An engine needs an air filter to remove particles of airborne dirt before it hits the engine. Most (if not all) modern vehicles have a disposable paper element that is changed at service intervals (another throw away item).
The Oil Bath Air Filter on the Series Land Rovers is a magnificent thing. Magnificently oily, and here’s how they work….
Air is drawn into the filter body from a ring of fins in the top of the unit, pulled down the filter body and through a bath of engine oil. Any large particles are deposited in the oil bath, sink to the bottom and form a claggy mess.
The air continues back up the middle of the filter body through a course steel mesh. Inevitably, this course steel mesh is also soaked in oil and the cleaning process continues. By the time the air reaches the carburettor, its safe to assume its a lot cleaner the it was before it went through the filter…. albeit it may smell a bit oily.
Oil bath air filters were (and still maybe) used on agricultural machinery as they operate in very dusty environments…. (think harvest and threshing… lots of dust). The Land Rover was designed as a farm implement (and a stop gap for the Rover company whilst Britain got back on its feet after WW2) so the oil bath air filter was the natural choice.
Sadly I didn’t take any picture of the strip down of the oil bath air filter but took some of the finished article. The housing (which also carries the battery) is more recent news and theres a few more pics of that.