Abstract: There is disclosed herein an improved machine tool holder/adapter and drive spindle nose. The drive spindle nose is tapered and includes a circumferential locking groove. The tool holder/adapter includes a tapered central recess for receiving said spindle nose and a plurality of radially movable lock pins. Biasing means are provided for direct coaction with the lock pin means so as to urge the lock pins in an outward direction. The length of the pins, the size of the spindle nose and the diameter of the circumferential groove are selected so as to prevent the spindle nose from striking the lock pins as the spindle nose moves into the tool holder/adapter for lockingly engaging said tool holder/adapter.

Abstract: There is disclosed herein an improved tool holder/adapter for use in a mechanical and automatic machine tool. The machine tool includes: (1) a drive spindle; and (2) a rotary turret for releasably storing a plurality of tool holder/adapters. Each holder/adapter is secured to the turret by a set of radially movable locking pins which are cammed to a radially outward position. There is also provided a set of axially movable travel limit stop pins for cooperation in maintaining the locking pins in a radially outward position. The travel limit stop pins cooperate with the spindle for releasing the locking pins and permitting them to move radially inwardly so as to release the tool holder/adapter from the turret. The stop pin construction and location combine to provide both positive and blocking engagement between the lock pin and stop pin so as to prevent unintentional inward movement of the lock pin and possible unintentional holder/adapter-turret disengagement.