Unit Description
22
Diesel Engine
The unit uses the TK486V25, a 4-cylinder, water
cooled, direct injection diesel engine.
The engine is coupled directly to the compressor
on Standard Units. A centrifugal clutch transfers
power from the engine to the compressor on
SmartPower Units. Belts transmit power to the
AC generator, water pump, and alternator.
AC Generator
An AC generator provides AC electric power for
the condenser and evaporator fan motors during
diesel engine operation. The AC generator is
mounted under the diesel engine and driven by a
belt. The engine speed determines the output
frequency of the AC generator, which affects the
fan speeds.
In standard units an alternator provides 12 Vdc to
charge the battery and power the 12 Vdc control
system.
An optional battery charger is available to replace
the alternator. The battery charger converts AC
power from the AC generator (or the electric
standby power source) to 12 Vdc to charge the
battery and provide power for the 12 Vdc control
system.
Condenser Fans
There are two condenser fans located near the top
of the unit. Each condenser fan has its own
electric motor and contactor, which allows the
condenser fans to be controlled separately. The
roadside condenser fan rotates counterclockwise
when viewed from the top. It draws air through
the roadside condenser coil and the radiator coil.
It also draws air up through a cooling channel to
cool the battery (and battery charger if used). The
curbside condenser fan rotates clockwise when
viewed from the top. It draws air through the
curbside condenser coil. During engine operation
the condenser fan speed varies with the engine
speed.
Figure 3: Top View Showing Condenser Fans
Evaporator Fans
The evaporator fans are axial blower type fans
mounted on both ends of a single evaporator fan
motor. The evaporator fans (and motor) are
mounted in the evaporator, but are accessed from
the front of the unit through an access panel
located in the top of the unit between the
condenser coils. The evaporator fans rotate up
(from bottom to top) when viewed from the front
of the unit through the access panel.
Because the evaporator fan speed varies with the
engine speed, a two-speed motor and two
contactors are used. Usually when the engine is
running in low speed, the evaporator fan contactor
connected to the high speed windings is energized
and the evaporator fans run at approximately 1770
rpm. When the engine is running in high speed,
the evaporator fan contactor connected to the low
1.
Alternator in SmartPower Unit Location
(Standard Unit Location behind AC
Generator)
2.
Standby Electric Motor (SmartPower
Units Only)
3.
AC Generator
Figure 2: TK486V25
ARA1955
1
3
2
