Question 2
Marks : +2 | -2
Pass Ratio : 100%
The load cup of a screw jack is made separate from the head of the spindle to
Explanation: For the prevention of the rotation of load being lift, the load cup of a screw jack is made separate from the head of the spindle.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
Multiple threads are used to secure
Explanation: The power screws with multiple threads such as double, triple etc. are employed when it is desired to secure a large lead with fine threads or high efficiency. Such type of threads are usually found in high speed actuators.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
While designing a screw in a screw jack against buckling failure, the end conditions for the screw are taken as
Explanation: For buckling failure, The screw is considered to be a strut with lower end fixed and load end free. For one end fixed and the other end free, C = 0.25.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
To ensure self locking in a screw jack, it is essential that the helix angle is
Explanation: A screw will be self locking if the friction angle is greater than helix angle or coefficient of friction is greater than tangent of helix angle i.e. μ or tan φ > tan α.