Machine Design
Jam nut is a locking device in which

A slot is cut partly in middle of nut and then slot reduced by tightening a screw
A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter spitted and bent in reverse direction at other end
One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming

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Machine Design
In order to determine the stresses in a thin cylinder due to an internal pressure, it is assumed that

The effect of curvature of the cylinder wall is neglected
The tensile stresses are uniformly distributed over the section of the walls
All of these
The effect of the restraining action of the heads at the end of the pressure vessel is neglected

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Machine Design
The creep in the belt is due to

Material of belt
Effect of temperature on belt
Unequal extensions in the belt due to tight and slack side tensions
Stresses beyond elastic limit of belt material

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