ohm will allow a current of 1 ampere to flow
RADIAL ENGINE--An engine with each cylinder
through it when 1 voltage is applied.
located on the radius of a circle and with all
cylinders disposed around a common crankshaft.
RESISTOR--In an electrical system, a device made of
resistance wire, carbon, or other resisting material,
RADIAL TIRE--A tire having plies parallel and at
that has a definite value of resistance and serves a
right angles to tread pattern.
definite purpose in the system by virtue of that
RADIAL--Pertaining to the radius of a circle.
resistance.
RADIATOR--A device in the cooling system that
RESPONSE TIME--The time lag between a signal
removes heat from the coolant passing through it,
input and the resulting change of output.
permitting the coolant to remove heat from the
R E S T R I C TO R -- A d ev i c e t h a t r e d u c e s t h e
engine.
cross-sectional flow area.
RADIUS--The distance from the center of a circle or
RESTRICTOR, ORIFICE--A restrictor, the length
from the center of rotation.
of which is relatively small with respect to its
RANKINE SCALE--A thermometer scale based on
cross-sectional area. The orifice may be fixed or
absolute zero of the Fahrenheit scale, in which the
variable. Variable types are non-compensated,
freezing point of water is approximately 492 R.
pressure compensated, or pressure and temperature
compensated.
RATIO--The value obtained by dividing one number
by another, indicating their relative proportions.
RETURN LINE--A line used for returning fluid back
into the reservoir or atmosphere.
RECEIVER--A container in which gas is stored
under pressure as a supply source for pneumatic
RHEOSTAT--A variable resistor used for regulating
power.
the current in a circuit.
RECIPROCATING--Moving back and forth, as a
RICH MIXTURE--A fuel-air mixture with a high
piston reciprocating in a cylinder.
proportion of fuel.
RECTIFIER--An electrical device that changes
RIM--That part of a vehicle wheel on which the tire is
alternating current to direct current.
mounted.
REFRIGERANT-12--See FREON-12.
RING GEAR--A gear in the form of a ring such as the
ring gear on a flywheel or in a differential.
REGULATOR--A device used to control or maintain
the output of a system at a predetermined value.
ROCK POSITION--The piston and connecting rod
For example, the regulator in an automotive
position (top or bottom dead center) at which the
electrical system, controls the output of the
crank can rock or rotate a few degrees without
charging system. Regulators are also use in fluid
appreciable movement of the piston.
power (hydraulic and pneumatic) systems.
ROCKER ARM--A device used to direct upward
RELAY--An electromagnetic device with one or more
motion of the push rod into downward motion to
sets of contacts that change position (open or close)
open the valve. Used in overhead valve installa-
by magnetic attraction of a coil to an armature in
tions.
response to voltage or amperage changes in a
ROD CAP--The lower detachable part of the
controlling circuit.
connecting rod that can be taken off by removing
RESERVOIR--A container for storage of liquid in a
bolts or nuts so the rod can be detached from the
fluid power system.
crankshaft.
RESIDUAL MAGNETISM--The magnetism re-
ROD--See CONNECTING ROD.
tained by a material after all magnetizing forces
ROLLER BEARING--A type of bearing with rollers
have been removed.
positioned between two races.
RESISTANCE--The opposition a device or material
ROTARY ENGINE--A piston engine in which the
offers to electric current flow. The effect of
crankshaft is fixed and the cylinders rotate around
resistance is to raise the temperature of the device
the crankshaft.
or material carrying the current. A resistance of 1
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