The door moves up and down by a screw mechanism. It cannot move up or down unless the motor is turning. The threaded rod turns via a 6 volt geared motor. It will easily lift a 2 1/2 lb door which is about the size of a 12 inch by 12 inch piece of 1/2" plywood.
For the Ladies First Door opener to work well there should be plenty of wiggle room between the door and the rails it rides up and down on. There shouldn't be any binding or sticking when the door moves. If the door is too hard to lift a replaceable fuse will blow saving the motor and electronics. The fuse holder is located on the outside of the box on the left handed side.