Efficiency of screw depends upon lead of the screw.
Explanation: Efficiency= WL/[Pπd].
Efficiency of the screw depends upon helix angle but does not depend on friction angle.
Explanation: Efficiency=tan(ἀ)/tan(Ǿ+ἀ) where ἀ=Helix angle and Ǿ=Friction angle.
Efficiency of the screw _______ with increase of coefficient of friction.
Explanation: Efficiency is inversely proportional to tan of the sum of helix and efficiency angle.
Maximum efficiency of a square threaded is given by
Explanation: Efficiency=Sin(2ἀ+Ǿ)-Sin Ǿ /Sin(2 ἀ+Ǿ+Sin Ǿ),For max efficiency, sin(2ἀ+ Ǿ)=1.
If friction angle is 30’ then the maximum efficiency of the screw is
Explanation: Maximum efficiency=1-sinǾ/1+sinǾ.
Maximum possible efficiency of a self-locking screw is
Explanation: For self locking screw Ǿ(friction angle)>ἀ (helix angle), hence efficiency < tanǾ/tan(Ǿ+ἀ) or efficiency < tanǾ(1-tan²Ǿ)/2tanǾ.
In trapezoidal threads, f (coefficient of friction) can be taken as
Explanation: The normal force acting on the thread is W sec θ therefore the effect of the thread angle is to increase the frictional force by a term sec θ.
Clutch and coupling can be considered to be same.
Explanation: Clutch is a temporary join while coupling is a permanent joint.
Cold rolled components have higher strengths and hardness than hot rolled components.
Explanation: During grain re-structuring, original strength of material is lost.
Which of the following are true?
Explanation: Properties of cold working.