Any one who has observed the action of a two-horse team will have noticed that, unless the pavement is very smooth, the tongue continually swings from side to side, and occasionally with a considerable amount of violence. It will be evident from this fact that if the front axle of an automobile were the same as that of a horse vehicle, the driver would have an unpleasant task, to say the least, in holding the steering lever in position, and should one of the wheels drop into a rut, the handle would be jerked violently out of his hand and the vehicle would sheer off to one side, possibly with serious results. To avoid this difficulty the front wheels of horseless carriages are arranged so as to swing round on a center close to the hub, if not actually within it. The most common construction is illustrated in Fig. 10, the first being a view of the axle and wheels as seen from the front, and the second a view from above. On the left-hand side of Fig. 10, _A_ is the axle proper, and _BB_ are the portions upon which the wheels are placed. The central part _A_ is held rigidly to the body of the vehicle or to the truck which carries it, and the ends _BB_ are swung round the studs _PP_ in a manner more clearly indicated on the right-hand side. Here the levers _CC_ are shown, and these extend from the side of _BB_. The right-angle lever _E_ is connected with the steering lever _G_ by means of rod _F_, hence, when _G_ is moved, rod _D_ moves, and thus levers _CC_ are rotated round the studs _PP_, and in that way the supporting studs _BB_ which carry the wheels are turned. As the studs _PP_ are not exactly in line with the plane passing through the center of the rim of the wheel, there is a slight tendency to jerk the steering handle round when a wheel drops into a hole in the pavement, but the leverage of _B_ being very short, this tendency is so small as to be hardly noticeable. [Illustration: FIG. 10. ARRANGEMENT OF AXLES AND WHEELS.] [Illustration: FIG. 11. FRONT AXLE.] [Illustration: FIG. 12. FRONT AXLE WHEELS.]