COMPRESSION RINGSThe upper rings on a
piston; the rings designed to hold the compression
in the cylinder and prevent blow-by.
COMPRESSION STROKEThe piston stroke from
bottom dead center during which both valves are
closed and the gases in the cylinder are compressed.
CONCENTRICHaving a common center, as circles
or spheres, one within the other.
CONNECTING RODLinkage between the
crankshaft and piston, usually attached to the piston
by a piston pin and to the crank journal on the
crankshaft by a split bearing and bearing cap.
CONTROL PINONA collar engaging the plunger
and having a segment of gear teeth, integral or
attached, which mesh with the control rack.
CONTROL RACKA toothed rod inside mechanical
injection pumps that rotates the pump plunger to
control the quantity of fuel injected.
COOLANTThe liquid that circulates in an engine
cooling system that reduces heat generated by the
COOLING FANThe fan in the engine cooling
system that provides a forced circulation of air
through the radiator or around the engine cylinders
so that cooling is affected.
COOLING PINSThe thin metal projections on the
air-cooled engine cylinder and head that greatly
increases the heat-radiating surfaces and helps
provide cooling of engine cylinder.
COOLING SYSTEMA system that reduces heat
generated by the engine and thereby prevents
engine overheating, including liquid-cooled
engines, engine water jackets, radiator, and water
CRANKCASEThe lower part of the engine that
serves as a housing for the crankshaft.
CRANKSHAFTThe main rotating member or shaft
of the engine that converts rotary motion into
CYCLEA series of events with a start and finish
during which a definite train of events takes place.
CYLINDER A hollow tube that contains the actions
of combustion gases and the piston in an internal
CYLINDER BLOCKThe part of the engine to
which and in which other engine parts and
accessories are attached or assembled.
CYLINDER HEADThe part of the engine that
encloses the cylinder bores; contains water jackets
(on liquid-cooled engines) and valves (on I-head
CYLINDER SLEEVEA pipe-shaped removable
insert used as the cylinder wall on some engines.
DASHPOTA device that controls the rate at which
the throttle valve closes.
DEAD CENTEREither of the two positions when
the crank and connecting rod are in a straight line at
the end of the stroke.
DELIVERY VALVEA spring loaded valve which
opens at some predetermined pressure to permit
fuel flow from the injector plunger and bushing
DETERGENTA chemical sometimes added to the
engine oil, designed to help keep the internal parts
of the engine clean by preventing the accumulation
DETONATIONIn the engine, excessively rapid
burning of the compressed charge which results in
DIESEL ENGINEAn engine using the diesel cycle
of operation; air alone is compressed and diesel fuel
is injected before the end of the compression stroke.
Heat of the compression produces ignition.
DIESEL FUELA light oil sprayed into the cylinders
of a diesel engine near the end of the compression
DIESELINGA condition in which a spark-ignition
engine continues to run after the ignition is off;
caused by carbon deposits or hot spots in the
combustion chamber glowing sufficiently to
furnish heat for combustion.
DIPSTICK See OIL-LEVEL GAUGE.
DISPERSANTA chemical added to oil to prevent
dirt and impurities from clinging together in lumps
that could clog the engine lubrication system.
DISTRIBUTOR PUMPAn injection pump where
each metered delivery is directed to the appropriate
engine cylinder by a distributing device.
DOHCDouble overhead camshaft.