My pulley story is about one of the tools the Egyptians used to build the Pyramids.
It is called the Four Lobe Pinion Pulley.
It was used for getting heavy stone blocks up to the top of the pyramids.
The four lobes are the cradles, these were tied to the sides of the heavy stone blocks.
This turned the stone block into a small gear.
The big gear was the steps on the pyramid.
They then got really strong rope and some really strong men they put it over their shoulder and they pulled the pulley up to the top of the pyramid.
The steps on the pyramid lined up with the lobes on the block to stop it from wobbling and falling off. A bit like gears.
The other way of doing it was to turn the block into a cylinder.
When you turned the block into a cylinder you needed a ramp instead of steps.
My pulley is the same as the one invented by Archimedes except it does not have a fixed pulley. The cylinder is the pulley and the man is the energy to move it, the point at the top is the fixed point. Because half of the weigh of the block is on each rope the weigh on the rope is halved.
1 comments:
Alice, this would have be one of the best and most interesting explanations I have read! I have learnt so much - I din't know there was such a thing as a 'Four Lobe Pinion Pulley'!
Good on Dad learning how to access the Blog too!
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