Question
Download Solution PDFWhich of the following equations is valid for the maximum efficiency of a square threaded screw?
[where α = Helix angle, ϕ = Friction angle]
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
The maximum efficiency of screw jack is when helix angle α is
\(\alpha = 45^\circ- \frac{\phi }{2}\)
Note:
If the friction angle is greater than the helix angle, the torque required to lower the load will positive, indicating that an effort is applied to lower the load. Such a screw is known as a self-locking screw.
Additional Information
Screw jack
- A screw jack is a portable device consisting of a screw mechanism used to raise or lower the load. There are two types of jack Hydraulic and mechanical
- A Hydraulic jack consists of a cylinder and piston mechanism. The movement of piston rod is used to raise or lower the load.
- Mechanical jack can be either hand operated or power driven
The maximum efficiency of screw jack is:
\(\eta = \frac{{1 - sin\phi }}{{1 + sin\phi }} \)
Last updated on Jul 1, 2025
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