PURPOSE: To reduce the inertia of a traveling power transmission system so as to smoothly carry out a shift operation by actuators by disposing a forward- to-reverse switching mechanism not within the traveling power transmission system but in another position, in the travel speed changing structure of a working vehicle wherein the shift operation of the traveling system is done by the actuators used for the shift operation of a traveling gear shifter and by a clutch for transmitting power for traveling.
CONSTITUTION: A first forward hydraulic clutch 5 and a second reverse hydraulic clutch 6 are arranged in parallel on the lower side of an engine 1 and a traveling gear shifter A and a transmission clutch 19 are arranged on the lower side. When a shift operation by actuators T1, T2 is started, the transmission clutch 19 is operated to speedily shut power and an operation for reducing the operating pressure of the first or second hydraulic clutch 5, 6 to a predetermined low value is carried out. After the shift operation has been completed, the transmission clutch 19 is speedily operated to the transmission side and an operation for slowly building up the operating pressure of the first or second hydraulic clutch 5, 6 is carried out.
URA TAKESHI
HASEGAWA SHIGEKAZU
