Subject:
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Re: Boosting power in a gear train / torque amplifier
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Newsgroups:
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lugnet.technic, lugnet.robotics
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Date:
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Wed, 21 Mar 2007 06:31:19 GMT
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Viewed:
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1797 times
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I think one way to do this uses a differential
<<http://media.peeron.com/pics/inv/custpics/6573.1089273590.jpg>>
and a pole reverser
<<http://media.peeron.com/ldraw/images/7/3x/6551.png>>.
I don't have a picture to hand but the idea is simple. One side of the
differential is connected to the low torque "input axle". The differential
housing is connected to the rotating axle of the pole reverser. The other side
of the differential is the "output axle", and is also connected to a motor.
Finally, the electric power to the motor comes from a battery box via the pole
reverser (one needs to get the polarity correct).
The differential housing measures the difference in rotation angle between the
input and output, and the mechanism acts to keep this difference within a fixed
range. If the difference strays too far in either direction, the motor is
activated and corrects the difference.
One drawback is that there is a bit of "slack" between the input and output,
determined by the range of motion of the pole reverser between its forward and
backward positions. The slack can be reduced by "gearing up" from the
differential housing to the pole reverser, but this will increase the torque
needed to turn the input. Another improvement might be to replace the pole
reverser with a custom switch with smaller range of movement and/or less
friction.
Regards, Alexander
In lugnet.technic, Rafe Donahue wrote:
> I have a gear train that is driven by a very weak input, very small torque.
> There are some places in the gear train where I have some worm gears driving
> some 'regualr' gears. As I go along the gear train, I boost the output as much
> as I can with 'gearing it down', so that I have worm gears driving 24-tooth
> gears, and such. [Yes, I know there are issues with friction here and there and
> that fewer transitions is better.]
>
> Since it is geared down, the final output rotation is quite slow, as one might
> imagine. I want to add some power to the output to speed it up, say, adding a
> motor somewhere, along with gearing it up, so that I can get more speed AND
> power to maintain that speed. In a sense, it seems to me like a power steering
> kind of problem.
>
> If I use my NXT motors and put them on really low power (like single digit
> levels), then they don't have enough power to turn the output shaft unless I
> turn the input shaft, because the worm gearing prohibits the output from driving
> the input. But unless I constantly turn the input shaft, the friction induced
> by the motor builds up and actually makes it harder to turn the input shaft,
> kind of like putting pennies in a door jamb to lock the deadbolt so that your
> college friends can't get out during a fire drill.
>
> Anyway, anybody got any ideas about boosting power in a gear train?
>
> Much thanks!
> Rafe
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Message is in Reply To:
 | | Boosting power in a gear train
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| I have a gear train that is driven by a very weak input, very small torque. There are some places in the gear train where I have some worm gears driving some 'regualr' gears. As I go along the gear train, I boost the output as much as I can with (...) (18 years ago, 20-Mar-07, to lugnet.technic, lugnet.robotics)
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