PURPOSE: To maintain the direction of bodies when the direction of trucks is changed, by setting guide rails to the conveyer bodies.

CONSTITUTION: Conveyer bodies 4 are towed by a chain 3, and the direction of the conveyer bodies 4 is changed by sprockets 2. During linear motion of the chain 3, a guide rail 15 is also linearly set in parallel, when rotary motor of the chain 3 is started by the sprocket 2, the guide rail forms a curved guide part synchronously with a turning point. Front and rear knuckle arms 14 of a truck are connected and a steering link is movably fitted to the guide rail 15 by a direction change pin 12, when the chain 3 is applied curved motion, the direction changing pin also reaches a guide part 16 and is pressed to the outside, then an actuator lever 11 operates cranks 10, 9, thus wheels 8 of the truck 7 are changed their direction through the knuckle arms 14 toward the center of rotation of the sprocket.