Patent ID: 7081068

Claim:
A transmission system for a work vehicle having a plurality of speed gears and a friction clutch provided for each speed gear and converting the output torque of an engine into torque according to work load by gear shifting operations performed through disengagement/engagement of the friction clutches comprising: friction clutch controlling means for controlling the disengagement/engagement of the friction clutches; and engine controlling means for controlling the output of the engine in a full load operation mode and a high power operation mode, and said full load operation mode set for a rated power of the engine, and said high power operation mode set for a power higher than the rated power of the engine; wherein if a downshift from a higher speed gear to a lower speed gear, which is one of said gear shifting operations, is effected while the engine operating in said full load operation mode, the friction clutch controlling means causes the friction clutch corresponding to the higher speed gear to slide so as to enable power transmission and the engine controlling means causes the engine to perform in said high power operation mode during the sliding of the friction clutch.