US3596973A

US3596973A - Automatic grapple device

Info

Publication number: US3596973A
Application number: US850410A
Authority: US
Inventors: Adolph Anderson; Donald R Hodgin
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-08-15
Filing date: 1969-08-15
Publication date: 1971-08-03
Anticipated expiration: 1988-08-03

Abstract

An automatic grapple for universal application including a support member having a loop for attachment to a hoist, a pair of crossed, barbed tongs pivoted to one another at their crossing point, links connecting one end of each of said tongs to said support member, a ram pivotally connected at one end to the pivot of said tongs, means on said support member defining a path for movement of said ram during closing and opening of said tongs, a trigger extending into said path to be struck by said ram, cooperating latching elements carried by said ram and support member for holding said tongs open, and link mechanism connecting said trigger to one of said latching elements and operative to move said one latching element into and out of latching engagement with the other latching element when actuated by movement of the trigger.

Description

United States Patent [72] Inventors Adolph Anderson 238 39th Ave. 5., West Richland; Donald R. Hodgin, 1316 Birch Ave.. Richland, both of, Wash. 99352 [2 l Appl. No. 850,410 [22] Filed Aug. 15, 1969 [45] Patented Aug. 3, 1971 [54] AUTOMATIC GRAPPLE DEVICE 12 Claims, 11 Drawing Figs.

[52] 0.8. CI. 294/110, 294/ l 19 [5]] Int. CL. B25b 5/08 (50] Field ol Search 294/88, l06,ll0,ll8,ll9

[56] References Cited UNITED STATES PATENTS 2,629,627 2/1953 Stone 294/110 2,776,l64 l/l957 Eckstein 2,894,782 7/1959 Puckettetal.

Primary Examiner-Even C. Blunk Assistant Examiner-Johnny D. Cherry Attorney-Berman, Davidson and Berman ABSTRACT: An automatic grapple for universal application including a support member having a loop for attachment to a hoist, a pair of crossed, barbed tongs pivoted to one another at their crossing point, links connecting one end of each of said tongs to said support member, a ram pivotally connected at one end to the pivot of said tongs, means on said support member defining a path for movement of said ram during closing and opening of said tongs, a trigger extending into said path to be struck by said ram, cooperating latching elements carried by said ram and support member for holding said tongs open. and link mechanism connecting said trigger to one of said latching elements and operative to move said one latching element into and out of latching engagement with the other latching element when actuated by movement of the trigger.

AUTOMATIC GRAPPLE DEVICE This invention relates to an automatic grapple device for universal application, and more particularly to a self-acting grapple adapted to be used with a hoist, or the like, and which automatically opens and closes to clamp a log, or other load, upon movement of the grapple, under control of the hoist operator, without the need for stationing a man at the load, to assist in the clamping, or unclamping action.

It is a primary object of the invention to provide a grapple, for lifting logs, or other heavy loads, which is self-acting to clamp and unclamp without the need for manual assistance, the clamping and unclamping taking place automatically by relative movements of the device and the load under control of the hoist operator in lifting and lowering the grapple.

It is an important object of the invention to provide a grapple, having the above described characteristics, which saves manpower and thereby reduces operational costs.

It is another object of the invention to provide a grapple, having the above described characteristics, which is of mechanical construction, designed toclamp and unclamp only when the grapple is moved in a selected direction and then in the opposite direction, whereby accidental operation is unlikely.

Yet another object is to provide an improved grapple having increased safety, due to avoidance of manual operation, and which prevents accidental unclamping, or falling of the clamped loads, whereby injury to persons, who would normally be stationed at the load to assist in clamping and unclamping, is eliminated.

A further object of the invention is to provide an automatic grapple, having the above described characteristics, so designed as to clamp and remain clamped to a load without danger of accidental release due to swinging of the load, or the striking of the load against other objects.

A still further object of the invention is to provide an automatic grapple, having the above described characteristics, which is capable of application in many industries in addition to the logging industry, and particularly in industries involving the handling of loads without direct or proximate contact of the loads with people, as for example, in raising and lowering of loads from and into water, and in handling loads of dangerous nature.

Yet another object of the invention is to provide an automatic grapple, having the above described characteristics, which is of relatively simple construction, yet strong and durable, easy to fabricate, and easy and economical to use.

The grapple device according to the present invention and which meets the above described objects, will be described in its form primarily adapted for logging timer on the ground, or in water. It will be understood, however, that the grapple is adaptable to other uses, such as for example, in retrieving sunken objects, boats, or the like, in clearing areas of obstructions, refuse, trash, or partly demolished buildings, and in handling dangerous or hazardous materials. It should be clear, therefore, that the automatic grapple is capable of universal application.

The grapple according to the invention may be briefly described as comprising a pair of pivoted tongs connected by links to a support member adapted to be raised or lowered by a hoist. The support member is provided with a vertical, inner tube whose bore presents a guide path for movements of a ram connected to the pivot of the tongs and which movements clamp and unclamp the tongs. A trigger extends across said path and is connected by linkage to a pivoted latching element which turns into said path to permit downward movement of the ram and clamping of said tongs. When the trigger is struck by the ram, the latching element is moved by the linking mechanism to a locking position across the bore of the tube for cooperation with a locking element on the ram to hold the ram in elevated position and the tongs in open condition. Thus, the grapple may be lowered to engage the open tongs on a log, or other load, such engagement raising the ram to strike the trigger, causing the trigger linkage: to unlock the latching elements and move the pivoted latching element out of said tube bore so that upon subsequently lifting the grapple, the tongs and the ram are free to descendby gravity and clamp the log. When the grapple is subsequently lifted, the log is lifted also and may be moved to any desired location. To release the log from the grapple, it is necessary to first lower the grapple so that the log is deposited on a surface causing the ram to again ride upwardly against the trigger. Actuation of the trigger by the ram moves the pivoted latching element across the path of the ram so that upon subsequent raising of the grapple, the ram is latched in its raised position and as a result, the tongs are in their open condition ready to be moved to pick up another log.

With the above outline of the structure and mode of operation, it should be clear that the grapple is automatically operated, first to clamp the tongs on the load, by a downward movement followed by upward movement. Unclamping is also performed by the same movements, first lowering the grapple until shortly after the load rests on a surface, whereby to lift the ram and open the tongs, and then raising the grapple to remove the same from the load. The tongs are maintained in their open condition and when the grapple is lifted vertically. In this fashion, the grapple is clamped and unclamped automatically by a pair of opposite and sequential movements in the preselected vertical direction, ruling out accidental uncoupling by movements in other directions, by swinging movements, or by striking the load, or the grapple, against other objects.

A grapple constructed as described Ihasmany advantages. Primary among these are the avoidance of need to position one or two men at the load, to assist in the clamping and unclamping of the load. The construction of the grapple is such that once clamped it is virtually impossible to unclamp without following the above described sequence of movements. Accidental unclamping, therefore, cannot take place, yielding increased safety. the grapple may be made in any size to lift any load.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention, itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, wherein like reference characters indicate like parts throughout the several FIGS., and in which:

FIG. 1 is a front elevation of a grapple according to the invention with the front cover wall removed and the tongs shown in open condition;

FIG. 2 is an elevational view looking from the right side of FIG. 1 and with the cover of the device shown in phantom;

FIG. 3 is an enlarged fragmentary sectional view taken on line 3-3 of FIG. 3, and looking in the direction of the arrows;

FIG. 4 is an elevational view taken from the left side of FIG. I with the housing omitted and the tongs extended in their clamping condition;

FIG. Sis an elevation taken from the right side of FIG. 4;

FIG. 6 is a sectional view taken on line 66 of FIG. 4, and looking in the direction ofthe arrows;

FIG. 7 is a fragmentary sectional view taken on line 7-7 of FIG. I, and looking in the direction ofthe arrows;

FIG. 8 is a fragmentary sectional view taken on line 88 of FIG. 4, and looking in the direction ofthe arrows;

FIG. 9 is an enlarged, fragmentary front elevation showing a portion of the link mechanism connecting the trigger to the latching element in its condition as in FIG. 1 wherein the tongs are held in their open condition;

FIG. 10 is an enlarged fragmentary view similar to FIG 9, but wherein the tongs have moved to their closed condition; and

FIG. 11 is an enlarged fragmentary elevation similar to FIGS. 9 and 10, but wherein the tongs and said link mechanism are in an intermediate position.

Referring now more particularly to the drawings, a preferred embodiment of the invention is shown as comprising a support member 10, a pair of tongs 12, a trigger 14, a ram 16, cooperating

latching elements

18,20, FIG. 9, carried by said ram and support member, respectively, for holding the tongs open, and link mechanism 22 connecting said trigger to one latching element 20 and operative to move said latching element into and out of latching engagement with the other element upon actuation by movement of the trigger.

The support member 10 comprises an inverted U-shaped metal channel 24 having depending

platelike sides

26,28 connected by an upper bight 30. To each

side

26,28 is hinged a pair of tongs, as later to be described, while integrally secured, or formed, with the bight 30, in the center thereof, is an upstanding vertical tube 32 at whose upper end is fixed a loop 34 for reception of the chain, or hook, of a hoist, crane, or the like, used in lifting the grapple. The vertical tube 32 is slotted in one of its walls'from its upper end downwardly as indicated at 36, FIGS. 1 and 3, to receive and permit movement of the trigger 14. Another slot 38, FIG. 7, is formed in an opposite wall near the bottom of the tube 10 to permit passage of the latching element 20. A boxlike housing 40 is seated on the bight 30 of the U-shaped member 24 and secured thereto by any conventional means. Preferably, the housing is formed by a pair of frames, not shown, to which four sidewalls and a top wall are removably secured by bolts, or the like, also not shown. The function of the housing is to enclose the operating mechanism of the grapple and to protect the same from entrance of moisture, dust, dirt, etc.

One pair ofcrossed tongs 12 formed of

arcuate members

13 and 15 having inwardly directed, barbed, lower ends 42, are rotatably secured at their crossing point to a pivot bolt 44. The upper ends of the tongs are pivoted at 46,48 to the bottom ends of

links

50,52, whose upper ends are pivotally secured by pivot bolt 54,56 to one flange 26 of the support channel 24. An identical pair of

tongs

13,15 are secured in the same manner to the opposite flange 28 of the support member 24. The tongs 13 are connected together by one or more stiffeners 58 secured by welding, or otherwise, and the tongs 15 are likewise braced by stiffeners 58. The pairs of

tongs

13,15 thus described are light, strong and rigid, yet operate in the same manner as if a single pair of heavy tongs were utilized. The

upper end ofa bracing link 60 or stabilizer arm for tong 13 is pivoted at 62 to the support plate 26 at a point spaced on the opposite side of ram 16 from the link pivot 54, and at its lower end the bracing link swivels on pivot 64 to the upper end of tong 13. A similar stabilizer arm 60 is correspondingly secured on the tong 15 of the other pair of

tongs

13,15 to more uniformly distribute the weight of a load being lifted and to smooth and better the clamping and lifting action.

The ram 16 as best seen in FIGS. 1, 3 and 6, comprises a vertical tube 66 which slidably fits within the tube 32 of the support member 10. Internally, the tube 66 is braced by a pair of longitudinal strips 68, each of which is horizontally slotted at 70 to receive the pivot bolt 44 of the pairs of tongs 12 with some play. Above the pivot slot 70 a stop flange 72 is integrally secured to each strip 68 to limit upward movement of the ram by engagement with the bottom of the support member 30. The tubular portion'66 of the ram has a vertical slot 74 at its upper end which aligns with the trigger-receiving slot 36 of the tubular portion 32 of the support 10, and in its opposite wall at the lower end has a vertical slot 76, FIG. 7, to

the ram so as to cross an intermediate portion of the slot 74.

The roller 84 serves to strike the trigger and actuate the trigger link mechanism, as will be hereinafter explained.

Secured to the support tube 10 by welding, or otherwise, are a pair of spaced support brackets 86, FIGS. 1 and 3, to which are attached,-in conventional fashion, a pair of bearings 88, and a trigger shaft passes through aligned apertures in said support brackets and is journaled for rotation in said bearings. The trigger 14, FIGS. 1 and 6, comprises an arm extending through the aligned

slots

36,74 in the support tube and ram so that it crosses the bores of these elements. One end of the trigger arm 14 is enlarged as a collar 92 fitting over the trigger shaft 90 in the space between the support brackets 86. The collar and trigger shaft are keyed together so that the trigger will pivot around the axis of the shaft from its normal position shown in FIGS. 1 and 6, to an upwardly inclined position when struck and so moved by the roller 82 in the ram. During suchmovement the roller turns lessening the wear and shock.

The trigger shaft 90 extends beyond one of the journal blocks 88 and to the protruding end is affixed the collar 94 of an actuating arm 96. As best seen in FIGS. 6 and 7, a second shaft, or latching shaft 98 is similarly mounted for rotation in the bearings 100 secured by screws 102 to a pair of mounting plates 104 on the opposite wall of the support tube 32 and at a lower elevation. The latching shaft 98 passes through aligned apertures 106 in said support plates and the latch 20 in the form of a bar, or finger, extends radially from a collar 108 which is keyed at 110 to the latching shaft. The latch bar 20 extends through the

slots

38,76 in the support tube and ram in one position to engage under the latch bar 18 welded across the bore of the ram thus holds the ram up and the tong open. Latch shaft 98 will, upon turning, pivot the latch bar out of the support tube 32, permitting the ram to descend and the tongs to close.

On one protruding end of the latching shaft 98, FIG. 7, is keyed a crank arm 112 to whose end spaced from the shaft is a hooked, or otherwise secured, one end ofa biasing spring 114, best seen in FIG. 4. The other end of the biasing spring is secured in any conventional manner to a lug 115 extending from a wall of the support tube 32. On the other protruding end of the latching shaft is keyed a collar 116 having a radial arm 118 and an outwardly bent axial leg, or dog 120. This leg passes through and rides in an arcuate slot 122 shaped as the segment ofa circle coaxial with shaft 98 and formed in a disc 124 which is rotatably journaled on the shaft 98. Outwardly of the disc 124 is provided a cam 126 in the form of a radial protuberance on collar 128, FIG. 9, which is also keyed to shaft 8. To cooperate with cam 126, the disc 124 carries a cam follower in the form of an arm 130 pivoted at 132 near one edge of the disc and having a follower wheel 134 journaled at the inner end of the follower arm, as best seen in FIGS. 9 and 10. A coil spring 136 mounted between a lug 138 and the cam follower arm 130 urges the follower wheel 134 against the cam 126. Pivotal movement of the cam follower arm is permitted about the axis ofpin 132, but is limited by stop arm 140 secured to the disc and riding in an arcuate slot 142 coaxial with the pivot 132.

The link mechanism 22 connected the trigger 14 to the latch element 20 is completed by an actuator link 144 formed in two telescoping parts, as best seen in FIGS. 1, 2 and 8. The bottom of the lower part 146 is pivotally connected at 148 to a point near the rim of the disc 124 and extends upwardly having an offset section 150 to permit space for the latching shaft 98. The upper end of part 146 above section 150 is of tubular shape having a piston 152 riding in its bore. A piston rod 154 extends trough an aperture 156 in the cap of the tubular portion, and a nut 158 threaded on the piston rod 154 limits downward movement of the piston, as viewed in FIG. 8, upward movement being limited by engagement of the piston 152 with the cap 160 threaded on the tubular portion. The described arrangement of piston 152 and associated parts yields a small amount of play and adjustment thereof. The

upper end of the piston rod is pivoted by pin 162 to the free end 'of the trigger actuator arm 96. This arm is biased" downwardly by coil spring 164 hooked thereto and secured at its other end, in an convenient manner, to a lug 166 on the wall of the tubular support 32. Coil spring 164 biases the actuator arm to its down, or normal position, as illustrated in FIG. 1, which correspondingly positions the trigger across the bore of the tubular support, as shown in the same Figure.

It will be apparent from close examination of FIGS. 9-H that in the normal position of the trigger with the ram raised and the tongs in open condition corresponding to FIG. 1 that the locking arm 20 extends partly across the bore ofthe tubular support and under the cooperating latching bar, or element 18 which is welded, or otherwise suitably secured within the bore and to the walls of the ram. This prevents downward movement of the ram and closing of the tongs. In this condition, the actuator link M6 is pivotally secured to the disc 12 at a location below and slightly to the left of a vertical plane passing through the trigger shaft 126, so that upon actuation of the trigger lifting of ram 16 the actuator arm 146 will lift and turn the disc 1416 clockwise, as indicated by the arrow in FIGS. 9 and III. This will cause the lower end of slot 122 to engage and turn the dog I20 pivoting the latch bar out of the bore of the ram into its unlatched condition shown in FIG. 6. FIG. 11 shows an intermediate position wherein the disc has turned partly. Since the cam follower ll34l is being carried by the disc in the same direction as the latch 20 and the cam 126, the follower and cam will not change position relative to one another.

When the ram releases the trigger M and starts downwardly, pin 148 will still be to the left of the vertical plane through the center of latching shaft 93. As a result, spring 1641 will lower arms 96 and I46, the later turning the disc I24 counterclockwise and moving to the position shown in FIG. 10. During this return slot 1122 does not engage dog 120 so that the latch bar 20 remains in its unlatched position. The spring 114 previously described as being connected to the crank arm 112 on the latching shaft is much stronger and in its FIG. 5 position exerts a much greater biasing force on the latching shaft than does the spring 136 which biases the cam follower against the cam 126. Return rotation of the disc 124 wherein the cam follower and its spring oppose the action of spring 114 will result in moving the cam follower 134 to override the cam and take position on the opposite side of the cam. Thus, the lock bar will remain in its unlocked position despite return ofthe disc.

A similar action occurs upon reverse movement of the lock bar 20 when the grapple is lowered and raised to release a load. In this instance, lifting of the ram and trigger through actuator link M6 first turns the disc, as in FIG. 10, counterclockwise moving the lock bar 20 in the same direction. Upon release of the trigger and downward movement of the ram the disc will turn clockwise and return to its FIG. 9 position, the cam follower overriding the cam thus holding the latch bar 20 in its locking position. In this way, the cam and follower arm do not prevent the movement ofthe locking lug 20 to latching, or unlatching positions. However, once either of these movements is completed, the linkage mechanism 22 under the influence of the trigger actuator spring 164 moves back toward its initial position corresponding to the normal position of the trigger M, but the locking lug remains stationary.

The described structure operates in the following manner. Assuming that the parts are in their positions illustrated in FIG. 1 with the tongs locked in open condition, and a hoist, or crane, hooked to the loop 34, the hoist operator lowers the grapple to engage a log, or other load, disposed on the ground. When the upper surface of the log strikes the tongs just under their pivot pin 44 the tongs, pivot pin and ram 16 will elevate with respect to the support member lltl and the ram will slide upwardly in the bore of the tubular portion 32 of the support member until the roller b2 contacts the trigger and moves it upwardly. The trigger and trigger shaft 90 will turn against the bias of spring 164 causing the actuator arm 96 to rotate counterclockwise in FIG. 1. As a result, the disc 24 will rotate clockwise from its FIG. 9 position and upon release of the trigger, will return to its FIG. position, as previously explained, moving the locking lug out of the bore of the tubular support 32. The hoist may then be operated to lift the grapple during which movement the ram 16 will slide downwardly in the bore of the tubular support 32, and not being impeded or prevented by the unlatched lug 20, the tongs will move with the ram and by gravity to closed position to clamp the log. Continued upward movement of the grapple will, therefore, lift the log, or other load, from the ground, and the load then may be moved to any desired location. During such movement, the cam follower engages the upper side of the cam 126 in the manner shown in FIG. 1b, holding the latching element 20 out of the bore of the tubular support so as to free the same for subsequent upward movement of the ram within the support bore. During all lifting and transporting movements of the grapple, the tongs will be in closed condition, held and tightened therein by the weight of the load and will extend downwardly as shown in FIG. 5.

To unclamp the grapple from the load, it is merely necessary to again lower the grapple until the log is deposited on and touches the ground, or any surface intended to receive the same. If the grapple is then continued to be lowered a slight distance, the ram will slide upwardly in the unimpeded bore of the tubular support and again strike and lift the trigger, open ing the tongs to release the load. This movement of the trigger will elevate the actuator link arm 146, rotating the disc K24 counterclockwise, as viewed in FIG. 10, and returning the locking element 20 to latching position as previously explained. Raising the grapple will lower the ram in the bore of the tubular support away from the trigger until the latching bar 10 seats on latch element 20, holding the tongs open. The return movement of the disc 124 to its condition shown in FIG. 9 has previously been explained. The log having been released by initial opening of the tongs will not be reclamped by the tongs as the grapple is lifted further, and the grapple is then in condition to be applied to another log, the tongs being open and ready to repeat the clamping action described in the preceding paragraph.

It should be clear from the above that the described device is self-operating, clamping the load automatically by merely lowering the grapple to engage the load, and subsequently raising the grapple. Thus, the clamping is accomplished by a sequence of two opposite movements in the same vertical line. Correspondingly, to unclamp the load, the grapple is again lowered vertically and upon triggering is then elevated to remove the grapple from the load. Obviously, these simple movements can be performed easily by the hoist, or crane operator without the need of assistance of another man, or men, positioned at the load, or the grapple. Furthermore, the construction of the grapple is such that once clamped, the load is safely held and carried by the hoist without danger of unclamping. Even swinging movements and striking of either the grapple or the load against a foreign object will not unclamp the grapple, it being necessary to follow the described sequence of movements in a straight line first in one direction and then in the other direction to accomplish the unclamping. While the preferred embodiment entails vertical clamping and unclamping movements, the device may be modified to utilize movements in other directions. Although embodiment of the invention has been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not intended to be restricted to the exact showing of the drawings and description thereof, but is considered to include reasonable and obvious equivalents.

We claim:

II. An automatic grapple device comprising a support member having means for attachment to a hoist, a pair of crossed, clamping tongs pivoted to one another at their crossing point, link means connecting the upper ends of said tongs to the lower end of said support member, a ram connected at one end to the pivot of said tongs, means on said support member defining a path for movement of said ram during closing and opening of said tongs, a trigger fixed to a pivot shaft and extending into said path to be struck by said ram, cooperating latching elements carried by said ram and support member for holding said tongs open, and link mechanism connecting said trigger to one of said latching elements and operative to move said one latching element into and out of latching engagement with the other latching element when actuated by movement of the trigger, said link mechanism comprising an actuator arm secured at one end to said pivot shaft, an actuator link pivotally secured at one end to the other end of said actuator arm, a second shaft rigidly mounting said one latching element, and means connecting the other end of said actuator link to said second shaft operative to rotate said one latching element to either latching or unlatching position, said last-named means including a disc rotatably mounted on the second shaft and pivotally connected to the actuator link, a slot in said disc shaped as a segment of a circle and coaxial with said second shaft, and an arm secured to said second shaft and having a dog extending into said slot, whereby turning of said disc by movement of said actuator arm results in turning of said second shaft through engagement of the ends of said disc slot with the dog of said arm secured to the second shaft.

2. An automatic grapple device according to claim 1, wherein a stabilizer arm pivotally connects the upper end of one ofsaid tongs to the support means at a point spaced on the other side of the ram as the connection of the corresponding link means supporting the same tong.

3. A grapple device according to claim 1, wherein said means defining a path for movement of said ram comprises a vertical tube in which said ram slides, said tube having slots in its wall permitting movements of said trigger and said one latching element across the bore of the tube.

4. A grapple device according to claim 3, wherein said trigger is positioned near the upper end of said tube and above said one latching element when the latter is disposed across the bore of the tube.

5. A grapple device according to claim 3, wherein said ram comprises a hollow tube having slots in its wall permitting movements of said trigger and said one latching element acrossthe bore of the ram.

6. A grapple device according to claim 5, wherein said ram is provided with a trigger actuator in the form of a roller journaled in the wall of the tubular ram adjacent the upper one of said slots.

7. A grapple device according to claim 6, wherein said latching element carried by the ram comprises a latch bar secured in the bore of the tubular ram immediately above the lower one of said slots.

8. A grapple device according to claim 1, wherein said second shaft has a cam affixed thereto, a cam follower being pivotally secured to said disc, biasing means urging said cam follower against said cam so as to prevent rotation of the second shaft, a second biasing means of greater force than said first biasing means connected at one end eccentric to said disc and fixed at the other end to said support member, whereby said second biasing means overcomes said first biasing means and causes the cam follower to override the cam to retain the second shaft and connected latching element in either latched or unlatched position on return movements of the trigger and disc.

9. A grapple device according to claim 8, wherein a third biasing means is secured between said support member and said trigger actuator arm to oppose movement of the trigger and return the trigger to its normal position across the bore of said path in said support member.

10. A grapple device according to claim 8, wherein said pivotal connection of said actuator link to said disc is offcenter thereof and so arranged in relation to said cam follower and cam as to be beyond center of said second shaft in both the latching and unlatching positions thereof, whereby said discs and connected parts act as a toggle under force of said second biasing means to hold the said latching elements in both their latched and unlatched positions, and each successive trigger actuation will through resulting movement of said actuator link move said disc to rotate in the opposite direction from the precedin movement. I

11. A grapple evice according to claim 10, wherein said actuator link is formed of a pair of telescoping members having stop means limiting relative motion therebetween in both directions, whereby the resulting movements imparted to said discs and one latching element by the actuator link are accomplished with a snap action during a limited portion of movement ofsaid trigger.

12. A grapple device according to claim 8, wherein said cam follower comprises a wheel rotatably mounted on an arm one end of which is pivoted to said disc, said first biasing means urging said arm in a direction to engage said wheel against said cam, said cam, arm and wheel being so arranged that turning of the second shaft in either direction as result of return force of said second biasing means will cause the cam to override the follower wheel depressing the follower arm against the urging of said first biasing means.

Claims

1. An automatic grapple device comprising a support member having means for attachment to a hoist, a pair of crossed, clamping tongs pivoted to one another at their crossing point, link means connecting the upper ends of said tongs to the lower end of said support member, a ram connected at one end to the pivot of said tongs, means on said support member defining a path for movement of said ram during closing and opening of said tongs, a trigger fixed to a pivot shaft and extending into said path to be struck by said ram, cooperating latching elements carried by said ram and support member for holding said tongs open, and link mechanism connecting said trigger to one of said latching elements and operative to move said one latching element into and out of latching engagement with the other latching element when actuated by movement of the trigger, said link mechanism comprising an actuator arm secured at one end to said pivot shaft, an actuator link pivotally secured at one end to the other end of said actuator arm, a second shaft rigidly mounting said one latching element, and means connecting the other end of said actuator link to said second shaft operative to rotate said one latching element to either latching or unlatching position, said last-named means including a disc rotatably mounted on the second shaft and pivotally connected to the actuator link, a slot in said disc shaped as a segment of a circle and coaxial with said second shaft, and an arm secured to said second shaft and having a dog extending into said slot, whereby turning of said disc by movement of said actuator arm results in Turning of said second shaft through engagement of the ends of said disc slot with the dog of said arm secured to the second shaft.

2. An automatic grapple device according to claim 1, wherein a stabilizer arm pivotally connects the upper end of one of said tongs to the support means at a point spaced on the other side of the ram as the connection of the corresponding link means supporting the same tong.

5. A grapple device according to claim 3, wherein said ram comprises a hollow tube having slots in its wall permitting movements of said trigger and said one latching element across the bore of the ram.

10. A grapple device according to claim 8, wherein said pivotal connection of said actuator link to said disc is offcenter thereof and so arranged in relation to said cam follower and cam as to be beyond center of said second shaft in both the latching and unlatching positions thereof, whereby said discs and connected parts act as a toggle under force of said second biasing means to hold the said latching elements in both their latched and unlatched positions, and each successive trigger actuation will through resulting movement of said actuator link move said disc to rotate in the opposite direction from the preceding movement.

11. A grapple device according to claim 10, wherein said actuator link is formed of a pair of telescoping members having stop means limiting relative motion therebetween in both directions, whereby the resulting movements imparted to said discs and one latching element by the actuator link are accomplished with a snap action during a limited portion of movement of said trigger.