Cooperating bolster and fixture construction for quick-change fixturing

A machine tool bolster and fixture combination, comprising:

• said bolster including a fixture support surface having an opening extending therethrough;
• a pressure-operable clamp device received in said opening and serving as sole means for clamping the fixture to the support surface;
• said clamp device including an upper end defined by a clamp element holder, a plurality of clamp elements mounted in the holder for horizontal movement between respective extended positions, wherein they extend beyond an outer periphery of the holder, and respective retracted positions and a pressure operable means for simultaneously moving said clamp elements from their retracted to their extended positions when pressurized;
• said fixture including a locating plate engaging said support surface and being provided with a receptacle receiving said clamp element holder;
• said receptacle including surface means surrounding the periphery of said holder and being disposed for engagement by and for cooperating with the clamp elements as sole means for effecting the disposition of the locating plate in a preselected location against said locating surface when the clamp means are moved to their extended positions by said pressure operable means, such movement also effecting clamping of the locating plate against the support surface.