Traffic signsChile

Learn traffic rules with clear explanations and visual examples in our illustrated book, designed to make studying simple and engaging.


126. Tyre code

A tyre code is the series of letters and numbers marked on a tyre's sidewall that identifies important characteristics such as tyre width, aspect ratio, construction, wheel diameter, load capacity and speed rating. A typical example is 205/55 R16 91V.

Drivers should use tyres whose specifications are suitable for the vehicle. The required tyre sizes and ratings can normally be found in the vehicle handbook, certificate of conformity or other manufacturer information.

Tyre code
Diagram explaining the markings in a tyre code.
Wikimedia.org • F l a n k e r • CC BY
What does a tyre code such as 205/55 R16 mean?

205 indicates the nominal tyre width in millimetres, 55 is the aspect ratio between sidewall height and tyre width, R indicates radial construction and 16 indicates the diameter of the wheel rim in inches.

What do numbers and letters such as 91V mean on a tyre?

The number is the load index, which identifies the maximum load the tyre is designed to carry under specified conditions. The letter is the speed rating or speed-category symbol, which indicates the tyre's approved speed capability.

What other markings can appear on a tyre?

Tyres can carry additional markings indicating approval, manufacturer information, production date, suitability for winter conditions, reinforced construction or other technical characteristics. The exact markings depend on the tyre type and applicable standards.

127. Winter tyres

Winter tyres are tyres designed to provide improved traction and braking performance in cold weather, snow and other winter conditions. Their tread pattern and rubber compound are designed to remain effective at lower temperatures and provide better grip than ordinary summer tyres in appropriate winter conditions.

Winter tyres can be identified by markings on the sidewall. The 3PMSF symbol, showing a snowflake inside a three-peaked mountain, indicates that the tyre has met specified performance requirements for severe snow conditions.

Winter tyres
Winter tyre displaying mountain-and-snowflake symbol.
Wikimedia.org • A7N8X • CC BY-SA
What is the difference between winter and summer tyres?

Winter tyres use tread patterns and rubber compounds designed to provide better performance in cold temperatures, snow and other winter conditions. Summer tyres are optimised primarily for warmer conditions.

What does the 3PMSF symbol mean?

The Three-Peak Mountain Snowflake symbol identifies a tyre that has met specified performance requirements for use in severe snow conditions. It provides a more specific indication of tested snow performance than an M+S marking alone.

Are winter tyres compulsory everywhere?

No. Some countries require winter tyres during particular months or whenever winter conditions occur, while others have no general requirement. Drivers travelling abroad should check the rules of every country on their route.

128. Tyre pressure

Tyre pressure is the amount of air pressure inside a vehicle's tyre. Correct tyre pressure helps the tyre maintain its intended shape and contact with the road and is important for handling, braking, tyre wear and fuel consumption.

Tyre pressure should be checked regularly and adjusted to the pressure specified by the vehicle manufacturer. The recommended pressure can vary according to the vehicle, tyre size and load, and the front and rear tyres may require different pressures.

Checking tyre pressure with a pressure gauge.
Wikimedia.org • JEG14 • CC0
Why is correct tyre pressure important?

Correct tyre pressure helps provide predictable handling, braking and tyre wear. Incorrect pressure can reduce performance, increase tyre wear and increase fuel consumption.

How do you know the correct tyre pressure?

Use the pressure specified by the vehicle manufacturer rather than the maximum pressure marked on the tyre. The recommended values can normally be found in the vehicle handbook or on a vehicle information label.

Should tyre pressure be checked regularly?

Yes. Tyres gradually lose air over time, so their pressure should be checked regularly and before demanding or long journeys. The pressure should be adjusted to the manufacturer's recommended value.

129. Snow chains

Snow chains are traction devices fitted around vehicle tyres to improve grip on roads covered with snow or ice. They are especially useful on steep or mountainous roads where ordinary tyres may not provide sufficient traction.

Snow chains should be fitted according to the vehicle and chain manufacturer's instructions, normally on the driven wheels. They should be removed when they are no longer needed because driving with chains on clear roads can damage the tyres, chains and road surface.

Snow chains
Snow chain fitted to a Honda vehicle.
Wikimedia.org • Domitori • CC BY-SA
What are snow chains used for?

Snow chains increase traction when driving on roads covered with snow or ice. They can help a vehicle accelerate, steer and brake where ordinary tyre grip is insufficient.

Which tyres should snow chains be fitted to?

Snow chains are normally fitted to the driven wheels, but the correct arrangement depends on the vehicle and its drivetrain. Drivers should follow the vehicle and chain manufacturer's instructions.

Are snow chains compulsory everywhere in winter?

No. Requirements vary between countries and roads. Some countries require chains to be carried during certain periods or fitted when indicated by traffic signs or winter conditions, while others impose no general requirement.

130. Bicycle tyre

A bicycle tyre is the rubber tyre fitted around a bicycle wheel and provides contact between the bicycle and the road or other riding surface. Its tread, pressure, width and construction affect grip, rolling resistance, comfort and handling.

Bicycle tyres should be properly inflated and regularly checked for wear, cuts, cracks, embedded objects or other damage. The appropriate tyre type and pressure depend on the bicycle, rider, load and riding conditions.

Bicycle tyre
Why are bicycle tyres important for safety?

Bicycle tyres provide the grip needed for steering and braking and help absorb irregularities in the road surface. Worn, damaged or incorrectly inflated tyres can reduce control and increase the risk of a puncture or loss of grip.

What should you check on a bicycle tyre?

Check the tyre for adequate pressure, excessive tread wear, cuts, cracks, bulges and objects embedded in the tread. The tyre should also be correctly seated on the rim.

Do all bicycles use the same type of tyre?

No. Tyre width, diameter, tread and construction vary according to the bicycle and its intended use. Road bicycles commonly use relatively narrow tyres, while mountain bikes generally use wider tyres with more pronounced tread.

131. Continuous track

Continuous track is a vehicle propulsion system in which a continuous belt or chain runs around a series of wheels or rollers instead of the vehicle travelling on conventional road wheels. It is commonly used on construction machinery, agricultural vehicles, military vehicles and other machines that need good traction on soft or uneven ground.

Continuous tracks spread the vehicle's weight over a relatively large contact area, which can improve traction and reduce ground pressure. Tracks may be made from metal, rubber or a combination of materials, and their suitability for use on public roads depends on the vehicle and applicable regulations.

Continuous track
Large tracked construction crane. (Auckland, New Zealand)
Wikimedia.org • Ingolfson • CC0
What is a continuous track used for?

Continuous tracks provide traction and distribute a vehicle's weight over a larger contact area than conventional wheels. They are particularly useful on mud, snow, loose soil, construction sites and other difficult terrain.

What are continuous tracks made from?

Tracks can consist of linked metal sections, continuous rubber belts or systems combining metal and rubber components. The design depends on the vehicle and its intended operating conditions.

Can tracked vehicles travel on normal roads?

Some tracked vehicles can use public roads when they meet the applicable vehicle, registration and road-use requirements. Restrictions may apply because certain track designs can damage road surfaces or because the vehicle has unusual dimensions, weight or speed characteristics.

132. Gross Vehicle Weight

Gross Vehicle Weight (GVW) is the actual total weight of a vehicle at a particular moment, including the vehicle itself, driver, passengers, fuel, luggage and other cargo. It changes as people or goods are added or removed.

GVW should not be confused with Gross Vehicle Weight Rating (GVWR) or Maximum Authorised Mass (MAM), which is the maximum permitted total weight specified for the vehicle. The actual gross vehicle weight must not exceed that permitted maximum.

What does Gross Vehicle Weight include?

Gross Vehicle Weight includes the weight of the vehicle itself together with the driver, passengers, fuel, luggage, cargo and other items being carried at that moment.

What is the difference between GVW and GVWR?

GVW is the vehicle's actual weight at a particular moment. GVWR is the maximum total weight the vehicle is designed or legally permitted to have when loaded. The actual GVW must remain within the applicable maximum.

Why is Gross Vehicle Weight important?

Vehicle weight affects braking, handling, tyre and axle loading and legal weight limits. Overloading can reduce safety and may also cause the vehicle to exceed permitted axle or total-mass limits.

133. Gross Vehicle Weight Rating

Gross Vehicle Weight Rating (GVWR) is the maximum total weight at which a vehicle is designed or approved to operate when fully loaded. It includes the vehicle itself together with the driver, passengers, fuel, luggage, cargo and other equipment carried by the vehicle.

GVWR is a fixed maximum value and should not be confused with Gross Vehicle Weight (GVW), which is the vehicle's actual weight at a particular moment. The actual loaded weight of the vehicle must not exceed its permitted maximum.

What does GVWR include?

GVWR represents the permitted maximum total weight of the loaded vehicle, including the vehicle itself, driver, passengers, fuel, luggage, cargo and other equipment carried by the vehicle.

What is the difference between GVWR and GVW?

GVWR is the maximum permitted or rated weight of the vehicle, while GVW is its actual weight at a particular moment. The GVW changes as passengers or cargo are added or removed, while the GVWR remains a fixed limit.

Why is GVWR important?

GVWR determines how heavily a vehicle may be loaded and can affect driving-licence categories, vehicle classification and other legal requirements. Exceeding the permitted maximum can also adversely affect braking, handling, tyres and other vehicle components.

134. Cargo

Cargo is the goods, materials, equipment or other items carried by a vehicle or trailer. Cargo can range from personal luggage and bicycles to commercial goods, machinery or bulk materials.

Cargo must be positioned and secured so that it cannot shift, fall from the vehicle, interfere with the driver's visibility or affect vehicle stability. The total load must also remain within the vehicle's permitted weight and axle-load limits.

Why must cargo be secured?

Unsecured cargo can move during acceleration, braking or cornering and can affect vehicle stability or fall onto the road. Proper securing protects the occupants, other road users and the cargo itself.

Can cargo affect vehicle handling?

Yes. Heavy or poorly distributed cargo can change the vehicle's centre of gravity, braking distance, steering and stability. Loads should therefore be distributed appropriately and kept within the vehicle's permitted limits.

Can cargo extend beyond a vehicle?

In some circumstances it can, but national rules normally limit how far a load may project beyond the front, rear or sides of a vehicle and may require projecting loads to be specially marked.

135. Car body

A car body, also called bodywork, is the outer structure of a car that surrounds the passenger and luggage compartments and gives the vehicle its shape. It includes components such as the roof, doors, bonnet, boot lid, wings, body panels and, on many modern cars, load-bearing structural sections.

The car body helps protect occupants and supports components such as doors, windows, lights and bumpers. Damage, corrosion or poorly repaired structural sections can reduce the vehicle's safety and should be repaired correctly.

Car body
What is the car body?

The car body is the structure and exterior bodywork surrounding the vehicle's occupants and cargo areas. It includes visible panels as well as structural sections that can contribute to the strength of the vehicle.

Is the car body the same as the chassis?

Not always. In some vehicles the body is mounted on a separate chassis or frame. Most modern passenger cars use a self-supporting body in which much of the body structure also performs the structural function traditionally provided by a separate chassis.

Why is the condition of the car body important?

The body helps protect occupants and supports many vehicle components. Serious corrosion, deformation, loose panels or structural damage can reduce crash protection or create hazards for other road users.

136. Trunk

A trunk, also called a boot or luggage compartment, is the enclosed storage area of a car used for carrying luggage, tools, shopping and other cargo. It is usually located at the rear of the vehicle, although some vehicles have a front storage compartment.

Items carried in the trunk should be positioned securely so that they cannot shift dangerously during braking, acceleration or cornering. Heavy objects should be placed carefully and the vehicle's permitted load and axle limits must not be exceeded.

Trunk
Luggage compartment of a Car2Go Smart car. (Seattle, Washington, United States)
Wikimedia.org • Atomic Taco • CC BY-SA
What is a car trunk used for?

A trunk is primarily used for carrying luggage and other cargo separately from the passenger compartment. Its size and location depend on the vehicle's design.

Should items in the trunk be secured?

Yes. Heavy or loose objects can move during sudden braking, acceleration or cornering. Cargo should therefore be positioned and secured so that it cannot affect vehicle stability or cause injury.

Can you overload a car trunk?

No. The combined weight of the vehicle, occupants and cargo must remain within the vehicle's permitted total and axle-load limits. Excessive loading can adversely affect braking, steering and stability.

137. Roof rack

A roof rack is a load-carrying system attached to the roof of a vehicle. It can be used to transport items such as luggage, bicycles, skis, surfboards or a roof box when they cannot conveniently be carried inside the vehicle.

A roof rack and its cargo must be securely attached and must remain within the vehicle manufacturer's permitted roof-load limit. Roof-mounted loads raise the vehicle's centre of gravity and can affect handling, stability, fuel consumption and overall vehicle height.

Mercedes-Benz E-Class estate fitted with a roof box.
Wikimedia.org • Matti Blume • CC BY-SA
What can be carried on a roof rack?

A suitable roof rack can carry items such as luggage boxes, bicycles, skis and other equipment, provided the rack and attachments are designed for the load and the vehicle's permitted roof-load limit is respected.

Does a roof rack affect vehicle handling?

Yes. Weight carried high on the vehicle raises its centre of gravity and can affect stability, particularly during cornering or sudden manoeuvres. Drivers should secure the load carefully and adapt their driving accordingly.

How do you know the maximum roof load?

Check the vehicle manufacturer's specifications and the limits of the roof rack itself. The permitted load can vary significantly between vehicles, and the lowest applicable limit should not be exceeded.

138. Windscreen

A windscreen, also called a windshield, is the transparent front window of a vehicle through which the driver views the road ahead. It also helps protect occupants from wind, rain, debris and other external elements.

The windscreen must provide the driver with a clear and sufficiently undistorted view. Cracks, chips, dirt, stickers or other objects can reduce visibility, particularly when they are located within the area swept by the windscreen wipers.

Large windscreen on a Scania truck.
Wikimedia.org • Vcx • CC BY-SA
What is the purpose of a windscreen?

The windscreen allows the driver to see the road ahead while protecting vehicle occupants from wind, rain, insects, stones and other debris.

Can a cracked windscreen be dangerous?

Yes. Cracks, chips or deformation can interfere with the driver's view and may weaken the windscreen. Damage in the driver's main field of vision is particularly important and should be repaired or assessed promptly.

Why must windscreen wipers keep the glass clear?

Windscreen wipers remove rain, snow and dirt from the driver's viewing area. A clear windscreen is essential for maintaining adequate forward visibility in poor weather.

139. Emergency hammer

An emergency hammer is a safety tool designed to break certain vehicle windows when normal doors or exits cannot be used during an emergency. It is commonly found in buses, coaches and other passenger vehicles near windows designated as emergency exits.

An emergency hammer should only be used when evacuation through the normal exits is impossible or unsafe. The tool must remain accessible and, where provided for an emergency window, should be used according to the instructions displayed in the vehicle.

Emergency hammer
An emergency hammer in a train.
Wikimedia.org • Santeri Viinamäki • CC BY-SA
What is an emergency hammer used for?

An emergency hammer is used to break a suitable vehicle window so occupants can escape when normal doors or emergency exits cannot be opened.

Where are emergency hammers normally located?

In vehicles equipped with them, emergency hammers are normally mounted in an easily accessible position close to an emergency window or other designated escape point.

Can an emergency hammer break every vehicle window?

No. Vehicle windows can use different types of glazing, and not every window is designed to be broken as an emergency exit. Occupants should use designated emergency windows and follow the instructions provided in the vehicle.

140. Car battery

A car battery is an electrical energy-storage device that supplies power to a vehicle's electrical system. In conventional petrol and diesel cars, the 12-volt starter battery provides the high current needed to start the engine and supplies electrical equipment when the engine or charging system is not providing enough power.

Car batteries gradually lose charge and capacity with age and use. A weak battery can cause slow or unsuccessful starting, electrical problems or warning messages, and the replacement battery should have specifications suitable for the vehicle.

Car battery of a Volkswagen Golf.
Wikimedia.org • Filipograf • CC BY-SA
What does a car battery do?

A car battery stores electrical energy, supplies the power required to start the engine and supports the vehicle's electrical and electronic systems when necessary.

What are signs of a weak car battery?

Possible signs include slow engine cranking, difficulty starting, dim or unstable electrical equipment and battery or charging-system warnings. Similar symptoms can also have other causes, so the charging system may need to be checked.

Can any replacement battery be fitted to a car?

No. The battery must have specifications and technology suitable for the vehicle. Cars equipped with start-stop systems, for example, may require AGM or EFB battery technology designed for repeated starting and charging cycles.

141. Traction battery

A traction battery is a rechargeable battery that stores electrical energy used to propel an electric or hybrid vehicle. It supplies power to one or more electric traction motors and is normally much larger and more powerful than the vehicle's conventional 12-volt starter battery.

Traction-battery capacity is commonly expressed in kilowatt-hours (kWh) and strongly influences an electric vehicle's driving range. Its performance and usable capacity can gradually decrease with age, charging cycles, temperature and use.

Traction battery
Lithium-ion traction batteries of a SOR EBN 11 electric city bus at IAA 2014. (Hanover, Germany)
Wikimedia.org • Spielvogel • CC0
What does a traction battery do?

A traction battery stores electrical energy and supplies it to the electric motor or motors that propel the vehicle. In hybrid vehicles it works together with another power source, while in battery-electric vehicles it provides the main source of propulsion energy.

What is the difference between a traction battery and a 12-volt car battery?

The traction battery provides the large amount of electrical energy needed to propel the vehicle. The conventional 12-volt battery mainly supplies low-voltage systems and supports functions such as vehicle electronics, control systems and starting procedures.

What does traction-battery capacity mean?

Battery capacity indicates how much electrical energy the battery can store and is commonly expressed in kilowatt-hours (kWh). A larger usable capacity generally allows more electrical energy to be available for driving.

142. Suspension

Suspension is the system that connects a vehicle's wheels and axles to its body or chassis. It includes components such as springs, shock absorbers, control arms, joints and links that allow the wheels to move while helping keep the vehicle stable and comfortable.

The suspension helps maintain tyre contact with the road, absorbs bumps and contributes to steering, braking and vehicle stability. Worn or damaged suspension components can reduce handling and increase uneven tyre wear.

Suspension
Front swing-arm suspension of a Vespa PX scooter.
Wikimedia.org • Khaosaming • CC BY-SA
What does a vehicle suspension system do?

The suspension supports the vehicle, allows the wheels to move over uneven surfaces and helps keep the tyres in contact with the road while controlling body movement.

What components are part of the suspension?

Common suspension components include springs, shock absorbers or dampers, control arms, bushings, ball joints and other links connecting the wheels to the vehicle structure.

What are signs of worn suspension?

Possible signs include excessive bouncing, unusual noises, poor stability, uneven tyre wear, excessive body movement in bends or a vehicle that sits unevenly. These symptoms should be inspected because they can also have other causes.

143. Shock absorber

A shock absorber is a suspension component that controls the movement of a vehicle's springs and wheels. It reduces excessive bouncing after bumps and helps keep the tyres in consistent contact with the road.

Worn or damaged shock absorbers can reduce vehicle stability, increase body movement and negatively affect steering and braking behaviour. They should be inspected if the vehicle bounces excessively, handles poorly or shows signs of fluid leakage.

Shock absorber
Miniature oil-filled shock-absorber components for scale-model cars.
Wikimedia.org • Avsar Aras • CC BY-SA
What does a shock absorber do?

A shock absorber controls suspension movement by damping the repeated movement of the springs. This helps stabilise the vehicle and maintain tyre contact with the road.

What are signs of worn shock absorbers?

Possible signs include excessive bouncing, increased body movement, poor stability, unusual suspension noises, uneven tyre wear or visible fluid leakage from the shock absorber.

Are shock absorbers the same as springs?

No. Springs support the vehicle and allow the suspension to move over bumps, while shock absorbers control and damp that movement. The two components work together as part of the suspension system.

144. Spring

A spring is a suspension component that supports the vehicle's weight and allows the wheels to move vertically over bumps and uneven road surfaces. Common types include coil springs, leaf springs, torsion bars and air springs.

Springs absorb and store energy as the suspension moves, while shock absorbers control that movement. A damaged or broken spring can change the vehicle's ride height, handling and stability and should be repaired promptly.

Spring
Assorted coil springs.
Wikimedia.org • Qz10 • CC BY-SA
What does a suspension spring do?

A suspension spring supports the vehicle and allows the wheels to move over uneven surfaces while helping maintain the vehicle's normal ride height.

What types of suspension springs are used in vehicles?

Common designs include coil springs, leaf springs, torsion bars and air springs. The type used depends on the vehicle and suspension design.

What are signs of a damaged suspension spring?

Possible signs include an uneven ride height, unusual suspension noises, poor handling or a visibly cracked or broken spring. A suspected spring defect should be inspected promptly.

145. Exhaust

An exhaust system carries combustion gases away from a vehicle’s engine and releases them safely behind or beneath the vehicle. The exhaust system can include pipes, silencers or mufflers, catalytic converters, particulate filters and other emissions-control components.

A damaged or leaking exhaust can increase noise, allow harmful gases to escape in unintended locations and interfere with the vehicle's emissions-control system. Exhaust components should therefore remain securely attached and in good condition.

Exhaust
Exhaust system of a car.
Wikimedia.org • Steevven1 • CC BY
What does a vehicle exhaust system do?

The exhaust system carries combustion gases away from the engine and directs them out of the vehicle. It can also reduce exhaust noise and use emissions-control equipment to reduce pollutants.

What are signs of an exhaust problem?

Possible signs include unusually loud exhaust noise, rattling, visible damage, unusual exhaust smells, warning lights or emissions problems. A suspected leak should be inspected promptly.

What is included in an exhaust system?

Depending on the vehicle, the system can include an exhaust manifold, pipes, silencers, catalytic converters, particulate filters, sensors and other emissions-control components.

146. Exhaust gas

Exhaust gas is the mixture of gases and particles produced by an internal-combustion engine and discharged through the vehicle's exhaust system. It contains combustion products such as carbon dioxide and water vapour and can also contain pollutants including carbon monoxide, nitrogen oxides, hydrocarbons and particulate matter.

Modern vehicles use emissions-control systems such as catalytic converters and particulate filters to reduce harmful exhaust emissions. The amount and composition of exhaust gas depend on factors including the fuel, engine design, operating conditions and condition of the emissions-control system.

Exhaust gas
Exhaust-gas measurement on a vehicle.
Wikimedia.org • Santeri Viinamäki • CC BY-SA
What is contained in vehicle exhaust gas?

Exhaust gas contains products of fuel combustion and can include carbon dioxide, water vapour, carbon monoxide, nitrogen oxides, unburned hydrocarbons and particulate matter. The quantities depend on the engine, fuel and emissions-control system.

Why can exhaust gas be harmful?

Some exhaust components, including carbon monoxide, nitrogen oxides and fine particles, can harm human health or contribute to air pollution. Exhaust should therefore never be allowed to accumulate in an enclosed space.

How are harmful exhaust emissions reduced?

Vehicles can use technologies such as catalytic converters, particulate filters and electronic engine-management systems to reduce pollutants. Emission standards also limit the amount of certain pollutants that vehicles may produce.

147. Soot

Soot is a dark, carbon-rich form of particulate matter produced by incomplete combustion. In road vehicles, it is mainly associated with exhaust from diesel engines and consists of very small particles that can contribute to air pollution.

Modern diesel vehicles use particulate filters to trap much of this material before it leaves the exhaust. Excessive soot emissions can indicate problems with combustion, the engine or the emissions-control system.

Soot
Bus leaving a trail of black exhaust smoke. (Tomsk, Russia)
Wikimedia.org • Ilya Plekhanov • CC BY-SA
What causes soot in vehicle exhaust?

Soot is produced when fuel does not burn completely. Diesel engines can produce particularly significant amounts of particulate matter, especially when combustion or emissions-control systems are not functioning correctly.

What does a diesel particulate filter do with soot?

A diesel particulate filter traps a large proportion of the soot particles in the exhaust. The filter periodically removes accumulated material through a process known as regeneration.

Can excessive soot indicate a vehicle problem?

Yes. Unusually high soot emissions can result from engine faults, poor combustion, a defective particulate filter or other problems with the emissions-control system.

148. Catalytic converter

A catalytic converter is an emissions-control device fitted in a vehicle's exhaust system. It uses chemical reactions to convert harmful exhaust pollutants into less harmful substances before the exhaust gases are released into the atmosphere.

Depending on the engine and system, a catalytic converter can reduce pollutants such as carbon monoxide, unburned hydrocarbons and nitrogen oxides. It must reach an appropriate operating temperature to work effectively and can be damaged by contamination, overheating or engine faults.

Catalytic converter
Vehicle catalytic converter used in emissions research.
Wikimedia.org • Oak Ridge National Laboratory • CC BY
What does a catalytic converter do?

A catalytic converter reduces harmful pollutants in engine exhaust by converting them through chemical reactions into less harmful substances before they leave the exhaust system.

Where is the catalytic converter located?

It is installed in the exhaust system between the engine and the exhaust outlet. Its exact position varies between vehicles and may be relatively close to the engine so that it reaches its operating temperature quickly.

What are signs of a faulty catalytic converter?

Possible signs include an emissions or engine warning light, excessive exhaust emissions, reduced engine performance, unusual exhaust smells or failure of an emissions test. These symptoms can also have other causes and should be diagnosed properly.

149. Engine

An engine is the machine that produces the power needed to propel a motor vehicle. In conventional vehicles, an internal-combustion engine burns fuel such as petrol or diesel, while electric vehicles use one or more electric motors instead of a combustion engine.

An engine contains many components that work together to convert energy into mechanical power. Proper lubrication, cooling, maintenance and emissions control are important for reliable operation and vehicle safety.

Engine
A side-angle view of the Ferrari F140B engine used in the Enzo Ferrari car.
Wikimedia.org • Yanko Malinov • CC BY-SA
What does a vehicle engine do?

An engine converts energy into mechanical power that can be used to drive the vehicle's wheels. Internal-combustion engines obtain this energy by burning fuel, while electric vehicles use electrical energy in traction motors.

What are common signs of an engine problem?

Possible signs include unusual noises, loss of power, excessive smoke, overheating, fluid leaks, difficult starting or an engine warning light. These symptoms can have many different causes and should be investigated when necessary.

Why is regular engine maintenance important?

Maintenance helps keep lubrication, cooling, fuel, ignition and emissions systems working correctly. Following the manufacturer's service requirements can improve reliability and help prevent serious mechanical damage.

150. Petrol engine

A petrol engine is an internal-combustion engine that normally uses spark plugs to ignite a mixture of air and petrol. For this reason, it is also known as a spark-ignition or positive-ignition engine.

Petrol engines convert the energy released by combustion into mechanical power that drives the vehicle. Modern petrol engines use electronic engine management and emissions-control systems such as catalytic converters to improve efficiency and reduce harmful exhaust emissions.

Petrol engine
Volkswagen W16 petrol engine.
Wikimedia.org • Florian Lindner • CC BY
How does a petrol engine work?

A petrol engine draws or injects fuel and air into the engine, compresses the mixture and ignites it using a spark plug. The resulting combustion produces pressure that moves the pistons and generates mechanical power.

What is the difference between a petrol and diesel engine?

A petrol engine normally uses spark ignition, while a diesel engine uses compression ignition. The two engine types also differ in fuel, combustion characteristics and emissions-control systems.

What emissions can a petrol engine produce?

Petrol-engine exhaust can contain pollutants such as carbon monoxide, hydrocarbons, nitrogen oxides and, particularly with some direct-injection engines, particulate matter. Modern emissions-control systems are designed to reduce these pollutants.