590 10 TERMINOLOGY
Rated horsepower – Maximum brake horsepower
output of an engine as certified by the engine
manufacturer. The power of an engine when
configured as a basic engine. (SAE J1995 JUN90)
Rated net horsepower – Engine net horse p ower at
rated speed as declared by the manufacturer. (SAE
J1349 JUN90 )
Rated speed – The speed, as determined by the
manufacturer, at which the engine is rated. (SAE
J1995 JUN90 )
Rated torque – Maximum torque p roduced by an
engine as certified by the manufacturer.
Read Only Memory (ROM) – Computer memory
that stores permanent information for calibration
tables and operating strategies. Permanently stored
information in ROM cannot be changed or lost
by turning the engine off or when ECM power is
interrupted.
Reference voltage (V
REF
)–A5voltreference
supplied by the ECM to operate the engine and
chassis sensors.
Reserve capacity – Time in minutes that a fully
charged battery can be discharged to 10.5 volts at 25
amperes.
Signal ground – Thecommongroundwirefromthe
ECM for the sensors.
Speed Control Command Switches (SCCS) – Aset
of switches used for cruise control, Power Take Off
(PTO),andremotehandthrottlesystem.
Steady state condition – An engine operating
at a constant speed and load and at stab ilized
temperatures and pressures. (SAE J215 JAN80)
Strategy – A plan or set of operating instructions
that the microprocessor follows for a desired goal.
Strategy is the computer program itself, including
all equations and decision making logic. Strategy is
always stored in ROM and cannot be changed during
calibration.
Stroke – Stroke is the movement of the piston from
Top Dead Center (TDC) to Bottom Dead Center
(BDC).
Substrate – Material that supports the wash coating
or catalytic materials.
Sulfur dioxi de (SO
2
)–Sulfur dioxide is caused by
oxidation of sulfur contained in fuel.
Switch sensors – Switch sensors indicate position.
They operate open or closed, allowing or preventing
the flow of current. A switch sensor can be a voltage
input switch or a grounding switch. A voltage input
switch supplies the E C M with a voltage when it is
closed. A grounding switch grounds the circuit closed,
causing a zero voltage signal. Grounding switches
are usually installed in series with a current limiting
resistor.
System restriction (air) – The static pressure
differential that occurs at a given air flow from air
entrance through air exit in a system. Usually
measured in in ch e s (millimete rs) of water. (SAE
J1004 SEP81)
Tachometer output signal – Engine speed signal for
remote tachometers.
Thermistor – A thermistor sensor changes its
electrical resistance to temperature. Resistance in the
thermistor decreases as temperature increases, and
increases as temperature decreases. Thermistors
works with a resistor that limits current in the ECM
to form a volta ge signal matched with a te mperature
value.
Thrust load – A thrust load pushes or reacts through
abearinginadirectionparalleltotheshaft.
Top Dead Center (TDC) – The highest position of the
piston during the stroke.
TopDeadCenter(compression)–Top Dead Center
(compression) is when the piston is at the highest
position and both intake and exhaust valves are
closed.
Torque – Torque is a m easure of force producing
torsion and rotation around an axis. Torque is the
product of the force, usually measured in pounds, and
radius perpendicular to the axis of the force extending
tothepointwheretheforceisappliedorwhereit
originates, usually m easured in feet.
Truck Computer Analysis of Performance and
Economy (TCAPE) – Truck Computer Analysis of
Performance and Economy is a computer program
that simulates the performance and fuel economy of
trucks.
Turbocharger – A turbine driven compressor
mounted to the exhaust manifold. The turbocharger
increases the pressure, temperature and density of
intake air to charge air.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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