PROBLEM TO BE SOLVED: To easily constitute a mechanism which lowers a rear wheel automatically to correct a front-rear inclined attitude of a body by controlling an increase in the weight of the body and in the cost. SOLUTION: A rear-wheel transmission case 30 of a rear-wheel lowering device is constituted around a rotation pivot P which is located forward of a rear-wheel axle shaft 31 with possible up-and-down rotation. Then a compression spring 34 is provided which performs the rotational energization of the rear-wheel transmission case 30. At the time of normal travelling, the compression spring 34 contracts because of the self-weight of the body, and the rear wheel 3 is brought into a raised-motion state. Then at the time when a drive load, which exceeds a predetermined value, is generated on the rear wheel because of the travel of the body, the rear-wheel transmission case 30 is rotated downward because of the driving reaction force, and the rear wheel 3 is brought into a lowered-motion state. COPYRIGHT: (C)2007,JPO&INPIT
