three of these are needed to produce a perpetual turning movement, independently of a fly-wheel.
THE FUNCTION OF THE FLY-WHEEL.
A fly-wheel acts as a reservoir of energy, to carry the crank of a single-cylinder engine past the "dead points." It is useful in all reciprocating engines to produce steady running, as a heavy wheel acts as a drag on the effects of a sudden increase or decrease of steam pressure. In a pump, mangold-slicer, cake-crusher, or chaff-cutter, the fly-wheel helps the operator to pass his dead points—that is, those parts of the circle described by the handle in which he can do little work.
THE CYLINDER.
