Compound axis in peritrochio

The principle of the wheel and axle (the lifting of a large load by a much smaller one) is utilised in the windless and capstan. This object illustrates how, by the addition of a pair of gear wheels, a greatly increased mechanical advantage can be obtained.

A small weight is supported by the string wrapped around the brass pulley, of diameter 2 inches; the steel axle of this wheel also carries small pinion of eight teeth, which engages with a larger brass cog, having forty teeth. This larger cog has a steel axle, of diameter ¼ inch, around which is wound the cord supporting the large weight. The mechanical advantage of the compound system mis 40, whereas without the gearing a value of only 8 would be available.