Prestolite Generator Brush Check

[Beast Driver]

Hi, new guy here. I have never taken apart an M37 Generator before. It is the standard Prestolite 24v. I cannot find any information on how to get the thing apart and check the brushes anywhere. Does anyone have a TM, or instructions, pictures, anything? Thanks in advance.

 

[AZK9]

I wish I was able to help you locate the info you're after. All I can do is welcome you to the forum
and tell you that most of the fun is the 'digging' it takes to discover what you're looking for.

Welcome from Arizona!

 

[AZK9]

For example... check out the link below:

http://www.steelsoldiers.com/showthread.php?108307-M37-generator-rebuild

Locating that link requires putting a couple of keywords into the search box and then
seeing what turns up. Have fun. There's a lot more to discover!

 

[Katavic918]

I don't know and haven't done much research on it but I have been wanting to check mine as well. I crawled under there the other day an it appears to just be 2 or 4 (I can't recall) bolts that hold the end cap on. If it's like some electric motors, then you should be able to remove those bolts and slide the cap/housing off and the brushes should be in there. I'm sure you could search for and find a diagram.

 

[Katavic918]

I guess we had the same thought azk9.

 

[AZK9]

http://www.steelsoldiers.com/attachment.php?attachmentid=433294&d=1370880476

http://www.steelsoldiers.com/attachment.php?attachmentid=433295&d=1370880839

 

[Katavic918]

****. I'm thinking about a starter. Been a long day.

 

[Beast Driver]

O.k, nothing so far is it. But thanks for the effort. I have been searching forums, google, websites etc. for days (including this one) trying to find instructions on how to just take it apart. I have the pulley off, all the screws out of both ends, but there is some sort of serious pressure inside from something that is not letting either of the covers (front or back) to come off. Does it take a gear puller or something? Doesn't seem like it should be this hard. In that a new one is $300.00 plus the core; I really don't want to force it and break something. I just wanted to inspect the brushes. (It is not charging, and yes I have polarized it). Surely someone on here has taken an M37 sealed unit Prestolite/Autolite generator apart before.

 

[T. Highway]

The TM that you are looking for is TM 9-1825B

I have rebuilt several of these and they are really straight forward as long as you know a couple of the tricks.

The rear side is the end that the brush plate is screwed to. The cover will need a few light taps with a soft faced hammer to loosen it from the main body.

USE CAUTION WHEN IT BREAKS FREE SLIGHTLY. If you remove the rear cover quickly, you will run the risk of the brushes slapping the rear bearing and chipping them.
HERE IS THE TRICK: As soon as the rear cover clears the housing, push the cover away from the mounting lug by about a 1/2". This will allow the brush spring pressure to be released from the commutator without damage to the brushes.

Gently pull the rear cover the rest of the way out slowly, to prevent damage to the lead wire attached to the insulated brush.

The drive end is removed the same way with a soft faced hammer and gentle taps to loosen it. The armature will come out with the drive end cap. The bearing on the drive end is held to the cover with a retainer ring that will need to be removed before pressing the bearing off, if your going this far with the disassembly.

If you open the generator up and everything is coated with oil, you will want to replace the front bearing with a modern sealed bearing and abandon the oil fill cup / old school open bearing which are prone to seal failure.

PLEASE NOTE:
If everything is oil soaked internally use great caution in the cleanup. DO NOT SOAK the armature or the field coils in solvent because it will remove the varnish and cause more grief down the road very quickly. It is OK to lightly soak a rag in mineral spirits and wipe these components down without getting too aggressive.

USE CAUTION not to damage the Mica on the armature.

DO NOT TOUCH THE COMMUTATOR WITH YOUR BARE HANDS. Clean or not because this will cause major problems shortly down the road.

Hope this helps you.

Please check out the G741.ORG site for more information about the M37 and all of the variants.

Bert

 

[T. Highway]

Forgot to mention:

A) Welcome to the site
B) The end caps have "O" ring seals that is why they feel so tight. Probably hasn't been apart for many years. (No screwdriver to pry the ends off either because it will surely wreck the "O" rings.

How about a picture of this M37?????

Bert

 

[Beast Driver]

T.Highway, thank you for all the relevant, to the point, assistance. I will take these things into serious consideration. Alas, I am about 3 hours too late in reading your post. I used a big screwdriver to pry the back end off and tore one of the wires out of a brush exactly like you said I would. How prescient that was.

P.S.: That is one beautiful generator on the inside - very high quality. I can now understand why they cost so much. Will have to order new brushes now. The old ones were fine, but like I said, I did one in. I will have to post a picture soon. She's not much but she is all there. My 15 year old son and I love working on it. It is so refreshing not to see a single part made in China.

 

[T. Highway]

No oil contamination internally?

Do you have the test leads to check output once this is reinstalled on the truck?

Is the regulator the old adjustable style or new Solid State version?

Bert

 

[Beast Driver]

Thanks Bert. I got it apart by forcing it under duress to give up the ghost with a large screw driver. Everything looked great on the inside, even the brushes. Alas in forcing it apart I pulled the wire out of one of those brushes. I wonder can I drill out the hole in the brush where the wire goes, insert the wire again, then drip solder into the hole to hold it there. If not I need two brushes and am not really certain where to get them.

 

[Beast Driver]

Oh, also - no oil on inside, regulator is the modern solid state style, and no I do not have any of the actual testing equipment. I do have a multi-meter but that is about it. It just may be I was polarizing it wrong. Went from hot on starter to "b" on generator plug. Maybe it did not work. Everything seems to be fine. Could be the regulator also. Gonna work on that picture thing.

 

[T. Highway]

Good news that you have no oil splattered around the inside.

Brushes can be found at Vintage Power Wagon or Midwest Military has complete rebuild kits.

You will need the proper test leads to check the output of the generator and or trouble shoot the regulator.

Bert