Two of the more expensive components of your portable drill rig are the diesel engine and the air compressor. Both of these components are built of large rotating masses that depend on low-friction bearings to turn freely. Bearing life is shortened significantly when there is exposure to contaminants, such as silica particles or other abrasive solids that are by-products of drilling. This is why a good air induction maintenance program is one of the critical requirements for the life of these components. Air cleaners and all of the components that make up the air induction system should be inspected at every oil change interval.
The air cleaner assembly itself consists of many different components that should net you the cleanest possible air for your engine and compressor. At the air cleaner opening, there is a grille that prevents large debris from entering. The air then travels to the bottom of the assembly and is lifted through a series of tubes called the pre-cleaner. This path allows heavier solids to drop from the air stream to the dust pan. On the bottom of the dust pan is a Vacuator valve that will allow the dust pan to drop all solids when the rig is shut off. When the rig is running, negative pressure on the inside of the unit (a vacuum) will pull the Vacuator valve to a closed position that will prevent foreign matter from entering.