OILERS SUCCEED UNDER DIFFICULTIES
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I N a recent address, Signor Santa Maria, who is connected with the tramway and bus undertaking in Rome, gave some interesting details of the tests which have been carried out in the Italian capital with oil-engined buses. Since 1930, the tramways in the centre of the city have been replaced by bus services. The need for reducing operating costs has been met by the oil engine.
Various types of bus are in use, among them being four-wheeled and six-wheeled Alfa-Romeos with 110-115 b.h.p. five-cylindered engines. Lancias with Junkers-type 64 b.h.p. two-cyl4ndered and 96 b.h.p. three-cylindered power units, O.M. vehicles with 100 b.h.p. six-cylindered engines made under a Saurer licence, and fourwheeled Fiats with 115 b.h.p. sixcytindered engines of Fiat design and construction.
The success of the oiler in Rome is all the more noteworthy in view of the extremely difficult operating conditions. Not only are the routes served hilly, but the roads are tortuous, whilst stops are numerous, averaging about one every 260 yds. Moreover, at certain hours of the day the buses are overloaded, despite which an average
speed of nearly 9i m.p.h. has to be maintained.
Signor Santa-Maria gave the following examples of fuel consumption in litres per bus-mile:—Six-wheeler, 0.912 to 0.928; long four-wheeler, 0.720 te 0.880; four-wheeler (Junkers engine), 0.600 to 0.608; short four-wheeler, 0.480. Over the same routes the average consumption of petrol-driven four-wheeled buses per vehicle-mile is 1.142-1.168 litre.
The author mentioned that there were still a few drawbacks to oilers, notably the emission of smoke and vibration. As regards smoke, whilst much improvement has been effected in engine design, this can also he reduced by careful and regular attention to the injectors and injection pump.
The question of overcoming engine vibration remains one of the difficulties. Discomfort to the passengers from this cause is, however, being reduced by more careful attention to bodywork.
In addition to the oil-engined vehicles running in central Rome, trials have recently been carried out on a suburban route with a 100-passenger six-wheeled buS and a 90-seater three-deck _sixwheeler, which have shown low fuel costs.