COMPRESSED AIR AND BRAKE SYSTEM OPERATION (Contd)
Central Tire Inflation System (CTIS).
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.
PNEUMATIC CONTROLLER - Directs air pressure according to ECU commands.
ELECTRONIC CONTROL UNIT (ECU) - Contains CTIS selector panel so that operator can change tire inflation
during vehicle operation.
AIR PRESSURE SWITCH - Protects air brake system for a minimum supply of 85 psi (586 kPa) of air.
AIR DRYER AND FILTER - Separates moisture from compressed air system and filters impurities from
compressed air before they enter CTIS.
EXHAUST VALVES - Exhausts air from tires during deflation.
WHEEL VALVES - Isolates air pressure in the tires during normal operation and for tire removal.
SPEED SIGNAL GENERATOR - Signals ECU to automatically inflate CTIS when vehicle speed exceeds the top
speed setting for the selected mode by 10 mph (16 km/h).