ST Head disassembly

[dkwflight]

Hi
I decided to take my 20k ST head apart and replace the bearings due to noise indicicating a failure was on the way.
I was useing a rubber mallet to move the end housing, brush end.

Well, long story short, I broke the houseing. I think I can repair the houseing. The section that broke was 1/8" thick

So A word to the wise. Go easy.

The bearing on the drive side was bad, from rust during shipping. both sides had rust. and very little grease.
I can't help but think if the bearings had a proper amount of grease when assembled they would have lasted longer.

I will replace with sealed bearings

This was a Power Solutions head.

Dennis

[Doug]

So exactly how did this brake?

Were you trying to beat it off the bearing?

Generaly you should be able to wigle it off the bearing, but even if you did hit it with a rubber mallet it shouldn't have broken.

I've done this a lot, at one point I even rammed the shaft with back of a littel fork lift to knock the rotor out of the end bell on one big machine and even when using some very big " tools " I don't think I ever cracked a housing.

You better pot some pictures of the damaged end bell and explain exactly what you did.

A rubber mallet on a end bell in a head the size of a ST 20 should not have been an issue.

How old is this head?
How many hours before bearing failure?

Doug

[dkwflight]

Hi Here is a link to a picture of the end bell.

http://s29.photobucket.com/albums/c294/dkwflight/?action=view&current=100_0195.jpg

Wiggling the end bell wasn't working too well.

I think I can braze this piece back on OK.
Dennis

[Doug]

OK that's a bummer but not a write off.

That end bell might be too tight, but there's not a lot you can do about it short of taking it too a machine shop.

Check the housing for rust dirt ect. If you find something clean it was best you can and a very quick rub with some crocous cloth to clean any rust is about all you can do.

Gently warm the end bell for assembly but it should never be heated to the point its too hat to handle bare hands.

A little oil will help the assembly.

I don't understand why these have open bearings. Don't use open bearings get some 2Z or better yest 2RS and forget. If you use the 2 Z fill the inner side if the end bell housing with some #2 moly befoe assembly. Everything touchiong that grease must be clean. A 2Z bearing will pump a certan amount of grease threw the opening at the sheild to inner race and dirt will get sucked in if you weren't careful about keeping clean.

If you decide you want grease niples, also make a hole for a purge port so you can push the old grease out when you relube.

You picked a bad place to hit that end bell, how hard were you hitting it? 

best way to get the drive end apart is to lift the whole rotor and end bell assembly no more than 4-6 inches and drop it shaft first on a hard wood block. This will drop 99% of all stuborn end bells.

rears try driving it with a soft brass drift back threw the stator ( if the cooling fan permits )

Don't be too agressive with the dropping sometimes a rotor will shift on a shaft and you create a new problem that needs a press.
 

[rmchambers]

you ought to be able to find someone who can weld that up.  The thread here about welding cast in very small runs so as not to heat up the surrounding area too much would serve you well.

Couldn't help but notice you weren't wearing any shoes.  Is this a whole Zen Indian thing?  It was made without shoes it should be worked on without them.

Robert

[dkwflight]

Hi
I only dashed out to take the pic.
I wore shoes to take it apart Maybe I would have had better luck bare footen!

Sealed bearings fer sure are going back in.

As heavy as this thing is I am surprised that the castings are as thin as they are.

I won,t have any problem brazing this thing
Dennis

[Doug]

These things happen:

Utterpower has a note somewhere on the site discribing problems with thin castings on some of their heads. Is this an older head?
I think the casting problems they had are resolved ( or I thought )
A lot also has to do with where you hit thats a weak point and cast has lilttle strenght in tension

Doug

[dkwflight]

Hi
I bought it last year but that doesn't say when it was made.
Dennis

[Doug]

Bearing failure at 77 hours?

Something is wrong here.....

I'd email George at Utterpower and see what he says. Not to say he will send you parts, after a year I'd say thats unlikely but he might have some insights into why these bearings failed.

[dkwflight]

Hi
It's well documented that the bearings from china are like what I found. I didn't try to lube them when I got the thing.
I figured I would replace them.
They made noise from new.
I bought from John alvan. He is no longer in the listeroid business as far as I know.
He never checked wether I was having any problems ETC.
Won't answer e-mails.
Another dealer come and gone.
Oh Well.
Dennis

[Doug]

Who made the head?
I assumed from your signature it was a PS head....

Doug

[rpg52]

I took my 5 Kw PS head apart to re-grease the bearings without incident.  They already had sufficient grease, but I wanted to make sure.  My 12 Kw head has never been apart.  Next to the Detroit Diesel that is the prime mover, I can't hear anything, but the case remains cool to the touch after running for an hour or so.  I'm assuming it is ok - plan to remove and re-grease within a year or so, it hasn't had much running time yet.
Ray

[dkwflight]

Hi
Who makes the Power Solutions head. Mabe someone will tell?
The bearings had a rumble from new.

I got the second one of today, Drive side. I think the bearings had some rust from the salt air. The grease was very stiff and dark.

The sound had changed, more like a hum

The open bearings would probably work OK if grease fittings were installed and fresh grease were applied, enough that the excess grease acted like a seal, keeping dust etc. out of the bearings.
I will get bearings with seals and forget about them.

Effective mufflers alow the sounds from the gen head to be heard.

Dennis

[dkwflight]

Hi
I started back together today. No problems. Cleaned everything up well and rubbed on the shaft with some emery and cleaned again. I used some Lucas oil stabiliser as lube on the shaft and bearings to help them slide home and provide some rust protection.

The drive side end bell had quite a few pits(1/8") size and the casting is just as thin as the other side.
I got dark so I'll have a go at getting it together tomorrow.

The rotor sure is heavy. It would be nice to be able to use a shop crane to help. Or a big friend!
Dennis

[ronmar]

How do you get the rotor in/out without a second person?  I had my wife help with my ST5 as I didn't want to drag the rotor across the stator windings.  Even at that small size, it was hard on the fingers reaching thru the stator and lifting the brush end up to guide it thru the stator.    I guess you could make up a lift structue to grip the shaft from both ends and allow the use of a shop crane to remove the rotor horizontally.  Unless you are running 24/7, with good quality sealed bearings I doubt you will ever do this again.
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