Reversible underground piercing device

摘要

A reversible pneumatic underground piercing tool of the type having a reciprocating striker with the impact of the striker on the front or the rear of the tool being controlled by the longitudinal position of a valve element in the tool. An interengaging pin and slot arrangement in the tool defines the longitudinal the valve element which is positively maintained in the selected position by the supplied air pressure. The longitudinal position of the valve element may be changed for reversing the direction of movement of the tool by interrupting the compressed air supply and rotating the air supply hose a small amount in one direction or the other to reposition the pin in the slot.