Subject:
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Re: A free motorized switch with every compressor
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Newsgroups:
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lugnet.technic, lugnet.robotics
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Date:
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Wed, 11 Jun 2003 17:35:22 GMT
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Viewed:
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256 times
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In lugnet.technic, Thomas Avery wrote:
> In lugnet.technic, Kevin L. Clague wrote:
> > I love differentials.
> >
> > I wanted to share another trick I figured out while playing with pneumatics. By
> > combining a differential with the motor(s) and pump(s) of a compressor, you can
> > make a motorized switch.
> >
> > http://www.brickshelf.com/gallery/kclague/compressors/p6070073.jpg
>
> Pretty cool. I like the way you've symmetrically supported the large hand pump.
> You've placed a gear on both sides of the handle.
>
> Now this may seem the obvious thing to do with the large pumps, given the
> relatively large force required to push them. But I've always wondered if it
> would be beneficial to do the same with the small compressor tubes (i.e. the
> small "pumps").
>
> Typically, when people build compressors using the small pumps, the support peg
> or axle that attaches to the end of the pump is cantilevered out from the wheel.
> Given the tolerances of LEGO and the "stretchability" of ABS, this peg or axle
> can bend out of axis. In other words, if your peg or axle is horizontal, it will
> bend upwards when loaded. This causes side load on the pump.
>
> If you support it on either side (like you did with the large pump), you remedy
> this problem. I'm just wondering if this would be effective or not in making a
> more efficient pump.
I beleive so. The most important part of the stroke for highest pressure is
most compressive part (making sure the pump compresses completely). The
compressed air in the pump doesn't want to do that so it pushes back on the
thing trying to make it compress.
In your example three things bend really: the axle coming from the motor, the
gear/pulley connected to it, and the pin/axle connecting the pump to the gear.
Driving the pump symetrically helps reduce bending in all three cases.
This means that the pump is driven more to complete compression and the
resulting pressure will be higher.
Complete compression of the large pump is what made the perfect large pump
geometry something worth sharing.
>
> -TJ
Kevin
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