PROBLEM TO BE SOLVED: To enhance efficiency of harvesting work by securing functions of a reel lifting and lowering cylinder and a second mower lifting and lowering cylinder required for the harvesting work even when the amount of an action oil is in short supply caused by the increase of a traveling load.SOLUTION: A hydraulic circuit is constructed by feeding a pressurized oil discharged from a hydraulic pump (51) to a travelling hydraulic circuit (54) for regulating a plurality of hydraulic clutches (57, 58, 59, 60) and a harvesting hydraulic circuit (55) for regulating a harvesting cylinder (61) for lifting and lowering a harvesting unit (4), and diverging the pressurized oil fed through either one of the travelling hydraulic circuit (54) and the harvesting hydraulic circuit (55) by a priority type flow dividing valve (62) to feed a constant flow of the pressurized oil to a hydraulic circuit (64) in the front part of a machine body equipped with the reel lifting and lowering cylinder (14) and the second mower lifting and lowering cylinder (66), while feeding the residual pressurized oil to a machine body hydraulic circuit (56) equipped with rolling cylinders (68, 69) and a pitching cylinder (70).COPYRIGHT: (C)2012,JPO&INPIT【課題】走行負荷が増大して作動油量が不足しても、収穫作業に必要なリール昇降シリンダ及びセカンドモア昇降シリンダの機能を確保し、収穫作業の能率を高める。【解決手段】油圧ポンプ(51)から吐出される圧油を、複数の油圧クラッチ(57,58,59,60)を制御する走行油圧回路(54)と刈取部(4)昇降用の刈取シリンダ(61)を制御する刈取油圧回路(55)に供給し、該走行油圧回路(54)と刈取油圧回路(55)のうちのいずれか一方の油圧回路を経て供給される圧油をプライオリティ型分流弁(62)で分流して、リール昇降シリンダ(14)及びセカンドモア昇降シリンダ(66)を備えた機体前部油圧回路(64)に一定流量の圧油を供給し、残りの余剰圧油をローリングシリンダ(68,69)とピッチングシリンダ(70)を備えた機体油圧回路(56)に供給する構成とする。【選択図】図5
