US3764111A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Free fall circuit for hydraulic winch
Assignee: NORTHWEST ENGINEERING Co A CORP OF
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Filing: 1971-10-26
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Granted: 1973-10-09
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Expires: 1991-10-26
Abstract
Abstract A free fall operating circuit for a hydraulic winch of the type including a hydraulically releasable free fall clutch includes a pump normally operable to release the clutch and a sensing valve operable to cut off the pump and allow the clutch to reset whenever there is relatively higher pressure in either main operating line for the winch motor, the net result being that there is free fall action whenever the main valve operating lever is in neutral. The circuit includes a lockout valve, and this is interlocked with the machine start circuit to prevent starting while the clutch is released. A safety valve and circuit prevent resetting of the clutch while the winch drum is in free fall motion.
Inventors
- 👤 R Dummer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:32
CPC Classifications
B; B66; B66D; B66D1/00; B66D1/02; B66D1/08; B66D2700/00; B66D2700/01; B66D2700/0125; B66D2700/0133; Y; Y10; Y10S; Y10S60/00; Y10S60/905
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
185 words
In a free fall actuating circuit for a hydraulic winch of the type including a reversible hydraulic motor, a pair of opposite main fluid lines connected to the motor, control valve means in the main fluid lines movable between a first position in which there is relatively higher pressure in one main fluid line and a sEcond position in which there is relatively higher pressure in the other main fluid line and a neutral position in which the pressures in the main fluid lines are substantially equal, a rotatable drum driven by the motor, and a normally set, hydraulically releasable free fall clutch operatively associated with the drum, the combination comprising: hydraulic release means operative to release the clutch only when the control valve means is in neutral position; and hydraulically operable sensing means interposed between the main fluid lines and release means and automatically operable to deactivate the which means to allow the clutch to operatively engage the drum in response to relatively higher pressure in either main fluid line caused by shifting of the control valve means to either first or second position.
Claim 2
Dependent Claim
185 words
In a free fall actuating circuit for a hydraulic winch of the type including a reversible hydraulic motor, a pair of opposite main fluid lines connected to the motor, control valve means in the main fluid lines movable between a first position in which there is relatively higher pressure in one main fluid line and a sEcond position in which there is relatively higher pressure in the other main fluid line and a neutral position in which the pressures in the main fluid lines are substantially equal, a rotatable drum driven by the motor, and a normally set, hydraulically releasable free fall clutch operatively associated with the drum, the combination comprising: hydraulic release means operative to release the clutch only when the control valve means is in neutral position; and hydraulically operable sensing means interposed between the main fluid lines and release means and automatically operable to deactivate the which means to allow the clutch to operatively engage the drum in response to relatively higher pressure in either main fluid line caused by shifting of the control valve means to either first or second position.
Claim 3
Dependent Claim
134 words
The combination of claim 1 wherein: there is a safety means associated with the sensing means, said safety means having a normal open position in which the sensing means is operable and being movable to a closed position in which the sensing means is inoperable; and there is a safety circuit that is operable when completed to move the safety means from open to closed position, said safety circuit including a first element which is operatively associated with the drum and which is operable to complete the safety circuit only when the drum is rotating at or above a selected minimum speed, and a second element in series with the first element which is operatively associated with the clutch and which is operable to complete the safety circuit only when the clutch is released.
Claim 4
Dependent Claim
82 words
The combination of claim 1 wherein the elements thereof are incorporated in an appartus having a start circuit and wherein: there is a lockout means associated with the release means that is movable between an ''''on'''' position in which the release means is operative and an ''''off'''' position in which the release means is not operative; and there is a switch means associated with the lockout means which completes the start circuit only when the lockout means is in its ''''off'''' position.
Claim 5
Dependent Claim
134 words
The combination of claim 3 wherein: there is a safety means associated with the sensing means, said safety means having a normal open position in which the sensing means is operable and being movable to a closed position in which the sensing means is inoperable: and there is a safety circuit that is operable when completed to move the safety means from open to closed position, said safety circuit including a first element which is operatively associated with the drum and which is operable to complete the safety circuit only when the drum is rotating at or above a selected minimum speed, and a second element in series with the first element which is operatively associated with the clutch and which is operable to complete the safety circuit only when the clutch is released.
Claim 6
Dependent Claim
158 words
The combination of claim 1 wherein: the release means includes a free fall fluid source and an actuating line leading from the fluid source to the clutch, the fluid source being operable to deliver fluid through the actuating line to release the clutch whenever the actuating line is open; and the sensing means includes a sensing valve in the actuating line, said sensing valve being biased toward a normal, centered position in which the actuating line is open therethrough and being hdraulically pilotable to opposite bypass positions in both of which the fluid source side of the actuating line is cut off and the clutch side is opened to exhaust; and there are a pair of hydraulic pilot lines, one connected between each main fluid line and a respective end of the sensing valve so that the sensing valve is shifted to one of its bypass positions when there is relatively higher pressure in either main fluid line.
Claim 7
Dependent Claim
92 words
The combination of claim 5 wherein: the sensing valve is a normally centered, three position valve with two inlet ports and outlet port means; and the actuating line includes a first portion leading from the fLuid source to one inlet and a second portion between the clutch and the other inlet; and in the centered position of the sensing valve the inlets are connected to one another; and in both bypass positions the inlets are connected to the outlet port means; and the outlet port means is connected to a return line.
Claim 8
Dependent Claim
176 words
The combination of claim 5 wherein: there is a safety valve interposed in both of the pilot lines, said safety valve being biased toward an open position in which the pilot lines are open and being shiftable to a closed position in which the main fluid line sides of the pilot lines are cut off and the sensing valve sides are communicated with one another equalize pilot pressure on the opposite sides of the sensing valve; and the safety valve is shifted from open to closed position in response to completion of an electrical safety circuit including a speed sensing electric switch operatively associated with the winch drum, said switch being normally open and being adapted to close in response to rotation of the drum at or above a selected minimum speed, and a pressure sensing electric switch connected in series with the speed sensing switch that is associated with the actuating line, said pressure sensing switch being normally open and adapted to close in response to a selected minimum operating pressure in the actuating line.
Claim 9
Dependent Claim
124 words
The combination of claim 5 wherein the elements thereof are incorporated in an apparatus including an electrical start circuit and wherein: there is a lockout valve in the actuating line between the fluid source and sensing valve, said lockout valve being movable between ''''off'''' position in which the fluid source side of the actuating line is cut off and the clutch side is opened to exhaust and an ''''on'''' position in which the actuating line is open through the lockout valve; and there is an electrical switch means operatively associated with the lockout valve to be actuable in response to movement of the lockout valve, said switch means serving to complete the start circuit only when the lockout valve is in its ''''off'''' position.
Claim 10
Dependent Claim
177 words
The combination of claim 8 wherein: there is a safety valve interposed in both of the pilot lines, said safety valve being biased toward an open position in which the pilot lines are open and being shiftable to a closed position in which the main fluid line sides of the pilot lines are cut off and the sensing valve sides are communicated with one another to equalize pilot pressure on the opposite sides of the sensing valve; and the safety valve is shifted from open to closed position in response to completion of an electrical safety circuit including a speed sensing electric switch operatively associated with the winch drum, and switch being normally open and being adapted to close in response to rotation of the drum at or above a selected minimum speed, and a pressure sensing electric switch connected in series with the speed sensing switch that is associated with the actuating line, said pressure sensing switch being normally open and adapted to close in response to a selected minimum operating pressure in the actuating line.
Claim 11
Dependent Claim
91 words
The combination of claim 9 wherein: the sensing valve is a normally centered, three position valve with two inlet ports and outlet port means; and the actuating line includes a first portion leading from the fluid source to one inlet and a second portion between the clutch and the other inlet; and in the centered position of the sensing valve the inlets are connected to one another; and in both bypass positions the inlets are connected to the outlet port means; andthe outlet port means is connected to a return line.
Claim 12
Dependent Claim
59 words
The combination of claim 10 wherein: there is a signal pressure generating means in each main fluid line between the motor and the point of connection of the associated pilot line, said signal pressure generating means serving to develop a pilot pressure sufficient to shift the sensing valve before there is an operating pressure sufficiEnt to operate 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) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |