PURPOSE: To make a truck optionally selectable on each track in a limited space by installing a wheel group (b) for a track B in a vehicle so as not to interfere with another track A, and when the vehicle on the track A is stopped at a track crossing part, lifting the track B just under the wheel group (b) with a lifting gear.

CONSTITUTION: A truck travels on a track A by wheel groups a1-a4, and at a time when wheel groups b1-b4 are reached to place just above a lifting rail 20 in a state of being downed, a coupler 41 of a lifting gear 40 is driven upward. If so, the lifting rail 20, where rails 21 and 22 are connected by means of hinges, rotates upward with pins 31, 32 as the center, caning into contact with the wheel groups b1-b4. When the lifting gear 40 goes up as far as the specified value even afterward, the whole truck 10 is somewhat pushed up, and consequently the wheel groups a1-a4 on rails A2 and A2 of the track A are moved upward, separating from these rails A1 and A2, thus the truck 10 comes to such a state as being mounted on rails B1 and B2 of a track B by the wheel groups b1-b4.