US3800535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic transmission control system
Assignee: Eaton Corp
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Filing: 1973-02-07
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Granted: 1974-04-02
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Expires: 1993-02-07
Abstract
Abstract An improved hydrostatic transmission control system includes a speed control valve which facilitates inching or creep control by effecting a relatively small change in the output speed of a hydrostatic transmission with each increment of movement of a control rod or member during low speed operation of a vehicle. During high speed operation of the vehicle, each increment of movement of the control rod results in a relatively large change in the output speed of the hydrostatic transmission. To obtain the different changes in hydrostatic transmission output speed with equal increments of movement of the control rod, the speed control valve includes a valve spool which is biased against movement relative to the control rod by springs having different spring rates or stiffnesses. During low speed operation of the vehicle, incremental movement of the control rod relative to the valve spool compresses a relatively weak spring to provide a small increase in the biasing force applied against the valve spool. However, during high speed operation of the vehicle, incremental movement of the control rod relative to the valve spool compresses only a relatively strong spring to provide a relatively large increase in the biasing force applied against the valve spool.
Inventors
- 👤 H Ward
- 👤 E Hicks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:35
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; B; B62; B62D; B62D11/00; B62D11/02; B62D11/06; B62D11/10; B62D11/14; B62D11/18; B62D11/183; F16H61/438
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
140 words
An apparatus for controlling the operation of a hydrostatic transmission, said apparatus comprising actuator means for varying the output speed of the hydrostatic transmission in response to a variation in control fluid pressure, and control means for regulating the control fluid pressure conducted to said actuator means, said control means including a movable control member and valve means for effecting a relatively small change in the control fluid pressure conducted to said actuator means in response to movement of said control member through a first distance when the hydrostatic transmission has a relatively low output speed and for effecting a relatively large change in the control fluid pressure conducted to said actuator means in response to movement of said control member through a second distance equal to said first distance when the hydrostatic transmission has a relatively high output speed.
Claim 2
Independent Claim
140 words
An apparatus for controlling the operation of a hydrostatic transmission, said apparatus comprising actuator means for varying the output speed of the hydrostatic transmission in response to a variation in control fluid pressure, and control means for regulating the control fluid pressure conducted to said actuator means, said control means including a movable control member and valve means for effecting a relatively small change in the control fluid pressure conducted to said actuator means in response to movement of said control member through a first distance when the hydrostatic transmission has a relatively low output speed and for effecting a relatively large change in the control fluid pressure conducted to said actuator means in response to movement of said control member through a second distance equal to said first distance when the hydrostatic transmission has a relatively high output speed.
Claim 3
Dependent Claim
32 words
An apparatus as set forth in claim 1 wherein said valve means includes a first biasing spring having a first spring rate and a second biasing spring having a second spring rate.
Claim 4
Dependent Claim
106 words
An apparatus as set forth in claim 1 wherein said valve means includes a valve member which is movable relative to said control member, means for exposing said valve member to a feedback force which varies as a function of variations in control fluid pressure transmitted to said actuator means, and spring means for applying to said valve member a biasing force which varies by a first amount in response to movement of said control member through said first distance and which varies by a second amount which is greater than said first amount in response to movement of said control member through said second distance.
Claim 5
Dependent Claim
60 words
An apparatus as set forth in claim 1 wherein said valve means includes a valve member slidably disposed on said control member, and first and second spring means for resisting movement of said valve member relative to said control member, said first spring means having a spring rate which is different than the spring rate of said second spring means.
Claim 6
Independent Claim
181 words
An apparatus for controlling the operation of a hydrostatic transmission, said apparatus comprising actuator means for varying the output speed of the hydrostatic transmission in response to a variation in control fluid pressure, and control means for regulating the control fluid pressure conducted to said actuator means, said control means including a control member, valve means connected with and movable relative to said control member between actuated and unactuated conditions to vary the control fluid pressure conducted to said actuator means, biasing means for effecting operation of said valve means from the unactuated condition to the actuated condition to increase the control fluid pressure conducted to said actuator means in response to movement of said control member, and feedback means for effecting operation of said valve means from the actuated condition to the unactuated condition against the influence of said biasing means in response to an increase in the control fluid pressure, said biasing means including first spring means having a first spring rate and second spRing means having a second spring rate which is greater than said first spring rate.
Claim 7
Independent Claim
181 words
An apparatus for controlling the operation of a hydrostatic transmission, said apparatus comprising actuator means for varying the output speed of the hydrostatic transmission in response to a variation in control fluid pressure, and control means for regulating the control fluid pressure conducted to said actuator means, said control means including a control member, valve means connected with and movable relative to said control member between actuated and unactuated conditions to vary the control fluid pressure conducted to said actuator means, biasing means for effecting operation of said valve means from the unactuated condition to the actuated condition to increase the control fluid pressure conducted to said actuator means in response to movement of said control member, and feedback means for effecting operation of said valve means from the actuated condition to the unactuated condition against the influence of said biasing means in response to an increase in the control fluid pressure, said biasing means including first spring means having a first spring rate and second spRing means having a second spring rate which is greater than said first spring rate.
Claim 8
Dependent Claim
25 words
An apparatus as set forth in claim 5 wherein said first and second spring means are disposed in a coaxial relationship with said control member.
Claim 9
Independent Claim
296 words
An apparatus for controlling the operation of a hydrostatic transmission, said apparatus comprising means for providing control fluid, actuator means for varying the input to output speed ratio of the hydrostatic transmission in response to variations in control fluid pressure to which said actuator means is exposed, and pressure controller means operable to any one of a plurality of settings to vary the control fluid pressure to which said motor means is exposed in accordance with variations in the setting of said pressure controller means, said pressure controller means including valve means for varying the control fluid pressure to which said motor means is exposed, said valve means being operable between an actuated condition varying the control fluid pressure to which said actuator means is exposed and an unactuated condition in which the control fluid pressure to which said actuator means is exposed is maintained substantially constant, manually adjustable control means selectively movable between a plurality of settings for effecting operation of said valve means between the actuated and unactuated conditions to adjust the control fluid pressure to which said motor means is exposed in response to a change in the setting of said manually adjustable control means, fluid pressure feedback means for urging operation of said valve means from the actuated condition to the unactuated condition under the influence of a fluid pressure force which varies as a function of variations in the control fluid pressure to which said actuator means is exposed, and biasing means for urging said valve means against operation to the actuated condition with a second force which varies in response to variations in the setting of said control means, said biasing means including spring means having one of two different spring rates depending upon the setting of said control means.
Claim 10
Independent Claim
296 words
An apparatus for controlling the operation of a hydrostatic transmission, said apparatus comprising means for providing control fluid, actuator means for varying the input to output speed ratio of the hydrostatic transmission in response to variations in control fluid pressure to which said actuator means is exposed, and pressure controller means operable to any one of a plurality of settings to vary the control fluid pressure to which said motor means is exposed in accordance with variations in the setting of said pressure controller means, said pressure controller means including valve means for varying the control fluid pressure to which said motor means is exposed, said valve means being operable between an actuated condition varying the control fluid pressure to which said actuator means is exposed and an unactuated condition in which the control fluid pressure to which said actuator means is exposed is maintained substantially constant, manually adjustable control means selectively movable between a plurality of settings for effecting operation of said valve means between the actuated and unactuated conditions to adjust the control fluid pressure to which said motor means is exposed in response to a change in the setting of said manually adjustable control means, fluid pressure feedback means for urging operation of said valve means from the actuated condition to the unactuated condition under the influence of a fluid pressure force which varies as a function of variations in the control fluid pressure to which said actuator means is exposed, and biasing means for urging said valve means against operation to the actuated condition with a second force which varies in response to variations in the setting of said control means, said biasing means including spring means having one of two different spring rates depending upon the setting of said control 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) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |