A clamping fixture features a chuck provided with a locking mechanism for releasably locating a workpiece pallet. The locking mechanism comprises a plurality of clamping members which in the locked position are engineered to engage a clamping spigot connected to the workpiece pallet. Each clamping member, or alternatively an actuating member assigned to a clamping member, is provided with a feedthru bore which on correct locking and/or release of the corresponding clamping members is closed off at one end. The feedthru bores are connectable by a common connecting conduit to a compressed air source. In addition, at least one sensor is provided for sensing air flow in the connecting conduit by means of which it can detected whether the clamping members are correctly released or locked.