PURPOSE: To obtain stabilized running at the time of running on a curve by providing a vehicle interval adjusting means for automatically the adjusting vehicle intervals in front and rear direction of the running trucks in response to the curve of rails.

CONSTITUTION: In car truck running on rails R, provided a pair of drive wheel 2 to which a motor 2a is connected, and a pair of drive wheels 3 are arranged in their front and rear direction, respectively on a chassis 10 and a pair of driven wheels 3 are arranged in their front and rear direction. In this case, a pair of LM(Linear Motive) guides 11 are installed, and a pair of driven wheel 3 are supported in the state capable of moving in the longitudinal direction of the chassis 10. Also, a pair of power cylinders 12 are installed between the front & rear driven wheels 3, 3 and their rod edge are fixed respectively to the housings 3a of the driven wheels 3. Then, the quantities of intake & exhaust of air for each power cylinder 12 are subjected to control by the control part so that the driven wheels 3 may move to a proper position in response to the curvature of the rails R.