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126. Tyres
Tyres are the rubber components fitted around a vehicle's wheels that provide contact with the road. They transmit braking, acceleration and steering forces and play an important role in vehicle stability and road holding.
Tyres should have sufficient tread depth, correct pressure and no serious damage or excessive wear. Drivers should use tyres that are suitable for the vehicle and regularly check their condition, particularly before long journeys or driving in difficult weather.
Wikimedia.org • Ambiguous • CC BY
Why are tyres important for road safety?
Tyres are the vehicle's contact with the road and transmit the forces required for steering, acceleration and braking. Their condition and available grip therefore directly affect vehicle control.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
Should tyres on the same axle match?
Requirements vary between countries, but tyres fitted to the same axle should be compatible in dimensions, construction and performance. National rules may impose specific matching requirements.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
127. 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.
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.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
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.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
128. 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.
Wikimedia.org • A7N8X • CC BY-SA
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.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
129. 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.
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.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
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.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
130. 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.
Wikimedia.org • Domitori • CC BY-SA
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.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
131. 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.
Wikimedia.org • Ivan Radic • CC BY
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.
🔗 michelin.co.uk • Michelin, choosing bicycle tyres, road/off-road tread and intended use
Do all bicycles use the same type of tyre?
No. Choose tyres suited to the bicycle and riding conditions. Road and off-road tyres make different compromises between rolling resistance, grip and puncture protection; mountain-bike tyres typically have more pronounced tread for rough or muddy ground.
🔗 michelin.co.uk • Michelin, choosing bicycle tyres, road/off-road tread and intended use
132. 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.
Wikimedia.org • Ingolfson • CC0
Can tracked vehicles travel on normal roads?
Some can, subject to the local vehicle and road-use requirements. For example, British rules allow qualifying tracked agricultural vehicles on roads only with rubber or other composite tracks that do not damage the surface. Registration, driver entitlement and other vehicle restrictions must also be checked.
🔗 legislation.gov.uk • UK legislation, special-type vehicles and rubber tracks
🔗 gov.uk • DfT, tractors and tracked vehicles on public roads
133. 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?
The actual laden mass includes the vehicle, occupants, fuel, luggage, cargo and equipment being carried. Be careful with the term Gross Vehicle Weight: some authorities, including British guidance, use GVW for a maximum authorised weight rather than the actual mass at that moment. Check the definition on the document.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
Why is Gross Vehicle Weight important?
Actual loaded mass and the permitted ratings both matter. Stay within applicable total, axle, tyre and combination limits, and secure and distribute the load correctly. Do not assume that a figure labelled GVW always means the vehicle’s current measured mass.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
134. 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 is the loaded-weight rating specified by the manufacturer for a single vehicle. It covers the vehicle and everything carried, including occupants, fuel and cargo. The legal mass allowed on a particular journey may also be limited by registration, axle, road or other rules.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
Why is GVWR important?
GVWR helps identify the manufacturer’s loading limit and can be relevant to vehicle and licensing classifications. Check every applicable limit: a lower plated, axle, tyre or road limit may also apply. Staying below one total rating does not excuse an overloaded axle or an insecure load.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
135. 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.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
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.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
136. 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.
Wikimedia.org • Cjp24 • CC BY-SA
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.
137. 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.
Wikimedia.org • Atomic Taco • CC BY-SA
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.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
138. 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.
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.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
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.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
139. 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.
Wikimedia.org • Vcx • CC BY-SA
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.
140. 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.
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.
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.
141. 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.
Wikimedia.org • Filipograf • CC BY-SA
What does a car battery do?
A low-voltage vehicle battery powers electrical equipment and control systems. In many combustion-engine vehicles it also supplies the starter motor. In an electric-drive vehicle, the auxiliary battery has a different role from the high-voltage traction battery that supplies propulsion energy.
🔗 afdc.energy.gov • US Department of Energy AFDC, auxiliary versus traction battery
🔗 varta-automotive.com • VARTA, replacing AGM/EFB start-stop batteries
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.
🔗 afdc.energy.gov • US Department of Energy AFDC, auxiliary versus traction battery
🔗 varta-automotive.com • VARTA, replacing AGM/EFB start-stop batteries
142. 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.
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.
🔗 afdc.energy.gov • US Department of Energy AFDC, all-electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, fuel-cell electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, hybrid-electric vehicle components
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.
🔗 afdc.energy.gov • US Department of Energy AFDC, all-electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, fuel-cell electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, hybrid-electric vehicle components
143. 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.
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.
🔗 monroe.com • Monroe, shocks, struts and spring-support/damping functions
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.
🔗 monroe.com • Monroe, shocks, struts and spring-support/damping functions
144. 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.
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.
🔗 monroe.com • Monroe, shocks, struts and spring-support/damping functions
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.
🔗 monroe.com • Monroe, shocks, struts and spring-support/damping functions
145. 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.
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.
🔗 monroe.com • Monroe, shocks, struts and spring-support/damping functions
What are signs of a damaged suspension spring?
Possible signs include one side sitting lower, a collapsed or leaning corner, or a spring displaced from its seat. A spring can also break. These signs need a garage inspection; they do not by themselves prove which suspension component has failed.
🔗 kyb-europe.com • KYB, coil-spring function and fault symptoms
146. 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.
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.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
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.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
147. 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.
Wikimedia.org • Santeri Viinamäki • CC BY-SA
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.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
148. 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.
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.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
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.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
149. 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.
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.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
What are signs of a faulty catalytic converter?
An emissions or engine warning, or an unsatisfactory emissions test, can lead to checks of the catalytic converter along with the engine-management system and sensors. These signs do not prove that the converter itself is faulty; proper diagnosis is needed.
🔗 hella.com • HELLA, exhaust system components and design
🔗 hella.com • HELLA, exhaust gas aftertreatment, catalytic converters and particulate filters
150. 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.
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.
🔗 energy.gov • US Department of Energy, Internal Combustion Engine Basics
🔗 afdc.energy.gov • US Department of Energy AFDC, electric traction motors
🔗 hella.com • HELLA, petrol/diesel exhaust aftertreatment and pollutant control
🔗 gov.uk • Great Britain Highway Code, Annex 6, maintenance; national guidance example
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.
🔗 energy.gov • US Department of Energy, Internal Combustion Engine Basics
🔗 afdc.energy.gov • US Department of Energy AFDC, electric traction motors
🔗 hella.com • HELLA, petrol/diesel exhaust aftertreatment and pollutant control
🔗 gov.uk • Great Britain Highway Code, Annex 6, maintenance; national guidance example