US3736018A - Hydraulic claw with locking mechanism - Google Patents

Abstract

A claw for grasping and recovering an object is articulated by a hydraulically responsive actuator which additionally has the capability for exerting a substantial gripping force on the object. After the object has been gripped, allowing its recovery, a pawl and ratchet carried on the claw mutually engage to lock the claw in its gripped position. The hydraulic actuator and the pawl-ratchet combination are hydraulically coupled to retain the claw in its locked gripped position in the event of hydraulic failure. With availability of hydraulic pressure, suitable hydraulic connections allow disengagement of the pawl from the ratchet when hydraulic pressure is fed to the claw actuator for causing release of the claw. In an electrohydraulic system, a solenoid actuated pawl and ratchet mechanism, with appropriate connections also provide for locking the claw in its locked position and for its subsequent release.

Description

United States Patent [191 Sayre, Jr. et al.

[54] HYDRAULIC CLAW WITH LOCKING MECHANISM [75] Inventors: Jack L. Sayre, Jr., Glendora; Kenneth R. Fishel, Del Mar, both of Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Sept. 10, 1971 [2]] App]. No.: 179,348

[52] US. Cl. ..294/88, 294/66 R, 294/106 [51] Int. Cl. ..B66c 3/16 [58] Field of Search ..294/88, 103, 104,

[56] References Cited UNITED STATES PATENTS 1,166,382 12/1915 Morse ..294/104X [111 Mama 51 May 29, 1973 Primary ExaminerHarvey C. Hornsby Assistant Examiner-Johnny D. Cherry ABSTRACT A claw for grasping and recovering an object is articulated by a hydraulically responsive actuator which additionally has the capability for exerting a substantial gripping force on the object. After the object has been gripped, allowing its recovery, a pawl and ratchet carried on the claw mutually engage to lock the claw in its gripped position. The hydraulic actuator and the pawl-ratchet combination are hydraulically coupled to retain the claw in its locked gripped position in the event of hydraulic failure. With availability of hydraulic pressure, suitable hydraulic connections allow disengagement of the pawl from the ratchet when hydraulic pressure is fed to the claw actuator for causing release of the claw. In an electrohydraulic system, a solenoid actuated pawl and ratchet mechanism, with appropriate connections also provide for locking the claw in its locked position and for its subsequent release.

4 Claims, 4 Drawing Figures Patented May 29, 1973 2 Sheets-Sheet 1 FIG.|

INVENTORS JACK L. SAYRE JR. BY KENNETH R. FISHEL THOMAS GLENN KEOUGH ERVIN E JOHNSTON ATTORNEYS Patented May 29, 1973 2 Sheets-Sheet 2 INVENTORS JACK L. SAYRE JR. KENNETH R. FISHEL THOMAS GLENN KEOUGH ERVIN E JOHNSTON ATTORNEYS HYDRAULIC CLAW WITH LOCKING MECHANISM STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Hydraulically actuated tongs and claws exist in a wide variety of configurations. From a safety standpoint, most of them include a mechanical locking arrangement which holds the claws in engagement with an object after it has been gripped. However, if it is desired to change the position of the tongs or regrip the object in a different position, an operator is required to disengage the mechanical locking device to allow the claw to reopen. Similarly, mechanical tong-like arrangements supported by cables maintain their grip on an object only so long as a lifting force is exerted by a supporting cable. In none of these systems is there an assembly which automatically locks the claw in its gripped position which does not release should there be system failure and later provides for release upon restoration of power. A continuing need exists for such a safety feature.

SUMMARY OF THE INVENTION The present invention is directed to providing a system for engaging and gripping an object. A pair of jaws are sized to grasp the object and are mounted for relative pivotal motion. A source of hydraulic power provides controllable hydraulic pressures to a hydraulic actuator carried on the jaws for forcefully, bidirectionally rotating the jaws open or closed. A ratchet member and a pawl mechanism are controlled by a suitable means to lock the jaws in their gripping position and to maintain this position in the event of hydraulic failure. With availability of hydraulic pressure or upon its restoration, suitable connections ensure release of the pawl from the ratchet member to allow responsive release motion of the jaws.

The prime object of the invention is to provide a means for locking hydraulically actuated jaws in a gripped position.

Another object of the invention is to provide a resetable locking mechanism for holding the jaws closed in the event of hydraulic failure.

Yet another object is to provide a positive, reliable and releasable locking mechanism for a claw type device to ensure recovery of an object.

Yet another object is to provide a system insensitive to ambient pressure variations making the system adaptable to a deep-ocean environment.

These and other objects of the invention will become more readily apparent from the ensuing specification when taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the hydraulically actuated claw.

FIG. 2 is an expanded frontal view of a portion of FIG. 1.

FIG. 3 is an expanded side view of the hydraulically actuated claw.

FIG. 4 is a schematic diagram of the hydraulic interconnections.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a hydraulically actuated claw 10 is shown positioned about an object schematically shown in cross section. The claw is connected to a source of controllable hydraulic pressure 11 through a pair of feeder lines 12 and 13 to allow a selective gripping and retrieval of the object. Depending upon whether or not the claw is opening, closing or exerting a gripping force, the lines trade the function of being a supply line or a return line with respect to the hydraulic power source and are fabricated to ensure sufficient strength and durability. The claw is supported and emplaced by a cable or a remotely controlled manipulator, not shown, via a claw pad eye 10a.

In the preferred embodiment, the claw includes a fixed jaw 14 and a movable jaw 15 pivotally connected by a heavy duty pin 16 having a key 16a wedged into an appropriately shaped keyway. The inner surfaces of the jaws, those surfaces which are intended to come in contact with the recoverable object, each carry a compliant pad 17 or 18 accommodating the objects outer surface. An auxiliary pad 19 is included to provide an additional contact surface between the claw and object and to lessen the chances of damaging the object when positioning the claw. The pads also serve the purpose of taking up slack in the jaws due to play in the locking pawl and ratchet.

The two feeder line supply hydraulic pressure creating a pressure differential across a hydraulic actuator 20 mounted on the back of fixed jaw 14 and having its pinion 20a coaxially secured to pin 16. The pin, being journaled through the fixed jaw and keyed to the movable jaw imparts responsive bidirectional pivotal motion when discrete pressure variations are received. A typical hydraulic actuator operating on a pressure differential across a two-headed piston is commercially marketed by the Ohio Oscillator Company and is identified as a Rotary Hydraulic Actuator," Model 1837.

This hydraulic actuator 20 is shown in FIG. 4 in schematic form and contains as its principal components a journaled pinion 20a disposed for mechanical cooperation with the pair of rack elements 20b and 200 secured to piston elements 20d and 20d. When high pressures are fed to closing ports 20c and 20f and a lower pressure exists at opening port 20g, the pistons reciprocally travel inward and rotate the pinion in a clockwise direction to close the jaws. Conversely, if the relative pressures are reversed, the pistons are displaced reciprocally outwardly and pinion 20a along with pin 16 rotate in a counterclockwise direction to open the jaws.

Novel provision is made in the invention by including a safety locking feature having a reset capability. A ratchet member 21 is bolted onto movable jaw 15 and has an arcuate, outwardly facing surface shaped with a plurality of teeth 21a.

Appropriately positioned for mechanical cooperation with the ratchet, a pawl mechanism 22 is secured to fixed jaw 14 (see FIG. 2). A piston 23 carrying several suitably placed 0 ring seals, is axially contained in the pawl mechanism and serves to impart reciprocal displacement to a pawl 24. Two pawl teeth 24a are disposed on the outwardmost extension of the pawl to engage the ratchet and have a configuration and orientation to prevent the opening of the claw when engaging the ratchet to lock the claw in position. Greater locking strength is provided by including a guide 25 for directing the reciprocal travel of the pawl to prevent bending of the pawl and a consequent unlocking of the pawlratchet interconnection. A biasing spring 26 aids in maintaining the pawl in its locked engagement and further tends to maintain such engagement in the event of hydraulic failure.

Piping reaching from the controllable source of hydraulic pressure 11 is fed to both the hydraulic actuator and the pawl mechanism in a novel way providing a locking safety feature heretofore not appreciated. Looking to the plumbing diagram of FIG. 4, hydraulic actuator 20 is schematically represented as pinion 20a for imparting opening counterclockwise motion to movable jaw and closing clockwise motion and gripping force to the movable jaw via pin 16.

Opening the jaws calls for first retracting pawl teeth 24a from the ratchet teeth 21a. This is accomplished by feeding pressurized hydraulic fluid to line 12 and impressing a lower relative hydraulic pressure on line 13. Pressure line 27 is plumbed to connect pawl mechanism 22 hydraulically in-series with the hydraulic actuator. A pawl mechanism port 22a vents the pressurized hydraulic fluid to the interior of the pawl mechanism first to overcome the biasing action of biasing spring 26 and second to reciprocally displace piston 23 withdrawing pawl teeth 24a from the ratchet. After a sufficient axial travel, a second pawl mechanism port 22b feeds the pressurized hydraulic actuator 20. Since both ports e and 20f are joined to the lower hydraulic pressure level in feeder line 13, the former by pressure line 29, the higher pressure at opening port 20g causes a counterclockwise opening pivotal motion of jaw 15. A check valve prevents bypassing of the pawl mechanism and ensures the routing of the hydraulic circuit through the pawl mechanism to disengage the pawl from the ratchet prior to any rotation imparting forces being transmitted to pin 16. To repeat, prior to disengagement of the pawl from the ratchet, any rotation imparting hydraulic pressures are blocked from reaching opening port 20g of the hydraulic actuator by virtue of piston 23s covering pawl mechanism port 22b.

After the jaws have been opened, the pawl remains retracted from the ratchet and the jaws are positioned about an object. Should it be desired to close the jaws, source of hydraulic pressure 11 feeds pressurized fluid to feeder line 13 and it becomes the line of higher pressure while the pressure in feeder line 12 has a lower relative magnitude. The higher pressure is fed to the closing ports 20e and 20f directly from the feeder line 13 and indirectly through pressure line 29. Although a pressure line 32 connects the source of higher pressure to a pawl mechanism port 220, the jaw closing pressure by itself is insufficient to move piston 23 to reengage the pawl and ratchet with any significant force since only a slight back pressure is present.

The pressure lines from the hydraulic actuator to the pawl mechanism join the two hydraulically in-parallel during the closing and gripping operation to provide for closing the jaws and gripping the object prior to engaging the ratchet by the pawl. When the jaws 14 and 15 are not in contact with the object, very little pressure is required to close them.

When merely closing the jaws, return fluid from the hydraulic actuator must pass from opening port 20g and through pawl mechanism ports 22b and 22a to balance the pressure at port 220. Such a path is necessary because of the preload on check valve 30. A typical check valve employs a ball bearing biased by a spring to allow only a one-way fluid flow in pressure line 31 after a predetermined pressure differential has been established. The springs constant is chosen to create a suitable back pressure equal to the predetermined pressure differential to permit closing the jaws without effecting the condition of the pawl member. However, when the jaws begin gripping the object, the pressure differential between lines 12 and 13 immediately significantly increases. The biasing springs action is overcome and fluid flows through check valve 30 and line 31 back to feeder line 12. Under these conditions, a sufficient differential force is created across piston 23 to outwardly displace the pawl and engage pawl teeth 24a with ratchet teeth 21a. Since it is nearly impossible to provide an infinitely fine resolution between the teeth of the ratchet and the teeth of the pawl, the compressible pads 17 and 18 are bonded to the inside surface of claw arms 14 and 15. These pads maintain pressure against the object and allow positive engagement between the ratchet and pawl while maintaining a substantial gripping force on the object.

The resolution of the pawl and ratchet is increased without sacrificing strength by forming two teeth on the pawl. Although there is less strength per pawl tooth, since there are two of them, there is the same strength capability using the two smaller teeth as would be the case if one larger pawl tooth were substituted. Because of the compressible pads, if the dimensions of the object being gripped are such that the pawl teeth are not located at the very root of the ratchet teeth when locking engagement is made, the gripping pressure may be slightly relaxed until such a condition does exist and in such a case the pads 17 and 18 expand against the object to maintain the jaws gripping force. In the event of a subsequent hydraulic failure, mechanical cooperation between the pawl and ratchet continue to secure the jaws around the object and subsequent restoration of hydraulic pressure facilitates opening the jaws in the manner identical to that disclosed above.

In order to allow operation in a deep ocean environment, where high ambient pressures would normally operate against the pawl piston rod face 24b and prevent its extension, the back side of the pawl piston is provided with a dummy rod extension 23a, properly sized to balance the ambient forces on the piston and in fact improve and control its operating characteristics.

As an alternate embodiment to the hydraulically powered system, a composite electrohydraulic system having an electrically actuated solenoid in place of the hydraulically actuated pawl mechanism calls for the additional inclusion of a microswitch responsive to permit hydraulic actuation after the solenoid has withdrawn the pawl from the ratchet. A similar pressure responsive switch contained in the hydraulic lines actuates the silenoid to engage the pawl in the locked position after a predetermined gripping force is exerted.

"Obviously, many modifications and variations of the present invention are possible in the light of the above teachings, and, it is therefore understood that within the scope of the disclosed inventive concept, the invention may be practiced otherwise than specifically described.

What is claimed is:

l. A system for engaging and gripping an object comprising:

a pair of jaws sized to grasp said object joined for relative pivotal motion each carrying a compressible pad member on its inner surface to ensure a secure said gripping of said object;

a source of hydraulic pressure for enabling the manipulation of said jaws;

actuator means being hydraulically actuated and carried on said jaws connected to and being responsive to the source of hydraulic pressure to impart bidirectional said pivotal motion and to exert a gripping force on said object;

a ratchet member secured to one jaw;

a pawl mechanism mounted on the other jaw and oriented for selective engagement with said ratchet member and having a biasing element for automatically locking said jaws in place in the event of failure of said source of hydraulic pressure; and

hydraulically actuated means controlling said selective engagement joined to said pawl mechanism connected to and being responsive to said source of hydraulic pressure ensuring said selective engagement after said jaws have exerted said gripping force and thereafter maintaining said selective engagement locking said jaws in place should there be a subsequent said failure of said source of hydraulic pressure, the hydraulically actuated controlling means is coupled hydraulically in-series with said hydraulically actuated actuator means when said jaws are being opened and hydraulically in-parallel when said jaws are being closed and while exerting said gripping force, upon the reactuation of said source of hydraulic pressure, the hydraulically actuated controlling means is responsive to selectively disengage said pawl mechanism to allow the responsive articulation of said jaws,

2. A system according to claim 1 in which said one jaw is fixed and provides support for said enabling means, said actuator means, said pawl mechanism, and said controlling means and said other jaw is pivotally mounted with respect to said one jaw.

3. A system according to claim 2 in which said pawl mechanism is configured with a plurality of teeth for engaging said ratchet member giving higher resolution to said locking.

4. A system according to claim 3 in which a dummy rod is incorporated on the back side of said pawl actuator piston to control its operating characteristics in a deep ocean environment.

Claims (4)

1. A system for engaging and gripping an object comprising: a pair of jaws sized to grasp said object joined for relative pivotal motion each carrying a compressible pad member on its inner surface to ensure a secure said gripping of said object; a source of hydraulic pressure for enabling the manipulation of said jaws; actuator means being hydraulically actuated and carried on said jaws connected to and being responsive to the source of hydraulic pressure to impart bidirectional said pivotal motion and to exert a gripping force on said object; a ratchet member secured to one jaw; a pawl mechanism mounted on the other jaw and oriented for selective engagement with said ratchet member and having a biasing element for automatically locking said jaws in place in the event of failure of said source of hydraulic pressure; and hydraulically actuated means controlling said selective engagement joined to said pawl mechanism connected to and being Responsive to said source of hydraulic pressure ensuring said selective engagement after said jaws have exerted said gripping force and thereafter maintaining said selective engagement locking said jaws in place should there be a subsequent said failure of said source of hydraulic pressure, the hydraulically actuated controlling means is coupled hydraulically in-series with said hydraulically actuated actuator means when said jaws are being opened and hydraulically in-parallel when said jaws are being closed and while exerting said gripping force, upon the reactuation of said source of hydraulic pressure, the hydraulically actuated controlling means is responsive to selectively disengage said pawl mechanism to allow the responsive articulation of said jaws.

2. A system according to claim 1 in which said one jaw is fixed and provides support for said enabling means, said actuator means, said pawl mechanism, and said controlling means and said other jaw is pivotally mounted with respect to said one jaw.

3. A system according to claim 2 in which said pawl mechanism is configured with a plurality of teeth for engaging said ratchet member giving higher resolution to said locking.

4. A system according to claim 3 in which a dummy rod is incorporated on the back side of said pawl actuator piston to control its operating characteristics in a deep ocean environment.

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