delivered by the pump when the motor is overloaded as well as to carry fluid delivered reversely by the motor when the control is suddenly reversed and the motor load continues forwardly under momentum.
Claim 13
Dependent Claim
42 words
A transmission as defined in claim 1 wherein the outlet from the motor includes a back pressure valve selectively responsive either to a substantially high motor outlet pressure for braking purposes or to a substantially low motor inlet pressure for coasting purposes.
Claim 14
Dependent Claim
48 words
A transmission as defined in claim 12 wherein the back pressure valve is spring closed and has a pair of pistons of different areas effective to open the valve, the small area being connected to the motor outlet and the large area being connected to the motor inlet.
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) | 1975-03-21 | 1975-09-20 | 1976-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-21 | 1979-09-20 | 1980-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-21 | 1983-09-20 | 1984-03-21 | $7700.00 | Window Closed / Lapsed |