PURPOSE: To improve the quality of vehicle running, steering or the like, and enable enjoying the safe turning of a vehicle by providing turning means for turning a body with a brake mechanism and a steering mechanism interlocked, and a selector means for turning the body with a steering wheel while releasing the1 interlock of the aforesaid mechanisms.

CONSTITUTION: So far as a selector lever 88 is not gripped, a steering handle 7 and one of right and left disc brakes 40 and 41 are kept in an interlocked condition via a turning means. It follows, therefore, that when the steering handle 7 is turned during straight forward travel, one of the disc brakes 40 and 41 at the side of a turning direction is actuated, and a differential motion takes places between right and left drive wheels 8a and 8b, and 9a and 9b. As a result, the body 1 of a vehicle can be turned as desired, even at a place where the frictional coefficient of a ground surface is relatively small. On the other hand, once the selector lever 88 is gripped, the interlocked motion of the steering handle 7 and the disc brakes 40 and 41 is released, and the right and left drive wheels 8a and 8b, and 9a and 9b are driven with power transmitted from an engine 13. At the same time, the motion of the steering handle 7 is transmitted to a steering wheel 2.