Machine Design
If d is the normal diameter of a bolt in mm, then the initial tension in kg in a bolt used for making a fluid tight joint as for steam engine cover joint is calculated by the relation

151 d
168 d
124 d
138 d

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Machine Design
Castle nut is a locking device in which

One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
A slot is cut partly is middle of nut and then slot reduced by tightening a screw
Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin spitted and bent in reverse direction at other end
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

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