SPIGOT AND SOCKET JOINT(COTTER JOINT)

• Rods, having axial tensile or compressive forces are connected by cotter joints. Rods may be of different cross sections like circular or square.

• This is a temporary method of joining the rods.

• Cotter joints can be quickly assembled as well as disassembled.

SECTIONAL VIEW

SOCKET SPIGOT

COTTER

COLLAR

ROD

Cotter joint

FIG 01: ASSEMBLED COTTERED JOINT

Cotter joint – modes of failure

FIG 02: STEEL SPIGOT BREAKING IN TENSION OUTSIDE THE JOINT

F

F

TENSIO

N

FAILU

RE

FIG 02: STEEL SPIGOT BREAKING IN TENSION OUTSIDE THE JOINT

WROUGHT IRON ROD BREAKING IN TENSION OUTSIDE THE JOINT

FIG 05: SPIGOT BREAKING IN TENSION ACROSS SLOT

Cotter joint – modes of failure

TENSIO

N

FAILU

RE

FIG 07: SOCKET BREAKING IN TENSION ACROSS SLOT

TENSIO

N

FAILU

RE

Cotter joint – modes of failure

FIG 06: DOUBLE SHEARING OF COTTER PIN

FIG 09: DOUBLE SHEARING OF SOCKET END

SHEAR

FAILU

RE

Cotter joint – modes of failure

Cotter joint – modes of failure

FIG 11: SHEARING AWAY OF THE COLLAR IN THE SPIGOT

FIG 12: SHEARING AWAY OF SOCKET (IF dw < dl)

FIG 10: SHEARING OF SPIGOT END

SHEAR

FAILU

RE

FIG 08: CRUSHING OF COTTER PIN AGAINST SOCKET

BEARING

FAILU

RE

FIG 04: CRUSHING OF COTTER PIN AGAINST ROD END

Cotter joint – modes of failure

CRUSHING FAILURE OF SPIGOT COLLAR

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