field terminal wiring on a 1948 IH cub tractor

A wiring diagram posted on Yesterday's Tractor regarding wiring for a 1948 Cub Tractor with magneto ignition shows the field terminal from the generator wired into the light switch. No connection is made at the cut out field terminal on this particular diagram. Does the light switch act as a regulator for the amount of current produced by the generator?

That dia is wrong . You connect the field from the gen to the field terminal on the cut-out then the wire going to the lite sw also goes on the field term of the reg. It could be shown in your manual as some manuals did have the wiring dia in them.

That dia is wrong . You connect the field from the gen to the field terminal on the cut-out then the wire going to the lite sw also goes on the field term of the reg. It could be shown in your manual as some manuals did have the wiring dia in them.

Gene is correct.
The field terminal on a cutout relay is used when the tractor is setup with no lights from the factory. The assumption is that the battery will be charged at a rate that assures its recharging with no load placed on it other than starting. It is further assumed that it will be operated at engine speeds well above idle, and for hours at a time much of the time. Usually about 3 to 5 amps at 7 volts or a little more.
This was accomplished by using a fixed resistance to ground in the cutout box for the field.
If the tractor was equipped with lights, the charge rate was operator adjusted between low charge, high charge, high charge with the lights (Bright beam or Dim beam). This four position switch L-H-D-B had a resistor to ground for low charge, and all other positions was a direct to ground (full fielding the gen). The light switch was not connected (electrically) to the gen switching system other than rotating with it on the same shaft. Lights were power, field was ground.

A three position light switch O-D-B off dim bright
was used with a voltage regulator system on later tractors (or as an option or retrofit) to provide battery maintenance without the operator being mindful of the condition of the battery charge state.

If both the resistor in the cutout, and the light switch charge control are connected, the charge rate would be higher than expected. two resistors to ground in parallel provide fewer ohms. If it is a three position light sw. it will not have the correct terminals at all.Best of luck, I hope this explains it.

Jim

FWIW (not much actually lol) Im more in Jims camp then Genes on this one in that I would NOT connect the gennys Field post to BOTH FLD on a cutout PLUS any light switch terminal.

Seems to me if it has the original non lights set up and a cutout that has the FLD terminal, THEN IT SHOULDNT HAVE THE LHBD LIGHT SWITCH (or if it does simply DO NOT connect it to the gennys FLD). I view the LHBD switch for use on 2 wire (BAT/GEN) Cutout Relays but for older (NON light) 3 wire (BAT/GEN/FLD) cutout relays I just dont see (engineering wise) using any LHBD field resistor in addition the gennys Field wire to the 3 wire cutout. If you do then the 2 resistors in paralell (As Jim correctly noted) are less then designed for making the genny always charge at a higher rate possibly overcharging the battery.

I dont have any IHC specs but it just dont seem right to use BOTH a cutout field resistor PLUS a LHBD light switch resistor in paralell !!! if the tractor had BOTH a "true correct" LHBD switch PLUS a 3 wire cutout, Id use the LHBD ONLY as one can choose Low or High charge options

DO NOT confuse a VR here with a 3 terminal cutout yall

John T

This sure has turned into a long set of answers for some short questions.

I'm not sure if this is the same diagram you refered to, but it IS correct. And yes, the light switch does control the charge rate. The "F" terminal of the cut-out is only used on tractors without lights.

Jim,

Yes, that is the diagram. The Cub I am repairing has lights. Thank You for the information. How/where did You originally find this information?

Chris

John,

The farmall cub I am working on has the regulator with 3 terminals. Armature, field, battery. It also has lights what seem to be original lights. Light switch has 4 positions. I do not know what the positions do as yet. I'll put the generator back on this next week-generator just repaired-. What does the LHBD light switch stand for? From information you have provided I imagine L=low, H=high meaning charge. The tractor when I received it had the field terminal on the cut out wired to the generator. The light switch was connected to the load side of the amp gauge. The person who worked on the generator prior to me apparently re wired the generator incorrectly inside. This information was told to me by the generator repair person at Acme Electric here in Seattle.

Thank you again,

for the information. T

Gene,
Thank you for the information. I will look through manuals I have for International Cub to see if I missed the wiring diagram you mentioned.

Chris

Chad Penny drew that diagram for me to include in the ATIS Cub FAQ. We didn't have an easy-to-read Cub diagram at the time and based it on the diagram in the IH service manual for the A/B. It was done in 2002. That was long before Bob Melville did his drawings (or at least before I was aware of them). If his had been available at the time, we probably wouldn't have done one from scratch. By the way, this diagram agrees with his #4 drawing.

By the way, I am reasonably sure you have a cut-out, not a regulator. The 4 positions on your switch are:
L = Low charge
H = High charge
D = Dim lights
B = Less dim lights

Since your generator has been in a shop, be sure to polarize it when you reinstall it.

The LHBD is for Low Charge,,,,,High Charge,,,,,Bright Lights,,,,,,,,,,Dim lights

IFFFFFFFFFFF you have a proper LHBD switch DO NOT USE FLD ON THE CUTOUT RELAY Simple as that, the Gennys FLD wires to the LHBD switch ONLY NOTTTTTTTTTTT it and the cutout

Got it???????

best wishes n good luck

John T

Try these Diagrams, they may answer a lot of your questions

http://s101.photobucket.com/albums/m46/farmallbob/Farmall%20Tractor%20Wiring%20Diagrams/

John T
Bobs Wiring Diagrams

Jim, Thank you for the information. I now understand why I had so much trouble with the generating system on the first 1948 Cub I rebuilt. Finally gave up on the 6 volt system and put a 12 volt internally regulated delco remy alternator on it--Changed system from positive to negative ground, and put 12 volt light bulbs in the lights. Had to design and build an attachment system for the alternator to make it fit under the hood gas tank. Chris

John,

Thank you for the information.

Chris