As a percussion hammer with a free piston operating percussion piston

摘要

The striker is mounted in a barrel for axial reciprocal movement thereby to impart successive hammer blows to the end of a tool shank element extending into one end of said barrel. An actuator is connected to the piston by lost-motion means. A motor driven, mechanical crank assembly is connected to the actuator for reciprocating the piston such that its velocity in the hammer-direction is greater than its velocity in the return-direction.