Formula for Efficiency – Power Screws – Backdrive `e_b` = `(1/tanlambda)[(cosphi_ntanlambda-mu)/(cosphi_n+mutanlambda)]` Enter Variables Lead angle, `lambda` = degrees Thread angle in normal plane, `phi_n` = degrees Coefficient of friction, `mu` = Calculate View Result Backdrive Efficiency, `e_b` = Copy Result