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High Gearing

The drive ratio that applies maximum engine output at a relatively high road speed.

High Head

A term used when the high-side pressure of a system is excessive.

High Heat Load

Refers to the maximum amount of heat that an be absorbed by a refrigerant as it passes through the evaporator.

High Impedance Meter

A meter that has a high opposition to the flow of electrical current on the voltage scale usually more than 10 Meg Ohms.

High Mobility Multipurpose Wheeled Vehicle (HMMWV)

A GM diesel powered, multipurpose four-wheel-drive vehicle developed by AM General and built in a variety of configurations for civilian and military use.

High Modulus Belt

Those belts designed with special reinforcing members with a high degree of elasticity such as steel, fiberglass, or aramid fiber.

High Output (hp)

A replacement device having a higher output than the original equipment device.

High Pedal

1. The position of a brake pedal when it is adjusted near the top of its upward gravel. 2. The position of the clutch pedal when engaged I high gear in the transmission of a Model T.

High Riser

1. The raised cylinder heads of the 427 cid Ford engine of the 1960s. 2. The term given to a manifold that places the carburetor above its original design location.

High Side

A term used for discharge side.

High Side Drivers

Control of the output device by varying the positive side voltage.

High Spot

The outward curvature of a normally flat or smooth surface.

High Suction

A term used when the low-side pressure of a system is higher than normal due to a malfunction of the system.

High Tech

A term for developments in technology resulting from new, or new uses of materials and machinery that produce products fully comprehensible only to experts in that particular technology.

High Vacuum

A vacuum below 500 microns (0.009 psia or 0.66 kPa).

High-efficiency Particulate Air Filter (HEPA)

A filter system that is 99.97% efficient in trapping particles.

High-energy Ignition (HEI)

A General Motors high-voltage ignition system.

High-lift Cam

A camshaft that provides increased valve lift.

High-lift Jack

A jack that is designed for use on lifted trucks or when a vehicle is off-road and may be higher off the ground than can be accommodated by a standard jack.

High-lift Rocker Arms

Rocker arms that provide increased valve lift.