A Generator Cooked to Imperfection!

[Tom Wesenberg]

For those who haven't seen thrown solder from a generator armature, here's what it looks like. Notice the silver splatter line in the first picture and the bright silver at the ends of many commutator bars. To go along with the thrown solder, notice how well done the field windings have been cooked. All the oil was gone from the front ball bearing also.

The best thing to do here is to find another generator and save the good parts from this one.

BTW, the cause of this damage was someone mixed up the field and output wires on the brushes.

 

[Patrick L.]

Nasty. I wonder how long it was run that way ?

 

[BudP]

Thanks again, Tom, for continuing our education!

 

[BashawT]

Nasty. I wonder how long it was run that way ?

Quite a while. Grandpa always pop started it and now I know why. I guess now I get to harass him for "rebuilding" it wrong.....

 

[bogdonj]

Would this of made a noise Tom or just start smoking?

 

[Tom Wesenberg]

Would this of made a noise Tom or just start smoking?

The dry front bearing makes a little noise, but nothing the driver could have heard. The driver might have smelled the smoke though.

 

[Bluebell]

Some maybe helpful info;
In service, this would happen when ;
A failure happened in the regulator (contacts arced together?)
Some one hooked the battery up the wrong way around (even momentarily)
The bearings fail in the generator (can be caused by belts being too tight)causing the armature to "pole"
With a generator and regulator set up the failure of one, can often damage the other.

Every time a generator is installed the polarity of the field coil permanent magnets needs to be set. This is achieved by hooking a wire to the live terminal of the battery, and then brushing the other end, momentarily, on the field terminal (usually the small one of the two) of your generator. It will cause a few small sparks,and then, the job is done.

 

[Willie Krash]

They use to make solder pots and you would dip the entire com in to it. I prefer to just re-solder them but I do little generator work anymore.
On a another mote bearing failures are typically due to loose belts. At least on "more" modern cars when charging system outputs went upwards in the 50++ amp range. Perhaps at 6-10 amps a slipping belt does not generate sufficient heat.
A 6203 bearing can take a tremendous load. Heat is what kills them.
My concern is for the water pump.
Now if somebody would just make a clutch pulley for an A.

 

[Bluebell]

Willie, the unit shown looks like it might be a product of the "Prince of darkness" (Lucas) which, although it runs a 6203 ball bearing at the drive end, only employed a sintered bronze bush at the com end. If the belt is too tight, the pull of the belt puts a cantilevered load on the bush, wearing it out prematurely, causing the armature to "pole" in the case.

 

[700rpm]

Some maybe helpful info;
In service, this would happen when ;
A failure happened in the regulator (contacts arced together?)
Some one hooked the battery up the wrong way around (even momentarily)
The bearings fail in the generator (can be caused by belts being too tight)causing the armature to "pole"
With a generator and regulator set up the failure of one, can often damage the other.

Every time a generator is installed the polarity of the field coil permanent magnets needs to be set. This is achieved by hooking a wire to the live terminal of the battery, and then brushing the other end, momentarily, on the field terminal (usually the small one of the two) of your generator. It will cause a few small sparks,and then, the job is done.

I think you must be referring to new or rebuilt units. A simple R&R doesn't need the polarity reset.

 

[Tom Wesenberg]

I should have mentioned that running a third brush generator (without an EVR) disconnected from the battery will also cook it as shown in the pictures. The generator when disconnected from the battery can reach as high as 40 volts output and will overheat the windings.

 

[Bluebell]

700rpm, Sorry, I should have said "pays to" rather than "needs to"
The reasoning is that a recond unit may have been in use with its polarity reversed, and that the auto electrician could easily have changed your unit while servicing it. It is just a safe approach, because failure to get it right usually results in a damaged generator and a damaged regulator.

 

[Tom Wesenberg]

I don't have air conditioning in my house, and it got up to 92* and high humidity today, so I decided to go to the basement and work on the armature shown in the first picture. Much to my surprize I was able to save it after hours of work. Time wise it was probably foolish to save it, but I don't like to cast off any original parts that can be saved.

The heat and humidity has been so high that the parts rust as soon as they are blasted. Maybe this weekend conditions will allow some painting to get the generator back together.