PROBLEM TO BE SOLVED: To allow a combine harvester to travel without troubles even in the event of a failure of a flow dividing valve by providing a hydraulic circuit structure such that pressure oil discharged from one hydraulic pump is supplied to a traveling hydraulic transmission and a mowing hydraulic transmission by the flow dividing valve.SOLUTION: The hydraulic circuit includes: a main hydraulic pump (11) which delivers pressure oil to a traveling clutch operation hydraulic circuit (T) and a main hydraulic circuit (W) which performs machine body attitude control and mowing/auger lifting control and a sub-hydraulic pump (22) which delivers pressure oil to a traveling continuously variable transmission circuit (1) and a mowing continuously variable transmission circuit (2). The pressure oil by the sub-hydraulic pump (22) is distributed to the traveling continuously variable transmission circuit (1) and the mowing continuously variable transmission circuit (2) by a variable-speed flow dividing valve (23), and a variable-speed supply conduit (41) for delivering pressure oil from the sub-hydraulic pump (22) to the variable-speed flow dividing valve (23) and a traveling distribution conduit (43) for delivering the pressure oil from the variable-speed flow dividing valve (23) to the traveling continuously variable transmission circuit (1) are allowed to communicate with each other by an emergency path (46) through an emergency check valve (40) which performs releasing operation at a predetermined pressure.COPYRIGHT: (C)2011,JPO&INPIT【課題】一台の油圧ポンプから吐出する圧油を分流弁で走行油圧変速装置と刈取油圧変速装置に供給する油圧回路構成とし、分流弁が故障しても走行を支障なく行えるようにする。【解決手段】走行クラッチ操作油圧回路(T)と機体姿勢制御および刈取・オーガ昇降制御を行うメイン油圧回路(W)とに圧油を送るメイン油圧ポンプ(11)を設け、走行無段変速回路(1)と刈取無段変速回路(2)に圧油を送るサブ油圧ポンプ(22)を設け、サブ油圧ポンプ(22)の圧油を変速分流弁(23)で走行無段変速回路(1)と刈取無段変速回路(2)に分配し、サブ油圧ポンプ(22)から変速分流弁(23)に圧油を送る変速供給管路(41)と変速分流弁(23)から走行無段変速回路(1)に圧油を送る走行分配管路(43)とを所定圧で解放作動する緊急チェック弁(40)を介した緊急路(46)で連通する。【選択図】図2
