Knuckle joint

Mechanical Joint-

A mechanical joint is a section of a machine which is used to connect one or more mechanical parts to another.

Knuckle joint-

A Knuckle Joint is used basically to connect two shafts, rods or bars where there is some necessity for flexibility and angular movement.

The axis must be on the same plane. The forces applied in the same plane.

It permits some angular movement between the rods (in their plane).

Parts of a Knuckle Joint -

Knuckle joint has the following parts - 

• Rods
• Fork end
• Eye end
• Knuckle pin
• Collar
• Taper pin

various parts of knuckle joint 

Failure mode of knuckle joints-

where,

d       = diameter of each rod (mm)

_d1      = enlarged diameter of each rod (mm)

d        = diameter of knuckle pin (mm)

d₀      = outside diameter of eye or fork (mm)

d₁      = diameter of pin head (mm)

t1        = thickness of each eye of fork (mm)

t        = thickness of eye end of rod B (mm)

Failure due to tensile stress

(D is the diameter of the rod)

Failure due to shear stress

(d is the diameter of the pin)

Crushing failure of eye end

P = d×t×σ(crushing)

Advantages of Knuckle Joint -

• Knuckle joint can withstand large tensile loads.
• It has good mechanical rigidity.
• It is easy to manufacture and set up.
• It can be easily dismantled and assembled.
• The design is simple and easy.

Limitations of knuckle joints-

• The joint cannot withstand large compressive loads.
• It permits angular movement in only one plane.

Applications of Knuckle Joint-

• Bicycle chains
• Robotic joints
• Structural members
• Cranes
• Automobiles wi[pers