US3576104A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for hydraulic motors
Assignee: Caterpillar Inc
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Filing: 1969-09-29
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Granted: 1971-04-27
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Expires: 1989-09-29
Abstract
Abstract A hydraulic control system for selectively operating a hydraulic motor in at least two operating speeds. The system including first and second pumps and a pilot valve having a fluid passage in communication with the first pump and the motor. First restrictive valve means provide restricted flow from the fluid passage to a first pilot flow passage and selectively communicate the fluid passage with a drain passage. Second restrictive valve means provide restricted flow from the second pump into a second pilot flow passage and selectively communicate the second pump with the fluid passage in the pilot valve and with the drain passage. The restrictive valve means are responsive to a main control valve effective to selectively communicate the first and second pilot flow passages to drain, thus providing for variable speed operation of the motor.
Inventors
- 👤 Joseph Kokaly
- 👤 Lawrence F Schexnayder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:17
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/17; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/44; F16H61/444
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
199 words
A hydraulic control system for selectively driving a hydraulic motor in at least two operating speeds, comprising: a first source of fluid under pressure having its outlet in communication with the motor, a pilot valve having a fluid passage in communication with the motor and the first pump outlet, first means for restrictively communicating the fluid passage with a first pilot flow passage and for selectively communicating the fluid passage with a drain passage, a second source of fluid under pressure, second means for restrictively communicating outlet fluid from the second source with a second pilot flow passage and for selectively communicating the second source outlet with the drain passage and fluid passage in the pilot valve, and a main control valve operable for selectively communicating the first and second pilot flow passages to drain, the first restrictive means being responsive to operation of the pilot valve for communicating at least a substantial portion of fluid flow in the fluid passage to the drain passage, the second restrictive means being responsive to operation of the control valve for alternatively communicating at least a substantial portion of outlet fluid from the second source to the fluid passage and to drain.
Claim 2
Dependent Claim
199 words
A hydraulic control system for selectively driving a hydraulic motor in at least two operating speeds, comprising: a first source of fluid under pressure having its outlet in communication with the motor, a pilot valve having a fluid passage in communication with the motor and the first pump outlet, first means for restrictively communicating the fluid passage with a first pilot flow passage and for selectively communicating the fluid passage with a drain passage, a second source of fluid under pressure, second means for restrictively communicating outlet fluid from the second source with a second pilot flow passage and for selectively communicating the second source outlet with the drain passage and fluid passage in the pilot valve, and a main control valve operable for selectively communicating the first and second pilot flow passages to drain, the first restrictive means being responsive to operation of the pilot valve for communicating at least a substantial portion of fluid flow in the fluid passage to the drain passage, the second restrictive means being responsive to operation of the control valve for alternatively communicating at least a substantial portion of outlet fluid from the second source to the fluid passage and to drain.
Claim 3
Dependent Claim
88 words
The invention of claim 1 wherein the first restrictive means comprises a spring loaded piston defining a restrictive orifice communicating the fluid passage with the first pilot flow passage and means for selectively communicating the fluid passage with the drain passage, the second restrictive means including a spring loaded piston defining a restrictive orifice for communicating outlet fluid from the second source with the second pilot flow passage and means for selectively communicating outlet fluid from the second source with the fluid passage and the drain passage respectively.
Claim 4
Dependent Claim
54 words
The invention of claim 2 wherein the main control valve is operable into a neutral position wherein both of the pilot flow passages are in communication with drain, a low-speed operating position wherein the first pilot flow passage is blocked and a high-speed operating position wherein both pilot flow passages are blocked from drain.
Claim 5
Dependent Claim
24 words
The invention of claim 3 further comprising relief vaLve means in effective communication with the fluid passage to relieve excessive hydraulic fluid pressure therein.
Claim 6
Dependent Claim
54 words
The invention of claim 1 wherein the main control valve is operable into a neutral position wherein both of the pilot flow passages are in communication with drain, a low-speed operating position wherein the first pilot flow passage is blocked and a high-speed operating position wherein both pilot flow passages are blocked from drain.
Claim 7
Dependent Claim
24 words
The invention of claim 5 further comprising relief valve means in effective communication with the fluid passage to relieve excessive hydraulic fluid pressures therein.
Claim 8
Dependent Claim
41 words
The invention of claim 1 further comprising a common drain reservoir for the two fluid sources and the motor, a single conduit communicating the fluid passage with the motor and a separate single conduit communicating the motor with the drain reservoir.
Claim 9
Dependent Claim
54 words
The invention of claim 7 wherein the main control valve is operable into a neutral position wherein both of the pilot flow passages are in communication with drain, a low-speed operating position wherein the first pilot flow passage is blocked and a high-speed operating position wherein both pilot flow passages are blocked from drain.
Claim 10
Dependent Claim
39 words
The invention of claim 8 further comprising an additional inlet conduit in communication with the conduit from the fluid passage to the motor for introducing additional fluid under pressure and providing for additional variation in operation of the motor.
Claim 11
Dependent Claim
35 words
The invention of claim 1 further comprising an additional inlet conduit in effective communication with the fluid passage for selectively introducing additional fluid under pressure and providing for additional variation in operation of the motor.
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) | 1974-04-26 | 1974-10-26 | 1975-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-26 | 1978-10-26 | 1979-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-26 | 1982-10-26 | 1983-04-27 | $7700.00 | Window Closed / Lapsed |