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GCM

Governor control module.

GCW

An acronym for gross combined weight.

GCWR

Abbreviation for Gross Combined Weight Rating. The maximum allowable combined weight of the tow vehicle and the attached towed vehicle. GCWR assumes both vehicles has functioning brakes, with exceptions in some cases for very light towed vehicles, normally less than 1,500 pounds. (check your chassis manual or towing guide) see also WEIGHTS.

Gd

Gadolinium An element with the atomic number of 64.

Ge

Germanium An element with the atomic number of 32.

Gear

1. A cogged device that mates or meshes with another. 2. One's personal belongings and/or equipment.

Gear Backlash

The measurable gap or slack between gears.

Gear Box

See gearbox.

Gear Carton

A transmission housing.

Gear Drive

A system of two or more gears, such as one that transmits power from the crankshaft or camshaft.

Gear Lubricant

A type of oil or grease especially formulated to lubricate gears.

Gear Oil

A thick lubricant, generally with an SAE number of 80 or above, used in standard transmissions or differentials. These often contain additives, such as an EP additive, to guard against being squeezed out from between gear teeth.

Gear Oil, Limited-slip

A lubricant specified for use in certain limited-slip differentials to prevent chattering during turns and/or abnormal wear to the parts.

Gear Pitch

The number of teeth in a given unit of pitch diameter.

Gear Pump

A positive-displacement pump that uses an inner drive gear and an outer driven gear, separated on one side by a crescent, to produce oil flow. Gear pumps may use either helical or spur gears and are sometimes called gear-and-crescent pumps.

Gear Ratio

1. The speed relationship that exists between a driving (input) and a driven (output) gear. For example, a driving gear that revolves twice for each driven-gear revolution has a 2 to 1 (2.

Gear Reduction

A condition in which the drive gear rotates faster than the driven gear. Output speeds of the driven gear is reduced, while output torque is increases.

Gear Rotor Pump

A type of pump that uses sun gears to move liquid.

Gear Shift

1. A floor- or steering-wheel-mounted lever used to manually change gears in the transmission. 2. A linkage-type mechanism by which the gears in a transmission are engaged.

Gear Throw

With a manual transmission, the distance the gear shift lever must move from one gear to the next. Short throws are considered optimal for racing and high-performance applications, since shifts are quicker.