Kinematic Pair Classification and Its Practical Examples

Kinematic pair

Kinematic pair is a joint of two Links (or elements) and it permit to relative motion. When the two links or element is having connected together that provide relative motion it is completed or successfully constrained is called kinematic pair.

The practical example for kinematic pair

  • Crank and connecting rod connected.
  • The connecting rod and Piston connection.
  • Piston and engine cylinder.

Kinematic pair classification as followed by:

Based on contact between two link or element (types of contact)

  • Lower pair
  • Higher pair

Based on relative motion (types of relative motion)

  • Sliding pair
  • Turning pair
  • Rolling pair
  • Spherical pair
  • Screw pair

Based on mechanical arrangement for constrain of relative motion

  • Closed pair
  • Un-closed pair

Kinematic Pair Based on contact between two link or element (types of contact)

Lower pair

The lower pair is a surface contact between joint of to links or element is called lower pair. Sliding pair, turning pair and screw pair are form of lower pair.

Practical example

  • Nut and bolt
  • Piston inside of reciprocating cylinder
  • The shaft rotating in bearing
  • Bolt and socket joint

Higher pair

The higher pair is a Line or Point contact between two links or element is called higher pair.

Higher Pair of cam and follower
Higher Pair of cam and follower

Practical examples

  • Belt, rope and chain drive that contact in lining.
  • Cam and follower, ball bearing, gears are contact in point.

Kinematic Pair Based on relative motion (types of relative motion)

Sliding pair

It is lower pair, because the slider contact having form of surface contact. So when the two links are sliding motion relative to each other is called sliding pair.

Kinematic pair of Sliding mechanism
Kinematic pair of Sliding mechanism

As shown in figure, the Bar A is sliding with successfully constrained relative to bearing B form of sliding pair.

Practical examples

  • Piston on the cylinder
  • Tail-stock in lathe machine
  • Ram and its guide way for Shaper.
  • Cross head and guide in steam engine

Turning pair

The two elements are connected in such a manner one element revolve around another, It form is known as turning pair.It is also called as Hinged pair. Which the turning pair is a single degree of freedom.

Turning Pair
Turning Pair

The shaft A with two collars rotate in inside of bearing B, It Form as turning pair.

Practical examples

  • For milling machine, the arbor supported in column.
  • In bicycle, the wheel rotated turning over their axles.
  • In engine, the crankshaft turns in journal bearing.
  • In lathe machine, the spindle supported in head stock.

Rolling Pair

When the element freely rolled over another, It form is rolling pair. As shown in figure, the belt and Pulley operated similar to rolling pair.

Rolling Pair of pulley and belt
Rolling Pair of pulley and belt

Practical examples

  • Roller and ball bearing.
  • The road roller rolling over Road.
  • The lawn move rolling over lawn.

Screw Pair

When one link is constraint, it has a combination of turning and sliding motion relative to other element. It is called screw pair.

Screw Pair
Screw Pair

Practical examples

  • Lead screw with nut in lathe machine.
  • Nut and bolt.
  • In bench vice, the threaded spindle and movable jaw.

Spherical Pair

When one link or element is constrained to swivel or about the other fixed point. Ball and socket joint are considered as Spherical Pair shown in figure.

Practical examples

  • Car mirror attachment
  • Pen supported joint in pen stand
  • Ball and socket joint

Kinematic Pair Based on mechanical arrangement for constrain of relative motion

Closed pair

The pair of two elements are helded together in mechanically, that consider for closed pair. All lower pair are self-closed pair.

Example:

  • All Lower Pair.

Unclosed Pair

The pair of two elements are not held together in mechanically it is called unclosed pair.

Practical examples

  • Cam and follower.
  • The flat belt running on pulley.

LEAVE A REPLY

Please enter your comment!
Please enter your name here