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They are used in deck and roof construction. I believe the name comes from their use in deck construction, in that case they are holding the cross supports down and in place in the case of strong upward/lateral winds.
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I have not actually put up my joists though and they are not the subject of this post. The real subject is a pedal powered generator.
A pedal power generator is a surprisingly simple thing. At least, to make it generate power. I have not yet hooked this thing up to charge a battery, which is what it will do eventually, and that I imagine is the more complicated part, I need to do more research because I am fuzzy on the details.
Anyway, a motor and a generator are the same thing. If you input electricity you have a motor, with a rotational output, and if you input the rotation you have a generator, with an electrical output. I am simplifying a lot, and possibly being a little bit liberal with my language, but if you have a motor and you hook it up to a voltmeter and turn the output shaft you will see that volts are happening.
For my generator I ordered an electric scooter motor off of ebay. It looks a lot like this:
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The first step was building the bike stand:
The bike is held up by the nuts that hold the tire on. The pipe on the right is adjustable, the bike is put in place then the pipe is slid over and locked in, and the tire rests on the output shaft of the motor.