M40e Cooling System Description
The cooling system includes a fan tray and several impellers that draw room air into the chassis to keep its internal temperature below a maximum acceptable level. When the temperature is below the maximum, the fans and impellers function at less than full speed. If the MCS detects that the temperature of a component has exceeded the acceptable maximum—for example, because an impeller is removed—it automatically increases the speed of the remaining impellers and fans to reduce the temperature. The fans and impellers can function at the higher speed indefinitely.
Cooling System Components
The cooling system has the following components. All are hot-removable and hot-insertable, as described in M40e Field-Replaceable Units (FRUs).
- Air intake vent, air filter, and intake cover—Provide
an opening for room air to enter the router. They are located at the
bottom of the chassis front, below the cable management system, as
shown in M40e Chassis Description. The air filter is removable and covers the air intake vent, preventing
dust and other particles from entering the cooling system. For maintenance
and replacement instructions, see Maintaining the M40e Air Filter. The nonremovable air intake cover
is located behind the air filter and provides EMC shielding.
Caution: Do not remove the air filter for more than a few minutes while the router is operating. The fans and impellers are powerful enough to draw in foreign material, such as bits of wire, through the unfiltered air intake, which could damage router components.
- Front cooling subsystem—Cools the FPCs, PICs, and midplane. It includes a fan tray located behind the cable management system and a large, central impeller behind the craft interface. For replacement instructions, see Replacing the Fan Tray on an M40e Router and Replacing the M40e Front Impeller Assembly.
- Rear cooling subsystem—Cools the SFMs, host module, PCGs, and power supplies. It includes one impeller located at the upper right of the chassis rear and another at the lower left, as shown in M40e Chassis Description. The upper and lower impellers are not interchangeable. For replacement instructions, see Replacing the M40e Rear Lower Impeller Assembly and Replacing the M40e Rear Upper Impeller Assembly.
Airflow Through the Chassis
Figure 1 shows airflow through the chassis and the location of the impellers and fan tray.
Figure 1: Airflow Through the M40e Chassis
