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Pullies Vs Gears

Can a gear train return the torque lost with pullies?

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Martin Kyte07/10/2016 14:02:14
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as I said

"If you really want to be lazy.

Fit a pulley to the floor and another to the ceiling. Run the clock line down to the floor round the pulley up to the ceiling and thus to the weight. You then have the full height of the room for the drop."

This just increases the drop and thus the going time.

regards Martin

Neil Wyatt07/10/2016 14:19:05
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Posted by Izack Madd on 07/10/2016 08:55:25:

Posted by Neil Wyatt on 07/10/2016 08:41:14:

The energy (potential for doing work) available is the weight multiplied by the distance it drops.

If you want to get the clock to run for longer, you have to reduce the work required to operate it - any change of puliies/gears/driving arrangements won't get you round the basic physics or otherwise you would be on the way to perpetual motion.

So... the best you can do is look very critically at each moving part in your clock and see if it can be improved to reduce friction. Did John Harris use lignum vitae or some other very hard oily wood for pivot bushes? Do you have teeth that could be brought to a better finish? Could you incorporate a ball bearing in the most heavily loaded pivots?

Neil

Hi Neil

I realise that I can't get back all the energy hence the reference to torque not speed. As I would be sacrificing speed to balance the equation and so it's not a perpetual motion device. Yes Harrison used Lignum Vitae for his bushings as well as some very complicated gear construction to compensate for humidity. Such as putting odd shaped pieces of different wood at angle to the growth rings. The original plans that have it running for just 1.5 days uses bearings and such likebut to still at its limit of power input to torque output. Once the power has gone through all the gears as they have to gear down the power as it's the number of teeth that's important. Not the torque as with a normal gear box.

My thought was as the speed is regulated by the mechanism not the drive force then the speed of the primary drive wouldn't matter so long as its faster than the minimum rpm the clock creates. Rather than the drive setting the speed.

I'm still baffled as to why gear can't compensate the loss of torque. As they seem to increase in power when geared up but loose speed. Which is fine. And would negate the problem of the loss of power of the increased travel of the weight on the pullies.

Because if you sacrifice speed to gain torque, you then have to gear up again or the clock will run slow, so and all the extra torque is lost...

Neil

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