PROBLEM TO BE SOLVED: To easily switch between forward and backward movements with a simple operation of a lever or a pedal for adjusting a cam plate 59 of a variable displacement hydraulic motor 29 without providing a separate and complex switching mechanism (switching mechanism between normal and reverse rotations) of forward and backward movements, to improve crawling running performance by easily securing output torque in standing start, and to easily improve working efficiency effectively using the output with high power transmission efficiency even in high load work.SOLUTION: This work vehicle has a complex transmission 64 for syntherizing respective outputs of a hydraulic transmission 30 for transmitting a driving force of an engine 2 and a transmission gear 32. The hydraulic transmission 30 is formed of a set of variable displacement hydraulic pumps 28 and variable displacement hydraulic motors 29, a synthetic output shaft 42 of the complex transmission 64 is changed in speed and rotated in the normal rotation direction by angle control of a cam plate 58 of the hydraulic pumps 28, and the synthetic output shaft 42 of the complex transmission 64 is changed in speed and rotated in the reverse rotation direction by angle control of the cam plate 59 of the hydraulic motor 29.COPYRIGHT: (C)2003,JPO【課題】 別途複雑な前後進切換機構(正逆転切換機構)など設ける必要なく可変容量形油圧モータ29の斜板59を調節するレバー或いはペダルの簡単な操作で前後進の切換えを容易に行うと共に、ゼロ発進時の出力トルクを容易に確保し微速走行性能を向上させ、しかも負荷の大きい作業においても高い動力伝達効率の出力を有効に利用して作業能率の向上など容易に図る。【解決手段】 エンジン2の駆動力を伝える油圧変速機構30と伝達ギヤ32の各出力を合成して変速出力する複合変速機構64を備えた作業車において、1組の可変容量形の油圧ポンプ28及び油圧モータ29で油圧変速機構30を形成し、油圧ポンプ28の斜板58角制御によって複合変速機構64の合成出力軸42を正転方向に変速回転させると共に、油圧モータ29の斜板59角制御によって複合変速機構64の合成出力軸42を逆転方向に変速回転させる。
