Bearing instead of brush contact?

[hobot]

Will a sealed ball bearing say the size of motorcycle wheel bearing allow

much low volts current to pass so it could be used instead of brush

pickup contact?

hobot

[DanB]

No...

the area of contact in a bearing like that is very small.  And steel is not a very good conductor.  There would be lots of little 'arcs' (sparking) and the bearing would quickly become pitted and fail.

[(unknown)]

I tried building a motor like this back in high school. At the time I thought "brush" was just crude for a bearing of some sort. I think a cylinderical bearing would work.

[Chiron]

One of the main failure modes for the large turbines that I've worked on is bearing failure from micropitting caused by stray currents going through the bearings.

The "fix" has been to use insulated ceramic bearings and seperate grounding brushes for the shaft. I wouldn't be too concerened about stray currents in small PM gens.

HTH

[Barnac]

It's not a good idea. Passage of current through bearing components is harmful to them. I work as a diagnostics specialist. Doing machinery condition monitoring is part of my duties and I know a little bit about it. So I digged in my favorites to see if I didn't had anything regarding damages caused to a bearing when an electric current passes through their components. Easier than trying to explain it myself ;-) and better written to...

It is not the first time I see someone proposing this or asking if it could be done. I invite you to have a look at it. There is also really good informations about bearing defects and their causes on that site.

Here is the link: http://www.vibanalysis.co.uk/technical/electric/electric.html

Hope that help

Barnac

In the still stupidly cold Montreal -21°C (-6°F) today, -32°C felt with chill factor (-25.6°F)

[hobot]

Well you bunch of spoil sports sure shot this conventant

item right out my stator but saved me a wasting of ideas.

Great bearing reference site BarnAC, will share with Brit

Iron vintage cycle friends.

While on subject of transmitting current across moving surfaces

 how about a brief listing of names for types of contacts

so I can look up. I only just now heard of liquid metal kind

but nothing more or what planet it might be meant for.

hobot

[juiced]

Hi there nieghbour!

  If you ever want to do an A.E./R.E. project around town, let me know!

[thunderhead]

Current does strange things to ball-bearings:-

http://homepage.ntlworld.com/electricstuff/bbmotor.html