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Category: Vehicle Structure

Last Updated: 24 June 2014

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Automobile, byname machine, conjointly known as car or automobile, a sometimes machine vehicle designed primarily for traveller transportation associate degreed usually propelled by an ICE employing a volatile fuel.
Today’s average car contains more than 15,000 separate, individual parts that must work together. These parts can be grouped into four major categories: body, engine, chassis and electrical system.

Body

An automobile body is a sheet metal shell with windows, doors, a hood and a trunk deck built into it. It provides a protective covering for the engine, passengers and cargo. The body is designed to keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle. A sedan has an enclosed body with a maximum of 4 doors to allow access to the passenger compartment. The design also allows for storage of luggage or other goods. A sedan can also be referred to as a saloon and traditionally has a fixed roof. There are soft-top versions of the same body design except for having 2 doors, and these are commonly referred to as convertibles.

The utility or pick-up carries goods. Usually it has stronger chassis components and suspension than a sedan to support greater gross vehicle mass.

Light vehicle vans can be based on common sedan designs or redesigns so that maximum cargo space is available.

The bodies of commercial vehicles that transport goods are designed for that specific purpose. Tankers transport fluids, tippers carry earth or bulk grains, flatbeds and vans are used for general goods transport.

Buses and coaches are usually 4-wheel rigid vehicles, but a large number of wheels and axles can be used. Sometimes articulated buses are used to increase capacity. Buses and coaches can be single-deck or double deck. Buses are commonly used in cities as commuter transports while coaches are more luxurious used for long distances.

Engine

The engine acts as power unit. The internal combustion engine is most common; this obtains it’s power by burning a liquid fuel inside the engine cylinder. There are two types of engine: gasoline (also called a spark-ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the power train.
The way engine cylinders are arranged is called the engine configuration. In-line engines have the cylinders in a line. This design creates a simply cast engine block. In Vehicle applications, the number of cylinders is normally from 2 up to 6. Usually, the cylinders are vertical. As the number of the cylinders increases, the length of the block and crankshaft can become a problem. One way to avoid this is with a V configuration. This design makes the engine block and crankshaft shorter and more rigid.

An engine located at the front can be mounted longitudinally and can drive either the front or the rear wheels. Rear engine vehicles have the engine mounted behind the rear wheels. The engine can be transverse or longitudinal and usually drives the rear wheels only.

Chassis

The chassis is an assembly of those systems that are the major operating parts of a vehicle. The chassis includes the power train, steering, suspension, and braking systems.

1. Power train system conveys the drive to the wheels. The power train transfers turning effort from the engine to the driving wheels. A power train can include a clutch for manual transmission or a torque converter for automatic transmission, a transmission, a drive shaft, final drive and differential gears and driving axles. Alternatively, a transaxle may be used. A transaxle is a self- contained unit with a transmission, final drive gears and differential located in one casing.
2. Steering system controls the direction of the moments. The directional motion of vehicle is controlled by a steering system. A basic steering system has 3 main parts: a steering box connected to the steering wheel, the linkage connecting the steering box to the wheel assembly at the front wheels and front suspension parts to let the wheel assembly pivot. When the drive turns the steering wheel, a shaft from the steering column turns the steering gear. The steering gear moves tie-rods that connect to the front wheels. The tie-rods move the front wheels to turn the vehicle right or left.
3. Suspension and wheels absorb the road shocks. The purpose of the complete suspension system is to isolate the vehicle body from road shocks and vibrations, which will otherwise be transferred to the passengers and load. It must also keep the tires in contact with the road regardless of road surface. A basic suspension system consists of springs, axles, shock absorbers, arms, rods and ball joints.
4. Brake slows down the vehicles. Drum brakes have a drum attached to the wheel hub, and braking occurs by means of brakes shoes expanding against the inside of the drum. With disc brakes, a disc attached to the wheel hub is clenched between two brake pads. On light vehicles, both of these systems are hydraulically operated. The brake pedal operates a master cylinder. Hydraulic lines and hoses connect the master cylinder to brake cylinders at the wheels. Most modern light vehicles have either disc brakes on the front wheels and drum brakes on the rear or disc brakes on all 4 wheel. Disc brakes require greater forces to operate them. A brake booster assists the driver by increasing the force applied to the master cylinder when the brake is operated.

Electrical System

The electrical system supplies electricity for the starter, ignition, lights and heater. The electricity level is maintained by a charging circuit.
Automobile Electrical System

1. Charging. The charging system provides electrical energy for all the electrical components on the vehicle. The main parts of the charging system includes: the battery, the alternator, the voltage regulator which is usually integral to the alternator, a charging warning or indicator light and wiring that complete the circuits. The battery provides electrical energy for starting, then once the engine is running, the alternator supplies all the electrical components of the vehicle. It also charges the battery to replace the energy used to start the engine. The voltage regulator prevents overcharging.
2. Starting. The starting system consists of the battery, cables, starter motor, flywheel ring gear and the ignition switch. During starting, two actions occur. The pinion of the starter motor engages with the flywheel ring gear and the starter motor then operates to crank the engine. The starter motor is an electrical motor mounted on the engine block and operated from the battery.
3. Ignition. A basic ignition system consists of the battery, low-tension cables, the ignition coil, distributor, coil high-tension cable, spark plug cables and spark plugs. The ignition system provides high intense sparks to spark plugs to ignite the fuel charges in the combustion chambers. The sparks must be supplied at the right time and they must have sufficient energy over a range of conditions to ignite the charges. The energy comes from the battery and alternator, and voltage is increased by the ignition coil. The system has two circuits. The primary or low-tension circuit initiates the spark. The secondary or high-tension circuit produces the high voltage and distributes it to the spark plugs.