Page:Popular Science Monthly Volume 75.djvu/31

Rh front wheels FF of the automobile are pushed against the ground with excessive force by the gyrostatic reaction of the fly-wheel in Fig. 15. When the automobile is turning to the left, as shown in Fig. 16, the gyrostatic reaction of the fly-wheel causes the rear wheels BB of the automobile to be pushed against the ground with excessive force.

When an automobile runs over a bump in the road, no gyrostatic action is produced if the engine shaft is crosswise of the car, but very severe gyrostatic action may be produced if the engine shaft is fore and aft, as shown in Fig. 17. In the vector diagram of Fig. 17,

S represents the spin-momentum of the fly-wheel at a given instant, S'represents the spin-momentum at a later instant, ΔS represents the increment of spin-momentum, and the arrow T represents the torque which must act upon the fly-wheel shaft. In order to produce the torque T, the bearing a must push the front end of the engine axle to the left (with reference to the driver), and the bearing b must push the rear end of the engine axle to the right (with reference to the driver); or, in other words, the front end of the engine axle pushes to the right against the bearing a, and the rear end of the engine axle pushes to the left against the bearing b. Thus, there is a tendency for the front end of the car to be suddenly thrown to the right, when the car rises upon the bump, and the supporting springs of the car body are subjected to a skew action which is apt to break them.

There has been designed and placed upon the market an automobile in which the engine shaft is vertical. This obviates all gyrostatic action in the turning of curves, but it does not reduce the severe gyrostatic reactions when the car runs over a bump.

Fig. 18 is a top view of a side-wheel steamer which is represented as turning to the right as indicated by the curved dotted arrow. The arrow S in the vector diagram represents the spin-momentum of the paddle wheels and shaft at a given instant, S' represents the spin-momentum at a later instant, ΔS represents the increment of