DEFINITION OF TERMS-CONTINUED
Needle Valve. The type of valve with a rod- shaped,
needle-pointed valve body that works into a valve seat so
Oil Control Rings. The lower rings on the piston that are
shaped that the needle point fits into it and closes the
designed to prevent excessive amounts of oil from
passage; the needle valve in the carburetor float circuit is
working up Into the combustion chamber.
Oil Cooler. A special cooling radiator through which hot
Negative. A term designating the point of lower potential
oil passes. Air also passes through separate passages
when the potential difference between two points is
in the radiator, providing cooling of the oil.
Oil Gage. An Indicating device that indicates the
Negative Terminal. The terminal from which electrons
pressure of the oil in the lubrication system. Also, a
depart when a circuit is completed from this terminal to
bayonet-type rod to measure oil In the crankcase.
the positive terminal of generator or battery.
Oil Gallery. A pipe or drilled passageway in the engine
A neutral-charge particle forming part of an
used to transport oil from one area to another.
Oil Pan. The lower part of the crankcase in which a
Nonferrous Metals. All metals containing very little or no
reservoir of oil is maintained.
Oil Pump. The pump that transfers oil from the oil pan to
North Pole. The pole of a magnet from which the lines of
the various moving parts in the engine that require
force are assumed to emanate.
No-Spin Differential. A special type of differential that
Oil Ring. Normally the bottom piston ring used to scrape
prevents the spinning of one of the driving wheels even If
excess oil off the cylinder wall.
it is resting on smooth Ice.
Oil Slinger. A device mounted to a revolving shaft such
Nozzle. An orifice or opening In a carburetor through
that any oil passing that point will be thrown outward
which fuel feeds Into the passing air-stream on Its way to
where It will return to the point of origin.
the Intake manifold.
Oil Strainer. A strainer placed at the Inlet end of the oil
A measure of the antiknock value of
pump to strain out dirt and other particles, preventing
these from getting Into moving engine parts.
Odometer. The part of the speedometer that measures,
One-Way Clutch. A device used to lock a shaft In one
accumulatively, the number of vehicle miles traveled.
direction while permitting rotation In the other.
Ohm. A measure of electrical resistance. A conductor
Otto Cycle. The four-stroke cycle composed of Intake,
of 1-ohm resistance will allow a flow of 1 ampere of
compression, power, and exhaust strokes.
current when 1 volt is Imposed on it.
Overflow Tank. A special tank In the cooling system (a
surge tank) for hot or dry country to permit expansion
a circuit or electrical machine.
and contraction of engine coolant without loss.
Oil. A liquid lubricant derived from petroleum and used
Overhead Valve. A valve mounted In the head above
In machinery to provide lubrication between moving
the combustion chamber, Valve In I-head engine.
parts. Also, fuel used In diesel engines.