Transcript Slide 1
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INTRODUCTION
Motor Car, any self-propelled vehicle with more than two wheels and a passenger compartment, capable of being steered by the operator for use on roads. The term is used more specifically to denote any such vehicle designed to carry a maximum of seven people.
The primary components of a car are the power plant, the power transmission, the running gear, and the control system. These constitute the chassis, on which the body is mounted. The power plant includes the engine and its fuel, the carburettor, ignition, lubrication, and cooling systems, and the starter motor.
Car Systems
Cars are powered and controlled by a complicated interrelationship between several systems. This diagram shows the parts of a car with a petrol engine and manual transmission (the air filter and carburettor have been removed to show the parts beneath, but are usually in the space above the intake manifold). The car’s major systems are the power plant, the power train, the running gear, and the control system. Each of these major categories includes a number of subsystems, as shown above. The power plant includes the engine, fuel, electrical, exhaust, lubrication, and coolant subsystems. The power train includes the transmission and drive systems, including the clutch, differential, and drive shaft. Suspension, shock-absorbers, wheels, and tyres are all part of the running gear, or support system. Steering and brake systems are the major components of the control system, by which the driver directs the car.
FOUR STROKE CYCLE
The overwhelming majority of car engines still employ the four-stroke cycle (four piston strokes per cycle), invented by Nicholas Otto in 1876.
The first down stroke of the piston that is attached to a connecting rod at its top end and to the crankshaft at the bottom draws a petrol-air mixture into the cylinder. This is then compressed, which is the second stage of the process. The volatile cocktail is then ignited by a sparking plug and the resulting explosion forces down the piston, so turning the crankshaft. The final phase of the operation is the stroke that expels the exhaust gases from the cylinder.
BATTERY The car’s management system is yet another component to make demands on the car’s battery. The system is charged by an engine driven alternator that, unlike the dynamo it replaced in the 1970s, is efficient at low speeds or when a car is “ticking over” in a traffic queue.
FUEL INJECTION
A carburettor had been used from the earliest days of motoring as a component in which the petrol-air mixture was created. The limitation of such an arrangement was that the mixture was unevenly distributed which resulted in incomplete combustion and an undesirable amount of unburnt fuel reaching the atmosphere.
As a result, the carburettor has now been replaced by fuel injection. This first appeared on high performance cars in the 1950s. Not only is a precise amount of metered petrol delivered by pump to each cylinder, but the air supply can also be carefully controlled by the use of an individual inlet manifold.
LUBRICATION
An engine cannot function unless it is well lubricated with oil. This is circulated under pressure from a pump that draws lubricant from a reservoir contained within the sump at the base of the engine. It is delivered under pressure to the main crankshaft bearings from a gallery located in the side of the block, and to the appropriately named big-ends of the connecting rods via holes drilled in the shaft. Oil reaches the bores by splash although it is pumped to the camshaft and valve gear.
COOLING As the combustion temperature of petrol is 2500 ° C, the engine must be cooled. The cylinders and head therefore incorporate water jacketing for a coolant that contains an antifreeze mixture circulated by pump. It is cooled in a radiator located at the front of the car by a passage of air that is drawn through it by a thermostatically operated electric fan
ELECTRICAL EQUIPMENT The car’s management system is yet another component to make demands on the car’s battery. The system is charged by an engine-driven alternator that, unlike the dynamo it replaced in the 1970s, is efficient at low speeds or when a car is “ticking over” in a traffic queue.
A key function of the electrical system is to start the car’s engine. This is usually undertaken by a pre engaged motor, in which a solenoid moves a bevel gear into mesh with the teeth on the engine’s flywheel. In addition to providing current for the car’s lights and windscreen wipers, modern electrical systems have to service a radio/tape recorder, cigarette lighter, heated rear window, central door locking, windows, air conditioning, and, more recently, seat adjustment.
BRAKES Most cars use disc brakes on their front wheels; these are fitted on front and back wheels on more expensive models. When the brake pedal is applied, hydraulic power is applied to calipers that grip the disc and so contribute to arresting the car’s progress. Drum brakes, that use internally actuated shoes, are often fitted at the rear. All cars feature a hand or parking brake that operates on the vehicle’s rear brake shoes or discs.
STEERING The most popular steering system is rack and pinion. Power-assisted steering, which is hydraulically activated by an engine driven pump and previously the preserve of expensive cars, is becoming increasingly popular.
PERFORMANCE & 4-WHEEL DRIVE From the 1970s the performance of such vehicles had also been enhanced by the development of the turbocharger. Driven by otherwise wasted exhaust gases, it is a small, high-revolution pump that forces air into the cylinders at pressure and is invariably used in conjunction with an intercooler. This cools incoming air to make it denser, further increasing engine power.
Performance cars were usually front engined (and sometimes rear-engined) until the appearance, in 1966, of the Lamborghini Muira, which had a mid-located power unit. This meant a better balanced car, but at the expense of greater interior noise and loss of rear seating.
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SAFTY Although cars have become faster, current models are safer than many of those manufactured in previous decades. Modern cars incorporate beams at their front and rear, which crumple progressively in order to absorb energy, while having a strong central cell to protect occupants in the event of a crash.
Braking has greatly improved in recent years and most systems feature servo assistance. This harnesses the vacuum produced by the engine to actuate the brakes, so that the driver does not need to apply an excessive amount of pressure to the pedal.
A further refinement is an automatic braking system. This sophisticated anti-locking device operates in conjunction with the vehicle’s engine management unit, and was initially used on expensive cars to prevent skidding
ELECTRIC CAR
The only vehicle to meet the requirements of the California Clean Air Act is the electric car. This type of car produces no harmful exhaust fumes, and does not absorb power when stationary. In 1996 General Motors became the world’s first major car manufacturer to put a purpose designed electric car, the EV1, into production.
Cars Through the Years Since they originated in the late 1800s, motor cars have changed and developed in response to consumer wishes, economic conditions, and advancing technology. The first vehicles looked like carriages with engines mounted underneath, because this was the style to which people were accustomed. By 1910, however, features like the front-mounted engine had been established, giving the car a look that was all its own. As public demand for cars increased, the vehicles became more stylized. The 1920s and 1930s saw the appearance of the sleek, individually designed luxury vehicles called the “classic cars.” Various oil shortages were reflected in the fuel-efficient cars made in the 1970s and 1980s. Current mass-produced designs continue to reflect motorists’ desire for economy, although markets exist for many more expensive types of car.
Horseless Carriage
The original “horseless carriage” was introduced in 1893 by the brothers Charles and Frank Duryea. It was America’s first internal-combustion motor car, and was followed by Henry Ford’s first experimental car that same year.
Silver Ghost
One of the highest-rated early luxury cars, the 1909 Rolls-Royce Silver Ghost featured a quiet 6-cylinder engine, leather interior, folding windscreens and bonnet, and an aluminium body. Generally driven by chauffeurs, the emphasis of the luxury car was on comfort and style rather than speed.
Phaeton
Cars of the 1920s exhibited such design refinements as balloon tyres, pressed-steel wheels, and four-wheel brakes. Although assembly lines (which originated with Henry Ford in 1908) continued to bring down the price of cars, many at this time were one-off vintage models, made to individual specifications. The 1929 Graham Paige DC Phaeton shown above featured an 8-cylinder engine and an aluminium body.
De Luxe Saloon
The roomy interior and rear-hinged back door of this 1937 Pontiac De Luxe saloon car represent a move towards a car suited to the needs of families. With these consumers in mind, cars were designed to be convenient, reliable, and relatively inexpensive. Vehicles in the 1930s were generally less boxy and more streamlined than their predecessors.
Studebaker
This 1940 Studebaker Champion two-door saloon was designed by Raymond Loewy and built by Studebaker craftsmen. Features emerging in the 1940s included automatic transmission, sealed-beam headlights, and tubeless tyres.
Gullwing
Powerful high performance cars such as this 1957 Mercedes-Benz 300SL were built on compact and stylized lines. Also called the Gullwing because its doors open upwards into the shape of a gull’s wings, the 300SL was capable of 230 km/h (144 mph), its on-road performance matching
Volkswagen Beetle
For many years few modifications were made in the design of Volkswagen’s classic small car. The name “Volkswagen” means “car for the people,” and the car served at least two important consumer needs. The rear-mounted engine and small, rounded, beetle-like shape represented an appealing combination of looks and economy that remained popular for more than four decades.
Mustang
More than 100,000 Ford Mustangs were sold during the first four months the model was on the market in 1964, making it Ford’s best early sales success since the introduction of the Model T. A high performance vehicle, the Mustang’s popular characteristics included a small, fast design, excellent handling, a powerful engine, and a distinctive appearance.
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ENGINE
A key function of the electrical system is to start the car’s engine. This is usually undertaken by a pre-engaged motor, in which a solenoid moves a bevel gear into mesh with the teeth on the engine’s flywheel. In addition to providing current for the car’s lights and windscreen wipers, modern electrical systems have to service a radio/tape recorder, cigarette lighter, heated rear window, central door locking, windows, air conditioning, and, more recently, seat adjustment.