Windlass Cogwheels Application

Man's Way of Helping Himself:
Windlass, Cogwheels. In the old-fashioned windlass used in farming districts, the large wheel is replaced by a handle which, when turned, describes a circle. Such an arrangement is equivalent to wheel and axle; the capstan used on shipboard for raising the anchor has the same principle. The kitchen coffee grinder and the meat chopper are other familiar illustrations.

Cogwheels are modifications of the wheel and axle. Teeth cut in A fit into similar teeth cut in B, and hence rotation of A causes rotation of B. Several revolutions of the smaller wheel, however, are necessary in order to turn the larger wheel through one complete revolution; if the radius of A is one half that of B, two revolutions of A will correspond to one of B; if the radius of A is one third that of B, three revolutions of A will correspond to one of B.

Experiment demonstrates that a weight W attached to a cogwheel of radius 3 can be raised by a force P, equal to one third of W applied to a cogwheel of radius 1. There is thus a great increase in force. But the speed with which W is raised is only one third the speed with which the small wheel rotates, or increase in power has been at the decrease of speed.

This is a very common method for raising heavy weights by small force.

Cogwheels can be made to give speed at the decrease of force. A heavy weight W attached to B will in its slow fall cause rapid rotation of A, and hence rapid rise of P. It is true that P, the load raised, will be less than W, the force exerted, but if speed is our aim, this machine serves our purpose admirably.

An extremely important form of wheel and axle is that in which the two wheels are connected by belts as in Figure. Rotation of W induces rotation of w, and a small force at W is able to overcome a large force at w. An advantage of the belt connection is that power at one place can be transmitted over a considerable distance and utilized in another place.

FIG. - Cogwheels.

FIG. - By means of a belt, motion can be transferred from place to place.