Gasoline motors are made with one, two or more cylinders, but in each cylinder the action that takes place is that described above. The actual construction of a motor is not so simple as might be assumed from the appearance of Fig. 1; many details are required which are not here shown. A more perfect idea of the actual construction of a gasoline motor can be had from Fig. 2, which is a working drawing of a recent European invention. In this design it will be noticed that the cylinder is cooled by radiation into the surrounding air, the exterior surface being increased by numerous circular ribs and also by extending a hollow trunk from the upper side of the piston, so as not only to increase the radiating surface, but also to allow the hot air to escape from the chamber _T_ in which the crank discs revolve. In this drawing _E_ is the explosion chamber, corresponding to _Q_ in Fig. 1, and the valve _s_ is the counterpart of _f_, while _s’_ corresponds to the valve _h_. The upper pipe _t_ is the pipe _e_ of Fig. 1 and the lower pipe _t’_ is the pipe _r_ of the same figure. Although the crank discs, connecting rods and other details are different in shape, it will readily be seen that their relation to each other is the same.
[Illustration: FIG. 3. REVERSING MECHANISM.]
Since a gasoline motor cannot start of its own accord, it is necessary in vehicles in which they are used so to arrange the driving gear that the motor may be kept in motion all the time and always in the same direction, hence, to reverse the direction of the carriage, reversing mechanism, independent of the motor, must be provided. The most simple mechanism for a gasoline vehicle employing spur gearing exclusively is shown in diagrammatic form in Fig. 3. In this figure _A_ represents the cylinder of the motor, _B_ the crank disc chamber and _M_ the vaporizing receptacle, which is generally called the carburator. The pinion _C_, on the end of the motor shaft, meshes into a gear _D_ which is mounted upon a sleeve _E_ which revolves freely round shaft _G_. This sleeve has its ends formed so as to engage with the gears mounted upon shaft _G_, and by means of a lever, which is not shown, but which works in groove _a_, the clutch either _s_ or _ss_ can be thrown into engagement with its corresponding gear. If _s_ is thrown into gear, as shown in the drawing, the wheel _F_ will turn _H_ and the pinion _I_ will rotate the gear _J_ which is mounted upon the axle of the carriage. If the clutch _ss_ is thrown into engagement, the gear _G_ will turn _K_ and this wheel will turn _l_; but, as can be clearly seen, the direction in which _l_ will revolve will be opposite to its motion when driven through _F_ and _H_, therefore, if when _F_ drives the carriage runs forward, when _G_ drives it will run backward, and when _E_ is moved to the central position, so that neither _s_ nor _ss_ engages with their respective gears, the vehicle will stand still, but the motor will continue to revolve.