CAT 955H Generator 2

The charged batteries are coming in at #1 12.36 and #2 12.94Vdc. The ammeter does not move positive, but it shows a draw under preheat.

I found the regulator on the inside of compartment under the seat. The hydraulic filter is mounted to the outside of the wall, covered by a guard. This tractor has a hyster 35,000 winch on its rear end so the #2 battery box is located above the hydraulic filter, with a guard below it. I removed the guard below the fuel tank and found the regulator inside there, although very difficult access. I cannot read which terminals are which, however based on your picture I polarized between the rearmost and middle terminals and got an arc that made me jump. No change in the ammeter, nor when I probe the battery with the multimeter, just reads the same 12.36 or 12.94Vdc.

The next step was to disconnect the field wire from the generator, and replace it with a wire from Field to a ground (grounded off to a bolt on the oil cooler). I disconnected the Arm wire and bolted my multimeter + probe to the Arm stud; and the negative probe I grounded against the body. At low RPM I got 4-6.5Vdc, and when I ran the throttle up full I got 15.5 to 16 Vdc or so.

So with a 24V generator (verified by nameplate) I'm thinking I should see well over 24Vdc on full throttle, so I think the generator is not producing enough voltage. I took it off and will hopefully take it in to get it bench tested and reworked.

But it was producing some power, up to 16Vdc. Why are the batteries showing no voltage increase at all?

How can the regulator be tested? Could it be stopping the charge from going to the batteries? When I reinstall the generator do I have to repolarize it again?

How can you tell, on a very difficult to access regulator which terminal is which (arm/bat/field)?

Once again, thank you for all your most generous help

• regulator and other pictures

They tried to bench test it but I guess the bearings on both ends were shot so they couldnt. They sold us a rebuilt one for $450 or so. With the motor running there was no way to tell the bearings were shot, and when I took it off, it turned smoothly. We also bought a new regulator at their suggestion.

So it sounds like because I got an arc when I polarized it, I might have a short. I guess I should disconnect it on both ends and add power to it. I really apologize but I am just learning automotive electrical by going out based on your instruction and figureing it out. Is this done with a multimeter on the ohms setting? How do I test for a short in the wire? I don't care for getting shocked.

Second, when I replace the regulator with the new one, can I just connect the old wires to the regulator just the way they came off? Note in the picture that they are all painted and I have no way of know what they are by color code. Also note in the picture that there is a 4th wire that bolts to the steel (a ground I guess) and another small wire to the left of the regulator. What are these extra wires? Do i have to polarize again at the regulator?

What should happen when I use the jumper to polarize if its not supposed to arc? How would I know I accomplished it (polarization)? The proceedure: Once I install the generator and regulator and hook up all the wires I need to turn ignition on (without the engine running), then jump bat and arm at the regulator. Do I need to take out the commutator before I do this? How would I take that out, when its mounted and the fan belt is on the pully?

Again, thank you fellas so much. I know this is very remedial for you but I sure appreciate you fellas taking the time to teach me. Its a great help and I really enjoy learning it too.

• WiringDia