GB190908917A - Improvements in Lifting Grabs or Dogs. - Google Patents

Abstract

8917. Thomas, F. April 15. Lifting - dogs. - The gripping - members o f lifting-dogs are formed by eccentric wheels or rollers, which are forced into the gripping position automatically by a spring or weight. Fig. 5 shows one form of apparatus in which eccentric gripping-rollers g are mounted in a U-shaped frame a and are geared to one another by a chain, rope, or band q passing round a central pulley p<1>. A spring i, Fig. 4, is mounted in a recess in each roller, and is attached at one end to a pin l on the roller, the other end bearing against a pin m on the frame. The gripping-members may b e weighted s o a s t o tend to close automatically, instead of a spring being used. A chain k or a handle w secured to the roller may be operated to open the gripping-members. In a modified form, endless chains lying in chain grooves on the periphery of the wheels are used. The gripping-members may be operated independently instead of being geared together; also two or more eccentric rollers may be provided in each jaw. Fig. 7 shows a dog with movable jaws. The jaws d<1>, e<1> are forked and are provided with dovetail projections fitting into similarly - shaped guiding- slots on each face of the frame a. A right and left handed screw, rotated by hand - wheels s<2> and prevented from longitudinal movement by a collar s', is used to position the jaws. A ratchet-wheel n<1> and pawl n<2> prevent backward rotation of the screw due to the pressure on the jaws. Handles x are provided on the frame to allow the frame to be guided when the dog is being used.