The air intake system filters air needed for combustion. The system components include:
– Air inlet tube
– Air cleaner housing and cover
– Unloader valve (and rubber cleanout valve)
– Primary air filter element
– Secondary (or safety) air cleaner element
– Air filter restriction indicator
– outlet tube
Air enters the air cleaner inlet tube and into the air cleaner housing, and is directed into the side of a shield. This starts a high-speed centrifugal motion of air which continues around the element until it reaches the far end of the air cleaner housing, to an unloader valve.
Most of the dust is separated from the air by centrifugal force that causes heavy dust particles to enter the opening at the top of the unloader valve. The air flows through the primary air filter element. The primary filter element filters the larger dirt particles before the air enters the secondary air filter element. The finer dirt particles are filtered out by the secondary air filter before the air enters the intake manifold.
The dirt that is deposited in the unloader valve is removed through the rubber diaphragm at the base of the air cleaner. When the engine is running, a pulsing action is created in the intake system by each intake stroke of the engine. This pulsing action causes the rubber diaphragm to open and close, thus emptying the unloader valve. The operator can squeeze the valve to let out the large particles.
The difference in pressure between the intake manifold and air cleaner is monitored by the Air Filter Restriction Indicator. As the air filters become clogged, and intake manifold vacuum increases, the restriction indicator piston is pulled down against spring tension, and is shows when it’s time to change air cleaner.