Many engines are also equipped with a precleaner. The precleaner is located before the inlet to the main air cleaner. The purpose of the precleaner is to collect much of the dirt before the air cleaner. This increases the service life of the air cleaner.
The simplest type of precleaner is a simple mesh cap at the top of the air filter housing inlet.
Another type of precleaner that is used on Caterpillar equipment is a spirally vaned drum. The vanes cause the incoming air to spin.
Because the dirt that is drawn in is heavier than the air, the dirt is forced to the outside due to the spinning action. The dirt then falls into a collection bowl.
Precleaners should be inspected and emptied on a daily basis.