Thursday, July 16

How your car works


Understanding the mechanics of a car can be simplified by dividing the car into the seven subsystems.

Knowing how a car works is the first step towards diagnosing what is wrong when a car does not work.

By knowing the fundamentals of maintenance you can also perform efficiently and correctly. Then you will be assured of getting the most out of your car availability. And you will be pleased with your efforts and savings (Refer Fig 1)

Vehicle system Fig 1

1. Engine: Temperatures of 4500 fah. or more are produced by the fuel burning inside the engine. Less than 20 per cent of this heat is converted into useful power. The remainder is dissipated through the cooling and exhaust systems. An engine has 120 to 150 moving parts that must be lubricated with oil to avoid excessive wear. (Refer Fig 2)

Radiator engine exhaust Fig 2

2. Drive train: In a conventional car, power is carried from the engine to the rear wheels by the transmission drive shaft differential  and rear axle. The transmission contains low gear that provide extra force for climbing hills or acceleration as well as high gears for economical highway cruising. (Refer Fig 3)

Brake system Fig 4

3. Wheels, tyres and brakes: After travelling 60,000 miles or average 5 years of normal driving a typical car wheel has turned 95 millions times and worn out nearly 2 sets of tyres. Each time a car come to stop from 60 mph the brakes generate enough heat to boil a half pint of wat. (Refer Fig 4)

Steering Fig 5

4. Steering: Without the sophication of modern steering equipment, the 1 to 2 ton weight of the average car would be too difficult to manouver, A driver must exert up to 30 lb. of effort on the steering wheel of a car with manual steering in order to turn it in a tight circle. Power steering cuts this effort to only 5 to 6lb. (Refer Fig 5)

Suspension Fig 6

5. Suspension: Modern suspension systems of torsion bars or springs anti sway bars and shock absorbers move, up and down hundreds of times a minute. They help to cushion car occupants against irregularities on the road surface and provide safe and stable handling when the car accelerates, brakes or turns. (Refer Fig. 6)

Electrical system Fig 7

6. Electrical system: A 12 volt battery provides the primary source of power needed to start the engine and operate the lights, radio ,horn, windshield wipers, aircond, instruments and other electrical accessories. This 12 volts are stepped up to as high as 40,000 volts in the engine’s ignition system. (Refer Fig. 7)

7. Body and chassis: Many new cars have no frame and it is the bodywork that holds the car together. The average car uses more than 400 sq ft of sheet metal which varies in thickness from 0.15 to 0.05 in. A car’s bodywork must be capable of withstanding great stressed impact when the is in motion.

Now you have completed the topic on How a Car Works and shall be able to:

1) Understand the following Seven Steps on How a Car Works and you will feel safe and confidence to drive your car on the road, the systems are:

i) Engine

ii) Drive Train

iii) Wheels, Tyres and Brakes

iv) Electrical

v) Steering

vi) Suspension

vii) Body and Chassis

2) Knowledge on technical terms like cooling system, exhaust system, radiator, front u joint, driveshaft, differential, transmission, low gear, battery, starter, alternator, windshield wiper, ignition system, front brake wheel, cylinder booster, brake pipe, wheels, brake system, steering system, power steering, tie rod, steering arm, steering pump, leaf spring, shock absorber and chassis.

Review Questions:

1. How many per cent of the heat being produced by engine be converted into power?

2. How does the wheels receive power?

3. Name the steering system parts.

4. Name the brake system parts.

5. Name the suspension system part.