Retracting bolster for a press

A press having a frame structure with a crown and a bed, a slide guided by the frame structure for reciprocating movement in opposed relation to said bed, and a bolster assembly mounted to said bed, said bolster assembly comprising:

• a base mounted to said bed,
• a bolster having an upper surface in facing relation to said slide,
• said bolster being supported on said base and guided by said base for movement in opposed relation to said bed and slide between extended and retracted positions,
• hydraulic piston and cylinder means associated with said base and bolster for rigidly holding said bolster in its extended position when charged with high pressure hydraulic fluid and for permitting said bolster to retract when the high pressure hydraulic fluid is released,
• selectively actuatable valve means for releasing hydraulic pressure in said piston and cylinder means to cause said bolster to retract to its retracted position thereby achieving slide and bolster separation sufficient to permit easy die access for maintenance purposes and the like,
• at least two movable clamp elements connected to one of said base and bolster and having first clamp surfaces,
• at least two second clamp surfaces on the other of said base and bolster, said second clamp surfaces being adjacent and in direct facing relation with said first clamp surfaces, and
• means for urging said clamp elements towards said second clamp surfaces such that said first clamp surfaces move into tight abutment with said second clamp surfaces so as to rigidly clamp said bolster against lateral movement.