regulator vs. cutout

Thu Aug 12, 2004 10:27 am

Hello All --

Was reading about Alwaysoily's charging problem and a post from Mr. Becker had me wondering. He wrote that from '47 to (I forget now) IH used only a cutout rather than an actual regulator. I have 1947 SN 5244 and it has a regulator and a shunt wound generator. I do not know if the generator is original, the regulator is newly replaced.

First question -- (now I'm new to IH but this is true of Fords and I thought of generators in general) I was told and have thusfar seen that generators used with cutout control only were either of the three-brush style (e.g. Ford 9N) and had a movable internal contact to alter the field strength up or down. Such generators would provide a constant charge regardless of battery condition. If not three brush, there were some with a constant, fixed field tap internally that were essentially a three brush genny without the movable third brush. These generators had one post only, the output post.

If using a regulator, one must use a shunt wound generator. The shunt wound style allowed the constant manipulaton of the field via grounding or opening the field via the regulator. In this way the battery would be charged at a maximum rate if low or not charged at all if up and any value in between. these generators have two posts, Armature and Field.

Now, one can use a shunt wound generator on a cutout system by permanently grounding the field, but that's not the original way. Am I misinformed about the generator styles and their compatibilities? If I'm correct then my Cub should not have a shunt wound generator and should only have cutout control. If IH did use shunt wound gennys and only used a cutout rather than a regulator, why?

Can anyone please set me straight on this,


Pete P.

Thu Aug 12, 2004 2:06 pm

Pete, your cub would have come out with a cut-out rather than a regulator.

Thu Aug 12, 2004 10:53 pm

All Delco generators used on the Cub have both A and F terminals. The field circuit runs from the F terminal to windings around each pole shoe and ends at a hot pickup.

In the earliest generators, this point was a movable third brush. The position of the third brush is such that its performance degrades as speed increases, thus it tends to self limit. The only regulation is done manually by grounding the F terminal either directly or through a resistor. If the tractor has lights, this control is built into the light switch. If equiped with starter only, it could be changed by moving a jumper wire (connect either to the F terminal of the cut-out or to a ground screw). This was common to most if not all International tractors at the time as well as other tractor brands.

Starting in 1950, the systems used a higher output generator. They still had a third brush but it was not adjustable. Output was controlled by a voltage regulator (still no current regulator). For these generators, the generator F needs to be connected to the F of a regulator.

My article (Jan-Feb 2004 Red Power Magazine) has more details on the early system.