Are axial fans the only types of fans used in vehicle engines, and what type of fan produces the most noise and a loud swooshing sound like some diesel engines have?

toughynutter

I think the sound you are referring to is a "Jake Brake" Unlike conventional gas engine there is little or no engine compression braking when you let your foot of the gas. Think of it this way going down hill in a car the engine slows the car down, If you push in the clutch to coast or put the var in neutral you speed up. In a diesel this does not happen. It is potential dangerous on long declines because the engine is only at an idle the air compressor for the brakes does not put out much also. A "Jake Brake" Uses a butterfly valve in the exhaust "exhaust brake" to create additional back pressure to slow the vehicle. Also there are engine valve changes than enhance the effect. So the swooshing sound you here is actually engine exhaust "All of the brake systems made by Jacobs Vehicle Systems can accurately be called "Jake brakes," not just their compression release engine brakes. They also produce the Jacobs Exhaust Brakes and Jacobs Driveline Brakes, both of which are nearly silent. The engine brakes are the ones that make that distinctive staccato sound, and if I could make a WAV, I'd include my imitation of it here. The Jacobs company blames the loud noise you hear from passing trucks on the use of engine brakes in vehicles with poorly muffled or unmuffled exhaust systems (straight pipes, for example), exhaust systems that have been illegally modified or are poorly maintained, and/or truckers who simply enjoy making noise. " http://www.straightdope.com/mailbag/mjake.html Mar 23 07, 9:50 PM

What-A-Mess

A Jake Brake sounds like a Truck Growling or passing gas (flatulence). It is nothing more than a cam shaft lobe that open a valve to release compression which in turn expels the compressed cylinder mass so the mass can not recoil the piston in a down stroke. A Jake Brake and an Exhaust brake work EXACTLY Opposite. The compression release brake is the industry standardized (generic) term "Jake Brake", not the exhaust brake. Mar 23 07, 10:01 PM

What-A-Mess

I must add that although the mechanisms work in exactly the opposite manner they are used to achieve the same outcome. A slowing of a large vehicle without burning out or overheating the brake liners. Mar 23 07, 10:47 PM