Ive always wondered why big rigs have abig woooooosh! when they stop. Ive alwyas thought that it was just excess compressed air.Is that true? and i really want that effect with my PSD, how can i achieve that. Any answers, questions, or links to websites would greatly be appreciated. Thanks, luke

 

that's the air brakes. When ever they release the brakes they let off a little air. When they apply the parking brake you hear more air and then the most is when they turn off the truck and empty the air tanks completely.

 

It is the driver backing off on the air brakes as they come to a stop. If you don't ease up, the vehicle lurches to a stop.

Each axle has a relay valve that matches the pressure coming from the driver's pedal. That way the entire volume of air doesn't have to run all the way from the pedal valve. To increase the pressure it lets air in to the brake diaphragms from a local reservoir. To decrease the pressure, it lets air out. What you're hearing is the relay valve on all of the axles along the combination bleeding out air.

If you really want that sound, you can get hydraulic over air valves. They are used when someone wants to pull a air brake trailer behind a truck with hydraulic brakes. Add a compressor and you'll have that sound.

 

Next you need a big ole air horn. That's what I want. Maybe you could rig up something to your brake pedal that releases some air when you step on it. Either which way your going to need some kind of compressor I would think. Or maybe record the sound and play it over a loudspeaker under your hood. HAHA.

 

That noise most of the time is from a air dryer, it bleeds off a little air to drain some mosture outta the lines, also when you step on the brakes, and then let off, you also get a woosh, or when they set the parking break.

If you put an on board air compresser, you can run a air dryer, I have one on my 1960 Chevy pickup, for the oba on it

 

Do any of you guys have a link that u could guide me to? Im going to put an onboard air compressor and big ole horns. But i really think that woosh sound of the air is an effect i really want.

 

Here is a link to an air dryer... is there a way to cut down the cost so it can be cheaper? Aftermarket 12-Volt AD-9 Air Dryer with Mounting Bracket and Wire Harness

 

any instructions anyone, just trying to get the PSD the best she caan be lol

 

what kind of instruction are you looking for??

 

on how to set up the air compressor to one of these air dryers or governor valves