BASICS OF AUTOMOBILE ENGINEERING

Automobile Engineering

Automobile engineering is an applied science that includes elements of Mechanical engineering, Electrical engineering, Electronic
Engineering, Software Engineering and Safety engineering as applied to the design, manufacture and operation of automobiles, buses and trucks and their respective engineering subsystems.

The word automobile comes, via the French automobile, from the Ancient Greek word (autos, "self") and the Latin mobiles ("movable"); meaning a vehicle that moves itself, rather than being pulled or pushed by a separate animal or another vehicle. The alternative name car is believed to originate from the Latin word carrus or carrum("wheeled vehicle)

What is an Automobile?

The automobile is a self propelled vehicle that travels on land. It usually has four wheels. An engine provides the power to move the vehicle. As the name implies, it is a mobile or moving power unit on road. Self- propelled means unit which contains its own power source, necessary for moving, within itself .As a vehicle ,it is used for transportation of passenger and goods.

HISTORY OF AUTOMOBILE DEVELOPMENT

The history of automobile development an growth is very fascinating. It runs together with the history of development of engines. This can studied as under.

European Development

 The awn of automobile history dates back to 1770 when a Frenchman, Nicholas Carnot, built the first road vehicle propelled by its own power. The French artillery officer built a three-wheeler steam tractor for handling a canon. It could work for 15 minutes only and attained a sped of about 2.5 mph.

The automobile or the car as we now today evolved from the horse-drawn carriage, and perhaps the 19th century tricycle; but as the years went by it gradually lost its likeness to any of its progenitors. The saga of the car really began as recently as 1860, when Jean Etienne Lenoir, a Belgian  inventor, built the first practicable gas engine. Etienne’s engine was fed on a mixture of coal gas and air and no compression meant that it was not efficient.

The next significant development came in 1876 when Count Nikolous Otto, a German engineer, successfully applied the four- stroke principle which enabled the charge to be compressed with significantly better performance. At about the same time petrol came to substitute the coal gas. During the 1880’s Germany was the hub of automobile development with Gottlieb Daimler and Carl Benz at the helms of affairs. They were building their cars for sale in 1886. The engine was placed in the front of the chassis, hooked up to a sliding gear transmission, brake pedal, clutch and acceleration were incorporated.

By the turn of the century, designers began increasing the number of the cylinder and a prototype in-line 6-cylinder engine appeared in 1902. The design improvement awakened the public to the next six years, production and sale of these vehicles became a business.

The early 1920’s saw the beginning of a  period of gradual change and refinement in automobile design. The spark ignition engine was the power plant of motor vehicle and kicked out steam and electrical rivals. Water-cooled engine were almost certain. The engine were located in the front of the chassis. The poppet valve was used in every engine design. Major improvements have been made in every car feature. The main design requirements emphasized on production of reliable vehicles to function at all times under all condition which would be increasingly comfortable to ride in and easy to operate.

 American Development

When Europe was struggling to make his vehicle run, came the period, in which the development of mass-production methods permitting lower prices played a dominant role in America. In 1908 Ford started off his Model T with an initial run of 2,000 vehicles, an output unheard of at that time. Ever since, the correlation of design and production efficiency has influenced the trend of modern vehicle construction and popularized the use of automobiles. The life of tyres has been increased, independent front-wheel suspension has been introduced; four-wheel hydraulic brakes have been incorporated, the higher compression ralios and availability of new materials have helped to enhance power-weight ratio.

Substantial progress has been made after the second world war in every car feature such as reliability and safety, ease and comfort, economy of operation, pleasing appearance. Safety and exhaust emission were the additional features. Research and development continue to produce computer controlled vehicles powered with nuclear engines and fuel cells.

Indian Development

At the end of 1900, the cars arrived in India and were used by Britishers and Kings of states. In pre-Independent India, cars were imported and it was only in 1946, Hindustan Motors was set up in Calcutta. It was followed by Premier Automobiles in 1947 to produce cars and Mahindra and Mahindra in 1949 to produce jeeps in Bombay. Standard Motors was established in Madras in 1950. The industrial giant, Tata introduced a plant for the manufacture was started in India with foreign collaborations and as such could not contribute much to improve the design and manufacture of new cars.

The production of all the cars was far below the nation’s demand. Maruti Udyog Limited was emphasized in 1982 in collaboration with Suzuki of Japan to manufacture small cars. It has helped to automobiles the country. New models have been introduced by various companies in recent years which have the latest features and machines available for all income group of the country’s population. The details of Indian automobile manufactures and specifications of their motor vehicles are listed in Appendix I.

VEHICLE OPERATION

There is a wide variety of motor vehicles but most of them perform their function in almost identical manner.

1. Rolling of Crankshaft

The driver turns on an ignition and starter switch. The battery starts supplying electrical current to a starting motor. The motor turns a flywheel and the crank shaft which are interconnected.

2. Running of Engine

The driver pushes the accelerator pedal to control the ate of flow of petrol into a carburettor. The carburettor helps to mix the petrol and air and prepares combustible mixture. This mixture is sucked into the engine cylinder and is compressed by the piston. An electric spark sets fire to the mixture and an explosion takes place. The high pressure of explosion pushes the piston out and the crankshaft and the engine start running. As the explosion process is repeated again and again, the crankshaft is disconnected from the starting motor and is turned continuously by the piston and connecting rod.

3. Transmission of Engine Power to Rear Wheels

Through a clutch, the driver connects the crankshaft to a set of gears (transmission). The power is thus transmitted from the engine to the rear wheels. By means of a gearshift lever, the driver shifts the gears of the transmission to suit driving conditions.

In case of vehicles equipped with automatic transmission, the driver selects the drive range for operation. The clutch and the selection of transmission gears are operated automatically.

4. Turning a Corner

The gear box is connected to a propeller shaft through a universal joint. As the transmission gears change, the propeller shaft is set into motion. The other end of propeller shaft is connected to the rear axle through a set in to motion. The other end of propeller shaft is connected to the rear axle through a set of bevel gears. The motion is turned at rightangles and thence to the rear wheels which are directly mounted on the rear axle.

The differential which is a set of gears is arranged in the rear axle and permits one rear wheel to turn faster than the other. This is necessary as and when turning a corner.

5. Control of Vehicle Motion

The motor vehicle is in motion and rolls along the road. The driver controls the direction of the vehicle by turning the front wheels with the help of a steering gear.

The driver is ready to slow down the vehicle or stop it with the help of a braking system.

6. Distribution of Vehicle weight

The order of the vehicle can experience the jolts by its forward movement and jerks due to unevenness of the road surface. These jolts and jerks are partially controlled by the spring mountings of front and rear axles, shock absorbers which dampen out sudden recoils in the springs, the padding and springs in the vehicle seats. The side swings are decreased by the chassis cross members and proper distribution of the weight of the chassis and the body between the front and the rear wheels.

SYSTEMS OF A VEHICLE

A motor vehicle has to perform meeting complex requirements. The main requirements expected from a modern automobile can be enumerated as follows:

1. Reliability and Safety

The vehicle should give long and trouble-free running with maximum safety features,

2. Ease and comfort

It should be easy to operate and park and running should be comfortable, without noise, vibration, pollution, heat and humidity.

3. Economic of operation

It should be cheap, fuel-efficient, maintenance free. Fuel, consumables, spare parts, labour should be easily available at low cost.

4. Maneaurability

It should be easy to drive the vehicle inside a city, on the highways and hills.

5. Appearance

The shape, size and colour should be pleasing. It should need minimum space for parking.

There are a large number of systems and parts used in a modern automobile to meet the above complex requirements.

Motor vehicles, both passenger and truck, are generally made up of two major assemblies, i.e., a chassis and a body.

(a) Chassis: It contains all the major units necessary to propel the vehicle, direct its motion, stop it and allow it to run over uneven surfaces;

A vehicle arrangement without body is called chassis (Chassis =Automobile-Body)

(i) The frame

(ii) The engine

(iii) The transmission system

(iv) The wheels and tyre assembly