Subject:
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Re: Motor Failure (was: lego Technic "class")
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Newsgroups:
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lugnet.robotics, lugnet.technic
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Date:
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Fri, 14 Sep 2001 17:28:47 GMT
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Viewed:
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4992 times
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Technic-heads, read this:
In lugnet.robotics, Rob Doucette writes:
> In lugnet.robotics, Ken McMullan writes:
> > > As an aside, has anyone had trouble with motors seizing up? I have had 4 of
> > > the geared motors before the two in RIS and one in Cybermaster. One is ok, two
> > > cannot be turned by hand and one has stopped altogether. Having completely
> > > dismantled the seized motor I discovered a fine black magnetic powder inside.
> > > Taking the motors apart is not to be recommended. Even popping the back off
> > > carefully can make a mess of the case.
> >
> > Actually, the reason I'm looking here is because I had a motor die recently
> > for no apparent reason. It's become really difficult to turn the spindle by
> > hand and it only gives about 100 RPM instead of the nominal 360.
> >
> > I HAVE found a good way to get the back off the motor without scoring the
> > four pins at the top. If you stick a thumbnail in the BOTTOM of the back
> > closure, the two retaining lugs there are easier to remove than the big ones
> > at the top.
> >
> > I remember seeing a site recently that described the internals of the motor
> > very well and I've ben searching for it for ages! Anybody got any pointers?
> >
> > I have 6 of these motors and all of them turn at different speeds from the
> > same battery. I have testing this with a Mindstorms RCX and an angle sensor.
> > I attach the motor to the sensor via a 3:1 gear and switch it on for 10
> > seconds counting the revolutions on the angle sensor. They do anything from
> > 290 to 340 RPM. I tested them 6 months ago and the speed of each has
> > decreased by about 7% on average. I'm not discounting the possibility that
> > this could be battery fatigue.
>
> I have had no problems with motors purchased w/Mindstorms (RIS, RoboSports,
> RDS), 8735s or other motorized Technic sets. I've had about a 15% failure
> rate on motors from ZNAP sets.
>
> The 5225 gear motors should coast when power is removed in both directions
> due to the internal flywheel. Motors that do not coast are headed for a
> seize up.
>
> BTW, LEGO Consumer Affairs has replaced all of the motors I've come across
> which were locked up 'out of the box'.
>
> A motor data link:
> http://web.mit.edu/sp.742/www/motor.html
>
>
> -Rob Doucette.
> DoucetteNet LEGO® on Brickbay
> http://www.brickbay.com/store.asp?u=robatworldnet
This isn't good news. I've recently aquired 4 geared motors and haven't had
any seize, but I haven't used them very much either.
What I have noticed is that on a few motors, when I turn the shaft slowly by
hand, it will bind up unless I apply a lot of torque. It almost feels like
there's a little piece of something that has meshed in the gears and has
bound them up. When more torque is applied, this little something gets
passed through the gears and the motor then operates freely. I hope this
isn't a sign of impending failure, I rather like the geared motors.
TJ
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Message has 1 Reply:
Message is in Reply To:
 | | Re: Motor Failure (was: lego Technic "class")
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| (...) I have had no problems with motors purchased w/Mindstorms (RIS, RoboSports, RDS), 8735s or other motorized Technic sets. I've had about a 15% failure rate on motors from ZNAP sets. The 5225 gear motors should coast when power is removed in (...) (23 years ago, 14-Sep-01, to lugnet.robotics)
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