TM 9-2320-272-24-1
1-23. COMPRESSED AIR AND BRAKE SYSTEM OPERATION (Contd)
h . Central Tire Inflation System (CTIS) (M939A2 Series Vehicles).
The CTIS is common to all M939A2 series vehicles. This system maintains tire air pressure depending on
which road type is selected. If this setting is changed, tires will automatically inflate or deflate to the new
setting.
Key Item and Function
1 PNEUMATIC CONTROLLER - Directs air pressure according to ECU commands.
2 PRESSURE TRANSDUCER - Mounted in pneumatic controller, it measures tire pressure and
sends information to ECU.
3 ELECTRONIC CONTROL UNIT (ECU) - Contains CTIS selector panel so that operator can
change tire inflation during vehicle operation.
4 AIR PRESSURE SWITCH - Protects air brake system for a minimum supply of 85 psi (586 kPa) of
air.
from compressed air before they enter CTIS.
7 WHEEL VALVES - Isolate air pressure in tires during normal operation and for tire removal.
exceeds the top speed setting for the selected mode by 10 mph (16 kmh).
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