Question:-
A screw jack is said to be self-locking if its efficiency is
Option (A)
Less than 50%
Option (B)
Equal to 50%
Option(C)
More than 50%
Option(D)
100%
Correct Option:
(A)
Question Solution:
For self locking Æ > a
h = (tan a / tan (Æ+a))
Put a = Æ
h £ (tan Æ / tan 2Æ)
(\ 2Æ > a + Æ)
£ {tan Æ(1-tan2Æ) / 2tanÆ} £ {(1-tan2 Æ) / 2} £ (1/2) – (tan2Æ / 2)
So it means that for self locking condition efficiency has to be less than 50%
question-answer-faq-9325