Look for a wiring schematic for my 50's D318 generator part no 21335. Bought this unit runs great but she don't make electricity:( . A wiring diagram would sure make it easier to figure out what ail's her. Any one have any insight. Thanks

I,d think a good electrician could help you figure it out and if not usually Cat dealers has a Gen Dept. service dept. but they charge big bucks unless you could get one to moon light a little to help you. Too bad you live so far away as I have a retired friend that was a generator service man for the Cat dealer here that we worked for.

First thing is is the belt on the exciter generator mounted on top good/tight?

An unknown generator like that can have major shorts, burned windings etc, so it might be a good idea to have it checked with a megger (after disconnecting any connections to the regulator-regulators don't like the high voltages applied by a megger). If you don't have one and it looks pretty good, you can let it test itself when it makes electricity. If it burns up, it will definitely have to go to the shop ;>)

Then check the brushes and sliprings in the main alternator, sliprings should be clean and brushes have tension on them, not be cocked in the guides because they're too short etc. The exciter generator on top has a commutator and brushes too. There are commutator/slipring dressing stones you can buy to clean these. They are a soft stone like limestone which wears away quickly as you hold it against the spinning ring. I have also used sandpaper in a pinch.
Maybe dry Bonami powder on a rag?

Once you get through with that, if it still won't generate, try to identify which brushlead is + (usually F1?) and which is - (F2?). Rig up a battery to flash the field with. You want to run the set and touch the BAT+ to F+ and BAT- to F- and see if AC voltage will build up. If it comes up, it should build up to full voltage quickly so remove the flashing jumpers as soon as the voltage begins to come up. If it comes up, but won't reach full voltage and hold, you will be safe leaving the flashing connection on until you see what final voltage you will get. You should get some fraction of full output voltage depending on the voltage you apply to the field.

Flashing restores some magnetic field to the iron. The generator has to have some "residual" magnetic strength left from the last run to begin to make voltage. In the case of your set with an exciter on top, the exciter is the component that has to make the starting voltage, but I believe flashing the brushes on the main generator will also flash the exciter at the same time.

Your generator probably also has a flashing relay that automatically connects battery voltage to the exciter field until it builds up voltage. If this functions properly and your set has batteries (does it have any?) it should take off on it's own every time no matter how long it has been since the last run.

Couple of pics I had on file from the last generator go-round:)

The chicken farmer i bought it from said it worked ok, it was used for emergency power. It has not run in about four years. Brush's are in real good condition no binding,slip rings are also good,all the windings appear good no opens,no shorts to ground allthough wire's no# 10 and 2 out of the main generator are connected to the neutral and ground these wire appear to be the wires that supply ac current to the rectifier bridge which then send's dc current to the excitor. Iam assuming this is how it works. It does not have a flash relay. I will try to flash it later today. Thanks again

Old Magnet Thank you for the pictures they will be very helpfull, are there anymore schematic's and how does one get such a manual. Thanks again

Hey FHP-
You may want to try the Sparks & Arcs Forum. It is just like ACMOC but deals with Vintage Generators-
www.smokstak.com/
Click on 'Generators & Motors'

Good Luck
CS

The service manual has two sections......twelve pages of trouble shooting information and 15 pages of service and repair information of which the diagrams I posted are included. That is all it has in the way of significant schematics.

Although the manual came in its own Cat yellow jacket there is no usual form number to go by and the 2H-340 number doesn't seem to identify it in the Cat Legendary Literature List.

It may have been part of another publication....I don't know.

Wires #2 and #10 are the neutral connections to the generator. The diagram shows a Wye connected generator and the center point is the neutral point. The exciter generator is self exciting and the power source for the main gen field. The main gen output is fed back to the exciter through the control field to regulate the output. As to "cleaning" slip rings and commutators, be very careful what you use. On silp rings, no abrasive at all. On the exciter commutator only commutator stones or felt block soaked with electrical contact cleaner. The old red can of CRC brake cleaner will work fine. TriChloroethane is what you should use. Taking a wild a** guess as to your problem, I would make sure that item J is clean and making good contact. If it is a wire wound resistor you can use a pencil eraser on it to clean it up and then clean off the eraser crud with the solvent. You have to see exciter output first before the main will do anything.

Small stator wire 2 is indeed connected to the Neutral point, but 10 is shown connected to T8 in the first schematic on the left, and probably is connected similarly on the others on the right of the page.

Anyway it should supply a 120 volt reference for the regulator. It would be better if it were referenced to the voltage between 2 lines.