Example 16 mm, pitch 4, lead 4

Worked inputs. Not a thread designation row.

Worked example

Lifting torque 1.3743 N·m

Lowering torque 0.0873 N·m

Efficiency 46.3248 %

T_R uses sec(alpha) plus collar torque

T_L uses the lowering fraction plus collar torque

(F × Lead) / (2 × pi × T_R) × 100

Efficiency uses the raising torque in the printed equation. A separate lowering efficiency is not calculated.

For these inputs, f x sec(alpha) is greater than tan(lambda). That is only the textbook comparison used here. It does not prove the screw will hold a real load.

Mean diameter and lead angle

Mean diameter 14 mm

d_m = major - pitch / 2

Lead angle 5.1965 deg

tan(lambda) = Lead / (pi × d_m)

Diameters are converted to meters so newtons give newton-meters. Alpha is the angle you enter. It is not defined as half of 29 or 30 degrees.