A simple description about spigot and socket joint which is known as cotter joint. It's a part of MDID (Machine Designing and Industrial Drafting) Subject in mechanical engg. GTU for semester 4th.

1. 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.

3. SECTIONAL VIEW

4. SOCKET SPIGOT
COTTER
COLLAR
ROD

5. Cotter joint
FIG 01: ASSEMBLED COTTERED JOINT

6. Cotter joint – modes of failure
FIG 02: STEEL SPIGOT BREAKING IN TENSION OUTSIDE THE JOINT
F
F
TENSION
F

7. 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
TEN

8. FIG 07: SOCKET BREAKING IN TENSION ACROSS SLOT
TEN
Cotter joint – modes of failure

9. FIG 06: DOUBLE SHEARING OF COTTER
PIN
FIG 09: DOUBLE SHEARING OF SOCKET END
SHEA
Cotter joint – modes of failure

10. 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
SHE

11. FIG 08: CRUSHING OF COTTER PIN AGAINST
SOCKET
BEAR FIG 04: CRUSHING OF COTTER PIN
AGAINST ROD END
Cotter joint – modes of failure

12. CRUSHING FAILURE OF
SPIGOT COLLAR
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