Headlight Switch

I am hooking up the headlights on a Farmall 340. Tractor has been converted to 12 volts and the headlights are 12 volt sealed beams. About 35 watts for each of the 2 lights. The switch is a 3 position type (off,dim,bright,rear).
Boy,that coiled spring type resistor on the back gets smoking hot when the switch is in the dim position. That got me to thinking that maybe I should be using a different switch, a 12 volt version?
And why did they make a dim position anyhow since it just burning off the electric to keep the lights dim. You are still draining your battery so why would you even use that setting?
Pete

If I remember right the dim setting was for driving on a public road and you met a car. Same setup as all motor vehicles.

[i:654c4848f0]If I remember right the dim setting was for driving on a public road and you met a car. Same setup as all motor vehicles. [/i:654c4848f0]
darn feds and all their regulations complicating things
the resistance wire must have been the cheaper and simpler way to provide a dim setting. Notice most cars going back a long time have seperate bulbs or different filaments for dim function. I have a 1929 Dyke's auto encyclopedia (it's like a how stuff works book for mechanics), and most of those cars have dim resistors in their light circuits. I would imagine the cars went away from a hot resistor to prevent fire as things got more complicated and fancy.

a perceived high/low switching to oncoming traffic is more important than specific ratings (within reason, still don't want to blind anyone) Whether you do it with a dimmed bulb or a set of lamps with a different focus is up to you. Usually farm equipment is given enough leeway to get the job done, within common sense. But check local laws, especially if you aren't farming with it.

our 400 had the dimmer disconnected for a long time. I hooked it back up and don't care for the results either. I observed without the resistor, there are enough contacts to control seperate light circuits, so one could use different lamps for different functions. The older switch contacts are all screwed together, but the newer ones are crimped and riveted. I think either way you can modify how your low and high work. [b:654c4848f0]just don't exceed the load of 2 (approx 35 watt each) headlights and one rear work light at any time![/b:654c4848f0] i feel this should also include the newer machines with floodlights and flashers tied into the light switch. Use relays to handle the extra lights and when you decide to use more powerful bulbs. and go up a wire size.
stay safe



karl f

Thanks Karl..I think you must be right about it being a cost thing. I'm not going to use the dim setting. The gas tank is way to close and exposed to that hot resistor for me to be comfortable. Besides, those tractor headlights even on the "bright" setting don't seem close to the light intensity of the high beams used on today's cars.
Pete

If you want them brighter, you can go to NAPA and get some aircraft landing lights (same bulb goes in a Piper Cub, but NAPA's are not certified for airplane use) that fit perfectly in the 12V sealed beam housing. You need to beef up the wiring, including the fuse. I did that after I switched to an alt in 2004. They're great. [Note: this tractor has not been on a public road since new in 1966 and has no plans for doing so, unless it runs away.]

The dimmer resistor wire went up in smoke (literally) the day I installed them. It is not missed.