US2323326A - Latch mechanism for hooks - Google Patents

Description

July 6, 1943- `R. K. HERTEL 2,323,326

LATCH MECHANISM FOR HOOKS Filed Jan. 9, 1942 ,0n/,4R0 A. Hanns-L,

INVENTOR l Patented July 6, 1943 UNITED STATES LATCH MECHANISM FOR HOOKS Richard K. Hertel, Los Angeles, Calif., assigner to Byron Jackson Co., Huntington Park, Calif., a corporation of Delaware 19 Claims.

This invention relates generally to hooks of the type employed in rotary well drilling operations. More particularly, it pertains to improvements in' the latch mechanism associated with the closing arms of such hooks. y

In my prior Patent No. 2,100,779, dated November 30, 1937, there is disclosed a closing arm latch mechanism embodying a main latch member mounted on the closing arm for movement between latched and released positions, and an auxiliary locking member mounted on the latch member and normally preventing the release of the latch member. Each member is resiliently urged toward its operative position by spring means, and may be retracted upon application of manual force. The arrangement is such that upon movement of the closing arm to closed position the latch member and the locking member are automatically retracted and then permitted to assume their normal operative positions. springs acting on the respective members are arranged at right angles to each other so that in the event the hook is subjected to a sudden jar in any direction, it will not be eective to momentarily move both members into their released positions and permit the closing arm to y open.

A latch mechanism of the aforementioned type has proven highly satisfactory in service on large, heavy duty hooks. that if the mechanism were reduced in size the requisite amount to permit its incorporation in a small capacity hook, it would lack the necessary ruggedness to withstand the severe service conditions, and the springs would not be of sufcient strength to provide adequate safety from inadvertent release of the latch.

A principal object of the invention is to provide a more compact and rugged latch mechanism without sacrificing any of the advantageous features of the latch mechanism briefly described above.

A further object is to provide a latch mechanism embodying an auxiliary locking member, wherein both the main latch member and the locking member are resiliently urged toward their respective operative positions by common spring means.

A still further object is to provide a latch mechanism wherein less force is required to manually retract the latch than would be required to release the latch inadvertently, thus permitting the use of a stronger spring that has been heretofore possible without rendering manual release unduly difficult.

The f However, it has been found Application January 9, 1942, serial No. 426,195

(Cl. 294-83)Y Other objects and advantages will be apparent from the following detailed description of a preferred embodiment of theinvention, reference being had to the accompanying drawing wherein:

Fig. 1 is a viewin side elevation of ia hook embodying the invention, with pa'rts'broken away to disclose details of the latch mechanism;

Fig. 2 is a fragmentary view ofl the-hook of Fig. 1, but showing the latch manually retracted prior to opening the closing arm; and

Fig. 3 is a fragmentary view showing the latch being cammed into retracted position as the closing arm approaches its closed position. l

The novel latch mechanism is susceptibler of embodiment in hooks of various designs, andin the present instance a more or less conventional hook has been shown. The hook body I includes a portion 2 adapted to receive a pivot pin 3 for pivotally connecting the body I to the lower end of a shank 4, which in turn is supported in any suitable mannerin a housing, the lower portion of which is indicated at 5. A bill 6 is formed integral with the lower portion of the body I, and partially denes a recess 'I for receiving a load-carrying member such as a swivel bail, shown in dotted lines at 8.

A closing arm, generally designated II, is pivotally connected at its lower end to the fr ee end of the bill 6 by a pivot pin I2, and is adapted to bridge the open side of the recess 1 to confine the bail 8 in the recess. Aprojection I3 is formed on the hook body at the upper side of the recess 1, and a corresponding recess I4l is formed in the free end of the closing arm I I to receive the projection when the arm is in closed position. If desired, only very slight clearance may be provided at I5 between the upper surface of the projection I3 and the upper wall of the recess I4, to enable a portion of the load to be sustained by the closing arm upon slight downward flexing of the bill 6 under load.

An inverted U-shaped closing finger IB is formed integral with the closing arm I I and projects inwardly from the lower portion of the arm and straddles the bill li. The medial portion I9 of the closing finger is adapted to rest on the upper surface of the bill 6 and is provided with an upper surface which conforms generally Ato the curvature of the bail 8. It will be apparent that when the closingvarm is in open position and the bail is inserted in the recess I, upon raising the hook to pick up the load the engagement of the bail with the closing finger I8 causes the closing arm I I to swing about its pivot I2l into the closed position shown in Fig. V1. It is, of

with the closing finger, a self-locking latch mechanism to automatically lock the closing arm in its closed position. My improved latch mechanism for this purpose will now be described.

A latch member, generally designated 2I, is mounted in a recess 22 in the closing arm II for limited sliding movement longitudinally of the arm and also for limited oscillation about a transverse axis. A nose portion 23 is provided at the upper end of the latch, and is adapted to normally project into the recess I4 in the arm and to be received within a downwardly opening recess 24 in the projection I3 when the arm is in closed position. At the base of `the nose portion 23, a projection 25 extends outwardly of the main body of the latch member. The upper surface of the projection constitutes a shoulder or abutment 25 which engages a roller 21 journaled on the arm II, to limit upward movement of the latch member. The lower surface of the projection 25 also provides an abutment 23 engaged by an outwardly projecting arm 29 on a locking member 30 pivotally mounted in a recess in the latch member on a pivot pin 3 I.

The locking member 3U is resiliently urged in a clockwise direction about its pivot pin 3l by a coil compression spring 32 interposed between the locking member and a recessed seat 33 in the arm I I, and it will also be evident that by reason of the engagement of the arm 29 of the locking member with the abutment 28 on the latch member 2l, the latter is also urged upwardly by the spring. v

It will be observed that the inner wall of the spring recess provides a shoulder 35 which underlies a portion of the locking member 3i) when the latter is in its normal position, as illustrated in Fig. 1. It is thus apparent that the locking member must iirst be rotatedl in a counterclockwise direction, either relative to the latch member 2| about the pivot pin 3l or as a unit with the latch member, before the latch member can be retracted downwardly. This counterclockwise rotation of the locking member` may be effected in either of two ways: i. e., by exerting a downward force on the arm 29, as is done when the latch is retracted manually prior to opening the arm II, or by exerting outward pressure on the inner, inclined face of the nose 23, as is done when the nose enga-gesthe projection I3 during closing of the arm.

A novel feature of the invention is the arrangement whereby the manual force required to depress the arm 29 on the locking member is subi stantially less than that required to compress the spring 32. This is accomplished by the provision of a cam surface 38 on the inner face of the locking member, which is adapted to engage an inclined wall 39 on the arm II, and thus provide a movable fulcrum point about which the locking member pivots. It will be apparent that the ratio of the downward pull on the arm 29, to the spring force, is in inverse proportion to the distances from the fulcrum point to the respective points of application of the two forces; inasmuch as the manual force is applied to the arm at a point more distant from the fulcrum point than the point of application of the spring force, the manual force required is less than the spring force. This is a distinct advantage, inasmuch as it permits the use of a relatively strong spring, with its attendant increased safety against accidental opening Vof rthe latch, without rendering manual opening of the latch unduly difficult.

course, Very desirable to provide, in conjunction The cam surface 38 is preferably, although not necessarily, a logarithmic cam, which causes the axis of the pivot pin 3I to move along a straight path as the cam surface rolls along the inclined surface 39.

It will be observed that the latch member 2I is provided with a depending tail portion 40 which at all times remains below the shoulder 35 and is guided in the recess 22. It will also be observed that the inner wall 4I of the tail portion 40 is inclined downwardly and outwardly, and that a substantial clearance is provided between the outer face of the nose 23 and the roller 21, to permit limited oscillation of the latch member in the recess 22. The reasons for providing for such oscillation will be apparent from the following description of the operation of the latch under the two different conditions of manual opening and automatic closing of the arm II.

When it is desired to open the arm I I to permit insertion or removal of the bail 8, the arm 29 on the 'locking member 39 is'depressed, either by hand or, if the hook is out of manual reach, by the use of the usual long-handled hoo-lc 45 (Fig. 2) provided for that purpose. The upper end of the spring 32 initially functions as a fulcrum, causing the locking member 30 and the latch member 2I 'to rotate through a slight angle in a counterclockwise direction, until 'the outer face of the nose 23 engages the roller 21, land the cam surface 38 on theflocking member engages the inclined surface 39 on the arm. This` initial movement is suflcient to cause the locking member to clear the shoulder 35, thus permitting downward movement of the latch member and locking member. During subsequent depression of the arm V29, the cam surface 38 rolls downwardly along the surface 39 and functions as a movable fulcrum for the locking member, as is most clearly illustrated in Fig. 2. The latch member 2I moves downwardly in a substantially straight path, the upper end thereof being guided by the roller "21. In view of the true rolling action between the surfaces 38 and 39 and between ,f the latch and the roller 21, there is no resistance due to sliding friction, thus providing maximum ease of operation and freedom from wear on the parts. When thelatch has been depressed to the position shown in Fig. 2, the arm II may be swung to open position, the extent of opening movement being limited by engagement of a pair of opposed abutments 49 and59 on the hook bill E and the arm II, respectively.

As previously stated, when the arm lI I is in open position and the bail 8 is inserted in the recess and the hook is raised to pick up the load, the bail engages the closing finger I8 and causes the closing arm to swing about its pivot I2 toward closed position. The projection I3 on the hook body is provided with a downwardly and inwardly inclined cam surface 52 which engages a similarly inclined cam surface 53 on the nose 23 Vof the latch member 2I as the arm II approaches its closed position. The latch member is. thus momentarily restrained against inward movement with the arm I I, and, as a result, continued move- 'ment of the arm I'I causes the roller 2l to engage the forward face of the nose 35 and rock the latch member in a counterclockwise direction about its point of engagement with the projection I3, into the position shown in Fig. '3. It will be observed that the locking member 3B is also constrained to Vmove with the latch member, because of the engagementrof lthe arm 29 of the locking member with the shoulder 28 on the 'latch member. The locking member is thus swung clear of the shoulder 35 on the arm il, allowing the latch member and locking member to :be forced downwardly in the recess 22 by the interengaging cam surfaces 52 and 53.

During the retracting movement of the latch member, the outer face of the nose portion 23 is in rolling contact with the roller 21, the line of contact between these members constituting the instantaneous fulcrum about which the latch member tends to pivot. It will be evident that the spring 32, acting through the locking member and the projection 25 on the latch member, exerts a force on the latch member which produces a turning moment in a clockwise direction, in opposition to the turning moment produced by the pressure of the cam surface 52 on the nose 23. By providing suitably shaped cam surfaces 52 and 53, the magnitude of the counterclockwise moment may lbe made equal to or slightly greater than the clockwise moment produced by the spring 32, and in this manner the tail portion Ml of the latch member will be initially maintained in the position shown in Fig. 3, with the inner surface -il thereof adjacent the inner wall of the recess 22. It is only necessary to maintain this condition until such time as the tail portion of the locking member 30 has moved downwardly and cleared the shoulder 35.

It will be evident that when the nose portion 23 of the latch member is aligned with the recess 24 in the projection i3, the latch will snap upwardly into latched position and the locking member will rotate into its locked position shown in Fig. l, thus securely locking the closing arm in its closed position.

Attention is directed particularly to the fact that the point of application of the spring force to the locking member and, through that member, to the latch member, is oiset laterally from the centers of mass of those members. The direction of offset is such that in the event the hook is subjected to a sudden downward jar, tending to move the latch member in releasing direction, the mass of the latch member, acting on the locking member through the pivot pin 3i, tends to rotate the locking member in a clockwise direction about the upper end of the spring. Thus, any tendency for the latch member to inadvertently release, results in the locking member being held even more rmly in its locking position overlying the shoulder 35.

From the foregoing description cf a preferred embodiment of the invention, it will be apparent to those familiar with the operating requirements of drilling, tubing and casing hooks that I have provided a latch mechanism for the closing arms of such hooks which provides increased safety against accidental opening and yet may be released manually with little eort. Because of the compact arrangement of parts, an exceptionally rugged latch may be incorporated in small capacity hooks in which the length of the closing arm is considerably less than in large capacity hooks.

It will be understood that the invention is not limited to the precise details of construction of the illustrated embodiment, and that various changes may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

l. A hook comprising a body with a bail-receiving notch, a closing arm pivotally connected to the body and adapted to close the entrance to the notch, a latch member mounted on the arm and having a portion adapted 'to 4cooperate Vwith the body to releasably latch the arm in closed poe sition and being movable into an inoperativeposition, a locking member cooperating with the latch member and having an operative position wherein it positively prevents movement of the latch member out of latching engagement with the body, said locking member being movable into an'inoperative positionr wherein it permits release of the latch member, and common resilient means yieldably retaining both the latch member and the locking member in their operative positions. y

2. A hook as set forth in claim l, in which said common resilient means comprises a spring member interposed between an abutment on the closing arm and an abutment on one of said members, said members having interengaging surfaces whereby the resilient means acts on the other of said members through said one member. i

3. A hook as set forth in claim 1, in which said common resilient means comprises a spring mem? ber interposed between an abutment on the closing arm and an abutment on the locking member, and in which the locking member and the latch member include interengaging surfaces through which the pressure of said spring means is transmitted to the latch member.

4. In a hook, a body having a bail-receiving notch, an arm pivotally connected to the body and adapted to close the entrance to the' notch, a latch member slidably mounted on the arm and having a portion adapted to cooperate with the body to releasably latch the arm in closed position, said latch member being movable longitudinally of the arm between latched and released positions, a locking member pivotally mounted on the latch member and having a portion adapted to cooperate with the arm to releasably lock the latch member in latched position, a spring seat on the arm, a spring supported on the seat and engaging the locking member and tending to rotate the same about its pivotal connection with the latch member into locked position, the latch member and locking member having interengaging shoulders limiting the pivotal movement of the latch member, said shoulders being arranged to transmit the spring pressure to the latch member to yieldingly urge the latter toward its latched position.

5. In a safety hook, a hook body having arecess, an arm pivoted to the body and normally closing the entrance to the recess, a latch member mounted on the arm and having a latch portion cooperating with the body for releasably latching the arm in closed position, resilient means urging the latch member toward latching position, and means for manually retracting the latch member comprising an operating member pivotally connected to the latch member and having a fulcrum portion engageable with said arm, and lever means on said operating member for rocking the same about its fulcrum on said arm to retract the latch member.

6. A safety hook as set forth in claim 5, in which the fulcrum portion on said operating member includes a cam surface having rolling contact with said arm.

7. A safety hook as set forth in claim 5, in which the fulcrum portion on said operating member includes a cam surface having rolling contact with said arm, said cam surface being shaped to cause the axis of pivotal connection between the latch member and the operating member to move in a rectilinear path during rolling; engagement of said cam surface with said arm.

8. A safety hook as set forth in claim 5, in which the fulcrum portion on said.v operating member includes a logarithmic spiral cam surface having its origin at the axis of pivotal connection between the latch member and the operating member.

9. In a safety hook, Ia hookV body having a 'recess, an arm pivoted to the body and normally closing the entrance to the recess, a latch member mounted on the arm and having a latch portion engageable with the body for releasably latchingY the arm in closed position, a locking member pivotally connected to the latch member and having a portion cooperating with the arm to releasably lock the latch member in latching position, resilient means urging said members toward their operative positions, said locking member having a fulcrum portion engageable with the arm and a lever portion, for rocking the locking member about its fulcrum on the arm to retract the latch member.

10. A safety hook as set forth in claim 9, in

which said resilient means comprises a single spring urging both members toward their operative positions. A

ll. A safety hook asset forth in claim `9, in whichv said resilient meanscomprises a spring interposed between opposed abutments onV the arm and the locking member, the locking member and latch member having opposed shoulders engageable to exert. spring. pressure, on the latch member through the locking member.

12. A safety hook as set forth in claim 9, in which said resilient means includes a spring interposed between opposed abutments on the arm and the locking member, the distance between the spr-ing abutment on the locking member and the fulcrum portion thereon being less, than the distance between the fulcrum portion and the lever portion.

13. A hook comprising aV hook body having a bail-receiving recess land an arm pivotally Aconnected to the body andl normally closing the entrance Ito the recess, a latch memberA mounted on the arm and having a latch portion cooperating with the hook body to releasably latch the arm in closed position, said latch member having limited rectilinear and oscillatory movement relative to the arm, resilient means urging the latch member toward latching position and tending to oscillate the same in one direction, means to retract the latch member and oscillate the same in the opposite direction, and roller means mounted on the arm and engageable with the latch member upon initial oscillation thereof in the opposite direction, said roller means providing antifriction rolling contact between the arm and latch member during rectilinear retracting movement of the latch member.

14. A hook as set forth in claim 13, in which the latch member includes a cam surface on the latch portion thereof, engageable with a `cooperating cam surface on the hookbody to move the latch member in releasing direction during closing movement of the arm.

15. A hook as set forth in claim 13, in which the latch member includes a cam surface on the latch portion lthereof, engageable with a cooperating cam surface on the hook body to move the latch member in releasing direction during. closing movement of the arm, and a locking member associated with the latch member for normally preventing release of the latch member, the engagement of said cam surfaces causing initial movement of the latch member in a direction to release the locking member, and causing subsequent retracting movement of the latch member.

16. A hook comprising a hook body having a recess and an arm pivoted thereto and normally closing the entrance-to the recess, a latch member mounted on the arm and cooperating with the body to releas'ably latch the arm in closed position, a locking member associated with the latch member and cooperating with the arm to releasably lock the latch member in latched position, the latch member being movable relative to the arm in a rst direction to release` the locking member 'and being movable in a second direction into retracted position, and means for sequentially moving the latch member in said first and second directions. I

17. A hook comprising a hook body having a recess and an arm pivoted thereto and normally closing the entrance to 'the recess, a latch member for releasably latching the arm in closed position, a locking member for releasably locking the latch member in latched position, means for manually actuating the locking member in a first direction to release the same and in a second direction to retract the latch member prior to moving the arm in opening direction, 'and means operable automatically during closing movement of the arm for moving the latch member in a first direction to release the locking member andv in a second direction to retract the latch member.

18. A hook comprising a hook body having a recess and an arm pivoted thereto and normally closing the entrance tothe recess, a latch member mounted on the arm and cooperating with the body to releasably latch the arm in closed position, a locking member pivotally mounted on the latch' member and cooperating with the arm to releasably vlock the latch member in latched position, the locking member being rotatable about its axis of pivotal connection with the latch member into a released position permitting retraction of the latch member, and being movable about a fulcrum on the arm to retract the latch member.

19. A hook comprising a hook body having a recess and an arm pivoted thereto Vand normally closing the entrance tothe recess, a latch member rockably and slidably mounted on the arm and cooperating with the body to releasably latch the arm in closed position, a locking member mounted on the latch member and cooperating with the armto releasably lock the latch member in latched position, a roller mounted on the arm, the latch member being rockable about the roller to move the lockingv member to released position andY being movable rectilinearly in rolling co-ntact with the roller into a retracted position, and means for sequentially rocking the latch member about the roller and then moving it rectilinearly into retracted position.

RICHARD K. HERTEL.

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