Allis Chalmers voltage regulator

A question on 3 terminal and 4 terminal voltage regulators. I am trying to put a 4 terminal voltage regulator for a D-10, D-12, D-15, D-17, D-17 diesel, into an ED-40. I understand how they are wired differently, the 3 terminal regulator not supplying power to the ignition and lights, while the L terminal on the 4 terminal supplies power to the lights and ignition. In looking at the internals of the regulator I see that the Bat. terminal connects to a large wire that makes 6 or 8 turns around the outside of a coil, then connects to the L terminal to supply power to the Bat terminal of the lights/ignition. On the 3 terminal the lights and ignition get power from the load side of the amp meter. My question is will the regulator function without a load (such as the ignition coil, on the L terminal? Since this regulator was for a D-17 diesel I would assume so. Is it necessary to remove the amp meter feed to the light switch when using such a regulator and replace it with a wire from the L terminal? Or will the regulator work anyway? The regulator that was on this tractor wasn't the correct one, too large to fit in the proper space, the D-10 had the right size and mounting and fits perfectly, and it would seem it would work. Thanks for any advise here. Tom

IGNORE the "L" terminal. NOTHING needs to be connected to it in your application, certainly not the ignition coil!

Tom, you ask..."My question is will the regulator function without a load (such as the ignition coil, on the L terminal? Since this regulator was for a D-17 diesel I would assume so.

YES, I agree with Bob, it will still function if you ignore the Load terminal. Even if it was on a diesel, it still has other non ignition coil loads like lights etc.


"Is it necessary to remove the amp meter feed to the light switch when using such a regulator and replace it with a wire from the L terminal? Or will the regulator work anyway?"

If its a 3 terminal VR (loads fed off load side of ammeter) or a 4 terminal VR (loads fed off VR's Load terminal) the ammeters SUPPLY terminal wires to the battery while its LOAD terminal feeds loads PLUS wires to BAT on the Voltage Regulator, so I don't understand any change on the ammeter regardless if its a 3 or 4 terminal VR ??????? Its SUPPLY wires to battery and its LOAD wires to BAT on VR, its just that on a 4 terminal VR loads feed from the VR instead of the ammeters LOAD terminal. YES REGULATOR WILL STILL WORK if you feeds loads off ammeter or L on the VR and YES ammeter still works if you feed loads off its load side or L on the VR.

NOT SURE I UNDERSTOOD YOUR SECOND QUESTION so does this answer it or not????????????

NOTE if I had a 4 terminal VR anyway, Id go ahead and re wire the loads off L on the VR instead of the ammeters Load terminal. Sure it still works either way.

John T

Thanks Bob and John. Yes you guys have answered my question. I just wondered if as the internal connection in the VR between the Bat and L termals coiled around a coil if it would need a load to make a magnetic field. From what you guys say all is well, and you have confirmed what I thought and hoped. Thanks again, Tom