Automobile Mechanical Q&A

Question 1

What is an internal combustion engine?

Answer 1

• Type of engine
• Using petrol or fuel oil
• Which is ignited inside the cylinder

Question 2

Name the strokes of a four stroke engine

Answer 2

1. Induction
2. Compression
3. power
4. Exhaust

Question 3

What happens in induction?

Answer 3

• Intake valve is open
• Exhaust valve closed
• Piston is descending
• A mixture of petrol and air is drawn into the cylinder

Question 4

What happens in compression?

Answer 4

• Intake and exhaust valves close
• Piston moving upwards from “bottom dead centre” to “top dead centre”
• Compress the mixture to about 1/6 of the original volume.

Question 5

What happens in power?

Answer 5

• The piston reaches “top dead centre”
• The spark plug ignites the compressed mixture
• The pressure forces the piston downwards
• Transmitting power through the connecting rod to the crankshaft.
• Both valves still closed

Question 6

What happens in exhaust?

Answer 6

• The piston reaches “bottom dead centre”, the exhaust valve opens
• While the the piston is returning towards “top dead centre” it expels the burnt mixture out of the cylinder through the open exhaust valve

Question 7

What is the use of the crankshaft?

Answer 7

• it is the main shaft of the engine
• it permits the backward and forward movements of the pistons by means of the connecting rods and big end bearings
• it also drives the camshaft at half the engine speed by means of a timing gear or chain

Question 8

What is the use of the camshaft?

Answer 8

• it operates the valves

- drives the mechanical fuel pump, oil pump and distributor shaft