US3604313A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic power circuit with rapid lowering provisions
Assignee: SPX Technologies Inc
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Filing: 1970-05-14
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Granted: 1971-09-14
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Expires: 1990-05-14
Abstract
Abstract A hydraulic power circuit especially useful as a lift circuit for front-end loaders and including a bypass valve separate from the directional control valve which is adapted to interconnect the contracting and expanding ends of the actuating cylinders and permit rapid lowering of the implement. The circuit is characterized by an actuating scheme for the bypass valve which opens that valve only when the directional control valve is shifted to float position and the load pressure in the contracting ends of the cylinders is below a preselected value. The directional control valve may be shifted by pilot pressures, and in this case the motive force for opening the bypass valve may be developed by the pressure in the pilot circuit.
Inventors
- 👤 Waldo G Fruehauf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:11
CPC Classifications
E; E02; E02F; E02F9/00; E02F9/20; E02F9/22; E02F9/2203; F; F15; F15B; F15B11/00; F15B11/02; F15B11/024; F15B13/00; F15B13/02; F15B13/021; F15B2011/0243; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/20507; F15B2211/20523; F15B2211/20576; F15B2211/30; F15B2211/305; F15B2211/3052; F15B2211/30525; F15B2211/3056; F15B2211/30565; F15B2211/3058; F15B2211/31; F15B2211/3105; F15B2211/3116; F15B2211/3122; F15B2211/3127; F15B2211/315; F15B2211/3157; F15B2211/31588; F15B2211/32; F15B2211/329; F15B2211/60; F15B2211/635; F15B2211/6355; F15B2211/70; F15B2211/71; F15B2211/7107; F15B2211/75; F15B2211/80; F15B2211/86; F15B2211/8609
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
140 words
In a hydraulic system including a double-acting cylinder (12 or 13) having opposed ends 12a, 12b or 13a, 13b) and arranged to actuate a load (11) which tends to contract the first (12a or 13a) of said ends, directional control valve means (16, 33) for controlling flow to and from said ends and having a float condition in which it establishes a regeneration path between the cylinder ends, and a separate bypass valve (17 or 17'') arranged to open and close a second regeneration path between the cylinder ends, the improvement which comprises actuating means (58, 59, 61-63 or 58'', 59'', 61''-63'', 64) for opening the bypass valve (17 or 17'') only when the pressure in the first cylinder end (12a or 13a) is below a predetermined level and the directional control valve means (16, 33) is in float condition.
Claim 2
Dependent Claim
140 words
In a hydraulic system including a double-acting cylinder (12 or 13) having opposed ends 12a, 12b or 13a, 13b) and arranged to actuate a load (11) which tends to contract the first (12a or 13a) of said ends, directional control valve means (16, 33) for controlling flow to and from said ends and having a float condition in which it establishes a regeneration path between the cylinder ends, and a separate bypass valve (17 or 17'') arranged to open and close a second regeneration path between the cylinder ends, the improvement which comprises actuating means (58, 59, 61-63 or 58'', 59'', 61''-63'', 64) for opening the bypass valve (17 or 17'') only when the pressure in the first cylinder end (12a or 13a) is below a predetermined level and the directional control valve means (16, 33) is in float condition.
Claim 3
Dependent Claim
104 words
The improved hydraulic system defined in claim 1 in which the actuating means includes a. means (58) biasing the bypass valve (17) in the closing direction; b. a pressure motor (59) for shifting the bypass valve in the opening direction; and c. means (61-63) effective when the pressure in said first cylinder end (12a or 13a) is below said predetermined level and the directional control valve means is in float condition to subject said pressure motor (59) to a pressure sufficient to enable it to overcome the biasing means, and effective at all other times to subject said pressure motor to a lower pressure.
Claim 4
Dependent Claim
49 words
shuttle valve means (61-63) responsive to the pressure in the first cylinder end (12a or 13a) for subjecting the second fluid pressure motor to said pilot pressure when the cylinder pressure is below said predetermined level, and, when cylinder pressure is above said level, for venting the second motor.
Claim 5
Dependent Claim
49 words
shuttle valve means (61-63) responsive to the pressure in the first cylinder end (12a or 13a) for subjecting the second fluid pressure motor to said pilot pressure when the cylinder pressure is below said predetermined level, and, when cylinder pressure is above said level, for venting the second motor.
Claim 6
Dependent Claim
20 words
a third fluid pressure motor (64) effective when pressurized to a certain level to maintain the bypass valve closed, and
Claim 7
Dependent Claim
20 words
a third fluid pressure motor (64) effective when pressurized to a certain level to maintain the bypass valve closed, and
Claim 8
Dependent Claim
54 words
valve means (61''-63'') responsive to the pressure in said first cylinder end (12a or 13a) for venting the third fluid pressure motor or pressurizing same to said certain level with fluid from said first cylinder end depending upon whether the pressure in the first cylinder end is below or above, respectively, said predetermined level.
Claim 9
Dependent Claim
54 words
valve means (61''-63'') responsive to the pressure in said first cylinder end (12a or 13a) for venting the third fluid pressure motor or pressurizing same to said certain level with fluid from said first cylinder end depending upon whether the pressure in the first cylinder end is below or above, respectively, said predetermined level.
Claim 10
Dependent Claim
81 words
The improved hydraulic system defined in claim 1 in which a. the directional control valve means includes a directional control valve m (16) having a float position in which it establishes said regeneration path, piloting means (14, 15, 33) for producing a variable pilot pressure, and a first fluid pressure motor (28) which responds to the pilot pressure and shifts the directional control valve to float position when the pilot pressure has a predetermined magnitude; and b. the actuating means includes
Claim 11
Dependent Claim
109 words
The improved hydraulic system defined in claim 1 in which the actuating means includes a. a first pressure motor (59'') for moving the bypass valve (17'') in the opening direction; b. means (14, 33) for supplying fluid under pressure to the first motor; c. a second pressure motor (64) for moving the bypass valve in the closing direction; and d. means, including a valve (61'') which responds to the pressure in said first cylinder end (12a or 13a), for subjecting the second motor (64) to a pressure sufficient to enable it to hold the bypass valve closed when the pressure in said cylinder end is above said predetermined level.
Claim 12
Dependent Claim
80 words
The improved hydraulic system defined in claim 1 in which a. the directional control valve means includes a directional control valve (16) having a float position in which it establishes said regeneration path, piloting means (14, 15, 33) for producing a variable pilot pressure, and a first fluid pressure motor (28) which responds to the pilot pressure and shifts the directional control valve to float position when the pilot pressure has a predetermined magnitude; and b. the actuating means includes
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) | 1974-09-13 | 1975-03-15 | 1975-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-13 | 1979-03-15 | 1979-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-13 | 1983-03-15 | 1983-09-14 | $7700.00 | Window Closed / Lapsed |