Alternator Strip Question

[aboard_epsilon]

I have a spare alternator I'm rebuilding with new bearings .

The front bearing near the pulley is a conventional tap home type ...fine

the rear ...a little bit smaller ...has a corrugated piece of tin around its circumference to make it fit in the recess.

why is this ...

1. did they not have the right external diameter of bearing to fit in the hole ?

2. is it there to give the bearing leeway ?

3. or another reason ..

should i buy a bearing the same size as the hole without the corrugated tin

or should i buy the same bearing again .

the alternators on this car...rover 420 , are short lived ........has massive serpentine Polly-v drive belt that drives... water pump ..steering pump..alternator.........and has a spring loaded tensioner ......im not joking ...has more than 50lbs pressure on the belt from the tensioner.

The bearing on the tensioner pulley has gone also ...all in less than 80,000 miles....which is normal for these cars.


foot note

im replacing both bearings allthough only the rear is trashed ...
All the best.....markj

[Peter N]

Mark, the corrugated piece of tin is a tolerance ring.

These are used for many reasons - broader machining tolerances, easier assembly, take-up of thermal expansion, torque limitation, and so on. A quick google will probably tell you more.
I think that there are several companies selling them, so you could always ring one up and sweet talk them into sending you a sample to fit your bearing size.

Or you could fit a bearing the same size as the hole as you mentioned, though I suspect this may be either over or under-sized, and may need a bit of machining or maybe a sleeve. Don't think it would hurt at all.

Peter

[tiptop]

Mark, I have not seen this before, but it sounds like a vibration dampener. It will be interesting to see what others say. Jay

[aboard_epsilon]

Thermal expansion may be it ..
as that bearing is only a couple of inches from the exhaust .....

alloy expands a lot when hot ...

so i imagine its there to keep the bearing tight in its alloy housing .

so peter may be right on that score...now i think about it.

the front bearing has cold air being drawn in by the alternator fan.

all the best.markj

[Mark McGrath]

These corrugated rings are called Rencol rings and were originally designed to allow slacker tolerances during machining to cut costs.Various other makes now available also.As only the one end is fitted with this I would suspect that the bearing had run in the housing at that end and this has been fitted by way of repair.Personally I would refit it as the housing bore is probably not true now.
I fitted one in the non drive end of a big spindle motor that Siemens would not sell me a new end housing for.I needed the machine in production and thought that it might last long enough to get the job out the door,five years later it`s still running fine and that`s in a big milling machine.
Mark.

[Dawai]

ALL ABOARD: (like I was a train nut?) Hi Bud..

http://www.youtube.com/watch?v=SsKgE2Uczvk

Altenator wind generator, runs this guys whole shop.. lathe, drill, lights off a battery bank.

Swapped rotor for a permenant magnet one.. You know just like a harley altenator?

Yea, the waffle mount is for different runs of bearings. takes up the slack.

[aboard_epsilon]

ALL ABOARD: (like I was a train nut?) Hi Bud..

http://www.youtube.com/watch?v=SsKgE2Uczvk

Altenator wind generator, runs this guys whole shop.. lathe, drill, lights off a battery bank.

Swapped rotor for a permenant magnet one.. You know just like a harley altenator?

Yea, the waffle mount is for different runs of bearings. takes up the slack.

nice David ...but...

i would have ten of them tomorrow

if i lived in the back and beyond

but............. our UK councils want £200 planning permission fees for each one ...thats two hundred fee, weather it gets permission or not.

like..... buy the time it pays its £200, in electricity generated... it will be just about wore out .

all the best.markj

[jdunmyer]

The alternator on my 1991 VW Jetta had a plastic (nylon?) ring in the rear housing in which the bearing seated. I assumed that it was to allow the outer race to come and go a bit with temperature.

Found this out when the bearing failed, ate the plastic ring, and damaged the housing. Couldn't get a replacement alternator to suit my time frame, so spent an afternoon with my lathe:

bored out the housing to make it round, after centering it on the face that mates to the stator.

turned down a large plastic pipe fitting, one of those things for the black coiled type of pipe. Cut it off and pressed it into the housing.

bored the plastic bushing out to fit the bearing.

Took it back to my alternator guy, he put it together and pronounced it "good as new", and it did in fact live at least as long as the original.

[wierdscience]

They are tolerance rings and they are used by rebuilders a lot for holes where the fit has been wrecked by a bearing that has been spun.Usually the old bore is shaved out to .001-.003" over the nominal dimension,then the tolerance ring,some anerobic and a new bearing are added and all is good.

Here they are sold in catalogs sized to fit common bearing OD diameters.Electric motor rewind shops sometimes carry them too.

http://www.mcmaster.com/

Page 1119 bottom of the page.

[oldtiffie]

Good stuff

Thanks Wierd.

I learned something today from that post and link. I had seen them but didn't know the name or full purpose of them.

I was amazed at the load-capacity of them. They could be quite life/job saver.

[davidh]

ive found a rubber type thingy on the ends of many 4-1/2" grinders, small drills and even some bosch hammer drills. . . . forget to put them back in ? ? wow, smoke and fire. . .