Test: Threaded Joints & Power Screws - 1 - Mechanical Engineering MCQ

Multi-start threads are used where
(i) large load is required without reducing the cross-section of nut.
(ii) easy screwing is desired as in fountain pens and tooth paste caps. It is used where the use is to impart quick motion in opening and closing without exerting much force.

The kinetic energy of the moving weight must be absorbed by the bolt upon impact

Stress area,
A = 0.785 x 12² x 10^-6
= 0.113 x 10^-3 m²

W₁ = Initial load
W₂ = External load Resultant load,

m = deflection in m/N of load for the bolted members
b = deflection in m/N of load for the bolt
Separation of bolted joint will occur if W₂ =W
As the material is same, m = b

Buttress threads combines the low frictional resistance of the square thread and the strength of vee-thread when the force acts in one directon only.

Resistance of a bolt can be increased by increasing the diameter of the threaded portion.

The threaded portion of a bolt is the part that provides the clamping force by engaging with the internal threads of a nut or a tapped hole. The larger the diameter of the threaded portion, the greater the clamping force that can be achieved at a given torque value. This is because the increased diameter increases the cross-sectional area of the bolt, which in turn increases its resistance to deformation or failure under loading.

Increasing the size of the bolt head or its length will not necessarily increase its resistance, as these factors do not affect the clamping force or the ability of the bolt to resist deformation or failure. Increasing the shank diameter may increase the shear strength of the bolt, but it will not necessarily increase its resistance to tension or compression.