PROBLEM TO BE SOLVED: To improve work efficiency by maintaining cooling efficiency of an engine, and to improve durability of a prime mover.SOLUTION: A hydraulic motor (300) for driving a fan (40) for cooling an engine (20) and a hydraulic pump (301) are connected by a high pressure side oil passage and a low passage side oil passage, and thus, a closed circuit is formed. The closed circuit has a switch valve (30E) capable of switching a direction to transfer oil from the hydraulic pump (301) to the hydraulic motor (300) between the forward direction and the backward direction, and an accumulator (AC), and an output rotation direction of the hydraulic motor (300) is switched between the forward direction and the backward direction through switching operation of the switch valve (30E), so that a working vehicle switches between a cooling state to suck in outside air from an outer side of a filter body (12) to an inner side thereof through forward drive of the fan (40) and a dust removing state to blow out air from the inner side of the filter body (12) to the outer side thereof through backward drive of the fan (40).COPYRIGHT: (C)2015,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)を駆動する油圧モータ(300)と油圧ポンプ(301)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(301)から油圧モータ(300)への送油方向を正逆方向に切り換え可能な切換弁(30E)とアキュムレータ(AC)を備え、この切換弁(30E)の切換作動によって油圧モータ(300)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(12)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(12)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25
