Machines used for lifting only are not called cranes, but winches, lifts or hoists, while the term elevator or conveyor is commonly given to appliances which continuously, not in separate loads, move materials like grain or coal in a vertical, horizontal or diagonal direction.
In geared hoists the drums. are on a separate shaft, driven from the crank-shaft by tooth or friction gearing, and make one revolution for, say, 4 or 5 double strokes.
Large and powerful geared hoists are not uncommon.
Eight hydraulic hoists, of the most up-to-date pattern, are capable of shipping 5,600 tons of coal per hour.
The massive iron bridges across the dock entrances are opened and closed by hydraulic power, which is likewise applied to the cranes, coal-hoists, warehouse-lifts and other machinery about.