Manual tong safety latch

摘要

A latch device for a manual tong apparatus that incorporates a secondary catch mechanism is presented. Such a secondary catch would assist in maintaining the tong assembly in it's closed position during a reversing operation or at a time when load applied to the manual tong device in the gripping direction is very low. Additionally the secondary catch would also provide some additional protection by holding the tong assembly together in the event of a failure of certain tong components. The mechanism of the secondary catch is spring loaded and operates through two secondary up-down catch arms that are deactivated by swinging a handle in the direction that corresponds to the operator's natural motion to open the lug jaw.