Cotter joints connect two rods to transmit axial motion without rotation. They contain a socket, spigot, and cotter wedge piece. Cotter joints are used in piston rods, valves, and pumps due to their simple design, easy assembly/disassembly, and tight securing force. Knuckle joints also connect rods but allow angular misalignment and some compression. They have an eye, fork, and pin components. Knuckle joints are commonly used in tie rods, bridges, valves, and levers due to their simple design and few parts. Both joint types are widely used for their reliability and cost effectiveness.

1. Presented By:- SHUBHAM ANAND
mechanical engg. dept

2. Cotter Joint

3. What Is A Cotter Joint?
• Cotter joints are the joints made with the help of cotter.
• Cotter joint is a flat wedge shaped piece of steel.

4. • cotter is used to connect rigidly two rods which
transmit motion in the axial direction, without
rotation.
• These joints may be subjected to tensile or
compressive forces along the axes of the rods.
• Examples of cotter joint connections are: connection
of piston rod to the crosshead of a steam engine,
valve rod and its stem etc.

5. Cotter joint contains has mainly three
components
1. Socket
2. Spigot
3. cotter

6. • In cotter joint there are two pipes having connection
with the help of cotter.
• One of the rods has a socket end into which the
other rod is inserted.
• the cotter is driven into a slot, made in both the
socket and the rod. The cotter tapers in width
(usually 1:24)* on one side of it.
*Reference: design of machine elements by V B bhandari, Tata Mc Graw Hill edu.

9. APPLICATION OF COTTER JOINT

10. Advantages of cotter joint
• Simple to design and manufacture
• Simple to assemble and dismantle
• Very high tightening force due to wedge action which
prevents loosening of parts in service

11. Applications of cotter joint
• Joint between the piston rod and the cross
head of a steam engine.
• Joint between the slide spindle and the fork of
valve mechanism.
• Joint between the piston rod and the tail and
pump rod
• Foundation bolt

12. Knuckle Joint

13. What is a knuckle joint?
• The knuckle joint is used to connect two rods under tensile
load.
• This joint permits angular misalignment of the rods and may
take compressive load if it is guided.

14. Components of Knuckle joint
• Eye
• Fork
• Pin

15. • These joints are used for different types of
connections e.g. tie rods, tension links in bridge
structure. In this, one of the rods has an eye at the
rod end.
• The other one is forked with eyes at both the legs. A
pin (knuckle pin) is inserted through the rod-end eye
and fork-end eyes and is secured by a collar and a
split pin.

17. APPLICATION OF KNUCKLE JOINT

18. Advantages of knuckle joint
• simple to design and manufacture
• fewer parts -less cost more realibility
• simple to assemble and dismantle

19. Application of knuckle joint
• Joints between the tie bars in a roof trusses.
• Between the links of suspension bridge.
• In valve mechanism of a reciprocating engine.
• Fulcrum for the levers.
• Joints between the links of a bicycle chain.

20. Thank you