Abstract: A hollow housing is provided for use in conjunction with an apparatus at least occasionally operative in a dust-laden atmosphere, having a liquid cooled combustion engine as a power source and wherein cooling liquid for the engine is passed through a heat transfer assembly in the form of an air-cooled radiator including intake and exhaust sides for cooling air. The housing includes one open side in substantially sealed communication with the intake side of the radiator and a second side of the housing remote from the one open side defines an air inlet for cooling air. Removable and replaceable air filter structure is provided in the housing between the open side thereof and the air inlet and the air inlet of the housing has the discharge end of an air duct sealingly communicated therewith.