US3918259A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Horsepower-limiting valve and linkage therefor
Assignee: Caterpillar Inc
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Filing: 1974-08-26
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Granted: 1975-11-11
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Expires: 1994-08-26
Abstract
Abstract A hydrostatic transmission having a variable displacement axial piston pump is provided with control means for controlling the displacement of the pump. The control means include servo-means having a manually operable valve means for normally establishing the displacement of the pump, and includes pressure-responsive actuator means operatively connected to the control means to override the manually selected position in response to pressure load in the system determined by the load imposed on the output of the hydraulic motor.
Inventors
- 👤 Cyril W Habiger
- 👤 Donald L Hopkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:55
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/42; F16H61/437; F16H61/478
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
130 words
In a hydrostatic transmission having a variable displacement axial piston pump in continuous open fluid communication with a rotary hydraulic motor, a control system comprising: a servo-actuator operatively connected for varying the Displacement of said variable displacement pump; a servo-valve for controlling said servo-actuator; manual control means for selectively positioning said servovalve; pressure-responsive actuator means responsive to the pressure output of said pump for overriding said manual control means for reducing the displacement of said variable displacement pump; and, lever means for pivotally interconnecting said servo-valve, said manual control means, and said pressure-responsive actuator wherein the pivotal connection of said lever to said pressureresponsive actuator means serves as movable fulcrum means for moving said lever in proportion to the pressure output of said pump for overriding said manual control means.
Claim 2
Dependent Claim
130 words
In a hydrostatic transmission having a variable displacement axial piston pump in continuous open fluid communication with a rotary hydraulic motor, a control system comprising: a servo-actuator operatively connected for varying the Displacement of said variable displacement pump; a servo-valve for controlling said servo-actuator; manual control means for selectively positioning said servovalve; pressure-responsive actuator means responsive to the pressure output of said pump for overriding said manual control means for reducing the displacement of said variable displacement pump; and, lever means for pivotally interconnecting said servo-valve, said manual control means, and said pressure-responsive actuator wherein the pivotal connection of said lever to said pressureresponsive actuator means serves as movable fulcrum means for moving said lever in proportion to the pressure output of said pump for overriding said manual control means.
Claim 3
Dependent Claim
42 words
The transmission of claim 1 wherein said control system comprises housing means defining a pair of parallel bores; said servo-actuator and said servo-valve are mounted in one of said bores and said pressure-responsive actuator is mounted in the other of said bores.
Claim 4
Dependent Claim
44 words
The transmission of claim 2 wherein said pressure-responsive actuator comprises double-acting piston means and means communicating the inlet of said pump to one side of said piston means and means communicating the outlet of said pump to the other side of said piston means.
Claim 5
Dependent Claim
24 words
The transmission of claim 3 wherein said pump is an over-center swash-plate type wherein reverse is achieved by swiveling the swash plate over center.
Claim 6
Dependent Claim
27 words
The transmission of claim 2 wherein said pressure-responsive actuator comprises single-acting piston means, and includes means for communicating the outlet of said pump to said piston means.
Claim 7
Dependent Claim
117 words
A hydraulic control system having a variable displacement axial piston pump, comprising: a servo-actuator operatively connected for varying the displacement of said variable displacement pump; a servo-valve for controlling said servo-actuator; manual control means for selectively positioning said servo-valve; pressure-responsive actuator means responsive to the pressure output of said pump for overriding said manual control means for reducing the displacement of said variable displacement pump; and, lever means pivotally interconnecting said servo-valve, said manual control means, and said pressure-responsive actuator means wherein the pivotal connection of said lever to said pressure-responsive actuator serves as movable fulcrum means, movable in response to the pressure output of said pump, for shifting said lever for overriding said manual control means.
Claim 8
Dependent Claim
117 words
A hydraulic control system having a variable displacement axial piston pump, comprising: a servo-actuator operatively connected for varying the displacement of said variable displacement pump; a servo-valve for controlling said servo-actuator; manual control means for selectively positioning said servo-valve; pressure-responsive actuator means responsive to the pressure output of said pump for overriding said manual control means for reducing the displacement of said variable displacement pump; and, lever means pivotally interconnecting said servo-valve, said manual control means, and said pressure-responsive actuator means wherein the pivotal connection of said lever to said pressure-responsive actuator serves as movable fulcrum means, movable in response to the pressure output of said pump, for shifting said lever for overriding said manual control means.
Claim 9
Dependent Claim
39 words
The control system of claim 6 including housing means defining a pair of parallel bores; said servo-actuator and said servo-valve are mounted in one of said bores and said pressure-responsive actuator is mounted in the other of said bores.
Claim 10
Dependent Claim
45 words
The control system of claim 7 wherein said pressure-responsive actuator comprises double-acting piston means and means communicating the inlet of said pump to one side of said piston means and means communicating the outlet of said pump to the other side of said piston means.
Claim 11
Dependent Claim
25 words
The control system of claim 8 wherein said pump is an over-center swash-plate type wherein reverse is achieved by swiveling the swash plate over center.
Claim 12
Dependent Claim
28 words
The control system of claim 7 wherein said pressure-responsive actuator comprises single-acting piston means, and includes means for communicating the outlet of said pump to said piston 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) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |