Automotive terms Modern H-I
Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.
The following are examples of Mid Modern technical terms recommended for general use worldwide. For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.
HALOGEN:
A special type of lamp known for its quality of brilliant white light. Originally used for fog lights and driving lights.
HARD CODES:
DTCs that are present at the time of testing; also called continuous or current codes.
HARSH (ROUGH):
An apply of a clutch or band that is more noticeable than a firm one; considered undesirable at any throttle position.
HEADER TANK:
An expansion tank for the radiator coolant. It can be located remotely or built into the radiator.
HEAT RANGE:
A term used to describe the ability of a spark plug to carry away heat. Plugs with longer nosed insulators take longer to carry
heat off effectively.
HEAT RISER:
A flapper in the exhaust manifold that is closed when the engine is cold, causing hot exhaust gases to heat the intake manifold providing better cold engine operation. A thermostatic spring opens the flapper when the engine warms up.
HEAVY THROTTLE:
Approximately three-fourths of accelerator pedal travel.
HEMI:
A name given an engine using hemispherical combustion chambers.
HERTZ (HZ):
The international unit of frequency equal to one cycle per second (10,000 Hertz equals 10,000 cycles per second).
HIGH-IMPEDANCE DVOM (DIGITAL VOLT-OHMMETER):
This styled device provides a built-in resistance value and is capable of limiting circuit current flow to safe milliamp levels.
HIGH RESISTANCE:
Often refers to a circuit where there is an excessive amount of opposition to normal current flow.
HORSEPOWER:
A measurement of the amount of work; one horse-power is the amount of work necessary to lift 33,000 lbs. one foot in one minute. Brake horsepower (bhp) is the horsepower delivered by an engine on a dynamometer. Net horsepower is the power remaining (measured at the flywheel of the engine) that can be used to turn the wheels after power
is consumed through friction and running the engine accessories (water pump, alternator, air pump, fan etc.)
HOT CIRCUIT:
(See circuit, hot; hot lead.)
HOT LEAD:
A wire or conductor in the power side of the circuit. (See' circuit, hot.)
HOT SIDE SWITCHING:
The electrical/electronic circuit control switch is located before the circuit load.
HUB:
The center part of a wheel or gear.
HUNTING (BUSYNESS):
Repeating quick series of up-shifts and downshifts that causes noticeable change in engine rpm, for example, as in a 4-3-4 shift pattern.
HYDRAULICS:
The use of liquid under pressure to transfer force of motion.
HYDROCARBON (HC):
Any chemical compound made up of hydrogen and carbon. A major pollutant formed by the engine as a by-product of
combustion.
HYDRODYNAMIC DRIVE UNITS:
Devices that transmit power solely by the action of a kinetic fluid flow in a closed recirculating path. An impeller energizes the fluid and discharges the high-speed jet stream into the turbine for power output.
HYDROMETER:
An instrument used to measure the specific gravity of a solution.
HYDROPLANING:
A phenomenon of driving when water builds up under the tire tread, causing it to lose contact with the road. Slowing down will usually restore normal tire contact with the road.
HYPOID GEARSET:
The drive pinion gear may be placed below or above the centerline of the driven gear; often used as a final drive gearset.
IDLE MIXTURE:
The mixture of air and fuel (usually about 14:1) being fed to the cylinders. The idle mixture screw(s) are sometimes adjusted as part of a tune-up.
IDLER ARM:
Component of the steering linkage which is a geometric duplicate of the steering gear arm. It supports the right side of the center steering link.
IMPELLER:
Often called a pump, the impeller is the power input (drive) member of a hydrodynamic drive, As part of the torque converter cover, it acts as a centrifugal pump and puts the fluid in motion.
INCH POUND
(inch lbs.; sometimes in. lb. or in. lbs.): One twelfth of a foot pound.
INDUCTANCE:
The force that produces voltage when a conductor is passed through a magnetic field.
INDUCTION:
A means of transferring electrical energy in the form of a magnetic field, Principle used in the ignition coil to increase voltage.
INITIAL FEEL:
A distinct firmer feel at start of shift when compared with feel at finish of shift.
INJECTOR:
A device which receives metered fuel under relatively low pressure and is activated to inject the fuel into the engine under relatively
high pressure at a predetermined time.
INPUT:
In an automatic transmission, the source of power from the engine is absorbed by the torque converter, which provides the power input into the transmission. The turbine drives the input(turbine)shaft.
INPUT SHAFT:
The shaft to which torque is applied, usually carrying the driving gear or gears.
INTAKE MANIFOLD:
A casting of passages or pipes used to conduct air or a fuel/air mixture to the cylinders.
INTERNAL GEAR:
The ring-like outer gear of a planetary gearset with the gear teeth cut on the inside of the ring to provide a mesh with the planet pinions.
ISOLATION (CLAMPING) DIODES:
Diodes positioned in a circuit to prevent self-induction from damaging electronic components.
IX ROTARY GEAR PUMP:
Contains two rotating members, oneshaped with internal gear teeth and the other with external gear teeth. As thegears separate, the fluid fills the gaps between gear teeth, is pulled across a crescent-shaped divider, and then is forced to flow through the outlet as thegears mesh.
IX ROTARY LOBE PUMP:
Sometimes referred to as a gerotor type pump. Two rotating members, one shaped with internal lobes and the other with external lobes, separate and then mesh to cause fluid to flow.
