PROBLEM TO BE SOLVED: To restrain the occurrence of cavitation in a supply oil passage for connecting a storage part and a hydraulic pump, when having an oil cooler in the supply oil passage for connecting the storage part and the hydraulic pump, in a hydraulic circuit structure of a working vehicle.SOLUTION: This hydraulic circuit structure includes the storage part 8 for storing a hydraulic fluid, a hydraulic mechanism 59, and the hydraulic pump 60 for supplying the hydraulic fluid of the storage part 8 to the hydraulic mechanism 59, and is constituted so as to return the hydraulic fluid of the hydraulic mechanism 59 to the storage part 8. The hydraulic circuit structure further includes the oil cooler 63 in the supply oil passage 62 for connecting the storage part 8 and the hydraulic pump 60, and a bypass oil passage 65 capable of supplying the hydraulic fluid of the storage part 8 to the hydraulic pump 60 by bypassing the oil cooler 63.COPYRIGHT: (C)2010,JPO&INPIT【課題】作業車の油圧回路構造において、貯留部と油圧ポンプとを接続する供給油路にオイルクーラーを備えた場合に、貯留部と油圧ポンプとを接続する供給油路でのキャビテーションの発生を抑える。【解決手段】作動油を貯留する貯留部8、油圧機構59、貯留部8の作動油を油圧機構59に供給する油圧ポンプ60を備え、油圧機構59の作動油を貯留部8に戻すように構成する。貯留部8と油圧ポンプ60とを接続する供給油路62にオイルクーラー63を備え、オイルクーラー63を迂回して貯留部8の作動油を油圧ポンプ60に供給可能なバイパス油路65を備える。【選択図】図3
