HCCI engine: An internal combustion engine in which well-mixed fuel and air mixture is compressed to the point of auto-ignition. Thus it has the characteristics of combustion of both the spark ignition as well as the compression ignition engine.

Halogen lamp: A type of incandescent lamp which is more efficient and has a much longer life than the common incandescent lamp. It uses a halogen gas, usually bromine or iodine, which causes the evaporating tungsten to be redeposited on the filament, thereby increasing its life.

Hall effect switch: A device for switching off or on the supplied voltage with the absence or presence of the magnetic field. Also called Hall generator, it consists of a rotor with vanes, a conductive element with a permanent magnet and the Hall IC.

Hall effect: When a thin semi-conductor chip (usually silicon) carrying current is crossed at right angles by a magnetic field, a potential difference is produced at the edges of the chip.

Gudgeon pin: A hollow cylindrical shaped pin connecting the piston to the small end of the connecting rod.

Governor run-out: The percentage speed change when the control rod is moved by the governor from the maximum fuel delivery position to the no-fuel delivery position.

Governor overrun: The difference between the governor cut-off speed and the governor cut-in speed.

Governor Hysterisis: The difference between the governor cut-off speed at which point fuel delivery just stops with the increasing injection pump speed and the cut-off speed at which fuel delivery just restarts with the decreasing injection pump speed.

Governor cut-off speed: The speed of the fuel injection pump at which the governor just stops the fuel delivery.

Governor cut-in speed: The speed of the fuel injection pump at which the control rack just starts to move away from the maximum fuel step, with the accelerator lever set for maximum output.

Governor: A mechanical or electronic device to restrict the performance of an engine usually for reasons of safety.

Glow plug: An electrically heated device placed in the pre-combustion chamber of a diesel engine to assist in starting from cold.

Gear pump: Positive displacement pump using two meshing gears. Commonly used in engine lubrication system.

Gasket: A thin laminate sandwiched between two mating surfaces to improve sealing between them.

Fuel rail: Metallic or plastic pipes carrying fuel from the fuel injection pump to the fuel injectors.