PURPOSE: To double the housing capacity of a transportation vehicle, by equipping a gate-type frame with a vehicle positioning mechanism and a hook mechanism, which is engaged with the bottom of the transportation vehicle to elevate it, to perform stacking at two levels in the vehicle.

CONSTITUTION: Guide plates 3 for the wheels 16 of a transportation vehicle A are placed inside the bottom of a gate-type frame 1. Hooks 2, which are operated by drive links 5 coupled to cylinders 4, are provided in a front and a rear positions at one side of each lower portion of the frame 1. A positioning mechanism 2 is composed of the guide plates 3 and the hooks 6. Chains 10 are secured on a pair of base frames 7 and engaged with a pair of right and left sprockets 8, which are rotated by a motor drive mechanism 9 to move the base frames 7 up and down. The frames 7 are fitted with hooks 12, which are operated by parallel links 11. These links are actuated by drive links 14 connected to cylinders 13.