<p>A tool holder system for stationary or rotatable tool holders in machine tools with manual or automatic tool change, has a tool holder provided with a mechanism for locking the tool head onto clamping surfaces, and integrated liquid coolant supply and a compressed air supply to the clamping surfaces. At the clamping end of the tool holder, a checkvalve is provided in the air supply passage to block incursion of liquid coolant even at high pressures of the latter and thus prevent corrosion and damage which may result from such corrosion.</p>
