Assertion (A) : Buttress thread is a modified square thread profile which is employed on the lead screw of machine tools.
Reason (R) : Frequent engagement and disengagement of lead screw for automatic feed is not possible with perfect square threads, therefore, the square profile has to be modified.
Option (A)
Both A and R are true and R is the correct explanation of A
Option (B)
Both A and R are true but R is NOT the correct explanation of A
A is true but R is false
A is false but R is true
Correct Option:
Question Solution:
Acme thread is used in lead screw and that is the modified form of square shaped square thread. Buttress thread is used in vices.
These Acme thread are strongest thread (more stronger than square less efficient than square threads).