OnBoard Air & Train Horn Install

9-5-08


     As anyone that does a good bit of offroading knows, airing down your tires to a lower psi will give you a bit more grip and help the mud clean out of your tires. After I starting airing down for the trails, it only took a couple times of using my cheapo MV-50 portable air compressor to realize I needed to install a complete onboard air setup. The small compressor would take several minutes per tire, and would end up getting very hot. Some of the other members of the offroad club would ask to use it also, but it was lucky to finish two vehicles before it overheated and shut itself down.
     Adding a tank to the setup creates a reservoir for air to fill, and takes some of the work off the compressor. At least it makes filling up much faster because you have a quantity of air at 100+ psi that can be used at a much higher flow rate than just the compressor. I wanted as much air stored up as possible, so I bought the largest tank I could fit in the Jeep without tanking up too much room. I went with a 5 gallon Siege Engineering tank, that I mounted over the rear passenger side tire well.

     All the other components were mounted up front under the hood. Which consist of the compressor, and a manifold that is used to attach all the fittings controls and pressure gauge. 3/8" diameter rubber hose runs to the back of the Jeep to the air tank.

     Here is a breakdown of how everything is hooked up. The compressor supplies air to the manifold with a section of 3/8" hose, which has a check valve installed on it. This allows the air to only flow into the manifold, this helps take stress off the compressors built in check valve when it is not running. It also acts as a safety, incase the hose were to rupture, or something in the compressor fails.
     A pressure gauge is then attached to the manifold so that I can monitor the pressure in the system from the front of the Jeep.
     Next is a section of hose that feeds air to the Train Horns. I also installed a manual cutoff valve in the section of hose, incase there was a problem with any of the hoses or fittings supplying the horns.
     Next to that is pressure activated control switch. This tells the compressor when to turn on and off. I have a main power switch on my dash, that I use to turn the system on. Once that is turned on the pressure switch monitors the pressure in the system, turning the compressor on if the psi drops below 85 psi, and turning it off once it reaches 105 psi. This way the system can be turned on, and left unattended, as you fill your tires, or anything else you want to use the air for.
     Then there is a T adapter with a manual release valve, and a quick connect coupling attached. I can use the valve to quickly and easily purge the air out of the system. The quick connect is used to attach the air line that you use to fill your tires, and other air accessories.
    Last is another 3/8" hose that runs to the back of the Jeep and connects to the 5 gallon air tank.

     The tank has an assortment of ports on it, not all of which I am currently using. The bottom of the tank has a drain valve, used to drain water that builds up in the tank over time from condensation. There is a safety release valve on the tank also, that will automatically open if the tank goes above 200 psi. This is incase the compressor fails to shut off, or if the pressure raises too much due to extreme temperature changes. There is another pressure gauge on the tank, so that I can monitor the pressure from the rear of the Jeep. And of course, another quick connect coupling for attaching the air line.

     I was wanting to upgrade the Jeeps factory horn for a while, then after I got the onboard air setup, I figured I might as well go all out and install a set of air horns. I tend to over do things, so I ordered a 3 horn 155 dB train horn. It was a challenge fitting all 3 horns under the hood, but after I replaced my stock air intake with a cold air intake pulling air from the cowl, I had alot of space where the stock air box was. Still, one of the horns had to be mounted on the hood. It was a bit tricky figuring out where it needed to be mounted, so that it would not hit anything when the hood was shut. It worked out well though, and the horns are positioned fairly close to each other once the hood is closed.

     The hose coming from the manifold first connects to an electric solenoid valve, which is mounted on the first horn on the hood. This valve is used to activate the horns, and is controlled by a tiny innocent looking red button on my dash. When the button is pressed, the solenoid opens the valve, and the air is then fed to the first horn. Which also has an outlet port that is then connected to the second horn, and from that horn, to the 3 and final horn.

     There is about a half second delay, as the air pressurizes the lines past the valve. You can kind of hear each horn fire up individually in quick succession. Much like a real train horn sounds. While I do not have a decibel meter, I can tell you, they are Quite Loud. I have only tested them up to 65 psi so far, I imagine the full 105 psi will be even louder!


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