Removing Generator Head: 5kW Coleman Powermate

[AUEngineer]

slip ring should be checked in lathe with dial indicator to be sure it is running true
if it fails it can be replaced with used slip ring from another rotor, does not have to be same model

I can have the machinist at work check the slip ring in the lathe, assuming I ever get this thing off the engine.
What +/- tolerances are acceptable when assessing flatness with a dial indicator?

Is there somewhere to buy used slip ring, or will I have to scavenge around for one?

Thanks for all the excellent feedback!

[smallen]

used rings you have to look for, find a shop in your area that does generators, should have some old coleman units
we save rotors out of these for this reason
i would have your buddy dress the slip rings before you put in back, those rings are warped some times from age and heating
the copper is about an 1/8" thick so they can be cleaned up pretty good,

[AUEngineer]

FINALLY got the rotor off!! Man, what a test of patience. Used a long tap and made myself 2.5" of threads (I think I just needed more than 1" of threads)--then used a push bolt (measured with depth gauge). Tightened down, wacked the coils, tightend some more--waited an hour--came back to it. Continued to repeat three times, finally it popped off! Rotor was rusted solid to the taper on the crank, this was the problem. Turns out the governor inside the engine was in pieces... chipped teeth, and the weights were in pieces in the bottom of the engine.

used rings you have to look for, find a shop in your area that does generators, should have some old coleman units
we save rotors out of these for this reason
i would have your buddy dress the slip rings before you put in back, those rings are warped some times from age and heating
the copper is about an 1/8" thick so they can be cleaned up pretty good,

How do you disconnect the slip ring? I pulled the two screws out, but obviously the copper rings are connected to the coils. Connection points are covered in some kind of silicon. Any hints or tricks for removing silicon and soldering these things off? Then I can have the machinist true them up (after I use CA glue to join the crack I made).

Thanks to everyone for the suggestions and assistance--would have given up long ago if it weren't for this forum.

[bgsengine]

FINALLY got the rotor off!!

GRATS!

How do you disconnect the slip ring? I pulled the two screws out, but obviously the copper rings are connected to the coils. Connection points are covered in some kind of silicon. Any hints or tricks for removing silicon and soldering these things off? Then I can have the machinist true them up (after I use CA glue to join the crack I made).

You don't - take the whole rotor to the machinist so they can chuck the rotor into the lathe and true the slip rings not only flat but in perpendicular to the center line of the rotor

[Arkie]

FINALLY got the rotor off!!

GRATS!

How do you disconnect the slip ring? I pulled the two screws out, but obviously the copper rings are connected to the coils. Connection points are covered in some kind of silicon. Any hints or tricks for removing silicon and soldering these things off? Then I can have the machinist true them up (after I use CA glue to join the crack I made).

You don't - take the whole rotor to the machinist so they can chuck the rotor into the lathe and true the slip rings not only flat but in perpendicular to the center line of the rotor

Yes, try what bsengine says FIRST, because a machine shop can true it in place and
probably even fix the cracked houseing with all in place and save you some more headaches.
I would make them aware they are playing with a dinosaur egg (obselete)

A large industrial type electric motor repair shop is also a option. they can test all before making repairs so as to make sure they are not whipping on a dead horse and after they repair. (they can test rotor and make sure it's still ok electrically)

[AUEngineer]

Yes, try what bsengine says FIRST, because a machine shop can true it in place and
probably even fix the cracked houseing with all in place and save you some more headaches.
I would make them aware they are playing with a dinosaur egg (obselete)

The machine shop I'll be using is a marine industrial shop--it's where I work, so the guys will do the work for free.
They are trained machinist, but not electric motor shop guys. How would I have them chuck this rotor in the lathe?

If it comes down to it, I still would like to know how you would take this ring off? Acetone to remove the silicon? Then solder off?

I've been reading about single phase generators, and am curious how this device actually works.
I think I understand that the stator makes two N-S magnetic poles?
The strength of these poles determines the output voltage (along with the speed at which the poles are broken by the rotor).
I also understand that the number of times the rotor brakes the poles establishes the frequency [hertz] output of the generator.
Since the speed is fixed (to maintain 60Hz), the strength of the magnetic poles is what basically controls the voltage.

I'm curious the function of the laminations and the two coils of wires on the rotor? The only connection to the end bell that the rotor seems to have is through the slip rings. Are the slip rings where the ultimate output voltage (120V x 2) is taken from? What purpose do the diodes and capacitor serve? I assume these serve to control the strength of the magnetism in the stator?

Can anyone help explain, or point me to a website or publication to further explain?

Thanks everyone!

[Arkie]

This Briggs and Stratton manual is a good one for gen's!

#86262-GS Familiarization and Troubleshooting Guide GENERATOR

Cost is about $25 with shipping (do a google search or check with Bruce at this Home Perr.com site and see if he still sells them.It's about 125 pages and covers both brush type and brushless with pictures and basic troubleshooting tips of the electrical sections of generators!

Another thing: Do not use acetone around your rotor. If a drop of acetone hits on the windings, it will ruin the rotor insultation! (acetone melts the enamel insulation that has been baked on the winding)

Send smallen a Pm and maybe he can guide you about removal of the slip ring if it becomes necessary!

[smallen]

you can use an old crankshaft, cut off at engine, use this to chuck up in lathe, or mochinist can turn an arbor tapered to match,
the capacitor and diodes are your exciter circuit that provides dc thru brushes to rotor winding
rotor is a rotating electrical field that produce your ac voltage in the stator winding
the 120/1240 v a/c power comes out the stator winding
pick the epoxy of the solder joint , unsolder the wire at edge if slip ring, careful not to break wire too short,
here are couple pics, one rotor mounted on lathe, not your slip ring
2nd pic is your style slip ring

http://i88.photobucket.com/albums/k163/ ... _lathe.jpg
http://i88.photobucket.com/albums/k163/ ... nrotor.jpg

[AUEngineer]

you can use an old crankshaft, cut off at engine, use this to chuck up in lathe, or mochinist can turn an arbor tapered to match,
the capacitor and diodes are your exciter circuit that provides dc thru brushes to rotor winding
rotor is a rotating electrical field that produce your ac voltage in the stator winding
the 120/1240 v a/c power comes out the stator winding

Thanks for the brief but concise explanation Smallen!
Let me see if I understand...

So the diode and capacitor circuit work as a rectifier?

Applying DC voltage to the rotor creates a magnetic field. I'm assuming the laminations act like the "nail" when compared to a homemade electro magnet--a battery hooked to insulated copper wire wrapped around a nail? The laminations serve to locate the N/S poles as close to the stator and as far apart as possible?

How large is the DC voltage applied to the exciter circuit? Average of 120VDC?

Overall it appears these generators work opposite of the animations I've seen.
Most animations I've seen show a conductor rotating in a magnetic field.
http://www.generatorguide.net/howgeneratorworks.html
In the case of these generators the magnetic field rotates within the conductor.

I've read a lot about having to "field-flash" a generator--now I think I understand better. If it takes AC voltage to get the DC voltage to create the magnetic field of the exciter circuit--you have a chicken and egg situation. So, when you don't need to field-flash a generator, how is the process started--are there magnets somewhere in the stator or rotor to get the process started (that might lose their magnetism over time)?

Thanks again!

One other practical question--I got some oil on the rotor from trying the "hydraulic method" of removal from the engine (overflow when I put in the press bolt).
What's a suggested means of cleaning the rotor safely?

-=RBR=-

[bgsengine]

What's a suggested means of cleaning the rotor safely?

-=RBR=-

water soluble degreaser, or simple green and water