US3967532A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Forward-reverse valve for elevating scraper drive
Assignee: Caterpillar Inc
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Filing: 1974-01-07
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Granted: 1976-07-06
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Expires: 1994-01-07
Abstract
Abstract There is disclosed a valve assembly in combination with a hydraulic circuit to operate a motor in the circuit in a forward and reverse direction. The valve assembly includes check valve means for regulating fluid flow to the motor, pilot valve means for operating the check valve means responsive to pressures within the circuit, and relief valve means for relieving overpressure within the circuit. The combination is constructed and arranged so that the valve assembly substantially prevents cavitation of the motor, and is also operative to and isolate the motor from external loading.
Inventors
- 👤 Joseph Kokaly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 07:11
CPC Classifications
E; E02; E02F; E02F3/00; E02F3/04; E02F3/64; E02F3/65; E02F3/654; E02F3/655; F; F15; F15B; F15B13/00; F15B13/01; F15B13/02; F15B13/04; F15B13/0401; F15B13/0405; F16; F16H; F16H39/00; F16H39/02; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/87169; Y10T137/87233; Y10T137/87241
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
402 words
In a hydraulic system comprising a fluid flow circuit having a fluid supply source including a pump and a tank, a reversible hydraulic motor, conduit means for communicating between said source and said motor, inlet control valve means for directing fluid through said conduit means in a forward or reverse direction for operating said motor in a forward or reverse direction, and exhaust valve means for communicating return fluid from said motor to said tank, the improvement comprising: a valve housing having first and second bores therein, said valve housing being disposed in said circuit between said supply source and said motor so that forward fluid flow within said circuit is sequentially directed from said supply source, through said first bore, through said motor, and through said second bore to said tank, and so that reverse fluid flow within said circuit is sequentially directed from said fluid supply source, through said second bore, through said motor, through said first bore through said exhaust valve means and to said tank; first pilot operated check valve means disposed within said first bore for regulating forward fluid flow from said supply source to said motor, said first check valve means opening in response to accumulated fluid pressure when fluid is flowing in a forward direction to permit fluid flow from said fluid supply source, through said first bore, to said motor, and pilot means responsive to pressure in said second bore for opening said first check valve means when fluid is flowing in a reverse direction; and, second pilot operated check valve means disposed within said second bore for regulating return fluid flow between said motor and said tank, said second check valve means including pilot means for opening said valve in response to accumulated pressure within said first bore to permit fluid flow from said motor, through said second bore, to said tank, when fluid is being supplied in said forward direction, and said second check valve means being responsive to a drop in pressure in said conduit means between said second check valve means and said motor to provide direct flow of fluid from said tank to said motor, and including relief means responsive to an excess of pressure in said conduit means between said second check valve means and said source to open said second check valve means to relieve said excess pressure to said tank via said second check valve means.
Claim 2
Dependent Claim
402 words
In a hydraulic system comprising a fluid flow circuit having a fluid supply source including a pump and a tank, a reversible hydraulic motor, conduit means for communicating between said source and said motor, inlet control valve means for directing fluid through said conduit means in a forward or reverse direction for operating said motor in a forward or reverse direction, and exhaust valve means for communicating return fluid from said motor to said tank, the improvement comprising: a valve housing having first and second bores therein, said valve housing being disposed in said circuit between said supply source and said motor so that forward fluid flow within said circuit is sequentially directed from said supply source, through said first bore, through said motor, and through said second bore to said tank, and so that reverse fluid flow within said circuit is sequentially directed from said fluid supply source, through said second bore, through said motor, through said first bore through said exhaust valve means and to said tank; first pilot operated check valve means disposed within said first bore for regulating forward fluid flow from said supply source to said motor, said first check valve means opening in response to accumulated fluid pressure when fluid is flowing in a forward direction to permit fluid flow from said fluid supply source, through said first bore, to said motor, and pilot means responsive to pressure in said second bore for opening said first check valve means when fluid is flowing in a reverse direction; and, second pilot operated check valve means disposed within said second bore for regulating return fluid flow between said motor and said tank, said second check valve means including pilot means for opening said valve in response to accumulated pressure within said first bore to permit fluid flow from said motor, through said second bore, to said tank, when fluid is being supplied in said forward direction, and said second check valve means being responsive to a drop in pressure in said conduit means between said second check valve means and said motor to provide direct flow of fluid from said tank to said motor, and including relief means responsive to an excess of pressure in said conduit means between said second check valve means and said source to open said second check valve means to relieve said excess pressure to said tank via said second check valve means.
Claim 3
Dependent Claim
32 words
The invention of claim 1, wherein said first and second check valve means include reciprocable valve plungers for reciprocation within the respective bores in response to accumulated pressures within said conduit means.
Claim 4
Dependent Claim
29 words
The invention of claim 2, wherein said valve plungers include passage means for conducting fluid through said bores, said passage means comprising orifices communicating with each valve plunger chamber.
Claim 5
Dependent Claim
52 words
The invention of claim 3, wherein each of said pilot means include piston means, each of said piston means having a neck-down portion abutting one of said valve plungers so that movement of said piston means toward said valve plunger causes unseating of said valve plunger and opening said check valve means.
Claim 6
Dependent Claim
46 words
The invention of claim 4, wherein said relief means further includes a piston disposed against said piston means for said second check valve means, so that accumulated fluid overpressure in the conduit means shifts said piston toward said piston means thereby opening said pilot valve means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-07-06 | 1980-01-05 | 1980-07-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-06 | 1984-01-05 | 1984-07-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-06 | 1988-01-05 | 1988-07-06 | $7700.00 | Window Closed / Lapsed |