Convert 3rd brush gen to regulator

What does it take to convert a 3rd brush gen to a fully regulated gen? This would be a Delco Remy generator.

All I can think is move the brush to full output, but then would you just wire the regulator as normal? I haven't compared the terminals on the different generators but I thought they were both just A and F.

Brandon

As I understand it on our 39 Chev which has a 3 brush generator, the 3rd brush is not adjustable, riveted in place, this controls the maximum amperage preventing burn out however the generator is controlled by a voltage regulator allowing varying output as needed to meet electrical needs. I will stand corrected if I misunderstand.

Two ways: doing as you describe is OK, it will work. A more complex method is to eliminate the third brush and wire the field to the armature brush connection. This might allow a couple of additional amps to be produced, but not much. The regulator is then connected as follows: a 3 terminal regulator with Bat ARM Field terminals is connected as follows-- Bat to the to the wire that was formerly to the Bat on the cutout. Arm to the generator Armature stud (might say Gen on it). FLD to the Gen Field stud (12 gauge wire). The wire from Arm to the Gen ARM should be 10 gauge. The wire going to the light switch for H L connection is disconnected and removed (best) or abandoned (confusing in the future). No polarizaation is needed as long as the battery polarity remains original or as it was. Jim

If the regulator is a 4 terminal with a terminal labeled L, the L terminal should attach to the 15 amp fuse for the lights. The original light supply wire is removed. Jim

When AC went to a voltage regulator, they went to a two brush generator. I have put a voltage regulator on a three brush generator just as you describe- set the brush at full output. Interestingly- I worked on a neighbors MF 65, and found a DR three brush generator with a voltage regulator mounted as original equipment.

My MF 35 and 65 both have 3 brush generators with voltage regulators. I believe that is the way they came from the factory.

nothing just get the regulator made for that DELCO # on the tag i get mine from CAR QUEST they have USA built regs or thats what the dealer told me i have one B with the 1101355 gen and a regulator been running and charging just fine tractor even spent winter at 10,000 ft under the house we had in the Gunnison area near famous PITKIN amazing tractor would set over winter and in the spring would start and run just fine a B FARMALL with a hy system and loader and log splitter many many fine memories

Brandon,

YES a typical Delco Class A Generator has the ARM and FLD posts REGARDLESS if 2 or 3 brush.

One way I have converted an old 3 brush genny (that used a manual Low High light switch charge control) to use like a 2 brush (with a properly matched 2 brush Voltage Regulator) genny is simply remove the old third adjustable brush and then the non grounded brush (which is 180 opposite the grounded brush) has its small flexible feed wire connected up to where the gennys internal ARM post wire is attached. Then use a proper (Delco literature if you can locate?) 3 terminal VR with BAT FLD and ARM. If before the gennys FLD post wired up to the light switches Low High charge you now remove that wire and instead wire the gennys FLD post to FLD terminal on the new VR......Bat on VR to Load (not battery/starter) side of ammeter..........Gennys ARM to Gen/Arm on new VR......

I have also just set any adjustable third brush to max charge location (close as possible to the fixed brush by it) and used a 3 brush VR BUT THATS NOT MY ADVICE OR RECOMMENDATION even if it can work. I doubt you will regulate and control the exact and enough field current to allow the genny to produce its max output if you do that but hey it can still work.

The old 3 brush used the third adjustable brush to regulate charge by moving the third (its where Field circuit and current starts) adjustable brush farther away from the fixed brush to reduce field current and instead of a full fledged Voltage regulator they used a Low High manual charge control. Then they went to a full fledged VR which automatically regulated field current.

Your tractor your choice but getting the best and correct new VR nowadays to match especially a modified genny may be hard HOWEVER what youre talking about or my advice can still pump some degree of charge to the battery and even if all new and perfect those may have only pumped a few up to say 10 or 20 amps !!!

Give it a try if you like

John T

John T

PS Correction.......My apology my bad Its the gennys FIELD windings (one on each side splices in the middle) that used to wire to the third adjustable brush THAT NOW WIRE INSTEAD UP TO THE INSIDE OF THE ARM POST....

On the old 3 brush the FIELDS started at the third adjustable brush while on the 2 brush they start at the ARM's inside terminal

Remove 3rd adjustable brush,,,,,,now the start of the FIELDS wires instead to the internal ARM no longer to the third brush

It so happens that the fixed non grounded brush is the same location electrically and wired to the ARM's internal post

Got in a hurry senior moment my fingers worked faster than my old brain grrrrrrr

John T

See my post, we do think in similar ways on electricity. Jim

Might it be said great minds think alike orrrrrrrrr even a blind squirrel finds a nut now n then lol

Yep we typically agree on sparky issues , must be right ya reckon ??

John T

If 3rd brush is left in place, that protects the generator from over-current. If removed, one needs to ensure that the regulator used has current regulation (matching the generator current rating) and NOT just voltage regulation as did some VR units. VRs without current regulation were used with 3rd brush generators.