The revolving wheel in a block. In the days of sail they were mostly made of lignum vitae or brass, sometimes a combination of the two, in which case the brass formed the bush of the sheave. The older name for a sheave is shiver, and many seamen used to spell sheave as shiv, using the same pronunciation. Modern sheaves are mostly made of aluminium or of composite construction with roller or ball bearings.
Subjects: Maritime History.