Abstract: An apparatus for fixing and changing tools on movable working machines, e.g. robot arms, comprising a retaining element (A) with a fixing trunnion (2) fixed to the working machine part and on which are formed retaining groove (4) at right angles to its axis; a fixing element (B) fixed to the tool and having a reception opening (9) for the fixing trunnion (2) and with fixing slides (6) engaging positively in the retaining grooves (4) and displaceable in the direction of the latter in opposition to the tension of springs (7) and which have in each case one fixing opening (8) aligned in the tool change position with the reception opening (9); a change element (C) for receiving the locking element (B) in the change position with a motor (operating cylinder (13)) displaceable change fork (14) for moving the fixing slides (6) out of the fixing position and into the change position in opposition to the tension of springs (7).

Abstract: A safety stoppage or disconnection apparatus for mechanically moved tools, particularly automatic welding guns, having a swashplate and an assembly casing, between which are arranged one or more spring elements and a switch operated by the relative movement between the swashplate and assembly casing. It is necessary with such safety apparatuses to prevent other adverse rotary movement between the swashplate and assembly casing. This is brought about by two facing bolts, whose heads projecting beyond the outer wall of the swashplate are guided in slots, which run in the inner wall of the assembly casing in the intended swashplate movement direction. The bolts are spring-loaded and preferably spherical.