To easily and quickly load and unload tools to be stored on a high plane, such as on a vehicle body.

A load carrying platform 3 allowing a tool such as a chair to be attached thereto and removed and a driveshaft 9 rotated in opposite directions by a drive source 4 are interconnected by a swing arm 11. Oscillation of the swing arm 11 causes the load carrying platform 3 lying on the vehicle body 1 to tilt and fall from the top of the vehicle body 1, with the connection between the platform and the swing arm 11 facing up. A speed governor 3 is attached to the driveshaft 9, and a counter torsional moment resisting the torsional moment produced by the swing arm 11 is produced on the driveshaft 9 according to the inclination of the swing arm 11. Thus, the swing arm 11 oscillates at a constant angular velocity, whereby the tool held on the load carrying platform 3 can be easily and quickly loaded and unloaded without plummeting.