Friday, 26 April 2024, 8:38 PM
Site: IMI eLearning
Course: IMI eLearning (IMI eLearning)
Glossary: Automotive Glossary
H
H.A.S.W.AHealth And Safety at Work Act 1974.(UK)" |
H20Water |
Half ShaftsShafts by which power is transmitted from final drive to driven wheels in an enclosed axle. |
Hall GeneratorAn electronic pulse generator using the Hall effect of a semiconductor to provide information to the ignition amplifier or ECU on engine position and speed. |
Hall ICIntegrated circuit as part of a Hall sensor. |
Hall SensorAn electronic pulse generator using the Hall effect of a semiconductor to provide information to the ignition amplifier or ECU on engine position and speed. Also used for sensing road speed etc. |
HalogenA description of a series of gases such as argon. |
HandbrakeHand operated parking brake usually with a mechanical linkage. Also forms the reserve or emergency brake on many vehicles. |
Handbrake CableA cable that operates the brakes when a lever is pulled. |
Handbrake LinkageCables or rods used to operate the parking/handbrake. |
Hard DiskA storage device that holds large amounts of data. |
HardenerA chemical specifically designed to ensure cure of a paint finish, filler, stopper, resin or adhesive. Also, another name for an activator. |
HardwareThe physical components of a computer system. |
HardwiredA physical connection between two or more electrical devices. |
Harmonic BalancerRotating or oscillating engine balance shaft. |
HarnessThe collection of vehicle cables wound together with an insulation tape. Also known as a 'wiring loom'. |
HazardousRisky. Potential to harm people or property. |
HazeThe development of a cloudy area in the paint film or in a clear liquid. |
HC(1) Hydrocarbon. (2) High compression. |
Head GasketSeal between cylinder block and cylinder head. |
Head-onViewing a repaired/re-painted area from an angle that is perpendicular (at 90°) to the car. |
Head-up DisplayProjection of instruments onto the windscreen so that the road and the instruments can be seen at the same time by the driver. |
Header TankThe expansion tank at the top of a coolant radiator, which can be part of the radiator or a separate tank. |
HeadlampVehicle lighting that provides illumination of the road for the driver. Usually consists of switched main and dipped beams. |
Headway SensorA device usually fitted in the front grill of a vehicle that in conjunction with a transmitter senses distance in front of the vehicle. Often part of an active cruise control system. |
HeatA form of energy in all materials that can be used to do work. |
Heat ExchangerA device for transferring heat from one system or place to another. |
Heat RangeApplies to spark plug construction where the rate of heat loss from the plug nose is controlled by the length of the insulation. Spark plugs are given a rating from hot to cold to classify the heat range and application. The plug tip temperature is controlled to keep the tip and electrodes clean. |
Heat SinkA plate to which electronic components are attached to dissipate heat. |
Heater MatrixSmall radiator used to exchange heat from the coolant to the vehicle cabin. |
HEGOHeated Exhaust Gas Oxygen Sensor. Also EGO Exhaust Gas Oxygen Sensor, EOS Exhaust Oxygen Sensor and Lambda sensor. Provides information to the fuel system ECU on the oxygen content in the exhaust gas. |
HEIHigh Energy Ignition. A distributor ignition system using electronic control of the coil secondary output. |
Helical GearA gear with teeth cut at an angle. |
Helical RotorA turbine or compressor in a turbocharger often has vanes that are helically shaped. |
Helical SpringMetal spring used in vehicle suspension. Also known as a coil spring. |
HemisphereA sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball - a hemisphere is half a sphere |
HeptaneA fuel used in research tests as a comparison when determining the octane rating of fuels. Octane value of zero. |
HertzThe number of oscillations per unit of time. The SI unit for frequency is the Hertz which equals one oscillation per second. |
HexShort for hexagonal. |
HgMercury |
Hide MalletSoft hammer made of hide (leather). Plastic types are also used. |
Hiding or Hiding Power(See 'Opacity') |
High BoilersSolvents with boiling points above 100 degrees Celsius. |
High Lift CamA special cam profile used on performance engines to increase the opening size of a valve. |
High resistanceAn unwanted resistance in a circuit that causes it to operate incorrectly. |
High SolidsPaints are described as having high solids when they contain more than 50-60% solids. High solids paints have lower VOC's. |
High TensionThe term used for the high voltage in the secondary circuit of the ignition system. |
HLGHall generator. A sensor using a Hall effect to provide signals to an ECU. |
HO2SHeated Oxygen Sensor |
HoistTo lift something or a term used to describe a vehicle lift or ramp. |
Hold-in WindingA winding in a starter motor solenoid that holds the switch contacts together and the drive pinion in mesh during engine starting. |
HoldoutThe ability of a surface to keep the topcoat from sinking in and causing a decrease in appearance or gloss. |
HomogenousUniform in structure or composition throughout. This is usually used to refer to a fuel air mixture in a cylinder that is a 'perfect' mixture of fuel and air. |
HoneA light grinding process applied to cylinder bores in preparation for the fitting of new pistons. |
Hooke's JointA drive shaft universal joint consisting of two yokes and a cross bearing. Also Cardan joint. |
Horizontally OpposedAn engine configuration where cylinder pairs are fitted on opposite sides of the crankshaft. Sometimes referred to as 'Boxer' engines. |
HorsepowerA measure of power equivalent to 0.746 Kilowatts. Defined by a rate of doing work of 33,000 foot pounds per minute (550 foot pounds per second). |
HOS HO2SHeated Oxygen Sensor. |
Hose ClampSimple ring type clamp to seal a hose onto a pipe. |
Hot Idle CompensatorA device to change idle or mixture settings when an engine is hot. |
Hot SprayThe technique of applying paint at elevated temperatures. The elevated temperature reduces the viscosity so that higher solids materials can be sprayed, and allows application with less solvent. |
Hot StampingA machine forging process using a series of dies to create the completed shape. |
Hot WireA small thin wire that is heated an placed in an air flow. The change in temperature is used to determine the rate of air flow. |
hpHorsepower |
HTHigh Tension |
HT CablesHigh tension leads (high voltage) used to supply the spark. |
HT LeadsHigh tension leads (high voltage) used to supply the spark. |
HubCentre of a wheel or gear or similar. |
Hub NutMain nut that secures a wheel hub. |
HueThe quality by which colours are distinguished from one another, such as">a red from yellow, blue, green, or purple, and all shades in between. |
HuntingUneven running of an engine, usually when the mixture is over rich. |
HVACHeating, ventilation and air conditioning. |
HVLP (High Volume, Low Pressure)Describes a paint gun that uses a high volume and low pressure of atomising air to apply material to a surface. This provides high transfer efficiency and lower overspray. |
HybridA hybrid vehicle is a vehicle that uses two or more power sources to move the vehicle. The term most commonly refers to hybrid electric vehicles (HEVs), which combine an internal combustion engine and one or more electric motors. |
Hybrid vehicleVehicles that use both a traditional engine (combustion) and a rechargeable system (typically operated by a battery) to improve mileage, cause less pollution, and decrease need for fossil fuel. |
HydraulicA system for transmitting and modifying force by the use of a liquid. Consists of a pump, control devices, hydraulic lines and slave cylinders. |
Hydraulic BrakeBrake actuated only by hydraulic pressure. |
Hydraulic ClutchA clutch, operated by fluid pressure. |
Hydraulic HosesHoses that carry fluid under high pressure. |
Hydraulic LiftersHydraulic cam followers in the valve opening mechanism. |
Hydraulic PedestalSelf-adjusting support for a finger tappet in the valve opening mechanism. |
Hydraulic PressurePressure applied by a fluid. |
Hydraulic TappetsSelf-adjusting cam followers in valve opening mechanism. |
Hydraulic ValvesValves used to control pressure or flow of a hydraulic fluid. |
HydrocarbonA compound which contains only carbon and hydrogen, which are distillate by-products of petroleum, natural gas and coal. |
Hydrocarbon (HC)Chemical compound which contains only, or principally, Carbon and Hydrogen. The principal constituent of liquid fossil fuels. |
Hydrocarbon EmissionsFuel vapours released into the atmosphere from a vehicle exhaust or fuel tank. |
HydrocrackTo break down (a hydrocarbon) by the process of hydrocracking. This is a catalytic cracking process of breaking down large hydrocarbon molecules into smaller ones |
HydrolysisReaction with water. Usually refers to a decomposition process leading to paint failure. |
HydrometerInstrument used for measuring specific gravity/relative density of a liquid (coolant, battery electrolyte). |
Hydropneumatic SuspensionA suspension system using a liquid to transfer suspension movements to pneumatic (gas) springs. |
HygrometerInstrument used for measuring relative humidity - in an automotive context it is used to check moisture content of brake fluid. |
HygroscopicA paint film or other solid that readily absorbs water. |
Hypoid GearingBevel gear with the axes of the driving and driven shafts at right angles, but not in the same plane, giving some sliding action between teeth. Widely used in rear axle final drives. |
HysteresisA characteristic of materials, sensors and sometimes instruments to make their behaviour dependent on the immediate history to which they have been subjected. Typically the final settling point is different when approached from above to when it is approached from below |