PURPOSE: To reduce the equipment cost, by inserting a pin provided almost in the center of truck into a pinhole opened in a floor to position the truck and moving down swivel casters from the truck to the floor and turning the truck.

CONSTITUTION: The truck 4 is stopped on a direction change center. The center pin 10 is moved down by a center pin elevator 11 and inserted into the center hole 3 opened in the floor to position the truck at a center of rotation. The swivel casters 7 are moved down to the floor by swivel caster elevators 8, thereby separating running wheels 5 from nails 1. The truck 4 is turned as a whole by a swivel caster driver 9, thus chaging the direction of the truck. Then, the swivel caster elevators 8 are lifted so that the running wheels 5 are brought into contact with the rails 1 and the swivel casters 7 are separated from the floor. The center pin 10 is pulled out of the center hole 3. This process reduces the equipment cost