Motor torque calculation for lift having chain drive

[mithleshkj]

i want to know how to calcuate Starting and running for motor in 2 post lift for lifting 3.0T.
Actually i have 2 columns having trapezoidal screw rod and nut in each side.
One column is getting drive by motor through pulley belt mechanism.
Another shaft is getting driven by chain at the bottom.
can someone tell us how to calculate the starting torque required at motor to lift load of 3000Kg via this chain drive??

 

[firavia]

visit this page it could help you : http://industrial.panasonic.com/ww/i_e/25000/fa_pro_sgeard_shing1_e/fa_pro_sgeard_shing1_e/ctlg_geared_e_9.pdf