US1840329A - Lifting tongs - Google Patents

Description

Jan. 12, 1932. A. PORTUONDO LIFTING TONGS Filed June 1, 1929 Patented Jan. 12, 1932 UNITED STATES PATENT OFFICE A'URELIO PORTU'ONDO, OF FELTON, CUBA, ASSIGNOR TO 13ETIFELEIEIEIVI STEEL COMPANY, A. CORPORATION OF PENNSYLVANIA LIF'IING TONGS Application filed. June 1,

This invention relates to lifting tongs, and more particularly to the automatic releasing type.

An object of my invention is to provide a tong which will securely grip an object while being lifted or lowered.

A further object is to provide a releasing device which will open the tongs and automatically lock them in that position to insure the release of the tongs from the object being handled.

My improved tong is particularly useful when handling explosive charges which are to be lowered into a hole. When the charge has reached the bottom of the hole, the tongs are automatically released from the charge and prevented from closing again while being withdrawn from the hole.

The novel features of my invention will be more fully understood from the following description and claims taken with the drawings, in which Fig. 1 is an elevation of the tongs in open and closed position. The full lines illustrating the relation of its parts when gripping an object and the dotted lines illustrating the relative position of its parts in open or released position.

Fig. 2 is a section taken on the line 22 of Fig. 1 and shows the gripping ends of the tongs in released position relative to the obj ect being handled.

Referring to the drawings: I have shown my device as comprising a pair of elongated lever members 10 pivotally connected near their lower ends by a rivet 11 or the like. At a point 12 slightly below the pivot, the levers are twisted at an angle of 90 and bent outwardly as shown at 13. The lower ends of the levers 14 are made wider than the main arms 10, and curved as shown in Fig. 2. The lower ends of the curved portions 14 are formed with lateral extensions 15 and comparatively sharp at their edges which constitute gripping jaws.

The upper ends of the levers are provided with holes 16 within which are engaged the links 17 which in turn are engaged within a ring 18 which is adapted to be engaged by a lifting hook or hoisting cable, not shown.

Intermediate the pivot 11 and the ends of the tongs 15, is provided a toggle joint 19. The joint comprises two short levers 20 and 21 provided with pivoted connections 22 at their outer ends to L shaped brackets 23 which in turn are secured to the bent portions 13 of the levers 10. The inner ends of the toggle levers are pivotally connected by a. riveted pin 24 or other suitable means. The toggle levers are provided with projecting faces 25 and 26 respectively, which are adapted to form jaws and to abut each other when the tongs are in an open or released position. It will be noted that when the tongs are in their released position, as shown by the dotted lines of Fig. 1, that the jaws 25 and 26 are so positioned relative to their angular movement that the pivoted center 24 lies above the line 27 intersecting the centers of the pivots 22, which constitutes the dead center of the joint. In other words, when the pivoted center of the toggle has passed over the dead center, further movement of the center joint in an upward direction is prevented by the abutting jaws 25 and 26.

It will be obvious that with the tongs suspended from a hoist line, that the tendency of the lower ends will be to move toward each other and to collapse the toggle joint either upwardly or downwardly but with the tongs in their opened position and the toggle prevented from further movement above the dead center point, the tongs cannot move inwardly until the toggle has been moved in a downward direction to break the joint.

In the use of the tongs, if the tongs are open and the toggle is in its uppermost or locked position, the toggle is broken by forcing it downwardly over its dead center point. The tongs are then lowered over the charge until the center portion 19 of the toggle rests upon the charge. The lower ends of the tongs are then brought together into gripping relation with the charge which causes a slight backward movement of the tongs relative to the charge which establishes their normal gripping position. vVhen a pull is applied to the hoist line, the upward strain on the ring 18 will cause the links 17 and the arms 10 of the tongs to be brought together and consequent- 1y swing the levers about the pivoted connection 11 so that the gripping jaws 15 will bindingly engage the charge as shown by the full lines in Fig. 1. The charge may then be low- 5 ered into the hole.

After the charge has reached the bottom of the hole, the hoist line is slackened which causes the gripping edges of the tongs to be released from the charge, and the tongslfy reason of their weight, slip downwardly over the charge. It will be seen that as the tongs move downwardly relative to the charge, and inasmuch that the center portion of the toggle is resting on the top of the charge, that the resulting action will be to straighten out the toggle joint which causes the tongs to open, and after the center of the toggle has passed beyond the dead center point and the opposing jaws of the joint are brought together,

that no further opening of the tongs can take place, and by reason of the relative position of the pivoted points of the toggle, the tongs will be held open, thereby allowing the tongs to be lifted and the ends prevented from closing until the toggle is again broken.

It will be seen from the foregoing description and a study of the drawings that I have provided a simply constructed and inexpensive tool which will be efficient and safe in use. The tongs are especially adapted to handle explosive charges which are to be lowered into a hole and thereafter to be automatically and positively released, without the accompanying danger of again engaging the charge in an insecure manner, whereby the charge might again be lifted and caused to fall with a possible resulting premature explosion.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and I desire therefore that only such limitations shall be placed thereupon as are imposed by the prior art, or as are specifically set forth in the appended claims.

Having thus described my invention what I claim as new and desire to secure by Let- 50 ters Patent is:

1. Tongs for lowering explosive charges into a deep hole, comprising crossed levers pivotally connected to each other, curved jaws at the lower ends of the levers, said jaws being of uniform section formed as sectors of a ring of greater length than their projecting width and having parallel longitudinal edges, gripping means at the ends of said jaws, a hoist line means connecting said hoist line with the upper ends of the levers for drawing them together, and means effective upon the slacking of said hoist line to automatically release the tongs when the charge has reached the bottom of the hole.

G 2. Tongs for lowering explosive charges into a deep hole, comprising crossed levers pivotally connected to each other, curved jaws at the lower ends of the levers formed as sectors of a ring with gripping means at their ends, said levers being twisted and outwardly bent at a point below said pivot t form connections between the levers and the jaws, means connected with the upper ends for drawng them toget 181 and means to automatically release the tongs from the charge and lock them in opened position when the charge has reached the bottom of the hole.

3. Tongs for lowering explosive charges into a deep hole, comprising crossed levers pivotally connected to each other, curved jaws at the lower ends of the levers, said jaws being formed as sectors of a ring of greater length than their projected width and having longitudinally straight inner and outer faces, gripping means at the ends of said jaws, and means to automatically release and open the tongs when the charge has reached the bottom of the hole and to hold the jaws in longitudinal parallel position when opened.

4. Tongs for lowering explosive charges into a deep hole, comprising crossed levers pivotally connected to each other, curved jaws at the lower ends of the levers, said jaws being formed as sectors of a ring of greater length than their projected width, gripping means at the ends of said jaws, and means to automatically release and open the tongs when the charge has reached the bottom of the hole and to hold the jaws in longitudinal parallel position when opened, the curved portion of the jaws being of substantially uniform section to a point above the article being handled when in gripping position.

5. Tongs for lowering articles into a hole, comprising levers pivotally connected to each other, curved gripping members of substantially uniform section at the lower ends of the levers and of greater length than their width, a toggle positioned adjacent the upper ends of the gripping members, said toggle comprising links having inner ends of greater bearing surface than their outer ends, the inner end of one of said links having a depending lip portion formed within the planes of the faces of said end, the other link having a projecting portion formed at right angle to its face and adapted to abut the l lip portion of its companion link when the tongs are in opened position, and brackets to connect the outer ends of the links to the tong levers.

' In testimony whereof I hereunto aflix my 125 signature.

AURELIO PORTUONDO.

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