INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-98
Published 07-19-16, Control # 249-01
HYDRAULIC COOLER FAN DRIVE
See Figure 1-65 for the following.
Description
The cooler fan drive assembly includes two hydraulic-driven
motor variable-speed fans. Each fan is 749 mm (29.5 in) in
diameter and has seven blades. The accessory pump
supplies the pressure to run the fan motors. As the engine
load increases, fan speed will also increase to meet the
engine’s cooling needs.
NOTE: If there is an electrical failure, the fan will default to
high-speed operation only.
A variable-speed fan provides several benefits over fans for
which operating speed is determined by engine speed.
These benefits include quieter operation, higher efficiency,
and longer fan life. This type of fan also helps keep the
engine running more consistently at its optimal temperature
and results in increased available engine power when full fan
speed is not required.
See the engine manufacturer’s operating instructions
manual for diagnostic information.
Maintenance
Fan speed is determined by the greatest demand of four
inputs:
• Coolant temperature
• Air intake temperature
• Hydraulic oil temperature
• State of the air conditioning clutch
The system monitors these inputs every 10 seconds and
adjusts the fan speed depending on the input readings.
A high-temperature fault may be triggered by a coolant, air
intake, or hydraulic oil temperature that exceeds the normal
temperatures. If such a fault occurs, the operator or service
person should investigate the cause.
FIGURE 1-65
Main Pressure
Through Accessory
Pump
Fan Motor #2
Fan Motor #1
Pump
20,7 bar
(300 psi)
276 bar
(4000 psi)
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