PURPOSE: To improve the small sharp turn performance and the running stability by extending the distance between front wheels and rear wheels during running straight and shortening it during changing the direction.

CONSTITUTION: The preceding car 1 provided with front wheels 3 and the succeeding car 2 with rear wheels 4 are connected as capable of approaching or separating, and a fluid hydraulic cylinder 9 is provided so that a piston rod 12 is pulled in when the turning angle of the handle 7 changing the direction of the front wheels 3 reaches a predetermined angle or more and the piston rod is pushed out when the turning angle is less than the predetermined angle. Therefore, when the vehicle is running straight or is turning extremely slowly with the handle 7 turning angle at zero or less than the predetermined angle, the distance between the front wheels 3 and the rear wheels 4 is lengthened and the running stability is excellent, but when the vehicle is turning quickly with the handle 7 being turned by the predetermined angle or more, the distance between the front wheels 3 and the rear wheels 4 is shortened, thus resulting in a small sharp turn.