Subject: Machine Design -I

Topic: Design against static Loads, Bolted and welded joints under eccentric loading. Power Screw

Difficulty: Medium

• A cotter joint is used to connect two co-axial rods, which are subjected to either axial tensile force or axial compressive force.
• A cotter is a wedge-shaped piece made of a steel plate.
• The cotter has uniform thickness and the width dimension b is given a slight taper.
• The construction of a cotter joint, used to connect two rods A and B is shown in Fig. Rod-A is provided with a socket end, while rod-B is provided with a spigot end. The socket end of rod-A fits over the spigot end of rod-B.
• The socket as well as the spigot is provided with a narrow rectangular slot. A cotter is tightly fitted in this slot passing through the socket and the spigot.

• From the constructional details it is clear that the manufacturing of spigot and socket is difficult than the cotter also if the cotter fails it is easy to replace with very less economical loss. Hence the cotter is kept as weakest part.