1745.
একটি স্কু জ্যাক-এর কার্যদক্ষতা সর্বোচ্চ হবে, যখন-
ব্যাখ্যা: The maximum efficiency of screw jack is when helix
angle a is a =45° -2/ ϕ
If the friction angie is greater then the helix angle, the torque required to lower the loud will positive, indicating that an effort is applied to lower the loud Such a screw is known as a self locking screw.