INTERNAL-COMBUSTION ENGINES 355 



bounds. For motor-cycles an air-cooled four-cycle single-cylinder engine of 3! H.P. 

 (not exceeding 500 cubic centimetres cylinder capacity) is the type most widely used. Such 

 an engine as made by Rudge Whitworth Ltd., bore 85 mm., stroke 88 mm., has given 8.4 

 brake H.P. at a speed of 3,060 revolutions per minute, in a bench-test of 87 minutes' 

 duration. The corresponding mean effective pressure on the piston, calculated from the 

 brake H.P. is 69 Ibs. per square inch. Twin-cylinder engines are also much ia favour; 

 while water-cooling and the two-stroke cycle are used on many motor-cycle engines. England 

 and America are pre-eminent in the motor-cycle industry. In France, the home of the motor- 

 car, its use of the motor-cycle is not so widespread as in England. In Germany, Belgium, 

 and Switzerland, excellent motor-cycle engines are manufactured. 



In motor-car engines, the four-cylinder water-cooled type 1 is pre-eminent. As an example 

 of modern performances of such engines, that of a 15 H. P. engine, 3! inch bore, 4f inch 

 stroke, by Crossley Motors Ltd., may be noted. The brake-tests show 40 H.P. at 2,400 

 revolutions per minute, 16 H.P. at 800 revolutions per minute, the corresponding M.E.P's. 

 on the piston calculated from the B.H.P. being respectively 90 and 108 Ibs. per sq. in. 



The sleeve-valve engine 2 is made by a few firms, but there are no signs of its wider 

 adoption by engine makers in place of the usual poppet-valve engine. 



An interesting petrol engine, designed by Dr. A. M. Low, has been recently made by 

 F. E. Baker, Ltd., the object being to obtain more power from an engine of given cylinder 

 capacity. The principal feature in the Low engine is that petrol vapour under high pressure 

 is injected into the cylinder, in which a charge of fresh air has previously been compressed. 

 Liquid petrol is pumped into an annular jacket surrounding the cylinder, when the engine 

 has been wanned up the petrol is vapourised, and the pressure in the jacket rises to 1 ,000- 

 1,500 Ibs. per sq. in. A valve controls the rate as well as the period of admission of the vapour, 

 which burns immediately it mixes with the air. This double control has the effect of render- 

 ing the engine extremely flexible, that is, it runs smoothly under all conditions of speed and 

 load. The engine made is of single-cylinder, four-cycle type, 78 mm. bore, 104 mm, stroke, 

 499 c.c. capacity, and is rated at 15 H.P. 



Commercial motor-vehicles are coming daily into wider use. In London the number 

 of motor-buses running in 1912 was over 2,000, and is still being increased almost daily They 

 provide facilities for passenger carrying which previously did not exist , and are gradually chang- 

 ing the character of the street traffic. The motor-bus has established itself in successful 

 competition with the electric tramway; in fact it may be said to have given a halt to any 

 further considerable extensions of tramway systems. The growth of the motor-car industry 

 is phenomenal. One American firm alone, The Ford Company, is said to have prepared for 

 an output of 200,000 cars for the year 1913. 



Gas Engines. Great activity is manifest in the production of large gas engines. 

 Germany led the way, and a few American makers, e. g. the Allis Chalmers Company, 

 Milwaukee, and the Snow Steam Pump Company, Buffalo, were early in the field; but 

 until a few years ago, British makers kept aloof from the production of large gas engines. 

 The Lilleshall Co., Ltd., Oakengates, Shropshire, however, have supplied for a railway 

 electric power station, near Yokohama, Japan, four engines of the Niirnberg type each 

 rated at 2,130 brake H.P. when running at 94 revolutions per min. Each cylinder is 1,200 

 mm. (47! in.) bore, 1,300 mm. (51^ in.) stroke. This type was first developed by the 

 Maschinen-Fabrik Augsburg-*Nurnberg A.G. and is now made by numerous licensees in 

 various countries. It works on the four-stroke cycle, is double-acting, has water-cooled 

 pistons and piston rods, and is usually made when space permits with two cylinders in 

 tandem. There are thus two effective strokes for each revolution of the crank-shaft. 

 In contradistinction to the usual practice in gas engines of moderate power, the cylinder, 

 with its water-jacket casing and the valve pockets, is made in one casting. The design 

 of the cylinder casting is such that there are no abrupt changes of form, and the water 

 space between the inner and outer cylinders is ample. The old trouble of cracking of 

 castings, exposed on one side to the heat of combustion of the gaseous fuel and on the 

 other side to the cooling action of the water, has been successfully overcome in, the sizes 

 of engines made up to the present. For successful design of large gas engines, such 

 castings should be of as simple and symmetrical form as possible. The large gas engines 

 of modified Oechelhauser type, 3 made by W. Beardmore & Co., Ltd., Glasgow, have their 

 long cylinders in which two barrel-pistons work, made each of three plain-flanged pipes, 

 the middle piece being short and forming, when the two pistons are closest together, the 

 combustion chamber. Separate annular castings for the inlet and exhaust boxes sur- 



1 See E. B. xx, 38, fig. 5. ~ See E. B. xx, 39 fig. 6. 



3 See E. B. xi, 500. 



