DEFINITION OF TERMS - CONTINUED
steering shaft. The pinion engages a long rack and is
connected to the steering arms via tie rods.
Rich Mixture. Fuel-air mixture with a high proportion of
Radial. Pertaining to the radius of a circle.
Rim. That part of a vehicle wheel on which the tire is
Radial Engine. An engine with each cylinder located on
the radius of a circle and with all cylinders disposed
around a common crankshaft.
Ring Gear. A gear in the form of a ring such as the ring
gear on a flywheel or differential.
Radial Tire. A tire having plies parallel and at right
angles to tread pattern.
Rock Position. The piston and connecting rod position
(top or bottom dead center) at which the crank can rock
Radiator. A device in the cooling system that removes
or rotate a few degrees without appreciable movement of
heat from the coolant passing through it, permitting
coolant to remove heat from the engine.
Rocker Arm. A device used to direct upward motion of
Radius. Distance from the center of a circle or from
push rod into downward motion to open the valve. Used
center of rotation.
in overhead valve installations.
Rectifier. An electrical device that changes alternating
Rod. See Connecting Rod.
current to direct current.
Rod Cap. The lower detachable part of the connecting
Refrigerant-12. A refrigeration gas commonly used in
rod that can be taken off by removing bolts or nuts so the
automotive air conditioning systems.
rod can be detached from the crankshaft.
Regulator. A device used to control output of the
Roller Bearing. A type of bearing with rollers positioned
between two races.
Relay. In the electrical system, a device that opens or
Rotary Engine. A piston engine in which the crankshaft
closes a second circuit in response to voltage or
is fixed and cylinders rotate around the crankshaft.
amperage changes in a controlling circuit.
Rotor. A part that revolves in a stationary part; especially
Residual Magnetism. The magnetism retained by a
the rotating member of an electrical mechanism.
material after all magnetizing forces have been removed.
RPM. Revolutions per minute; a measure of rotational
Resistance. The opposition offered by a substance or
body to the passage through it of an electric current.
SAE. Society of Automotive Engineers.
Resistor. In an electrical system, a device made of
resistance wire, carbon, or other resisting material, that
SAE Horsepower. A measurement based upon the
has a definite value of resistance and serves a definite
number of cylinders and the cylinder diameter.
purpose in the system by virtue of that resistance.
A cleaning or blowing out action in
Rheostat. A resistor for regulating the current by means
reference to exhaust gas.
of variable resistance.