Sep 132013

Many people have asked me to explain knuckle joint with its parts, advantages, disadvantages and applications. I decided to write this article. Read every section of this article carefully and refer the images for a clear understanding. This article has the following sections:

  1. Introduction
  2. Parts
    1. Exploded View
    2. Assembled View
  3. Advantages
  4. Disadvantages
  5. Applications

Introduction to Knuckle Joint:

Knuckle joint is a type of mechanical joint used in structures, to connect two intersecting cylindrical rods, whose axes lie on the same plane. It permits some angular movement between the cylindrical rods (in their plane). It is specially designed to withstand tensile loads.

Knuckle Joint

Knuckle joint is named so because it is free to rotate about the axis of a knuckle pin.

Parts of a Knuckle Joint:

A typical knuckle joint has the following parts:

  1. Fork end
  2. Eye end
  3. Knuckle pin
  4. Collar
  5. Taper pin

All the above parts can be visualized if you take a look at the exploded view shown below.

Exploded View of a Knuckle Joint

Exploded view of a Knuckle Joint

Coaxial holes are provided in the fork end, eye end and collar. The fork end and the eye end are held together in position by means of a knuckle pin. The knuckle pin is held in its position with the help of a collar and a taper pin.

The assembled view of a knuckle joint is shown in the image below. Both the fork end and the eye end are capable of rotating in their planes about the axis of the knuckle pin.

Assembled View of a Knuckle Joint

Assembled view of a Knuckle Joint

Whenever a tensile load is applied on the cylindrical rods, the fork end and eye end adjust their positions about the axis of the knuckle pin.

The knuckle pin remains stationary. It does not rotate about its axis.

Advantages of Knuckle Joint:

  1. Knuckle joint can withstand large tensile loads.
  2. It has good mechanical rigidity.
  3. It is easy to manufacture and set up.
  4. It can be easily dismantled and assembled.
  5. Design is simple and easy.

Disadvantages of Knuckle Joint:

  1. The joint cannot withstand large compressive loads.
  2. It permits angular movement in only one plane.
  3. It is not as flexible as universal joint.

Applications of Knuckle Joint:

Knuckle joints find a wide variety of applications. They are used in:

  1. Bicycle chains
  2. Tractors
  3. Trusses
  4. Automobile wipers
  5. Cranes
  6. Chain straps of watches
  7. Earth movers
  8. Robotic joints
  9. Structural members

Share your ideas about knuckle joint by commenting on this article :)

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Written by

I am a mechanical engineer with a passion for technical stuff. I am the founder and former editor-in-chief of

  • Velappan Senthilnathan

    wat r the types of knuckle joint boss……….

    • Surjeet S

      Knuckle joint can be classified into a large number of types based on its size, shape, specification, application and other criteria. Manufacturers usually have a model number for each type of knuckle joint they manufacture.

      Some prominent types of knuckle joint are:

      1. Rotary Knuckle Joint and
      2. Marine knuckle Joint

  • manish kumar

    could you please explain its design

    • Surjeet S

      Sure… when time permits… stay tuned with

  • Manoj Birhade

    why octagonal end provided to forked eye and eye end ?

    • Surjeet S

      Eye end and fork end are octagonal to some extent in order to facilitate adjustments during assembly of the knuckle joint.

      • Manoj Birhade

        and that octagonal, connected to rod HOW ?
        weld or threads?

        • Surjeet S

          The octagonal rod is integral to the fork end and eye end. It is usually produced with the help of milling machine.

  • Dhanasekaran

    Thanks for sharing your Knowledge..!!!

  • punit barange

    which material is used to make knuckle joints parts

  • ankur jain

    please tell me about knuckle joint in quad bikes….

  • Pendar

    I’m looking for double end knuckle joints with 1mm bore. I have searched all over the internet but can’t find anywhere to buy it. Do you have any idea where I could buy some?

  • piyush daddikar

    How to mfg. knuckle joints??? by which method???

  • Ankush Uppod

    I would like to know the manufacturing processes used for making knuckle joint?

  • vada pav

    Which process is used for forke?


    What is key and Riveted joint


    1.Knuckle joint withstand maximum tensile loads only.If try to compressive loads which parameters will change.
    2.How to provide clearance for insert Knuckle pin into eye.
    Please clarify sir


    knuckle joint maximum withstand tensile loads but not compressive loads.How to modify to withstand max compressive loads

  • EngMahmoud NABIL

    hey any one recommend me the best drawing book ?