Motor Road Transport For Commercial Purposes
(Liquid Fuel, Steam, Electricity)

118 MOTOR ROAD TRANSPORT consideration not only for their passengers, but also for their machines. In considering the different types of passenger- carrying vehicle, the chassis which is driven by means of a petrol engine with power transmitted by clutch and gear box to a rear live axle is the best known, and consequently the most widely used. At the same time there are two other kinds of chassis which deserve attention. The Petrol-Electric Chassis. One of these is the petrol-electric, and the other the automatically-fired steam car. Both of these systems are suitable for passenger transportation, and especially on services where many stops and starts occur, for the reason that machines of these descriptions are smooth and quick at taking up the load from rest. In the petrol-electric car the power is supplied by means of an ordinary liquid fuel engine, which drives a dynamo. Current is generated by the latter, and in turn drives an electric motor. The final transmission is obtained by the employment of a propeller shaft and live rear axle. If two electric motors are used, they may be arranged to drive the rear road wheels direct through suitable gearing, and thus the need for a differential gear is eliminated. The most customary practice, however, is to adopt the former design. The driver has no clutch or gear lever to manipulate, but merely the controller and speed regulator. In the best-known system—which has stood the test of a number of years— these are carried in separate aluminium cases, the controller being of the tramway type, with. screw adjustment to the contact fingers, and the speed regulator of the multiple contact make.