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Hydraulic Lifter

Valve lifter located between the camshaft and pushrod that uses internal oil pressure to sauce the lifter to expand lengthwise.

Hydraulic Pressure

A pressure exerted through the medium of a liquid.

Hydraulic Principles

The use of a liquid under pressure to transfer force or motion, or to increase an applied force.

Hydraulic Valve Lifter

A device using oil pressure to adjust its length and maintain zero valve clearance so that the valve noise is at a minimum. Also referred to as hydro.

Hydraulics

1. The study of liquids and their use to transmit force and motion. 2. Hydraulic ram units, installed in a low rider at each suspension point, to lower or raise the ride height. Also referred to as hydro.

Hydrazine

A highly explosive jet fuel sometimes used as an additive fuel for drag racing.

Hydro

1. A term used for hydraulics. 2. A term used for hydraulic-valve lifter. 3. A short term for hydromatic, a transmission built by General Motors.

Hydro Cam

A camshaft especially designed to operate with hydraulic valve lifters.

Hydro-boost

A type of brake power booster that uses hydraulic pressure provided by the power-steering pump to reduce pedal effort.

Hydrocarbon (HC)

A compound containing hydrogen (H) and carbon (C), such as gasoline.

Hydrocarbon Emissions

A term used for exhaust emissions or unburned hydrocarbons.

Hydrocarbon Reactivity

A measure of the smog-forming potential of a hydrocarbon.

Hydrocarbons

Any number of compounds of carbon and hydrogen used as fuel, such as gasoline.

Hydrocarbons

Any hydrogen and carbon compound. In the case of automobiles, HC is one component of an internal combustion engine's exhaust emissions. Hydrocarbon emissions occur when some fuel is not burnt during the combustion process. Hydrocarbons react with oxides of nitrogen and sunlight to form ground-level ozone, a major component of smog. Abbreviated HC.

Hydrochloric Acid

A corrosive acid produced when water and R-12 are mixed as within an automotive air-conditioning system.

Hydrochlorofluorocarbon

A group of refrigerants that contain the chlorine (CI) atom and the hydrogen (H) atom, which causes the chlorine atom to dissipate mor rapidly in the atmosphere.

Hydrofluorocarbon

A man-made compound used in refrigerants, such as R-134a.

Hydrogen

A colorless, odorless flammable gas.

Hydrolyzing Action

The corrosive action within the air-conditioning system induced by a weak solution of hydrochloric acid formed by excessive moisture chemically reacting with the refrigerant.

Hydrometer

An instrument used to measure the specific gravity of a liquid. A battery hydrometer is calibrated to read the expected specific gravity of the batteries electrolyte.