Pneumo-hydraulic booster with rapid-traverse feature

A pneumo-hydraulic booster having a rapid-traverse operation for driving a punching tool comprising

• a housing having first, second and third chambers therein;
• a first piston mounted to slide within said housing to repeatedly drive the punching tool by means of a power stroke and a return stroke;
• said first and third chambers being selectively connectible to sources of pressure fluid and a venting atmosphere;
• a second piston mounted to slide within said housing and positioned in tandem with said first piston, said second chamber being located on the side of said second piston remote from said first piston;
• a booster valve having a first connection to said first chamber, a second connection to said third chamber, and a third connection to said second chamber, said booster valve being responsive to the pressure differential between said first and third chambers;
• means actuating said first piston by directing pressure fluid into said first chamber, said first chamber thereby having a predetermined pressure to drive said first piston in a direction to establish contact with the punching tool;
• and said pressure differential being of a value to hold said booster valve in a first position allowing no pressure fluid to pass to said second chamber;
• said pressure differential being subject to variation by contact of said first piston with the punching tool, said booster valve thereby being movable to a second position due to said variation of said pressure differential, said second position of said booster valve allowing pressure fluid to pass to said second chamber to drive said second piston in said driving direction to contact said first piston to provide an increased driving force on the punching tool.