Intake systems

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Originally Posted by Brian Hjelm

Donaldson used to call these gadgets "swirl bowl pre-cleaners". They now call them "full view pre-cleaners". The catalogues have always listed them as for off-road use and their purpose is to extend the filter life of agriculture and construction equipment.

We were always told that they are a waste of money on anything other than stationary or slow moving equipment as they do virtually nothing when used in a stream of fast moving air as on a motor vehicle.

They have to be correctly selected for size to match the engine and air cleaner. Donaldson air cleaners have a centrifugal section and oversizing the air cleaner negates this effect. Heavier particles are spun out and trapped then engine intake pulses expel the particles through the vacuator valve.

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Given the swirling occurs inside the bowl I am not sure that stops when the machinery is on the move. I think it might be more a case of on a formed road the dust levels are not high enough to warrant the additional expense and your standard filter will cope without the precleaner.

If you are going to travel on dirt roads either be the first in the convoy or leave lots of distance between vehicles so the dust has time to settle, or use a cyclone or sock precleaner.

efectiveness in high stream airspeeds can influence the "upside down bowl" type snorkle head aircleaners.

they're still better than nothing but they get a high and low pressure side happening due to the air vortexing around the outlet tube in the center this disrupts the flow within the chamber.

If you have a look at the steam stacks on sugar cane gear or tall tower exhaust stacks you'll see they have a pair of spirals wrapped around them their purpose is to "wrap" air around the stack to off load the eddy at the lee side that traps smoke onto the stack and increases maintenance and cleaning costs. Its the same concept but upside down.