TM 9-2320-360-10
1-17. CENTRAL TIRE INFLATION SYSTEM (CTIS)
The Central Tire Inflation System (CTIS) allows the HET operator to adjust the vehicle tire pressure to
one of four predetermined settings. Each tire pressure setting has a vehicle speed limitation. If the
average vehicle speed exceeds this limit, the CTIS will activate an overspeed light.
The CTIS consists of five major components. A controller (1) mounted on the instrument panel contains
the switches and indicator lights for system operation. The power manifold (2) located under the drivers
seat contains operating valves, a low air pressure sensor, and a pressure sensor which monitors system
pressure. Located directly under the power manifold is the porting block (3), to which the air lines (4) to
the axles are connected. Air pressure passes through these lines and the axle assemblies to CTI wheel
valves (5). These wheel valves are opened and closed by the CTIS depending on pressures at the
porting block and individual tire pressures.
The air pressure to operate the CTIS comes from air reservoir no. 3. The CTIS will shut off its air supply
from the air system if the pressure drops below 85 psi or when the electrical power is interrupted. Air
pressure is present in the CTIS lines and hoses only when the system is monitoring (or adjusting) the tire
pressures, approximately once every 15 minutes. At all other times, the system has no pressure and the
wheel valves remain closed.
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