Consider a shaft of square-threaded screw with a mean radius of 20 millimeters and a lead of 10 millimeters in contact with a plate gear of mean radius of 35 millimeters. The coefficient of static friction between the screw and gear is 0.3. Evaluate the resisting torque on the plate gear that can be overpowered when a torsional moment of eight newton-meter is applied to the shaft. Initially, calculate the static friction angle using the coefficient of static friction and determine the lead angle by substituting the values of lead and mean radius. For an upward impending motion, the axial force developed in the shaft can be determined by substituting the corresponding values. The resisting torque on the plate gear equals the product of the shaft's axial force and the mean radius of the gear. By substituting the values, the resisting torque that can overpower the applied torsional moment can be determined. Here, the static friction angle is greater than the lead angle. So the shaft is self-locking even if the moment is removed.