Terms Starting with O
Octane number-A number used to identify the resistance to burning of gasoline.
Ohm’s law-Voltage equals amperage times resistance (E = I x R).
Oil gallery-The main or center passageway inside an engine block through which oil flows to feed all other components in the engine that need oil.
Oil relief-A small machined area on the side of a lifter that allows oil to circulate around the body of the lifter.
Open circuit-An electrical circuit that has a break or opening in a wire, producing infinite resistance.
Open loop-A computer condition in which the air-fuel ratio is being controlled on the basis of a set of preprogrammed conditions.
O-ring-A type of static seal used to eliminate fluid leakage between two stationary parts.
Oscillation-Fluctuation or variation in motion in an electrical current. In reference to an automobile, when the vehicle hits a bump in the road, the body oscillates up and down. Shocks are used to reduce oscillations.
OSHA-Occupational Safety and Health Act of 1970. This act provides safety regulations and rules for industry.
Overdrive-A gear system used on a transmission to reduce the speed of the input. Without overdrive, the highest gear ratio in a standard transmission is 1 to 1. Overdrive systems on a transmission have a higher gear ratio of approximately 0.8 to 1.
Overhead camshaft-An engine camshaft located directly on top of the valves, used on I-head engine designs.
Overrunning clutch drive-A type of drive on a starter motor that uses a series of rollers that lock up to cause the pinion gear to rotate.
Oxidation-The process of combining oil molecules with oxygen.
Oxidation inhibitors-Additives to fuels and lubricants that reduce their reaction with oxygen.
Oxides-Chemicals that form when certain pollutants combine with oxygen.
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