The screw of a car lift has 150 mm dia. with square threads of 50 mm pitch and lead of 100 mm. Assume 1000 N is required for lifting of the car and thread friction coefficient is 0.20.
(i) Compute the torques required to rotate the screw to raise the car and lower the car. Also compute the overall efficiency of the screw.
(ii) What is the flaw in the above design?