WORK VEHICLE

PROBLEM TO BE SOLVED: To provide a work vehicle, such as a tractor, having a higher-output transmission case including a hydraulic mechanical transmission while keeping the hydraulic mechanical transmission higher in efficiency, more lightweight, and lower in cost.SOLUTION: A transmission case 17 comprises: a main transmission input shaft 511 to which power is transmitted from an engine 5, and a main transmission output shaft 512 fitted to the main transmission input shaft 511 to relatively rotate. A hydraulic pump part 521, a cylinder block 800, and a hydraulic motor part 522 which constitute a hydraulic mechanical transmission 500 are arranged in series on the main transmission input shaft 511. Transmission power is transmitted to the main transmission output shaft 512 through the hydraulic motor part 522. The mission case 17 comprises a planetary gear mechanism 526 which composes the power from the engine 5 and the transmission power to the main transmission output shaft 512, and a transmission shaft 535 capable of transmitting the transmission power via the main transmission output shaft 512 and the composite power via the planetary gear mechanism 526.SELECTED DRAWING: Figure 13 【課題】トラクタのような作業車両において、油圧機械式変速機の高効率化、軽量化及び低コスト化を確保しながら、油圧機械式変速機を含むミッションケースの高出力化を図る。【解決手段】ミッションケース１７に、エンジン５から動力伝達される主変速入力軸５１１と、主変速入力軸５１１に相対回転可能に被嵌した主変速出力軸５１２とを備える。主変速入力軸５１１には、油圧機械式変速機５００を構成する油圧ポンプ部５２１とシリンダブロック８００と油圧モータ部５２２とを直列状に配置する。油圧モータ部５２２を介して主変速出力軸５１２に変速動力を伝達する。ミッションケース１７には、エンジン５からの動力と主変速出力軸５１２への変速動力とを合成する遊星ギヤ機構５２６と、主変速出力軸５１２経由の変速動力と遊星ギヤ機構５２６経由の合成動力とを伝達可能な伝達軸５３５とを備える。【選択図】図１３