Traffic signsSouth Africa

151. 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.

152. 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.

153. 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.

154. 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.

155. 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.

156. 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.

157. 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.

158. Diesel engine

A diesel engine is an internal-combustion engine that normally ignites fuel through the heat created by highly compressed air rather than by using spark plugs. For this reason, it is also known as a compression-ignition engine.

Diesel engines are commonly used in passenger cars, trucks, buses and machinery because they can provide strong low-speed torque and efficient fuel use. Modern diesel engines use emissions-control systems such as particulate filters and selective catalytic reduction to reduce harmful exhaust emissions.

159. Electric motor

An electric motor is a machine that converts electrical energy into mechanical power. In an electric or hybrid vehicle, one or more electric motors can provide the torque needed to drive the wheels.

Electric motors can deliver torque from very low speeds and operate without the combustion process used by petrol or diesel engines. During regenerative braking, some electric motors can also operate as generators and convert part of the vehicle's motion back into electrical energy.

160. Timing belt

A timing belt is a toothed belt in an internal-combustion engine that synchronises the rotation of the crankshaft and camshaft so that the engine's valves open and close at the correct time relative to piston movement.

The timing belt is a wear component and must be replaced according to the vehicle manufacturer's maintenance schedule. If it becomes excessively worn or breaks, the engine can stop suddenly and, in many engine designs, serious internal engine damage can occur.

161. Glow plug

A glow plug is an electrical heating element used in diesel engines to help ignite the fuel during cold starting. It heats the combustion chamber so that the compressed air reaches conditions suitable for reliable combustion.

Modern glow plugs can continue operating briefly after the engine starts to improve combustion, reduce cold-start emissions and help the engine run smoothly while warming up.

162. Cylinder

A cylinder is a chamber inside a reciprocating internal-combustion engine in which a piston moves up and down. Air or an air-fuel mixture is compressed inside the cylinder, and combustion produces pressure that pushes the piston and helps generate mechanical power.

Most car engines have several cylinders arranged in configurations such as inline, V-shaped or horizontally opposed layouts. The combined swept volume of all cylinders is known as the engine displacement or cylinder capacity.

163. Engine oil

Engine oil is a lubricant used inside an internal-combustion engine to reduce friction and wear between moving components. It also helps remove heat, keep internal surfaces clean and protect components against corrosion.

The oil level and condition should be checked according to the vehicle manufacturer's instructions. Only oil with the correct specification and viscosity should be used, and the oil and oil filter should be replaced at the recommended maintenance intervals.

164. Coolant

Coolant is a fluid that circulates through a vehicle's cooling system to remove excess heat from the engine or other components. It usually contains water mixed with antifreeze and corrosion inhibitors so that the cooling system can operate safely across a wide range of temperatures.

The coolant level should be checked according to the vehicle manufacturer's instructions. The correct coolant specification must be used, and the cooling system should only be opened when it is safe to do so because hot coolant can be under pressure.

165. Maintenance

Maintenance is the regular inspection, servicing and repair of a vehicle to keep it safe, reliable and in good working condition. It includes tasks such as checking fluids, tyres, brakes, lights and other components and replacing worn parts when necessary.

Maintenance should follow the vehicle manufacturer's recommended service schedule. Regular maintenance can help prevent breakdowns, reduce wear, maintain safety systems and identify defects before they become more serious.

166. Spare tyre

A spare tyre is an additional tyre, usually already mounted on a wheel, carried in a vehicle so that a damaged or punctured road wheel can be temporarily replaced. Vehicles may carry a full-size spare wheel, a compact temporary spare or a tyre-repair kit instead.

A temporary spare wheel is normally intended only for emergency and short-term use. Drivers must follow the manufacturer's restrictions concerning speed, distance, tyre pressure and installation and should replace or repair the damaged normal tyre as soon as possible.

167. Flat tyre

A flat tyre is a tyre that has lost enough air pressure that it can no longer support the vehicle or operate safely. It can result from a puncture, damaged valve, damaged wheel, tyre failure or a gradual air leak.

A flat tyre can seriously affect steering, braking and vehicle stability. The driver should reduce speed smoothly, avoid sudden steering or braking and stop in a safe place as soon as possible rather than continuing to drive on the damaged tyre.

168. Jack

A jack is a portable lifting device used to raise part of a vehicle off the ground, commonly when changing a wheel. Vehicle jacks can be mechanical, hydraulic or electrically operated.

A jack should only be used at the lifting points specified by the vehicle manufacturer and on a firm, stable surface. The parking brake should be applied and the vehicle secured against movement before lifting.

169. Vehicle inspection

A vehicle inspection is an official check to determine whether a vehicle is safe, roadworthy and compliant with applicable technical and environmental requirements. Depending on the country and type of vehicle, inspections may check the brakes, tyres, steering, suspension, lights, emissions, identification and other safety-related components. Inspection rules and intervals vary between countries: some vehicles require regular periodic inspections, while others may also need an inspection after major modifications, an accident, importation or a change of ownership.

170. Key

A key is a device used to unlock a vehicle and authorise its operation. Traditional vehicle keys use a mechanical blade, while modern vehicles commonly use electronic transponders, remote-control key fobs or keyless systems that communicate electronically with the vehicle.

Many modern keys work together with an immobiliser that prevents the engine or propulsion system from being activated unless an authorised key is detected. Replacement or duplicate keys may therefore need to be electronically programmed to the vehicle.

171. Dashboard

The dashboard is the area in front of the driver that displays important information about the vehicle and provides access to controls and warning indicators. It commonly includes the speedometer, fuel or battery level, warning lights, indicators and information about the engine, brakes and safety systems. Modern vehicles may use a digital instrument display instead of traditional gauges. Drivers should understand the main dashboard symbols and respond appropriately when a warning light appears.

172. Windscreen wiper

A windscreen wiper is a device that removes rain, snow, dirt and other moisture from a vehicle’s windscreen to maintain a clear view of the road. Most vehicles use electrically powered wipers with replaceable rubber blades and several operating speeds, often together with a windscreen washer system. Drivers should replace worn or damaged wiper blades when they leave streaks, skip across the glass or no longer clean the windscreen effectively.

173. Doors

Doors provide access to the vehicle and help protect occupants while the vehicle is moving. They must open and close correctly, remain securely closed during driving and have functioning hinges, catches and locking mechanisms. Damaged or loose doors can create a serious safety risk, especially if they can open unexpectedly or cannot be closed properly.

174. Glovebox

A glovebox, also called a glove compartment, is a storage compartment built into the dashboard in front of the passenger seat. It is commonly used to keep vehicle documents, the owner’s manual and other small items within easy reach. The glovebox should be kept closed while driving so that it does not obstruct passengers or allow loose objects to fall into the vehicle. Avoid storing valuables or items that can be damaged by the high temperatures that may develop inside a parked car.

175. Visibility

Visibility is the ability of a driver to see the road, other road users and potential hazards clearly, while also making the vehicle visible to others. Visibility can be reduced by darkness, fog, rain, snow, dirty or misted windows, glare and objects that obstruct the driver’s view. Drivers should keep windows, mirrors and lights clean, remove anything that blocks their field of vision and use the appropriate vehicle lights when visibility is reduced.