How Things Work

Four-cylinder turbo engine

Tap a numbered label or a part name to learn what it does.

Cylinder head close-up

Camshaft lobes

Part name · What it does

Illustrations show typical assemblies rather than a specific manufacturer’s engine. Valvetrain and fuel-system designs vary.

Automatic transmission breakdown

Explore a conventional torque-converter automatic transmission. Tap a number or part name to see what it does.

Main assemblies · 1–7

Additional components · 8–14

Tap a close-up to see that part’s name, purpose and location within the transmission.

Image labels 1–7 identify the main assemblies. The close-ups show parts 8–14; their locations are explained in the selected-part panel. Manual, dual-clutch and CVT layouts differ.

How an automatic changes gears

1. The engine drives the torque converter, which transfers torque toward the gear train.
2. The controller determines the appropriate operating ratio from vehicle conditions.
3. The hydraulic system applies and releases the required friction elements.
4. The planetary gear sets provide the resulting ratio and deliver torque toward the driveline.

Lock-up operation can reduce converter slip once conditions allow.

Reference resources: AISIN transmission overview · ZF torque converters

Alternator breakdown

See how a belt-driven alternator converts engine rotation into electricity.

Tap a numbered picture to see the part’s name and what it does.

Illustrative components and typical functions. Designs and component locations vary.

How it works

1. The engine’s drive belt turns the pulley and rotor.
2. The rotor’s magnetic field moves past the stationary stator windings, generating AC electricity.
3. Rectifier diodes convert that AC output into DC.
4. The regulator manages rotor field current to help control output for the vehicle’s electrical system.

Reference: DENSO alternators

Engine control module (ECM)

Explore the electronics that turn sensor information into engine-control commands.

Tap a numbered picture to see the part’s name and what it does.

Illustrative components and typical functions. Designs and component locations vary.

How it works

1. Sensors send information about engine position, air, temperature and other operating conditions.
2. Input circuits condition those signals so the controller can process them.
3. The processor uses its software and calibration data to calculate commands.
4. Output drivers control suitable actuators, while communication circuits exchange information with other modules.

Reference: Bosch engine control units

Hydraulic disc brakes

Explore the parts that turn pedal pressure into braking force in a typical passenger car.

Tap a numbered picture to see the part’s name and what it does.

Typical hydraulic disc-brake components. Drum brakes, truck air brakes and brake-by-wire systems use different arrangements.

How braking works

1. Pressing the pedal applies force to the master cylinder, assisted by the booster in this example.
2. The master cylinder creates pressure in the brake fluid. Pipes and hoses carry that pressure to the wheel brakes.
3. Caliper pistons press the pads against the rotating discs. Friction converts the vehicle’s motion into heat.
4. Wheel-speed sensors let ABS detect an approaching wheel lock. The hydraulic unit can reduce and reapply pressure at the affected wheel.

Reference resources: Bosch ABS · Bosch brake boosters · Brembo disc brakes

Inline-six diesel engine

Six cylinders in one row: six bores, six liners and six pistons.

Tap a numbered picture to see its name and what it does.

Inline-six example with six cylinder bores, six liners and six pistons. Illustrations show typical groups rather than a manufacturer-specific assembly.

Truck manual & automated manual transmission

Manual: the driver operates the clutch and gear selection. Automated manual: actuators operate the clutch and shifts. Pictures 5 and 6 show the automated controls.

Tap a numbered picture to see its name and what it does.

Illustrative heavy-duty automated manual components. This example uses a dry clutch rather than the car guide’s torque converter.

Heavy-duty truck automatic transmission

A torque-converter automatic with planetary gears and internal clutch packs. Tap picture 4 to explore the friction and steel plates.

Tap a numbered picture to see its name and what it does.

Illustrative heavy-duty automatic component groups. Truck specifications and internal designs vary.

Diesel turbo & charge-air system

Exhaust energy helps increase the air entering the engine.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Common-rail diesel injection

An example of modern electronically controlled diesel fueling.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Diesel emissions systems

Typical examples of modern diesel emissions hardware.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

EV traction battery

The energy-storage system for a battery-electric vehicle.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Electric motor & reduction drive

Electrical energy becomes driving torque.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

EV inverter

Power electronics connect the battery to the motor.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

EV charging

Different hardware is used for AC and DC charging.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Low-voltage power in an EV

The traction battery also supports the auxiliary electrical system.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Outboard engine powerhead

A representative gasoline outboard engine.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Outboard propulsion

Follow torque from the engine toward the propeller.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Outboard cooling

A typical raw-water cooling example.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Boat electrical system

Representative low-voltage starting and onboard power components.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Marine engine controls

Mechanical and electronic examples.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Motorcycle engine

A representative four-stroke combustion engine.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Motorcycle wet multi-plate clutch

A common example of motorcycle clutch design.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Motorcycle sequential gearbox

A typical constant-mesh motorcycle gearbox.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Motorcycle final drive

Three alternative designs, rather than parts used together.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Motorcycle charging system

A typical permanent-magnet alternator arrangement.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.

Regenerative braking

Recovering some vehicle motion energy as electricity.

Tap a numbered picture to see its name and what it does.

Typical component groups. Illustrations are learning references rather than manufacturer-specific service diagrams.