Speed control method for working vehicle

摘要

An object of the present invention is to provide a working vehicle having such a fine traveling feel that the vehicle traveling speed is increased in proportion to operation of a speed change operation means similar to a normal passenger car, while reducing noise and fuel consumption of an engine at the time of traveling in middle or high speed. While an operation degree of the speed change operation member is increased from 0 to a certain value, the increase of the vehicle traveling speed is produced by a first increase rate of the engine rotation speed and a first increase rate of a speed ratio (output/input rotation speed ratio of a speed change mechanism) increase rate, and while the operation degree of the speed change operation member is increased from the certain value, the engine rotation speed is kept to be the rated value and corresponding thereto, the increase rate of the speed ratio is set to a second increase rate of the speed ratio larger than the first increase rate of the speed ratio so that the vehicle traveling speed is always increased substantially in proportion to the acceleration operation of the speed change operation member.