CONVERTING ENGINES TO DIESEL PRINCIPLES.
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The Use of a Special Head and Special Pistons Permit an Engine of Normal Design to be Altered to Run on Heavy Fuel.
AN interesting heavy-oil equipment for industrial vehicles has just been brought to the practical stage in Germany after two years of experiment. Invented by Mr. Franz Lang, the appliance has been put on the market by the well-known magneto firm of Robert Bosch, in conjunction with a Swiss concern, the Aero Aktien Gesellschaft, of Kasnacht.
By means of the Aero-I3osch equipment, any ordinary lorry engine of normal design can be converted to the Diesel principle with the minimum of alteration, in so far as the main lines of the engine are concerned. The outfit is produced with a view to supplying the trade rather than the individual commercial motor user. Yhe idea is to provide a complete Diesel .equipment which engine builders and heavy vehicle manufacturers can purchase and fit to their engines just as they would purchase a proprietary make a magneto or carburetter. There is a good deal of wisdom in this, because the manufacturer is then in a position to co-ordinate the design of his engine to Diesel practice and to effect a definite saving by avoiding the use of any of the details necessary when a carburetter and electric ignition
device are provided. The conversion by al user would necessarily involve waste or avoidable cost.
The outfit comprises a set of special pistons, an injection pump, an oil-fuel distributor and a set of injectors.
In the Benz light Diesel engine, which we described some time ago, it may be remembered that the initial combustion takes place in a sort of pocket cast in the cylinder head. ThO Aero-Desch system also includes a pocket, but this time the cavity is arranged in the piston head, the equipment being designed, as stated, with a view to making as little change in the general design of the engine as may be possible.
The fuel injectors are fitted in the apertures usually occupied by the sparking plugs. The ordinary induction valves, which admit the explosive mixture when the engine is run on petrol, are used as air valves.
A special feature may be noted in connection with the arrangement of the combustion pocket in the piston head. This pocket is formed by a depression in a thin plate of special steel. This plate maintains a very high temperature when the engine is running and assists in vaporization as the fuel spray is directed on to its surface.
The Aero-Boseh installation is said to have given extraordinarily good results on road tests in Germany when fitted to various types of motor. It will be interesting to see how far the idea succeeds as a commercial proposition.
It seems to us to have been well thought out and to hold promise of success.
If it really proves quite a practicable proposition to modify an ordinary petrol engine in this manner to run as a light Diesel engine, and to make use of the heavier constituents of petroleum and, possibly, other oils which are home products, the outfit possesses unbounded possibilities, as it will do much to decrease fuel costs. It will also be realized that no magneto or carburetter is required.
There is a certain significance in such an outfit as this being brought out by a company,which owes its good name, in a great degree, to the magneto and other accessories to ignition. Does this mean that the company believes that the future of the external means for ignition is jeopardized by such possible developments in the type of engine in which the fuel is ignited spontaneously? Probably a market is scented for a class of engine and the endeavour is being made to cater for it.