Right up to the 1980s there were still a whole series of air-cooled motor car engines. Apart from the VW Beetle and the Porsche, there were also the 2CV, the Ami and the GS models from Citroen. For a long time, in the truck sector it was the Magirus Deutz (above figure) which drew attention to itself through the circular-saw like noise caused by its air-cooling. Nowadays, this type of cooling is to be found mostly only in stationary engines.
How it works
An axial- or radial fan transports air as evenly as possible to the individual cylinders. It is driven by the crankshaft and has the same or even higher RPMs. The cylinders are surrounded by a sheet-metal jacket. In addition, there are air-deflectors which also guarantee a circulation to the parts of the cylinders which are not directly in the air-flow from the fan. Thermo-stat controlled air flaps allow the influx of cool air-flow only when the engine is hot.
Air cannot freeze and thus needs no protection against frost. The servicing is limited to the perhaps available belt drive. For this reason, air-cooled engines are also popular, even today, as stationary engines. In addition, their compact and light construction method manages without a tubing system to the radiator.
The heating of the interior is, in the cold season, often not adequate enough. For this reason, fan-cooled engines are often combined with an additional heating. The fan uses more energy than the pump of a liquid cooling system does. Also the cooling cannot be distributed as evenly. 06/09
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