PURPOSE: To provide a high braking property while improving a step setting-over property by connecting first and second leaf springs suspending front front-axle and front rear axle through lever members respectively to a connecting rod to transmit the push-pull motion of the rod to both leaf springs in the opposite direction to each other.

CONSTITUTION: Leaf springs 21, 22 having front ends respectively journalled by brackets 25, 26 of a chassis frame 20 and the central part supporting axles 23, 24 are interconnected through an equalizer link mechanism. The leaf spring 21 is connected to one end of a connecting rod 30 by front side lever 31 and relay link 34 pivotably supported on a bracket 33 of a side member 20a and the other end and leaf spring 23 are interconnected by a rear side lever 35 and relay link 38. The other end and leaf spring 23 are interconnected by a rear side lever 35 and a relay link 38. The vertical movement transmitted from one of the leaf springs 21, 23 is transmitted to the other reversely by an equalizer link mechanism composed of these connecting rod 30, levers 31, 33 or the like. Thus, a portion of the weight of the shaft on the axle 22 is shared with the axle 24 so that a high step getting-over property and braking capability are attained.