Air Horn Pull Chain

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=112441
Printed Date: July 19, 2025 at 5:13 PM

Topic: Air Horn Pull Chain

Posted By: drsnoze
Subject: Air Horn Pull Chain
Date Posted: March 17, 2009 at 7:53 AM

I have to install a set of train horns in a customers vehicle with a pull chain and i dont want to install an air valve in the head liner. Can i accomplish this with a few relays? Basically what it needs to do is when you pull the pin switch it removes the ground and opens the relay.

Replies:

Posted By: i am an idiot
Date Posted: March 17, 2009 at 10:32 AM

This switch is also available without the roller.

https://www.radioshack.com/product/index.jsp?productid=2049719

Posted By: hotwaterwizard
Date Posted: March 17, 2009 at 10:29 PM

You could do it with a normally open pull switch. No extra relay needed.

Personally I would make my own switch.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: dualsport
Date Posted: March 18, 2009 at 11:42 PM

If this is supposed to be for a set of air horns with onboard compressor, how are you actuating the air valve?
Is there an electrically operated air valve somewhere in this setup?

How are we getting from electrical relay contacts to opening an air valve?

Posted By: hotwaterwizard
Date Posted: March 22, 2009 at 2:23 AM

Good Point dualsport

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: drsnoze
Date Posted: March 22, 2009 at 10:16 AM

it has an electronic air value

Posted By: dualsport
Date Posted: March 22, 2009 at 10:59 AM

So it seems you just need to find a pull chain switch and connect it to the chain, since your electronic air valve isn't likely to need much drive current.
Relays should only be needed if your switch is the wrong type (like NC vs NO) and you need to invert it or if your mechanical switch is too puny and can't handle the current needed for whatever device you're driving.
I guess there's no horn button on the steering wheel, or a pull chain is needed to simulate the full trucker experience?

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