Alt-BEAM Archive
Message #09053
To: beam@sgiblab.sgi.com
From: "Mike Kulesza" mikekulesza@hotmail.com
Date: Wed, 12 Jan 2000 00:35:13 GMT
Subject: [alt-beam] Motor Efficiency
So what is it that makes some motors more efficient and some less?? You
know, the low efficiency ones are harder and choppier to turn by hand, and
generate less current as a dynamo. The efficient ones spin longer when
turned by hand and generate more current.
______________________________________________________
9054 Tue, 11 Jan 2000 19:39:56 -0500 (EST) [alt-beam] Re: parts source beam@sgiblab.sgi.com jester96beam@iname.com Could it be that the reason for the different shape is to accomodate the magnets? Maybe if they were round, the diameter would be equal to the flat side, giving a smaller motor. Besides, I think most of those motors with the flat sides are actually LARGER than the pager motors, so the round parts are an addition to the motors, so perhaps the magnets are actually larger.
Chris
---- you wrote:
> Sorry Dave,
>
> I have to strongly disagree. Many motors have much higher efficiencies than
> pager motors, but also have flat sides. Motors such as the Mabucci FF-K10WA
> for example.
>
> Flat motors simply cannot have the same magnets as cylindrical motors, so the
> argument you make is flawed. A better brush can more than compenstate for a
> using different magnets.
>
> Dave Hrynkiw wrote:
>
> > At 05:52 PM 1/10/00 , Bumper314@aol.com wrote:
> > >yeah but flat sided ness is what some people are really looking for...you can
> > >solder to them alot easier...i would go for those if i could build anymore
> >
> > Flat sides mean that they went cheap on the magnets. They won't have as
> > good performance as fully cylindrical motors (assuming same magnets). As
> > for soldering on flats vs. cylinders, I'd take better performance anyday
> > for the extra effort.
> >
> > Regards,
> > Dave
> > ---------------------------------------------------------------
> > "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> > that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> > 2 vowels. Pronounciation? _SMITH_".
> > http://www.solarbotics.com
>
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9055 Tue, 11 Jan 2000 19:52:37 -0500 [alt-beam] Re: Pager Motors (Was parts source) beam@sgiblab.sgi.com Bob Shannon Dave Hrynkiw wrote:
> At 06:24 AM 1/11/00 , Jonathan D Rogers wrote:
> >Are there more effecient motors than pager motors out there? Because I'm
> >about to go buy some, but I'm not going to do that if there are better
> >motors out there...
>
> You bet. Pager motors are relatively efficient, but there's always better
> ones, especially depending on the application. Pager motors are designed
> for RPM, not torque, so if you want a slower, torquier motor, select one
> with a bigger outside diameter. If you want speed (rpm), narrower is
> better. I've got some killer "pancake" motors that are wide and flat, and
> have TONS of low-rpm torque. They were originally used for tape-transport
> mechanisms in old audio tape recorders.
Excellent point Dave,
The application of the motor really has more to do with the efficiency than
the specifications of the motor itself.
Using a pager motor to propell a small photovore, even with an efficienct
motor runs into problems. To keep motor speed up (for efficiency) the wheel
diameter (heat shrink) must be small. This gives you little contact with the
ground, where the rubber meets the road. Wheels slip, or get caught on small
obstacles and such and energy is lost.
Now use a motor with better torque production, and a larger wheel, and the
result can be much more efficient overall.
This also applies to selecting a gear ratio and leg design for a walker or
Turbot.
So when we speak about efficient motors, and 'more efficient', we really should
be a bit more specific. When I described the Mabucci FF-K10WA as being
'more efficienct' than a pager motor, I was really describing the application as
much as the motors themselves.
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