Had wanted to instal a train horn for a while. I wanted to piece it together myself, insted of buying a kit. This way I could customize it for my applications, use, and preferences.
Here's what I came up with, and my write up:
Started with a dead 3-gal compressor, found on Craigs List, for $20. Has drain valve, pressure switch, fittings, regulator, check valve, and is nice an skinny to mount anywhere.
Extract the dead 110V motor/compressor, keep the tank.
Frankenstien mock up of 12V compressor (from Harbor Freight) on tank.
I REALLY REALLY tried to mount the tank/compressor under the truck, but I have Amp Research Steps, which consume ALL the free under the doors. So I settled for an in-bed set up. Which I have come to appreaciate, becuase of security, easy access, and its out of the elements. Sadly, I had to drill holes in my bed. But it fits just perfectly in that little pocket, and there's clearance for my BedSlide to come out. One benifit of bed mounting, is using the rubber feet that came on the tank. So one could say, the compressor/tank is rubber mount isolated!
(this is an older pic, of just OBA setup, before I finished ALL the electrical wiring, and air tubing plumbing to the horns)
I ditched the pressure regulator, but kept the OEM (110V style) ON/OFF tank switch. The switch has 2 outlet fittings on it. One goes to air horns, the other goes to quick-connect fitting for air hose/ air tools, and a schrader fill valve so I can fill up with shop air, or gas station air if needed. Compressor came with a small storage bag, in which I keep 25ft coil hose, tire fill air chuck, air blow gun, and extra fuses.
Now on to the fun part:
United Pacific, 3-chime air-horn from a truck supply company in FL. This is the same horn that trainhornsoftexas.com sells with their kit. (I paid much less)
They are BIG. The long one is 17", the short one is 12".
These are nice looking, well made, cast aluminum, polished. The pic does not do it justice.
They come assembled on a large bracket. I promptly disassembled it all, down to the individual horns. The only bad part about these horns, was that all the air fittings are literally glued in place, with silicone caulk. I guess it didnt matter, becuase the mount bracket does all the work, in keeping them together. After dissassembly, and glue removal, I tapped all the blank air fitting holes for 1/8-NPT threads, for use with compression tube fittings.
The ideal mount location for the horns is in the front, behind the grill. Well, there is just not enough room... er... there is NO room behind the grill. So the alternate location was somewhere on the frame rails. The two shorter trumpets just barely fit, ahead of the front tires, less than 1/2" behind the front bumper.
I had to fab some mount brackets, and drill holes in my frame rails to accomplish this. But as they say in real estate; "Location, locatin, location!" Don't worry, there is PLENTY of clearance around the tires. The only risk is rocks being flung off the tires, and hitting the back of the trumpet.
Right side: Minimal risk of water injestion at these locations.
Left side: (you can see my combo use of compression and press fit fittings)
The long trumpet (17-inches (that's what she said)) is mounted on the frame rail, just behind the RT FT tire, under the passenger door. Angled down, for water drainage (if req'd)
Passengers tell me they can 'feel' the noise through the floor!
Now for the air line rounting. I used all 3/8 OD DOT Air-brake tubing. All compression fittings, and some press fit/quick connect fittings.
The blue air line goes from the air tank, through a OEM hole in the bed, down along the frame rails, then up to the engine bay where the solenoid valve and manifold are.
Note Red-switch(explained later) and blue air shut-off/isolation valve (to horns)
Routing along frame rail, at RT Rear wheel.
From the solenoid valve/manifold, then three lines down to each separate trumpet. It took about 50-ft total of 3/8 air line to route everything.
In hindsight, I wish I ran along the inboard side of the frame rail. But the trade off is easy access(?)
Just before the solenoid valve, there is a T-fitting, with 1/8 tubing going off to a pressure gauge I mounted in the cab. Next to the pressure gauge is a LED, compressor ON light.
Pressure gauge is 15/16 dia, from McMaster Carr, with 1/8-NPT fitting. Fabbed my own guage mount pod/bracket.
Finally, a schematic of it all.
The compressor is wired directly to the battery via 30A fuse, but inturrupted by a relay, which is activated by the pressure switch. The relay gets its power from one of the Upfitter switches, OR, a manual override switch on the compressor. This way, I can run the compressor without needing my keys, to get power from the upfitter switch.
Look for the red covered switch in the pics of the compressor?
Red cover down = remote turn on via up-fitter.
Red cover UP = manual override. Red switch also has a middle OFF position)
I mounted a small push button switch on the bottom of the steering colum. This powers the solenoid valve, and gets its power from Upfitter #1.
Now, Upfitter#1 acts as an arming switch for the buisness end of the system.
Compressor motor also has built in themal shutoff switch, and 30A fuse.
Yes, I could have wired the compressor directly to Upfitter #1, but then I'd ALWAYS need my keys in the ignition to run the compressor. I seem to be using the OBA more often for filling up tires and blowing dirt/dust with the air gun, than for the train horn function. Its nice to be able to do that via the manual override switch.
All in all, I am just under $300 into it. The compression fittings and DOT air line were the most expensive item(s). But now I have a sano instal, and reliable OBA. Oh, and I bought the 'extended warrenty' for the compressor, so I'll be 'trading-in' next year.
I can provide part numbers and vendors if needed. Let me know if you have any suggestions, questions or comments!
Thanks for looking!