Abstract: A system for controlling a reciprocable double acting air motor including a pair of power valves for reversing the inlet and exhaust air to and from opposite sides of the piston in the air motor. The control apparatus includes a pair of snap opening pilot valves which are unseated in response to momentary mechanical engagement with the piston of the air motor and which are then pneumatically shifted open so that the energy to effect the pilot valve shift is derived from the air supply line and not from the air motor piston. The return of the pilot valves to the closed position is in response to pressure reversal in the air motor. The power valves each include a pair of chokes, one of which is continuously operable and is of moderate flow restriction and the other of which is intermittently operable and is of high flow restriction.