Fixing a roller dynamo

The bearings on my Union 8601 generator light
are getting loose. It's clear they won't last
much longer.

Has anybody ever repaired one of these things?
It's not obvious how (or if) it can be worked on.
Yellow Jersey no longer sells them.

Any guidance appreciated, thanks for reading.

bob prohaska

On Friday, November 8, 2013 9:30:37 PM UTC-5, User Bp wrote:
The bearings on my Union 8601 generator light
are getting loose. It's clear they won't last
much longer.

Has anybody ever repaired one of these things?
It's not obvious how (or if) it can be worked on.
Yellow Jersey no longer sells them.

Any guidance appreciated, thanks for reading.

Sorry, but I can't be of help. I've disassembled and repaired (one broken wire) a Soubitez roller unit that was given to me, and I've read about people disassembling the Sanyo roller like James and I still have. But never that Union.

Unfortunately, the Union doesn't seem to have a very good reputation. There are bottle units on the market that are supposedly much better. And of course, there are hub dynos, if you want to go that route.

If you get into the Union, I'd be interested in its details.

- Frank Krygowski

On 11/8/2013 8:30 PM, User Bp wrote:
The bearings on my Union 8601 generator light
are getting loose. It's clear they won't last
much longer.

Has anybody ever repaired one of these things?
It's not obvious how (or if) it can be worked on.
Yellow Jersey no longer sells them.

Any guidance appreciated, thanks for reading.

bob prohaska


While it's probably technically possible I can't suggest any
cost effective approach and yes these are now no longer
manufactured.

A side mount bottle type dynamo may well be a reasonable path.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Sat, 9 Nov 2013 02:30:37 +0000 (UTC), User Bp
wrote:

The bearings on my Union 8601 generator light
are getting loose. It's clear they won't last
much longer.

Has anybody ever repaired one of these things?
It's not obvious how (or if) it can be worked on.
Yellow Jersey no longer sells them.

Any guidance appreciated, thanks for reading.

bob prohaska

One can usually find something about how it works in the patents. I
think (not sure) that this is the right one:
https://www.google.com/patents/EP0216282A2
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/9aa31f702f369ebe79d6/EP0216282A2.pdf
Not great, but better than zero.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 09/11/13 13:30, User Bp wrote:
The bearings on my Union 8601 generator light
are getting loose. It's clear they won't last
much longer.

Has anybody ever repaired one of these things?
It's not obvious how (or if) it can be worked on.
Yellow Jersey no longer sells them.

Any guidance appreciated, thanks for reading.

bob prohaska


I've only dealt with a Sanyo Dynapower roller dynamo. There are various
parts to disassemble before finally having the roller free of the rest.
Once at this stage, at one end of the roller is a plastic piece that
can be pushed out by gently persuading the opposite end of the axle.

Inside the bearings are just plain bush type bearings. If they have
worn there is no real path to replacement or to tighten them. They can
be cleaned and lubricated though.

A Union roller dynamo could be constructed quite differently I guess.

--
JS

Frank Krygowski wrote:

Unfortunately, the Union doesn't seem to have a very good reputation. There are bottle units on the market that are supposedly much better. And of course, there are hub dynos, if you want to go that route.

This is the second Union that failed in about five years, so I have to
second the "not very good reputation" vote. The first failed shorted,
when I took it apart I just dissected it roughly and tossed the parts.
This being the last in hand, I'm more interested now.....8-(

There's an old no-name bottle dynamo in the junk drawer and a Soubitez
on an unused bike. The concept of a hub dynamo is very appealing, but
the weight and price don't seem justified by the performance observed
so far with a Shimano DH-3n30 on a Breezer Uptown8. It works just fine,
but when one adds the cost of the hub to the cost of building a wheel
(which is otherwise not needed) battery units start to look cheap.

If you get into the Union, I'd be interested in its details.
When it finally gives up I'll try to put up a few pictures.


Thanks to all for reading and responding.

bob prohaska

James wrote:

I've only dealt with a Sanyo Dynapower roller dynamo. There are various
parts to disassemble before finally having the roller free of the rest.
Once at this stage, at one end of the roller is a plastic piece that
can be pushed out by gently persuading the opposite end of the axle.

Inside the bearings are just plain bush type bearings. If they have
worn there is no real path to replacement or to tighten them. They can
be cleaned and lubricated though.

That the Sanyo could be non-destructively disassembled is encouraging.

A Union roller dynamo could be constructed quite differently I guess.

Very true, but all engineers are driven by the same constraints. When
the constraints get tight enough the designs tend to converge.

Thanks for writing!

bob prohaska

On Saturday, November 9, 2013 3:14:16 PM UTC-5, James wrote:

I've only dealt with a Sanyo Dynapower roller dynamo. There are various
parts to disassemble before finally having the roller free of the rest.

Once at this stage, at one end of the roller is a plastic piece that
can be pushed out by gently persuading the opposite end of the axle.

Inside the bearings are just plain bush type bearings. If they have
worn there is no real path to replacement or to tighten them. They can
be cleaned and lubricated though.

A Union roller dynamo could be constructed quite differently I guess.

The Soubitez roller dynamo I've fixed (tiny broken wire, broken by the guy who gave it to me) has ball bearings running in plastic races. From what I've seen, I think a lot of other dynamos have sintered bronze ("Oilite") plain bearings, what many people call "bushings." Oilite bearings are porous, and contain oil in their pores, helping them to self-lubricate.

At first, it might seem the plain bearings would impose a lot of friction and wear quickly. But at just 12 mph = 20 kph, typical dynamos are rotating about 3000 rpm or more. With the light load imposed by contact with the tire, it should be no trouble to design a plain bearing that fully floats the shaft the shaft at that speed. This could give lower friction than a ball bearing, at least once the shaft floats.

But if they do run dry, or if contaminants get into the shaft-to-bearing space, I suppose wear would happen pretty quickly. So I suppose the devil's in the details, as usual.

- Frank Krygowski

Frank Krygowski wrote:

The Soubitez roller dynamo I've fixed (tiny broken wire, broken by the guy who gave it to me) has ball bearings running in plastic races.

My old Soubitez seems to have ball bearings as well, though I'd be very
impressed if the races are plastic. They do seem to be adjustable.

When my first Union dynamo failed I pulled out the bearings and found
they were rather well-sealed ball bearing units, which makes the present
unit's failure all the more puzzling. Getting the bearings out rather
thoroughly demolished the dynamo, thus my search for better guidance.

The old dynamo survived a 30 mile ride yesterday, so I'm not stuck yet.

8-)

bob