fourfold purchase

American  

noun

1. a tackle that is composed of a rope passed through two fourfold blocks in such a way as to provide mechanical power in the ratio of 1 to 5 or 1 to 4, depending on whether hauling is done on the running or the standing block and without considering friction.

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Example Sentences

We all know fifteen tons is enough weight for that size rope, even with a fourfold purchase, and we understand you say this stone weighs twenty-one.'

From Project Gutenberg