[ARC5] BC-454-B Dymamotor Question

[Clare Owens]

I had a real problem with a stuck low voltage brush on one of my BC-348
dynamotors and had to drive it out with a pin punch after disassembling the
LV end of the unit.  The replacement brush fitted into the holder very
nicely so it was the fault of the brush material, not the holder.  Can a
brush swell all by itself?  Well, I guess they can, this one did.

Clare

On Fri, Jan 18, 2013 at 1:45 PM, J. Forster <jfor at quikus.com> wrote:

> Ken,
>
> Agree on all points. However, I've never seen the commutator insulator
> segments get too high. It probably does happen as many manuals have
> directions for 'undercutting' the insulation after refinishing the
> commutators.
>
> Best,
>
> -John
>
> =================
>
>
>
> > On 17 Jan 2013 at 20:15, J. Forster wrote:
> >
> >> To me, from the downwards spike in the voltage waveform, indicates a
> >> brush
> >> is not making contact during part of the rotation.
> >
> > Yes. Definitely. That is what I meant by "...a brush not making
> > contact..." Thanks, John, for
> > the clarification and your input.
> >
> >> This could be caused by
> >> a stuck brush or some kind of commutator wear. It is most likely on the
> >> HV side.
> >
> > Agreed. The brush holder can get bent, causing the brush to hang up, or
> > the brush can get
> > "sticky", or the spring can get weak or out of shape or damaged by heat
> so
> > that it loses
> > tension, or the brush can just plain be too worn to make contact over the
> > full rotation of the
> > armature.
> >
> > Comutator insulator segments too high, caused by wear, can also cause
> this
> > sort of thing.
> >
> > Ken W7EKB
> > ______________________________________________________________
> > ARC5 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/arc5
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:ARC5 at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> >
>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>