Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical) PDF Download

COTTER AND KNUCKLE JOINTS

  • A cotter is a flat wedged-shape piece of rectangular cross-section and its width is tapered from one end to another for an easy adjustment. 
  • The cotter is usually made of mild steel or wrought Iron. A cotter joint is a temporary fastening and is used to connect rigidly to co-axial shafts which are subjected to axial tensile or compressive forces. 
  • It is usually used in connecting a position rods to the cross head of a reciprocating steam engine, strap end of connecting rod etc.
  • Types of Cotter Joints 
    • Socket and Spigot cotter joint 
    • Sleeve and cotter joint 
    • Gib and cotter joint.
  • Socket and Spoigot Cotter Joint

Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)

 

  • Formula
    • Failure of rods in tension
      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)
    • Failure of spigot in tension across the weakest section
      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)
    • Failure of the rod or cotter in crushing p = d2.t.sc
    • Failure of socket in tension across the slot.
      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)
    • Failure of cotter in shear (double shear) p = 2 bt. ts
    • Failure of socket collar in crushing  p = (d4 – d2) . t . sc
    • Failure of socket end in shearing p = 2(d4 – d2) c × ts
    • Failure of rod end in shear p = 2ad2 . ts
    • Failure of spigot collar in crushing
      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)
    • Failure eof spigot collar in shearing
      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)

 

  • Knuckle Joint
    • A knuckle joint is used to connect two rods which are under the action of tensile force. If the joint is guided, the rods may support a compressive load. 
    • Its use may be find in the link of a cycle chain, the rod joint for roof truss, valve rod joints with eccentric rod, pump rod joint, tension link in bridge structure and lever and connection of various types. 
    • The material used for the joint may be steel or wrought iron.

      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)
      Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical)
The document Cotter & Knuckle Joints | Mechanical Engineering SSC JE (Technical) is a part of the Mechanical Engineering Course Mechanical Engineering SSC JE (Technical).
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FAQs on Cotter & Knuckle Joints - Mechanical Engineering SSC JE (Technical)

1. What are cotter and knuckle joints in mechanical engineering?
Ans. Cotter and knuckle joints are mechanical joints used in mechanical engineering to connect two rods or bars. A cotter joint consists of a socket and a spigot, with a cotter pin passing through them to provide a secure connection. On the other hand, a knuckle joint is formed by a hinge pin that allows rotational movement between two parts, typically used in applications where angular motion is required.
2. What are the advantages of using cotter and knuckle joints?
Ans. Cotter and knuckle joints offer several advantages in mechanical engineering applications. Firstly, they provide a rigid and secure connection between two rods or bars, ensuring minimal movement and maintaining structural integrity. Secondly, they allow for easy assembly and disassembly, making them suitable for applications that require frequent maintenance or adjustments. Additionally, cotter and knuckle joints can handle high loads and resist shear forces effectively, making them reliable in heavy-duty applications.
3. What are the limitations of cotter and knuckle joints?
Ans. While cotter and knuckle joints have their advantages, they also have some limitations. One limitation is the potential for loosening due to constant vibrations or dynamic loads. To overcome this, periodic checks and maintenance may be required to ensure the joints remain tight and secure. Another limitation is the limited range of motion in knuckle joints, as they only allow rotational movement. If a joint requires both rotational and translational movements, additional mechanisms may be needed.
4. What factors should be considered when designing cotter and knuckle joints?
Ans. Several factors should be considered when designing cotter and knuckle joints. Firstly, the load requirements and expected forces acting on the joint should be analyzed to determine the appropriate size and material selection. Additionally, the range of motion and angular displacement needed should be considered to ensure the joint can accommodate the desired movement. Furthermore, factors such as ease of assembly, disassembly, and maintenance should also be taken into account during the design process.
5. What are some common applications of cotter and knuckle joints in mechanical engineering?
Ans. Cotter and knuckle joints find a wide range of applications in mechanical engineering. Some common examples include connecting piston rods to crossheads in engines, linking connecting rods to crankshafts, joining tie rods in suspension systems, and connecting steering linkages in automobiles. They are also used in various types of machinery, such as presses, cranes, and agricultural equipment, where a secure and reliable connection is required to transmit forces and motion.
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