Abstract: A failsafe hydraulically operated tool clamping system for use on press brakes comprising a series of pressure/spring actuated piston control units or actuators. These actuators are attached to the press brake tool clamps by a plurality of spaced bolts which extend through the actuators and the fixed and slidable members defining the tool clamps. Compression or Belleville springs urge the fixed and slidable clamp members into tight engage with the tool set punch and die. To open the clamp, pneumatic or hydraulic pressure is applied against the actuator piston thereby overcoming the force exerted by said springs and releasing the punch and die. Both tool set members remain firmly gripped within respective tool clamps in the event of system pressure loss thereby assuring failsafe retention thereof. The lower or bed clamp assembly comprises an L-shaped slidable member and a fixed member with a slot for receiving one leg of the L-shaped member.