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callum12

got a horn for my tractor

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callum12

hi all,
I was at a vintage car rally yesterday and i picked up a 335hz 12v hella horn, I am trying to find out if I need a relay or not? some people seem to say you do while other people say a good 5A switch will do it. I will of course be fusing the horn.
also would i wire the switch on the positive lead? 
thanks for you help,
callum

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squonk

I would put  a relay on it. Those 5 pin relays most cars use are plentiful at any Pick your part yard. Most of them have the pin diagram right on them. I have a drawer full of them.

 

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callum12

I think I've got a few somewhere, what sort of amperage is a horn? 
thanks for your help,
callum

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squonk

Horns vary. I've seen some as high as 15 amps

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Save Old Iron

given the short wiring run in the average LG tractor, and considering the horn will likely be less than 10 amps, forget the additional wiring required for a relay. Wire the horn thru a fuse then thru an automotive quality momentary switch directly to the horn.

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Save Old Iron


homework time for you

google "335hz 12v hella horn"

find the manufacture's data for power consumption

if power consumption is in watts, divide that number by 13.8 to give amps drawn when vehicle is powered up.

double that amp draw (for a generous safety margin) and select a switch for the doubled amperage.

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"D"- Man

I don't know what sort of steering wheel your tractor uses, assuming it's an A-800, but I am planning on using a Grant style steering wheel with a Corvette horn button/switch on my 18 Auto Resto-Mod, Mark.

478.jpg

Edited by 23 Automatic LSE
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callum12

yes it will be my A-800, that steering wheel will look really nice.  i was going to have the switch under the the aluminium dash box so it is out of the way but quick to get at (not that much happens quickly on a tractor!).
thanks for your helps save old iron, finally some homework i want to do!!
Callum

edit
here's my homework sir, 66W so 4.78A, i'll go for a 10A plus switch i think, maplin will do them. thanks for that.

Edited by callum12
hand in homework

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squonk

Using a relay takes 2 more wires. Big deal. I'd rather have the relay.

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callum12

I see your point, it is nice having that extra protection, but my WH does have to live outside sometimes (this is in the UK too). even though it will be well covered I rather keep electronics to a minimum really. If the horn only draws 4.7A and i use 25A switch with fuse i don't foresee any problems. 
thanks for your help,
callum 

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squonk

A 25 amp switch would be pretty big

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Save Old Iron

A 25 amp switch would be pretty big

you know the old saying...

big switch?   use a big fuse!
 

ms.gif

Edited by Save Old Iron

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callum12

haha, i'm using wire from pylons as well!
the switch i've got for my headlights is a 25A toggle switch, i think it is a bit bigger than the standard I'm not sure. a momentary switch of the same value might be quite a bit bigger possibly? I've found some 10A vandal proof switches! they look quite cool and have a cool name.

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george.stringer@frontier.c

You can go either way with your horn.  If you decide to not install a relay you will need a switch capable of passing high amperage.  If you install a relay it will cut the amperage at the switch and you can use mini push button switch.  Carefully remove the tin cover on the relay by bending the attaching prongs straight.  Use an ohm meter to see where the current goes when the blade on top of the coil is closed.  That post is where you attach the wire going to the horn.  Two other wires are needed - one to + bat and one to - ground.  Put your horn switch in the ground circuit with your fuse in the + circuit.  If you use a Delco Remy horn it can be mounted on the hood hinge above the axle.  I will  insert some pictures.  If you have more questions email me at george.stringer@frontier.com.  The picture with my hand in it shows the horn position with the hood closed. George
 

BACK TOGETHER 13.JPG

BACK TOGETHER 14.JPG

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