What Are the Different Cotter Joint Types?

Introduction Cotter Joint Types

Socket and spigot cotter joints fit a male projection into a female chamber and are held together by a cotter pin. A sleeve protects the junction in a sleeve and cotter joint, and a cotter pin binds the parts together. To ensure stability and force transmission in mechanical systems, these joints serve as crucial
linkages.

The Cotter Joint

Making a temporary joint enables us to disassemble the cotter joint as needed because it is an essential component.

• If a locking mechanism is used, the taper of a standard cotter can be raised to 1 in 8 from 1 in 48 to 1 in 24.
• On the bottom end of the cotter, we require an extra locking mechanism, such as a taper pin or a set screw, to keep the cotter in place.
• The cotter is typically constructed of mild steel or wrought iron.
• The cotter joint is a temporary fastening method.
• The two rods are then momentarily connected by forcing a cotter firmly through a hole.
• This type of cotter joint is used in well-known applications, such as • Connecting a piston rod to a reciprocating steam engine’s crosshead.
• Connecting a piston rod and its extension, which serves as a tail or pump rod,
• To the strap end of a connecting rod.

Cotter Joint Types

There are three kinds of cotter joints.

• Cotter Socket and Spigot Joint
• The cotter joint and the sleeve.
• Gib and Cotter’s Joint

1. Cotter Socket and Spigot Joint

The socket and spigot Cotter Joint are depicted in the image below.

One end of the rods in the above socket and spigot cotter joint is provided with a socket type of end, as shown, and the other end of the other rod is inserted into a socket.

• A fixture is the end of the rod that fits into a socket.
• In the socket and spigot, a rectangular hole is drilled.
• The two rods are then momentarily connected by forcing a cotter firmly through a hole.
• The load acts typically axially but can change direction, so the cotter joint must be designed to withstand both tensile and compressive loads.
• The collar on the spigot absorbs the compressive load.
• More on the Socket and Spigot Cotter Joint Design.

2. Cotter and Sleeve Joint

The Sleeve and Cotter Joint parameters are shown in the schematic diagram below.
As previously stated, the sleeve and cotter joint join two round rods or bars.
• In this type of joint, a sleeve, also known as a muff, is placed over the two rods, and two cotters (one on each rod end) are inserted into the holes in the sleeve and rods.
• Typically, the sleeve and cotter taper 1 in 24. It should be seen that the taper sides of the two cotters should face each other, as illustrated in the schematic diagram above.
• When the cotters are driven in, the clearance is set so the two rods move closer, tightening the joint.

Cotter Joint Applications

• The Cottar joint has historically been used to connect connecting rods to steam engines and pumps used in dumping mines.
• Cotter Joints are used between the piston rod and the pump rod’s tail.
• Cotter’s joints are used between the slide spindle and the valve mechanism’s fork.
• Cotter and Dowell make plans to connect two parts of a flywheel.
• Foundation bolts are primarily used to secure foundations and heavy machinery during construction.
• In automobile engines, the cotter joint connects the piston rod’s extension to the crosshead’s connecting rod.
• Historically, the Cottar joint was used to connect connecting rods to steam engines and dumping mine pumps.
• It connects the paddle to the sprocket wheel on bicycles.
• Use a wet air pump to connect a tail rod to a piston rod.
• It connects two rods of equal diameter that are subjected to axial forces.

Video 01: Cotter joint || animation|| and its parts