PROBLEM TO BE SOLVED: To enable a transmission structure within a transmission case to be made simple and an oil changing operation time to be shortened while omission of selection of speed at the transmission stored in the transmission case is being prevented.SOLUTION: This invention is constituted such that a selective gear type transmission 47 that can be changed in three stages is stored in a transmission case 43, an input shaft 44 of the transmission case 43 is installed at an output shaft 34 set at an external machine A cooperatively connected to the transmission case 43 under a state in which it is rotated in integral with the output shaft 34 around an axis center of the output shaft 34, each of a low speed driving gear 60, a middle speed driving gear 62 and a high speed driving gear 64 of the transmission 47 is installed at the input shaft 44 under a state in which it is rotated integrally with the input shaft 44, each of a low speed driven gear 61, a middle speed driven gear 63 and a high speed driven gear 65 of the transmission 47 is installed at a driven shaft 45 adjacent to the input shaft 44 in parallel attitude under a state in which its gear selecting operation by a shift mechanism 66 can be carried out, and the driven shaft 45 is installed at a lower position than the input shaft 44.COPYRIGHT: (C)2015,JPO&INPIT【課題】伝動ケースに内蔵した変速機の変速抜けを防止しながら、伝動ケース内での伝動構造の簡素化、及び、オイル交換に要する作業時間の短縮化、などを図れるようにする。【解決手段】3段に変速可能に構成した選択歯車式の変速機47を伝動ケース43に内蔵し、伝動ケース43の入力軸44を、伝動ケース43に連接する外部機器Aに備えた出力軸34に、出力軸34の軸心を中心にして出力軸34と一体回転する状態で備え、変速機47の低速駆動ギヤ60と中速駆動ギヤ62と高速駆動ギヤ64とのそれぞれを、入力軸44に、入力軸44と一体回転する状態で装備し、変速機47の低速従動ギヤ61と中速従動ギヤ63と高速従動ギヤ65とのそれぞれを、入力軸44に平行姿勢で隣接する従動軸45に、シフト機構66によるギヤ選択操作が可能な状態で装備し、従動軸45を入力軸44よりも下方の位置に配備した。【選択図】図7
