IN-LINE ENGINE--An engine in which all engine
IDLE CIRCUIT--The circuit in the carburetor
cylinders are in a single row, or line.
through which fuel is fed when the engine is idling.
INDEPENDENT SUSPENSION--A type of sus-
IDLER ARM--A steering system component
pension system designed to spring each wheel
designed to support one end of the center link.
separately, therefore allowing each wheel to move
IDLER GEAR--A gear placed between a driving and
independently from the other.
a driven gear to make them rotate in the same
direction. It does not affect the gear ratio.
engine power based on power actually developed
IDLING ADJUSTMENT--The adjustment made on
in the engine cylinders. See also BRAKE
the carburetor to alter the fuel-air mixture ratio or
engine speed on idle.
INDUCTION--The action or process of producing
IGNITION--The action of setting fire to. In an en-
voltage by the relative motion of a magnetic field
gine, the initiating of the combustion process in the
and a conductor.
INERTIA--The tendency of a body at rest to remain at
IGNITION ADVANCE--Refers to the spark advance
rest, and a body in motion to continue to move at a
produced by the distributor in accordance with
constant speed along a straight line, unless the body
engine speed and intake manifold vacuum.
is acted upon in either case by an unbalanced force.
IGNITION COIL--The component of the ignition
INHIBITOR--Any substance which slows or
prevents chemical reactions such as corrosion or
battery voltage to many thousand volts. The high
voltage then produces a spark at the spark plug gap.
INJECTOR--The mechanism, including nozzle, that
IGNITION DISTRIBUTOR--The component of the
ignition system that closes and opens the circuit
INSERT--A form of screw thread insert to be placed
between the battery and ignition coil, and
in a tapped hole into which a screw or bolt will be
distributes the resultant high-voltage surges from
screwed. The insert protects the part into which the
the coil to the proper spark plugs.
hole was tapped, preventing enlargement due to
IGNITION SWITCH--The switch in the ignition
repeated removal and replacement of the screw or
system that can be operated to open or close the
ignition primary circuit.
INSULATION--A substance that stops movement of
IGNITION TIMING--Refers to the timing of the
spark at the spark plug in relation to the piston
position in the engine cylinder.
INSULATOR--A substance (usually of glass or
IMPACT PRESSURE--The pressure of a moving
fluid brought to rest that is in excess of the pressure
INTAKE MANIFOLD--That component of the
the fluid has when it does not flow; that is, total
engine that provides a series of passages from the
pressure less static pressure. Impact pressure is
carburetor to the engine cylinders through which
equal to dynamic pressure in incompressible flow;
fuel-air mixture can flow.
but in compressible flow, impact pressure includes
the pressure change owing to the compressibility
INTAKE STROKE--The piston stroke from top dead
center to bottom dead center during which the
intake valve is open and the cylinder receives a
IMPELLER--The rotor of a centrifugal pump.
charge of fuel-air mixture.
IMPINGEMENT--The striking or dashing upon with
INTAKE VALVE--The valve in the engine that is
a clash or sharp collision, as air impinging upon the
opened during the intake stroke to permit the
rotor of a turbine or motor.
entrance of fuel-air mixture into the cylinder.
IMPULSE TURBINE--A turbine driven by a fluid at
INTEGRAL--Whole; entire; lacking nothing of com-
high velocity under relatively low pressure.
pleteness; included within or upon.