Cotter Joint – Parts and Applications

Cotter joint is a type of mechanical joint which is used to join two axial rods or bars. It is also known as spigot and socket joint.This joint doesn’t allow any angular movements of rods which it connects. This joint is applicable for tensile loads as well as compressive loads. It is a detachable joints. It consists of mainly three parts – i) Spigot ii) Socket iii) Cotter. Spigot is the male part of the joint and socket is the female part of the joint. The cotter is usually made of mild steel or wrought iron It is not suitable for connecting rotating shafts which torque.

Cotter joint is mainly made of three parts :-
i) Spigot
ii) Socket
iii) Cotter

i) Spigot :-
It is male part of the cotter joint. It is the part which gets inserted into the socket . It has a rectangular slot for the cotter to pass through it.Also,it has collar which rests against the socket end.

ii) Socket :-
It is female part of the cotter joint.It has a hole in which spigot fits. It also has rectangular slot for the cotter to pass through it.

iii) Cotter :-
It is the part after which the joint is named. It is wedge shaped piece of metal .This part enter into rectangular slot of spigot and socket. It first enter into upper slot of the socket, then pass through the spigot and then pass through lower part of socket.

The above three parts spigot, socket and cotter together forms the cotter joint.Spigot and socket are formed in one of the two connecting rods.
Firstly, Spigot enters into the circular hole of socket and then cotter fits tightly into the rectangular slots of spigot and socket which coincides with each other.
This cotter fix the spigot and socket with each other . A tapper is used to lock the joint. This tapper is easy to remove and makes the dismantle of joint an easy process. Tapper also ensures the tightness of the joints and prevents loosening of the parts.

There are three types of cotter joints :-
1) Socket and Spigot joints
2) Sleeve and Cotter joints
3) Gib and Cotter joints