Which of the following statement is correct regarding power screws?
A. The efficiency of a self locking screw can not be more than 50%
B. The efficiency of Acme (trapezoidal) thread is less than that of a square thread
C. If the friction angle is less than the helix angle of the screw, then the efficiency will be more than 50%
D. Both (A) and (B)
Answer: Option D
Options B and C correct
The efficiency of self locking screws is less than 50%
If friction angle is less than helix angle, then the screw will be Overhauling & efficiency of overhauling screw is more than 50%..so all options are correct