Hydraulic Four-Wheel-Drive Working Vehicle

A hydraulic four-wheel-drive working vehicle comprising a driving power source;

• a pair of left and right first driving wheels arranged on one side in a vehicle lengthwise direction;
• a pair of left and right second driving wheels arranged on the other side in the vehicle lengthwise direction;
• a hydraulic pump unit including a hydraulic pump main body operatively driven by the driving power source and a pump volume adjusting mechanism that varies a suction/discharge amount of the hydraulic pump main body upon manipulation of a main speed-change operation member capable of being manually manipulated;
• a pair of left and right first motor devices that respectively drives the left and right first driving wheels;
• and a pair of left and right second motor devices that respectively drives the left and right second driving wheels, the hydraulic four-wheel-drive working vehicle being characterized in that,
• each of the pair of first motor devices and the pair of second motor devices includes a hydraulic motor main body that is fluidly connected to the hydraulic pump main body via an HST line so as to form an HST in cooperation with the hydraulic pump main body, a motor volume adjusting mechanism that varies a suction/discharge amount of the hydraulic motor main body, a hydraulic actuating mechanism that operates the motor volume adjusting mechanism, and a housing that accommodates the hydraulic motor main body, the motor volume adjusting mechanism and the hydraulic actuating mechanism, and
• the hydraulic actuating mechanisms in the pair of first motor devices and the pair of second motor devices are operated and controlled with use of hydraulic fluid from a single hydraulic pressure source.