PREVOST X3-45 COMMUTER User Manual

SECTION 04 : EXHAUST AND AFTERTREATMENT
DOB 1300-1556 | X3-45 Commuter PA-1648 Maintenance Manual Section 04 revised March 2021
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2. EXHAUST AFTERTREATMENT SYSTEM
(EATS) OVERVIEW
FIGURE 1: EXHAUST SYSTEM
The technology behind clean emissions is
through the immediate aftertreatment of engine
exhaust. The process for reducing NOx via
aftertreatment is called Selective Catalytic
Reduction (SCR). It requires a catalytic
converter into which is injected Diesel Exhaust
Fluid (DEF). The primary component of DEF is
water; the active component is urea. Urea is a
nitrogen compound that turns to ammonia when
heated. When a urea-and-water solution is
injected into the exhaust stream and passed
over a catalyst, the urea reacts with the NOx to
form nitrogen and water vapor – two clean and
harmless components of the air we breathe. The
aftertreatment system primary function is to
capture and oxidize (regenerate) the particulate
matter (soot) in the engine exhaust gases and to
reduce NOx. To achieve this goal, the exhaust
aftertreatment system (EATS) is split into two
main sections: the exhaust gases first enter the
Diesel Oxidation Catalyst (DOC) and Diesel
Particulate Filter (DPF) assembly to capture
and regenerate the soot on a regular or passive
basis, then the exhaust gases flow through the
catalytic converter to reduce NOx to minimum
level. Through constant monitoring of the
exhaust gas temperature and the system back
pressure, the Engine management System
(EMS) is able to manage regeneration.
The EATS is rubber mounted to the vehicle
structure. This feature reduces the transmission
of vibrations to the EATS thus resulting in
extended life of the system, brackets and also
noise reduction.
IMPORTANT NOTE
Exhaust Aftertreatment System (EATS)
components must not be removed, altered or
modified in any way. In order to protect the
emission control
system from tampering,
inducement measures will occur if the
following states are detected:
• Disconnection of DEF tank level sensor
• Blocked DEF line or dosing valve
• Disconnection of NOx sensor
• Disconnected exhaust temperature sensor
• Disconnected DEF temperature sensor
• Disconnected DEF quality sensor
• Disconnection of DEF dosing valve
• Disconnection of DEF pump
• Disconnection of SCR wiring harness
Auxiliary Emission Control Device (EACD)
defines as any element of design which
senses temperature, vehicle speed, engine
RPM, transmission gear, manifold vacuum, or
any other parameter for the purpose of
activating, modulating, delaying, or
deactivating the operation of any part of the
emission control system.
Disconnection of the following EACD
produces immediate ac
tivation of the
Malfunction Indicator Lamp MIL and 25%
engine derate after three (3) hours of a
continuous open circuit.
• Intake throttle position sensor;
• Ambient air temperature sensor;
• Vehicle speed;
• Engine oil pressure sensor;
• Exhaust back pressure sensor;
• Camshaft speed sensor;
• EGR delta pressure;
• Fuel rail pressure
• Engine timing sensor;
• Engine coolant temperature;
• EGR temperature sensor.

PREVOST X3-45 COMMUTER Specifications

General

Engine	Volvo D13
Transmission	Allison B500
Fuel Type	Diesel
Length	45 ft (13.7 m)
Width	102 in (2.6 m)
Horsepower	500 hp
GVWR	54, 000 lbs
Height	141 in