Abstract: A gear mechanism is disclosed which is installed between the bottom of a trailer and the trunion shaft of a rear wheel assembly of the trailer to cause the rear wheel assembly of the trailer to rotate in the opposite direction from the turning direction of the forward end of the trailer. A plurality of pinion gears are rotatably mounted in the space between a hollow inner cylindrical member and a hollow outer cylindrical member. The inner and outer cylindrical members are secured at their bottom ends to a bottom ring gear and their top ends are received on thrust bearings mounted in a top ring gear. The top ring gear is attached to the bottom of the trailer and the bottom ring gear is attached to the trunion shaft of the rear wheel assembly. The toothed surface of the pinion gears are in rolling engagement on the rack gear portions of the top and bottom ring gears.