a selector device for moving at least one object such as a substrate to a processing station includes an object - holder rotatably mounted on a support and having areas for receiving objects to be processed which can be moved successively to the processing station . a force accumulator member connected to the object - holder rotates the object - holder in one direction . an incrementer mechanism has a stop system on the support and an abutment system on the object - holder and respectively associated with the receiving areas . the stop system cooperates successively with the abutments of the abutment system to hold the object - holder at successive positions such that the receiving areas are successively located at the processing station . a trigger arrangement operates on the incrementer mechanism so that the stop system passes selectively from one abutment to the next abutment after rotation of the object - holder by the force accumulator member .