Driving torque Ts of the transmission shaft Ts = Tp+Td+Tf (in fixed speed)
Ts = Tg+Tp+Td+Tf (when accelerating)
Tg: Acceleration Torque (1)
Tp: Load Torque (2)
Td: Preload Torque (3)
Tf: Friction Torque (4) (1) Acceleration TG
TG=J (kgf·cm)
J:Moment of Inertia (kgf·cm·S2)
: Angular Acceleration (rad/s2)
n: Revolrtions (min-1)
 t: Starting Time (sec) 
Fig.3.22 Moment of inertia of load [For reference] Moment of inertia of load (Table3.6)
J = JBS+JCU+JW+JM
JBS: Moment of inertia Ball screws shaft
JCU: Moment of inertia Coupler
JW: Moment of inertia Linear motion part
JM: Moment of inertia Roller shaft part of motor shaft (2) Load torque TP 
(3) Preload torque TD 
K: Internal coefficient (0.05 is usually adopted)
PPL: Preload (kgf)
l: Lead (cm)
: lead angle (4) Friction torque TF
TF=TB+TO+TJ (kgf·cm)
TB: Friction torque of bracing shaft
TO: Friction torque of free shaft
TJ: Friction torque motor shaft
The friction torque of the bracing shaft would be affected by the lubrication oil.Or special attention has to be paid to unexpected excessive friction torque which may be generated when oil seal is overly tight,or may result in temperature rise. Table 3.6 Conversion formula for moment of inertia of load 
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