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Page:Popular Science Monthly Volume 57.djvu/612

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602
POPULAR SCIENCE MONTHLY.

wide belt, which is marked G in both the line drawings. The driving pulley on the motor shaft is located at H, and the axle pulley at H'. Within the latter there is a train of gears for reversing the direction of rotation of the axle, and also for obtaining the differential velocities of the two driving wheels. There is no mechanism for variable speed, this being obtained wholly by changes in the velocity of the motor. The motor speed can be made to vary through a wide range by using four cylinders, with which it is possible to reduce the velocity so low that it would be likely to bring the machine to a standstill if provided with one, or even two, cylinders. The change in the motor velocity is obtained in part by the action of a governor located in a chamber at A, and in part by the action of the electric ignition device which is arranged so that the time when the spark is produced can be varied. The rear axle is so held that it can be moved through a short distance, horizontally, by manipulating the lever D, and in this way the belt G can be made tight or loose, thus affording another means for varying the speed. A brake is provided which presses against the inner side of the axle pulley, H.

PSM V57 D612 Elevation and plan of the vallee car.png
Fig. 12. Elevation and Plan of Vallée Car.

This brake is used ordinarily, but in the case of an emergency another brake can be operated which presses against the outside of the wheel in the space between the two sides of the belt. It is claimed for this vehicle that by the elimination of mechanical speed-changing devices, a great deal of weight is saved, and that this is more than enough to compensate for the extra weight of the motor, arising from the use of four cylinders. In most gasoline carriages it is necessary to provide a slow-speed gear for hill-climbing, as the motor cannot put forth a sufficient effort to ascend a steep grade at the normal velocity. With this racing-machine such a gear is not required owing to, the enormous power of the motor.

There are quite a number of gasoline automobiles manufactured in this country, and, as in the case of the steam and the electric carriages, they compare most favorably with the best European products, in so far as the artistic effect is concerned. That such is the case can be realized at once by an examination of Figs. 13 and 14. We regret our inability to illustrate the mechanism of these vehicles, but the truth is, that the manufacturers appear to be unwilling to make public the de-