PROBLEM TO BE SOLVED: To keep cooling efficiency of an engine to increase working efficiency and at the same time improve durability of a mover part.SOLUTION: A hydraulic pump and a hydraulic motor that are installed in a hydraulic infinite variable-speed drive 30 for use in driving a fan 40 for cooling an engine 20 are connected by a high pressure oil passage and a low pressure oil passage to constitute a closed circuit. This closed circuit comprises a change-over valve capable of changing-over an oil feeding direction from the hydraulic pump to the hydraulic motor in a normal-inverse direction and an accumulator. An output rotating direction of the hydraulic motor is changed over in a normal-inverse direction under a changing-over operation of this change-over valve so as to drive the fan 40 in a normal direction or inverse direction to change it over to a cooling state for sucking surrounding atmosphere from outside of a filter body to inside of it and a dust removal state in which the fan 40 is driven in an inverse direction to blow out air from the inside part of the filter body to its outside part.COPYRIGHT: (C)2014,JPO&INPIT【課題】エンジンの冷却効率を維持して作業能率を高めると共に、原動部の耐久性を向上させる。【解決手段】エンジン20冷却用のファン40を駆動する油圧式無段変速装置30に備えた油圧ポンプと油圧モータの間を、高圧側の油路と低圧側の油路で接続して閉回路を構成し、この閉回路には、油圧ポンプから油圧モータへの送油方向を正逆方向に切り換え可能な切換弁とアキュムレータを備え、この切換弁の切換作動によって油圧モータの出力回転方向を正逆方向に切り換えて、ファン40を正転駆動して濾過体の外側から内側へ外気を吸入する冷却状態と、ファン40を逆転駆動して濾過体の内側から外側へ風を吹き出す除塵状態とに切換わる構成とする。【選択図】図9
