be changed, while in many carriages the gearing also varies the ratio between the speed of the motor and the driving wheels. It is also quite common to combine in the train of gearing spur gears and sprocket wheels, and in some instances even belts. Fig. 4 illustrates a French gasoline automobile made by Underberg, of Nantes. The first figure is a side view, and the second is a plan of the truck and driving mechanism.
The motor, which is of the single cylinder type, cooled by radiation into the air, is located at N. The pinion on the end of the motor shaft engages with the wheel on the end of shaft A. This shaft carries four gears, which can be moved by means of lever C, so as to engage with corresponding gears on shaft B, thus providing four different speeds. The motion of B is transmitted to the rear axle by means of a belt that runs over the pulleys p and P, the latter being carried by a differential gear, so as to run the two driving wheels at proper velocities.
The circular ribs surrounding the motor cylinder are well shown in the figure, in which the carburator of C is also seen. The housing for the motor is open at the sides so as to give air currents free access. In Fig. 4 the speed changing gears are shown, the reversing train being omitted; but if it were also drawn in, the diagram would be far more elaborate than Fig 3.
Another form of variable speed gear is shown in Fig. 5. This provides for two speeds. The large wheel E is on the carriage axle, and it is driven either by a pinion F, or by J. Upon the shaft O there are two friction clutches C D, and when C acts the pinion F drives E, and when D acts the pinion G drives H, which in turn drives I, and this wheel is mounted on the same shaft as J.
Some of the best-known makers of gasoline vehicles do not employ variable gears and depend for changes in the speed wholly upon variation in the velocity of the motor. The De Dion carriages are made in this way, the gearing being substantially as illustrated in Fig. 3.