John Deere LA and BO Repairs

My 1941 JD LA has a battery but the only thing it is hooked to is the starter. Well, and the generator, but I'll get to that. The engine has a magneto so if I had a hand crank, I could start and run the tractor without a battery. The tractor did come from the factory with lights but the front one is currently missing and the rear one is not hooked up. The ammeter is also not hooked up, so yesterday (8/7) I remedied that. I wired up everything and installed a light switch. But it's not any ordinary light switch. Oh no no no no no. Let me explain.

Old tractors like this LA have a very rudimentary charging system. The generator has what's called a cut-out relay (not a voltage regulator), and its only job is to cut any voltage draw from the battery when the generator isn't charging, such as when the engine stops or the generator dies. Since the generator has the ability to put out 10 to 15 amps of current, with no regulator in the system it would boil a battery in short order if the engine ran, say, all day long.

Tractor manufacturers minimized excess current going to the battery by means of a resistor in the generator's field circuit, to lower output of the generator, and they decided to put the resistor on the light switch and they gave control of the resistor to the tractor operator. My LA's generator didn't have a light switch, and happened to be wired for full generator output all the time. Fortunately the engine doesn't run very well, so I think the battery isn't ruined....

The light switch has positions 1, 2, and 3. At the "1" position, the resistor is in the circuit so the generator puts out low current, maybe 4 or 5 amps. The "2" position takes the resistor out of the circuit so the generator puts out full power, maybe 10 to 15 amps. You'd use this if you were just running the tractor for a short time, so the battery could get recharged quickly. The "3" position turns the lights on, so whenever the lights are on, the generator is still putting out full power but some of it is powering the lights so the battery doesn't get full power..

Manufacturers in the mid- to latter-40s I believe started putting voltage regulators on tractors so the output from the generator was automated and more regulated than a system with only a cut-out relay and manually switched resistor.

I recently bought a resistor/light switch and installed it. This first photo is the switch I bought. The resistor sits on the top of the switch (white porcelain cylinder with resistor inside). There's also a fuse on the bottom to protect the light wiring.

In the photo below, the light switch is mounted and wired in. It's strange that John Deere mounted the switch on the engine cowl  To operate the switch, you have to stop the tractor, set the brakes (not an easy task, ask anyone who owns a JD L or LA), extract yourself from the seat (also not an easy task), and climb forward to pull or push the switch.

This next photo below shows the switch and ammeter wiring. I still need to find a front light and run a wire from the light switch to the two lights. Interesting tidbit, JD only put one light on the front of the LA's engine cowling, on the right side. The rear light by the operator is on the left. The industrial "LI" got two lights up front.

(This LA pulley and mirror installation is a month later than the above work and the BO work)

The previous owner had gotten a belt pulley for this tractor that he didn't install. My previous LA also came with a belt pulley that wasn't installed, as the guy I bought that tractor from didn't want the pulley on because it was "too dangerous". Yes they do hang out in space on the side of the tractor but if I have a belt pulley, it's going to be installed on the tractor. So, I installed the pulley on my prior LA and will install this one also. There's a square plate on the right side of the photo. That plate comes off and the belt pulley mounts in its place. The bolts weren't long enough so I had to dig around in BOB (bucket of bolts). It took a while but BOB didn't disappoint. I'm not sure why someone painted the end of the pulley yellow. Maybe to make it more visible? I suppose I could leave it yellow.

Now doesn't that just make the tractor? Huh huh? Yes, yes it does.

A gent from the tractor club gave me a rear view mirror. He'd bought a set of two but only needed one for his 1939 Allis Chalmers RC. Thanks John Olson! I was contemplating where to mount the mirror and my wife showed up. She said, "Why don't you put it on that clamp for the headlight bar?" Yep, that works better than where I was thinking. I drilled out the bolt hole a little larger to fit the mirror mount, and it fits great.

Now on to the 1936 BO. The first thing I did was repair the drawbar. It's supposed to be able to swing from side to side but it is currently missing the parts that allow it to swing along the framework, and it is currently just bolted to the frame on one side.

Things are difficult to see but I plasma cut two pieces of angle iron to bolt to the drawbar, then a long bolt will go through the uprights of the angle pieces and rest on top of the framework, with a piece of pipe to be used as a roller.

I had to drill another hole in the drawbar so the angle pieces wouldn't hit the framework so I don't think this drawbar is for a BO, but it will work fine.

The next photo shows the thing assembled, painted and pretty.

Below shows it installed. The yellow framework was missing a bolt (the hole in the yellow piece in the right foreground), but I rectified that minor problem. The hole had been stripped out and tapped to a larger size but I was able to find a bolt in the basement that fit.

That looks so much nicer than the "before" shot.

8/13/2024 update - I wired in the rear light on the LA today. It wasn't a big job but.... There's always a but. The light housing gets its ground through the light mount, then to the frame of the tractor, so any joint between the various parts that hold the light where it is in space need to have a good ground between them. The main issue I ran into was the little pedestal the light housing is mounted to. Once I got a good, clean surface between the several mating parts, the light worked. Then it was just a matter of running a wire from the light to the light switch. And another "but". There's a channel on the front side of the steering pedestal that the wire is supposed to run through. Well, it was crudded up with debris and what looks like an old wire. I was able to eventually jam a stiff wire completely through to clean out the rusty junk enough to get the light's wire through. This first photo below kinda shows some of the pile of rust that fell out. The channel is held to the pedestal with two screws but they are frozen solid and I didn't want to break them off today. Maybe someday I'll do that project.

And here's the light in all of its glory. Fortunately the bulb is still 6v.

This next photo below shows the ammeter charging at about 15 amps. This is with the light on and the switch in the high-charge position.

This next photo below shows the ammeter charging at about 5 amps with the switch all the way in, which is the low charge position. The main downside to this type of cut-out relay charging system is that the battery is always getting either 5 or 15 amps of current, whether it needs it or not. A regulator in newer tractors regulates the amount of generator output charge based on the needs of the battery, so a battery will typically last longer with a regulator-type system than with a simple cut-out relay. I probably already said this above somewhere...