Abstract: A tool changer including male and female flanges for respectively connecting end effectors to robot arms and the like. A male flange assembly having a tapered projection is inserted into a tapered female flange member having a rod aligned along the diameter of the tapered opening. A rotatably mounted locking stud is aligned within an opening in the male tapered projection and is machined to provide a slot having locking grooves as its lower end. The stud is rotated through a 35 degree angle causing the male and female flanges to be drawn together until the cooperating tapers are seated together. A spring retains the flanges in the locked position. A cooperating pin and pin receiving socket respectively provided on the male and female flanges at locations displaced from the male and female tapers are utilized to assure the proper orientation between flanges and to prevent rotation of the flanges.