The motor rotor inertia values are listed in the motor section of the catalog.

Please note there are two values listed for each motor size, with and without brakes.
The heavy flywheel is a cast iron high inertia fan available as an option with the NORD motors. It is used to soften the shock at start and stop. If you have no heavy flywheel set this value to 0.
Load moment of inertia reflected to the motor shaft.
To calculate this value pick:
   "Linear moving body inertia reflected to input" or
   "Reflected inertia from output to input"
The maximum available brake torque for a selected NORD motor is listed in the motor section of the catalog.
Load torque at the motor shaft or gearbox input shaft.
Peak Torque at Gearbox Output - Braking (stopping)
Variables   Units
JM Motor rotor inertia lb-ft2
JZ Heavy flywheel lb-ft2
JX Load inertia lb-ft2
Tb Brake torque lb-in
TX Reflected load torque to input lb-in
iG Gearbox reduction ratio  
ηG Gear efficiency %
TGST Peak torque at gearbox output - stopping lb-in