esign appeared - the wide-tracked Morris Minor and the 193km/h (120mph) Jaguar XK120 sports car. In 1955 the hydro-pneumatic suspension system of the Citren DS 19, a sophisticated successor to Citren's 1934 car, astonished the motoring world. The end of 1959 saw the introduction of the Morris Mini-Minor/Austin Seven, now universally known as the Mini. It had a transversally mounted engine, front-wheel drive, rubber suspension and short wheelbase.Since then the automobile has played a more and more important part in modern life, until now its numbers have become a threat to health, to energy resources (especially to non-renewable resource) and to mobility itself - hence the renewed interest in pollution-free electric cars.In the traditional steam engine, and even in a modern steam turbine, fuel is burned outside the engine. But it is more efficient to burn fuel inside the engine and let the expanding gases produced drive a piston or turbine.The first such internal combustion engine, running on gas, was build by the German engineer Nikolas August Otto (1832-91). His engine, demonstrated in Paris 1867, was large, noisy and not very efficient. But it became the forerunner of 99% of all today's engines.The four stroke cycleNine years after the first gas engine Otto devised another, based on the four-stroke cycle. The crucial advance in this engine was ignited, giving not only a considerable improvement in efficiency but also a marked reduction in fuel consumption.It takes four strokes of the engine to include one of power, so this system is known as the four-stroke cycle. It is by far the most common type of engine in use today. The four main stages are an induction stroke in which a downward movement of the piston sucks in the fuel-air mixture; a compression stroke in which upward movement caused by the explosion of the fuel; and an exhaust stroke in which the upward-moving piston forces exhaust gases out of the cylinder.Many motor cycles a...
