Abstract: In a structure of an engine compartment in a work machine such as a tractor, a bulldozer, a hydraulic excavator, a wheel loader, the air taken through vents, which are formed on side covers and a hood covering the engine compartment, is supplied directly to a radiator via ducts which are provided on the side of the side covers and the side of the hood respectively. The ducts cover the vents, thereby preventing noise within the engine compartment from escaping to the outside. Therefore it is possible to increase a cooling efficiency of the radiator by supplying the outside air, which does not take up the heat of an engine, directly to the radiator, as well as to reduce the engine sound and prevent the engine noise from escaping.

Abstract: A control system designed such that if a heavy load is imposed on a vehicle during running and a hydraulic relief state in which an oil pressure in a hydraulic circuit for a hydrostatic transmission unit exceeds a relief pressure is detected, the angle of a discharge controlling swash plate for a pump is reduced to a specified value (e.g., 50% of the maximum angle) or less, whereby the stall of the vehicle and the overheat of machine parts are prevented.