Vehicle Components and Engine Cycles

How a vehicle works

A modern vehicle is a set of parts working together, driven by an engine that turns fuel into movement. Understanding the main parts makes everything else easier. This module works through the whole picture: - The main components: the parts of a car and what each one does.\n- The engine cycle: how the four-stroke cycle produces power.\n- Petrol and diesel: how the two kinds of engine differ.\n- The engine parts: the main moving and fixed parts and their purpose. The lubrication and fuel systems and routine maintenance have their own module. Here the focus is the components and how the engine turns.

Words for vehicle technology

Five terms you need before you use them. Learn what each one means.

Match each component to its job

Petrol against diesel

Both engines turn fuel into motion, but they light the fuel in different ways, and that changes what each one is best at.

Which describes the power stroke?

In the four-stroke cycle, what happens during the power stroke?

• The burning gases push the piston down and turn the crankshaft
• The piston moves down and draws in fresh fuel and air
• The piston moves up and squeezes the mixture
• The burnt gases are pushed out of the cylinder

Tap the two moving engine parts

Tap the TWO engine parts that move while the engine is running.

• The piston
• The crankshaft
• The cylinder block
• The cylinder head

The four-stroke cycle in order

The four-stroke engine repeats the same four movements over and over, and each one has a clear job. First comes induction, where the piston moves down and draws fuel and air into the cylinder. Then compression, where the piston moves up and squeezes the mixture into a small space, ready to burn. Next is the power movement, where the mixture is lit and the burning gases drive the piston firmly down, turning the crankshaft. Last comes exhaust, where the piston rises again and pushes the burnt gases out. Then the cycle begins once more.

Pick the true facts about engines

Select the TWO statements that are true.

• A diesel engine uses compression to ignite the fuel
• The crankshaft turns the motion of the pistons into rotation
• The camshaft carries the drive to the road wheels
• A petrol engine never uses a spark to light the fuel

Order the four-stroke cycle

Put the four strokes of the cycle in the order they happen.

• The piston moves down and draws in fuel and air
• The piston moves up and squeezes the mixture
• The mixture burns and drives the piston down
• The piston moves up and pushes out the burnt gases

Choosing the right engine

Follow how two buyers chose between petrol and diesel for very different needs.\n\nA city driver: Ama does short trips around town. She chose a petrol car, which is lighter, cheaper to buy, and happy to rev freely in stop-start traffic. A haulage firm: a delivery company needed to pull heavy loads over long motorway runs. They chose diesel, because a diesel engine gives more pulling strength at low speed and uses less fuel on a steady run. The trade-off: petrol suits light, short journeys, while diesel suits heavy loads and high mileage. Yet both engines work the same way underneath: they move a piston up and down and turn that into rotation at the crankshaft. Only the way the fuel is lit sets them apart.

Complete the four-stroke facts

In the first stroke, _____, the piston draws in fuel and air. In the second stroke, _____, the piston squeezes the mixture. In the third stroke, _____, the burning gases drive the piston down. In the fourth stroke, _____, the burnt gases are pushed out.

Build an engine point

Choose the words that complete this statement about how an engine works.

The vehicle technology run

Five questions on vehicle components and engines. Three lives.

Diagnose the vehicle

Read each situation and choose the best answer, then think about why.

• A driver wants a vehicle to pull heavy trailers over long distances. Which engine suits best?
• An engine runs, but you need to name the part that changes the up-and-down motion into turning motion. Which part is it?
• A learner asks which stroke of the cycle actually produces the power. Which is it?

Explain how a vehicle and its engine work

A friend is starting this course and wants to understand vehicles. Explain how a vehicle and its engine work using what this module has covered.

• Explain the job of three main vehicle components
• Explain the four strokes of the four-stroke cycle
• Explain how petrol and diesel engines differ
• Explain what the crankshaft does
• Finish by explaining the purpose of one other main engine part