Are you sure you're seeing "rescuevators" and not brake release devices? A "rescuevator" would automatically cycle the elevators like you suggest, a brake release device is manually operated by a properly trained person to allow the car to drift according to its (im)balance... Bad things can happen if this is not used properly... BAD things... Also note all of the switches must be set properly so the battery is charged and the mainline disconnect should have an auxillary contact so the drift box only operates properly.
