30 m.p.g. with Double-deckers?
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THERE .was a hope of obtaining 1 30 m.p.g. with oil-engined doubledeckers running at 30 m.p.h., said Dr. E. M. Dodds, of the Esso Petroleum Co., Ltd., during a discussion last week at the Birmingham centre of the Institute of Road Transport Engineers. Dr. Dodds had read a paper, "Lubricating Oils and Greases for Road Transport Vehicles."
To obtain 30 m.p.g. it would be necessary to use an S.A.E.S oil and to cool the induction air and the injection pump. It would also be essential to maintain a high coolant temperature.
If the temperature of the fuel in the injection pump were raised from 25° C. to 40° C., he said, its specific gravity would be reduced by 1 per cent. and
the consumption increased by 31 cent. Moreover, with the thinner f there would be greater leakage lost Engine manufacturers agreed t cooler operation of the pump '1 beneficial, but in practice they took steps to improve the cooling.
Regarding the possibility of cool the radiator by an electrically dri.' Ian, Dr. Dodds agreed that the type fan used on the new Jowett Jupiter car could be employed with advant on commercial vehicles. He critici the conventional type of thermos when answering a question regard the use of an oil-water heat exchanj and said that with the normal by-p type there was liable to be a surge cold water from the radiator to engine cylinder block when thermostat valve opened.
A preferable system comprised perforated sheet-metal blanking pit for the radiator, relative Movement which varied the passage of air. 1 could be controlled by a pockt bellows.
Dealing with the possible bad eff. of fuel dilution when low-viscosity was used in a petrol engine, Dr. Do said that the consequent reduction viscosity would be proportionately than when an oil of higher viscosity employed.
Asked whether the use of thin in the back axle would increase the 1 lihood of leakage, Dr. Dodds said • in practice it had been found there less leakage with thin oil. The I type of lubricant for the preservai of seals was a synthetic oil. One the advantages of thin oils in this nection was that they reduced temperature of the seals and obvit perishing.