Farmall A Cutout Relay Question ...

Crazy Horse

Well-known Member
I have an earlier Farmall A with what I believe is a Delco generator (1101355) and a cutout relay box mounted on the generator. Although the relay box is somewhat large in size, it only has the cutout tower inside (with the corresponding BAT and GEN hookup locations on opposite sides of the tower.

The strange part is that there is actually a FIELD terminal on this box as well that goes nowhere inside, it's just "there" and I can't figure out what it's doing unless the same box is used for other models of electrical control where other towers might be used for voltage or current control. On this relay box, there are six spaces for hook up terminals, three on each side but only 3 are used (BAT,GEN, and this non-funtioning FIELD).

SO when rewiring everything, I hook up to the FIELD terminal on the generator case itself (and ignore the FIELD terminal on the relay cutout box), is that correct?
 
If your A is equipped with lights, the generator F post should connect to the field resistor terminal on the back of the light switch.

However if it does NOT have lights, the genny F post should connect to the cutout's FIELD terminal.

Simply grounding the generator F as you have it now does work. However it causes the generator to charge at its highest rate all the time.

This is not a problem if you use the tractor only intermittently. But if you run it hours at a time, the constant high charge rate will quickly ruin the battery. If this is the case replacing the cutout with a voltage regulator is highly recommended!
 
Pretty much the same as the discussion over on R & R and when and where to wire the gennys FLD post depending on if the tractor has lights huh? and that post even had a good picture of the internals including the wire wound field current limiting resistor itself. Stick around Bob youre a good hand on this stuff !!!!!!!!!! I"ve learned a thing or two from a "Mechanical" Engineer, I was sick the day they taught this at Purdue EE in the late sixties lol

John T
 
I have several of them on my As,BNs and Bs all are wired feild on the gen to field on the cut-out and the wire going to the lite sw like they came from the factory. Gen third brush is set for couple amps and hi-charge is around 7 or so they have been that way for many yrs and work just fine. I get 6 or more yrs on the battsat least most of the time i get 8 or better. They bring me tractors from time to time and thats the way i do them also. There is a regulator made for that gen series. The gen 1101423 also takes the same reg. The501,531 gens take a different regulator.
 
OK, if I read your post correctly you're saying you run both routes? One from the generator case field post to the cutout box F terminal, and another wire from the generator field post to the switch? Wouldn't a single wire from the generator field post to the switch be doing the same thing by itself? That is .... position #1, field through the switch resistor to ground for low charge rate, and in position #2, field through to ground directly at the switch for full charge?
 
To clarify, only a single wire is required - from the generator F post to the light switch field resistor terminal. Nothing is connected to the cutout box F terminal.
 
(quoted from post at 10:56:57 11/28/12) .....Stick around Bob youre a good hand on this stuff !!!!!!!!!! I"ve learned a thing or two from a "Mechanical" Engineer, I was sick the day they taught this at Purdue EE in the late sixties lol

John T
Hey John T - I've learned more than a thing or two from you too - both from your posts here and from your EXCELLENT seminars at the NY JD Expos!

Aso I gotta admit missing an EE class or two myself while down with "brown bottle flu"!

....Bob M
 
(quoted from post at 10:17:26 11/28/12)The strange part is that there is actually a FIELD terminal on this box as well that goes nowhere inside, it's just "there"
If you look at the bottom side of your cut-out, you will find the FIELD terminal is grounded through a resistor. Thus, connecting the generator F to this terminal gives you the low charge rate. As Bob already said, you only use this terminal if the tractor does not have lights.
 
Then why did they come from the factory wired to the gen F terminal. I have worked on several that still have the original wiring and thats the way they are hooked up. Mine are wired that way and the work. Its easy to see when the original wires are still there. Some diagrahms show them hooked that way and others dont.At leat 220,000 manuals were printed over the years when they were in production and changes were made in those manuals. Some for the B even showed pics of the A so there were mistakes made.
 
Aha! So you guys finally come out from behind the curtain, and admit to being "a engineer." Mechanical, myself, Maryland undergrad 60's, grads from Penn State. EE courses ~ useless on real stuff like tractors, but I've known where to find you guys for quite some time. Thanks from all of us for your help.
 
John T and Bob M are difficult to fault in the ways of tractor electrical reality. It is not merely ""learnin"", it is experience speaking. To hook both the resistor in that style cutout and the resistor in the light switch to the field terminal on the gen at the same time would surely give a higher charge rate than charge maintenance with no lights would require. It just isn't correct. Jim
 
Not quite sure what you are saying there Gene. I can't say what the wiring actually looked like when they came out of the factory. By the time I was old enough to understand these systems, they had all been out in the field a while.

IH had several different wiring diagrams, just for the A and B, not to mention all the other models. They had starter no lights, lights no starter and both. They had diagrams for adding lights to a starter system and for adding starter to a lighting system. There was one thing common to every one I have ever seen. If there were no lights, the two F terminals were jumpered together. If there were lights, nothing was connected to the cut-out F terminal.

I have in front of me the instruction manual for starting, lighting and starting - lighting for the A, B and BN. Maunual ID: INT 5402. 5-6-41-2B. On page 17, in the section for adding lighting to a tractor with a starter, it says:
"Remove short lead connecting field "F" to field connection on control box. Connect generator field to switch cable directly to field terminal on generator frame."
It says something similar for each other section that includes lights.

It also has an illustration of the tag shipped on the generators. It shows the jumper from F to F. I suppose the originals you have found with the jumper had the lights field installed and the installer didn't read the instructions.
 
Super A installation instructions, Paragraph 15.
Page%2004.jpg
 
The page you show is for a SA and they used a different generator with a REG unless its talking about the early ones as they could have used a cut-out as the early Cs also used a cut-out. I have never read when they did change from cut-outs to regs. I do know there is a reg listed in parts books for the three brush gennys 1101355 and 423. The later gens 1101501,531 take a different reg. There are a couple of Bs still original in my area wired with field going to the terminal on the cut-out also two early low serial #s Cs with cut-outs. I have redone the wiring on and early Cub and a B that came from gen shop wired from rebuilt shops and both of them came with wires connected checked out and ready to instal. Ive always connected the field to the cut-out as thats the way ive seen them and you sure can tell when its original wiring. The systems work and its quite a deal after 60pluss yrs to have an original system still working some owners took great pride in keeping tractors inside and in good repair.
 
This is for the early style with the cut-out. The Super A changed in 1950 or so. I don't recall the exact serial number but it can be found in the parts catalog.

These instructions wouldn't make any sense for the later style as all systems with a voltage regulator have a short wire from the generator F to the regulator F.

Here is a picture of a generator with the cut-out on top from the same book.
Page%2002.jpg
 
The factory doesn't know whether you will need the wire or not. So they put it on all of them. As shipped, both the generator terminals are grounded to reduce the chance of damage before it is installed.
 
When no lights were on the tractor, there was no other control for the gen. The cutout had that resistor to ground that allowed the gen to produce just enough that averaged tractor use charged the battery correctly. The third brush allowed a range of farmer selected adjustment to charge more or less. The operator may have had only the mag grounding mechanical pull wire kill switch to control running. Jim
 
It doesent give hi charge thats why you set the third brush. How many of those systems have you fixed. Ive been around those systems since 47 and they did come from the factory that way and they still work. The pull cable for the mags was used on the hand crank models with electric start the used a sw. Another quirck the drilled hole in the mags for that cable sw never was discontinued all thru the mag production. Just like the cams in those engines had a lobe for the fuel pump all thru production.
 
Don't be so insistant. Not a flame, I am a very experienced mechanic and electrical system professor. (not that it makes a difference) Jim
 
You still didnt answer the question how many of the cut-out systems do you have and have fixed. Also have you seen any still in their original state.
 
About 6 of them from retrofitted F series to Bs, Cs and As. All had either direct F to F from the cutout, or the light switch hooked up to the F terminal. I was born in 1949 and by the time I was 9 I was messing with them. (but that puts me at 100 series introduction, so) I have never seen a C or B or other system From the factory. Jim
 

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