PURPOSE: To move a heavy cargo at a low grounding pressure and extreme low speed, by coupling a cargo and a base plate by means of 3 pieces each of vertical support legs and travelling support legs, and by giving a forward and backward motion to the base plate with the travelling support legs expanded and contracted.

CONSTITUTION: A base plate 2 is located under a cargo 1, and these two objects are coupled by 3 pieces each of vertical support legs 3W5 and travelling support legs 6W8. The vertical support lege 3W5 and travelling support legs 6W8 form each plane equilateral triangle, the vertical support leg 5 and travelling support leg 8 are coupled with a revolving seat 9 so that the legs can swing in a vertical direction, and the vertical support legs 3, 4 and travelling support legs 6, 7 are coupled in such a manner that they can oscillate freely. When the travelling support legs 6 and 7 are shortened and the travelling support 8 is extended, and base plate 2 conducts a relative movement in a (A) direction against the cargo 2. And if the travelling support legs 6 and 7 are extended and the travelling support leg 8 is shortened, the base plate 2 moves in a (B) direction. The revolving motion can also be given to the base plate.