JD Model M noltage regulator.

I have a 1951 JD Model M Serial No. 50226 that I am rebuilding. It has 6 Volt positive ground electrical system. It has a 2 prong voltage regulator that I am having a tough time finding. There is a 4 prong, 6V positive ground available for a Model M via Yesterdays Tractor Co. Will it work instead of the 2 prong and if so what 2 of the 4 prongs do I use? Thanks for any help / advise provided.

It originally had a Cutout Relay, what youre calling a "2 Prong" That was NOT a Voltage Regulator

Its Possible to convert to what you call a "4 Prong" and if it has 4 terminals, its a Four Terminal VOLTAGE REGULATOR.

Originally the charge rate was manually controlled by a wire from the FLD Post on the Genny that wired to the Light Switch which had Low and High Charge settings

If you insist on changing it to a VR (Id leave it original if it were mine) you no longer use the wire from FLD on Genny up to the Light Switch but wire the genny and VR instead as follows:

BAT on VR to ammeters Load side terminal, thats the wire that used to wire to BAT on the Cutout Relay.....

FLD on VR to Gennys FLD Post, Do not run wire from FLD up to light switch any longer

GEN/ARM on VR to gennys ARM post

(L)OAD on VR feeds hot battery voltage to the light switch so loads like lights and ignition will work. The switch used to get its battery voltage off the ammeters Load side terminal but with the L VR terminal use it instead. NOTE the loads like lights and ignition would still work if you left them fed off the ammeter and didnt use the L on the VR

SURE YOU DONT WANT TO JUST BUY A "CUTOUT RELAY" (what you call 2 prong) and install its two wires same as old one and leave her original???

I have converted them and be sure the VR is suitable for your POS Ground

Get it?????

John T

I'm sure lots of places have the cut out. Sharps, for one. This site too, I bet. I found a couple of originals off junk tractors in a salvage yard. I literally poured water out of one of them, cleaned it up good, and it worked fine.

Cut out relay's were the early (pre) version of the voltage regulator. Anyone not running in to it before would call it a voltage regulator and have a hard time finding it. Cut out's are readily available. I'm pretty sure M's were the last Deere's to use one.

All the "M" series used the cut out, M, MT, MC. I see the 40 went to the voltage regulator.

Sorry, This diagram failed to show the borrowed good M Mans diagram on my first attempt?? It shows the ORIGINAL equipment as we all described for you "Cutout Relay" (what you call a 2 prong) and its wiring. True some replace it with a "Voltage Regulator" what you called a 4 prong as I described below. That drawing has one minor mistake but I forget where its at, I'd have to study on it some.

John T

T hanks again John for the help as well as all others who have responded. Much appreciated.
I.Cobane

Thanks for the feedback Leon