Gravity operated mechanical grab

Claim 1

A gravity-operated mechanical grab attachable to a single hoist line for automatically picking up and releasing loads, comprising: two telescopic members with one telescopic member attachable to the single hoist line and the other telescopic member slidable in relation to the one telescopic member; opposing jaw elements pivotally mounted on the other telescopic member for selectively closing to receive a load therebetween and opening to release the load; linkage means extending between the one telescopic member and the opposing jaw elements for pivoting the jaws in response to the relative movements of the telescopic members to automatically close the jaw elements as the mechanical grab is lifted and automatically open the jaw elements as the mechanical grab is lowered onto the ground; said telescopic members having corresponding side apertures formed therein which are aligned with each other when the jaw elements are open; a stop means mounted on the outside of the telescopic member having an end for pivotal movement into and out of the aligned apertures when the jaw elements are open to prevent and permit respectively relative movement between the telescopic members; a cam means mounted on the outside of the other telescopic member for movement therewith; an over-center spring means operatively connected to the stop means for biasing the stop means end into and out of the aligned aperture from a neutral position; a cam follower means mounted on the outside of the one telescopic member in the path of the cam means and operatively connected to the stop means for pivoting the stop means alternatively past the neutral position in opposite directions when engaged by the cam means to render the spring means effective to move the stop means into and out of the aligned apertures.