Motor car, road vehicle which first appeared in the 19th Century. The steam propelled the first cars, but such vehicles were not a success and the age of the motor car really dates from the introduction of the petrol-driven horseless carriages of Gottfrield Daimler and Karl Benz (1885-86). The internal combustion engine for these cars had been developed earlier by several engineers, most notably by the German, Nickolaus Otto, in 1876.
The main components of a motor car, from then till now, are a body or chassis to which are attached all other parts – including the engine or power plant, the transmission system for transferring the drive to the wheels, and the steering, braking and suspension mechanisms for guiding, stopping and supporting the car. A few experts assembled the first cars, but Henry Ford and R. E. Olds in the USA began modern mass-production in the early 1900s. By this means, the cost of a car was drastically reduced, and more people could afford done.
In most modern car factories component parts are put together on assembly lines – slow-moving conveyor belts. Each worker usually has a specific task, example fitting doors or crankshafts. Bodies and engines are constructed on separate assembly lines, which converge when the engine is installed. Overhead rail conveyors move heavy components to and along the assembly lines, and lower them into position. At a later stage on the assembly line such items as lamps are fitted, and electrical, braking and control systems are tested. The fully assembled car is road tested before sale.
The automobile was not invented overnight. It took shape from an accumulation of technical advances that resulted in a light and efficient engine. The accepted “fathers of the modern motor car” are two Germans, Karl Benz (1844-1929) and Gottfried Daimler (1834-1900), who built their first petrol-fuelled motor vehicles within a few months of each other (1885-6). More than a hundred years earlier, the first self-propelled road vehicle had rumbled through the streets of Paris at nearly 5km/h (3mph) when Nicolas Cugnot (1725-1804) demonstrated his steam-driven wagon.
The German Nikolas Otto (1832-91) made the first four-stroke internal-combustion engine in 1876 and in 1885 Daimler had installed a small four-stroke engine in a cycle frame. He drove his first four-wheeled petrol-driven vehicle round Cannstatt in 1886. In neighboring Mannheim, Benz had tested his three-wheeled car. Daimler licensed the French firm of Panhard and Levassor to build his engine. Levassor placed it at the front of his crude car and it drove the rear road-wheels through a clutch and a gearbox. Thus in 1891 the first car to use modern engineering layout was seen.
Within three years of the appearance of the first Panhard France was staging motor races on public road. At the turn of the century, petrol, steam and electric power shared almost equal popularity for powering cars. Steam was well tried and reliable and electric vehicles held the land speed record. France had several established motor manufacturers – Panhard, Peugeot, Renault, Daracq, Delahaye and others; in Germany Benz had made the world’s first standard production car, the Velo (1894), and the Daimler company was just about to present the
Mercedes to the public (1901). In the United States (USA) the automobile would develop along different lines. There the car was seen not as a rich man’s toy, but as a new method of communication in a continent in which travel had been restricted by a lack of roads and great distances. Great Britain (UK), slow to start, had legislated for the car in 1896 when the road speed limits were raised and soon such companies as Lanchester, Daimler (of Coventry), Wolseley and Napier were producing cars.
Encouraged by the keen interest shown by King Edward VII, motoring in Britain became an accepted method of travel – for the rich. Some British manufacturers began to contest French car supremacy and among them the partnership formed in 1904 between Charles Rolls and engineer Henry Royce was on of the most significant. At that time Henry Ford was preparing the motoring world for his Model T, this was introduced in 1908. By 1910 automobile design had become fairly settled, with a side-valve four-(or six-) cylinder front-mounted engine.
Weather protection had been developed, and the electric starter from America (1912) had encouraged women to take to the wheel by removing the physical hardship of the starting handle. Interchangeable parts made to fine limits opened the gates to mass production. The Edwardians had laid down the working principles and the following years saw more refinement than innovation. “Balloon” types, pressed-steel wheels and four-wheel brakes appeared. Heavy and unstable coach-built saloon bodies encouraged the trend to wood-and-fabric and later to the rigid, welded pressed-steel body.
Greater demand by the public in the 1920s brought cheaper cars on the market such manufacturers as Morris, Citroen, Opel, Austin and Fiat, although such exotic models as Hispano-Suiza, Maybach, Voisin and Delage still commanded respect – and a deep purse. The economic depression of the late 1920s closed down many companies of both classes, from Clyno to Bentley, and forced the production of even more basic cars. By the 1930s most cars were being made for the new middle-class “family” driver, uninformed in motoring matters and requiring a near foolproof vehicle.
There were some technical milestones, however. In 1934 Citroen produced the Traction Avant, the first medium-sized car to have front-wheel drive and independent suspension, and in 1938 the German car that was to become the Volkswagen (people’s car) was finalized and tested – the only car to have spanned four decades. The first postwar cars were similar to prewar models, but in 1948 two British cars destined to influence future design appeared – the wide-tracked Morris Minor and the 193km/h (120mph) Jaguar XK120 sports car.
In 1955 the hydro-pneumatic suspension system of the Citroen DS 19, a sophisticated successor to Citroen’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 cycle Nine 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 and few small cars use the two-stroke cycle first devised by Dugald Clerk in 1880. In this type of engine the movement of the piston admits the fuel and exhausts the burned gases by uncovering “ports” or holes in the side of the cylinder. Fuel and exhaust pass in and out of a four-stroke engine using a more sophisticated system of valves, controlled automatically by a camshaft driven direct from the engine’s crankshaft. As the engine operates, the valves are successively opened and closed. The moment of ignition of the fuel must also be accurately controlled.
This is done by a distributor, again mechanically connected to the crankshaft, which directs a current of electricity successively to each of the cylinders. This current “fires” a spark in the sparking plugs and the fuel is ignited. Otto’s engines ran on coal gas, a perfectly satisfactory fuel but one that is difficult to store. The gas engine was greatly improved by the use of liquid fuels such as petrol (gasoline) made by refining crude oil. To turn petrol into a combustible vapor it is mixed with air to form a fine mist of droplets that can be drawn into the cylinders.
The mixing is carried out in a carburetor. Unlike steam engines most internal combustion engines do not produce great power at slow speeds. The cylinders are small and each individual ignition stroke produces comparatively little power. To obtain a useful amount of work from such engine it must be run fast, to put the maximum number of ignition strokes into each second. Motor car engines commonly produce their maximum power at speeds of 5,000 revolutions per minute or more. The oscillating pistons and valve gear sets the upper limit on speed.
Specially prepared engines, in which great attention has been paid to balance and smoothness, can be obtained more power by running into speeds of 12,000 rpm or more. The Economical Diesel Engine The compression-ignition engine, designed by the German Rudolf Diesel (1858-1913) in 1896, dispenses with the carburetor and sparking plugs of the petrol engine. The gas inside the cylinder on the compression stroke is pure air, which is compressed to 1 : 14 to 1 : 20 of its initial volume – a much higher compression ratio than is used in petrol engines.
At the top of the compression stroke a fine spray of oil fuel is injected into the cylinder. As gas is compressed its temperature increases, so that the oil spray meets the air charge at a temperature sufficiently high to ignite it spontaneously. Because of its high compression ratio the compression-ignition or diesel engine is more efficient than a petrol engine. But for the same reason it must be more heavily built, thus offsetting the advantage somewhat.
Diesel engines offer economies in fuel consumption at the expense of a loss in performance; they are particularly suited to frequent stop and start duties, and as a result are widely used in taxis, buses and lorries. The gas turbine, a completely different kind of engine, was first devised at the beginning of the twentieth century (1900s) and perfected in the 1930s. It usually has a single shaft carrying a series of propeller-like fans divided into two groups, the compressor and the turbine. In an operating gas turbine air is drawn in the compressor fans and its pressure increased.
The compressed air is mixed with fuel and ignition takes place, further increasing temperatures and pressures. The burned mixture leaves the engine through the turbine, driving the blades round. The compressor, which is often driven directly by the turbine, takes up much of the power produced, but enough is left to make the gas turbine exceedingly powerful form of engine. Efficiencies are not high, but the good power-to-weight ratio of a gas turbine makes it suitable for aircraft propulsion. A gas turbine is about three times as powerful as a piston engine of the same weight.