US4123907A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic system having selective simultaneous pressure and flow control
Assignee: Caterpillar Inc
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Filing: 1977-04-19
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Granted: 1978-11-07
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Expires: 1997-04-19
Abstract
Abstract A pressure control valve is connected to selectively supply a control pressure signal to shift a relief valve from a first low pressure mode to a second higher pressure mode and for simultaneously supplying the control pressure signal to an associated variable displacement pump for reducing the relatively high output of the pump to a relatively lower output.
Inventors
- 👤 Donald L. Bianchetta
- 👤 Allan L. Freedy
- 👤 Sammy J. Rhodes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:38
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/17; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/2053; F15B2211/20546; F15B2211/20553; F15B2211/20576; F15B2211/25; F15B2211/50; F15B2211/505; F15B2211/50509; F15B2211/50536; F15B2211/52; F15B2211/528; F15B2211/60; F15B2211/63; F15B2211/6303; F15B2211/633; F15B2211/65; F15B2211/67; F15B2211/70; F15B2211/71
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
119 words
A hydraulic control system, comprising: variable displacement pump means driven by an associated prime power source and operatively connected for pumping power fluid to an associated work system at a relatively high output; pressure relief valve means operable for permitting the system to operate up to a first maximum pressure mode and selectively at a second maximum allowable pressure mode higher than the first pressure mode; and pressure control valve means operably connected to selectively supply a control pressure signal to shift the relief valve means from the first mode to the second mode and for simultaneously supplying the control pressure signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output.
Claim 2
Dependent Claim
119 words
A hydraulic control system, comprising: variable displacement pump means driven by an associated prime power source and operatively connected for pumping power fluid to an associated work system at a relatively high output; pressure relief valve means operable for permitting the system to operate up to a first maximum pressure mode and selectively at a second maximum allowable pressure mode higher than the first pressure mode; and pressure control valve means operably connected to selectively supply a control pressure signal to shift the relief valve means from the first mode to the second mode and for simultaneously supplying the control pressure signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output.
Claim 3
Dependent Claim
135 words
The system of claim 1, further comprising: speed sensing circuit means operably connected for supplying a pressure signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output in response to a predetermined increase in pressure in the system; pressure sensing circuit means operably connected for supplying a pressure signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output in response to a predetermined increase in pressure in the system; and resolver means operably connected for selecting the highest of the pressure signals from the speed sensing circuit, the pressure sensing circuit and the pressure control valve means and supplying the selected signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output.
Claim 4
Dependent Claim
129 words
A hydraulic control system, comprising: a prime power source; a supply of power fluid; variable displacement pump means driven by the prime power source and operably connected for pumping the power fluid from the supply to an associated work system; pressure relief valve means operably connected for permitting the system to operate up to a first maximum pressure mode and selectively at a second maximum allowable pressure mode higher than the first pressure mode; pressure control valve means operably connected to selectively supply a control pressure signal to shift the relief valve means from the first mode to the second mode; and a conduit connected to supply the control pressure signal to the variable displacement pump means simultaneously with the control pressure signal supplied to the relief valve means.
Claim 5
Dependent Claim
129 words
A hydraulic control system, comprising: a prime power source; a supply of power fluid; variable displacement pump means driven by the prime power source and operably connected for pumping the power fluid from the supply to an associated work system; pressure relief valve means operably connected for permitting the system to operate up to a first maximum pressure mode and selectively at a second maximum allowable pressure mode higher than the first pressure mode; pressure control valve means operably connected to selectively supply a control pressure signal to shift the relief valve means from the first mode to the second mode; and a conduit connected to supply the control pressure signal to the variable displacement pump means simultaneously with the control pressure signal supplied to the relief valve means.
Claim 6
Dependent Claim
46 words
The system of claim 3, further comprising: speed sensing circuit means operably connected for supplying a pressure signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output in response to a predetermined increase in pressure in the system.
Claim 7
Dependent Claim
46 words
The system of claim 4, further comprising: pressure sensing circuit means operably connected for supplying a pressure signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output in response to a predetermined increase in pressure in the system.
Claim 8
Dependent Claim
56 words
The system of claim 5, further comprising: resolver means operably connected for selecting the higher of the pressure signals from the speed sensing circuit, the pressure sensing circuit and the pressure control valve means and supplying the selected signal to the variable displacement pump means for reducing the relatively high output to a relatively lower output.
References Cited (Backward Citations)
US3922855A
Cited
US3841795A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-11-06 | 1982-05-08 | 1982-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-06 | 1986-05-08 | 1986-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-06 | 1990-05-08 | 1990-11-07 | $7700.00 | Window Closed / Lapsed |