Truck Air Horn - any Repair Info?

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Jack-the-Ripper
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Truck Air Horn - any Repair Info?

Post by Jack-the-Ripper » Mon Sep 27, 2010 9:37 pm

The two air horns on my dump truck only give a very low whistle. I've checked the air flow which seems to be good - even inserted air from the shop with different regulated pressures from about 10 to 90 psi in 10 lb increments. The horns have a metal disk inside that the air seems to blow across kinda like blowing air across the edge of a piece of paper to make it whistle. I don't see any other parts. To replace the horns means removing the headliner to get to the plumbing connections. I'd rather repair them if possible but couldn't find any information on the web to that effect, nor have any of the few old timers I've consulted around here known anything.

Since both horns don't work, I suppose there is the possibility that the pull chain valve isn't passing enough air. It also is not very accessible.
Do the horns require a large volume of air to make that wonderful deep air horn sound?

Thanks
JD450C (Jack the Ripper), JD450B (Jill the Wench), KomatsuPC120 (Ursa, The Big Dipper), Case580E (Ida Hoe), International 4400 Dump Truck

OneWelder
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Post by OneWelder » Tue Sep 28, 2010 5:26 am

take air supply line off , squirt a small amount of penetrating oil in there - you may need to do it more than once that should give the toot back to your air horns ,

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Willyr
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Post by Willyr » Tue Sep 28, 2010 7:45 am

The sound or pitch of the horn is created through the trumpet of the horn.

All I remember is the metal has to vibrate. Check to see if the metal is not fatigued and broken in middle or on one end. I believe this is a thin piece of spring steel.

Air horns are relatively cheap, or at least they were. A place to look for alternatives would be http://chromeshopmafia.com/
Last edited by Willyr on Mon Jul 04, 2011 8:48 pm, edited 1 time in total.
former owner of a 1956 420c
All help is greatly appreciated.

Proud owner of a project 1952 JD 60

http://www.youtube.com/watch?v=nFehqXVd9z4

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Jack-the-Ripper
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Post by Jack-the-Ripper » Wed Sep 29, 2010 6:50 am

Thanks for the tips. I'll work on it some more and report the results.
JD450C (Jack the Ripper), JD450B (Jill the Wench), KomatsuPC120 (Ursa, The Big Dipper), Case580E (Ida Hoe), International 4400 Dump Truck

markvdh
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air horns

Post by markvdh » Wed Oct 13, 2010 9:26 pm

On most air horns, you can adjust the tension on the disc by twisting the trumpet in or out. It doesn't take much twist to alter the output substantially. This adjustment regulates the amount of air that flows over the vibrating disk. If you are sure that you are getting enough pressure and volume, and the inside of the horn isn't plugged with dead bugs, etc., try adjusting it for the best sound. You can totally silence it (too tight) or just get a whooshing sound (too loose). A high pitched squeal is most likely a trumpet that is too tight.

Mark
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digitup2
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Post by digitup2 » Thu Oct 14, 2010 6:44 am

If you do it right you can get the most annoying pathetic sound from the horn do it right and have the dogs howling for miles around !!.Digitup.

markvdh
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air horns

Post by markvdh » Thu Oct 14, 2010 7:45 am

Hey, and you could design a cable to move the trumpet in and out while you're blowing the horns, then you'd not only annoy the dogs, but all the neighbors too! :lol:

WhaaaarrrrreeeeeWhaaaarrrreeeee...

Somebody ought to try it!

Mark
MC (x2)
420C
440ICD
450
1010C
Mooney M20C
Cessna C150E
Murphy Renegade
Keep 'em crawling (or flying)!

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pop pop
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Post by pop pop » Fri Dec 17, 2010 7:43 pm

did you ever get those hooters fixed???? 8)

i have fixed a few of them,, if you have a few hours , take them all apart. drill out rivets, etc, when you get them all apart, you'll see just what needs to be done.
otherwise, put a bunch of wd-40 in them and blow it through.
usually they have an accumulation of dust, bugs, small rock,sand,twig that keeps the reed(baffle), (usually brass) from resonating.
if the wd-40 works,.. fine,
if not , you'll have to take them apart.
might have to patch the baffle, or replace,
keep your eyes peeled for some of those clip-on "snow covers". they also keep everything else out.
440icd/602/8a,,440icd/831/ripper,,440icd/831/3pt.,misc. 440 parts, i have 5 of these now, but i can stop anytime :cry:

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Jack-the-Ripper
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Post by Jack-the-Ripper » Sat Dec 18, 2010 1:14 am

Thanks to all for the continuing stream of ideas.

I disassembled them. Yes, there were bugs, mostly paper wasp nests, and I cleaned out all the dirt and crud. Neither the horns nor their trumpets showed any adjustability as I remember. There was just the trumpet, the base with an input slot shaped with a sort of taper (terrible description - a photo would be better, maybe like the mouthpiece of a sax - the air comes in across the disc and perpendicular to the trumpet), a solid round disc and the back cover attached with six screws. I found no adjustment, which motivated me to post the question. I would just replace them but I'd have to remove the head liner of the cab which doesn't seem readily do-able.

Admittedly I got distracted with the pretty involved rebuild of the 450B (that now works wonderfully and steers right smartly (and the slight pitting of the existing clutch discs that I re-installed, seems to make no appreciable difference in its ability to push a load).

Now I'm on the road "snow birding," using my pent up energy to troubleshoot and repair a small older travel trailer. I look forward to working on the horns again upon my return in the spring.

Indeed, given my efforts at repair, I took it from the dog cringing screech to the exhalation of a dragon, fresh out of fire, all just by cleaning and reassembly. Thanks again for the input. Ralph
JD450C (Jack the Ripper), JD450B (Jill the Wench), KomatsuPC120 (Ursa, The Big Dipper), Case580E (Ida Hoe), International 4400 Dump Truck

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Jack-the-Ripper
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Finally, the answer.

Post by Jack-the-Ripper » Mon Jul 04, 2011 3:34 pm

While on the road I found some air horns in a friends garage and blew air through them. They worked perfectly. So I took one apart and found the chamber, the flat round disk, and, ... A spring!

I thought, 'Gee, I don't remember mine having springs between the back cover against the disk!'

Back home, indeed, mine don't have springs, but with hindsight and closer inspection there were remnants of long ago rusted out springs. I didn't even bother to Google air horn springs (hmm, that might be interesting.) I got some springs of about the right size and tension, as I remembered them, from the winter, cut them to an estimated length, bent the coils so the ends set flat, and installed them. Gee, quite passable horns!

Thanks again for all the helpful comments.

Ralph
JD450C (Jack the Ripper), JD450B (Jill the Wench), KomatsuPC120 (Ursa, The Big Dipper), Case580E (Ida Hoe), International 4400 Dump Truck

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Tractor 850
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Post by Tractor 850 » Tue Jul 05, 2011 7:21 pm

Back when I was a much younger lad the company I worked for bought a used Mack R700.
The air horns didn't work at all.
One of the old timers climbed up and starter working the trumpets back and forth while I held open the air.
A lot of debris blew out and they started working.
Worked fine for the next 5 years we had the truck.
Dave

JD440IC Ser#445235 W/ #63 Dozer
Ford 850 Ser#55497 W/Wagner Loader

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