Feet per Minute (ft/min)

The working unit for slow mechanical motion in British industry, from colliery winding gear to lifts and conveyor belts.

Miles per hour is a poor fit for machinery that moves deliberately: a lift travelling at four miles per hour tells an engineer very little. Feet per minute gives readable whole numbers across the range that matters, and it became standard for hoists, cranes, conveyors and the winding engines that raised coal and men from British pit shafts.