2. IN AN OVERHEAD CONVEYOR SYSTEM, THE COMBINATION COMPRISING A TRACK, A CARRIER UNIT MOVABLE ALONG SAID TRACK, SAID CARRIER UNIT HAVING A PLURALITY OF SIGNAL MEMBERS SELECTIVELY POSITIONABLE VERTICALLY ON SAID CARRIER UNIT, AND A MECHANISM FOR RESETTING THE SIGNAL MEMBERS POSITIONED ALONG SAID TRACK COMPRISING A PLURALITY OF CAM MEMBERS, MEANS FOR MOUNTING EACH SAID CAM MEMBER FOR MOVEMENT INTO AND OUT OF THE PATH OF THE SIGNAL MEMBERS ON THE CARRIER UNIT, AND INDIVIDUAL ELECTROMAGNETS FOR SAID CAM MEMBERS FOR HOLDING SAID CAM MEMBERS OUT OF THE PATH OF SAID SIGNAL MEMBERS AND MEANS FOR DEENERGIZING EACH SAID ELECTROMAGNET TO PERMIT ITS RESPECTIVE CAM MEMBER TO MOVE INTO THE PATH OF THE SIGNAL MEMBERS.