Marketed as " Weston Differential Pulley Blocks with Patent Chain Guides ", the pulley had good sales, namely, 3000 sets in 9 months.
2.
According to Richard Tangye's autobiography, the Weston differential pulley evolved from the Chinese windlass, with an endless chain replacing the finite length of rope.
3.
"Chain hoist " also describes a hoist using a differential pulley system, in which a compound pulley with two different radii and teeth engage an endless chain, allowing the exerted force to be multiplied according to the ratio of the radii.
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