Types Of Kinematic Pairs

Introduction:

When a rigid body is capable of moving over the other rigid body there exist mechanical constraint or joints in between two such rigid bodies. The kinetic pair or joints may one or more than one degrees of freedom. The kinematic pairs are classified as follows.

Classification of kinematic pair:

Based on nature of contact

Kinematic pair is of two types based on nature of contact as follows.

• Lower pair: The surface contact in between the two rigid bodies are said to have two links. It is referred as lower pair. Surface contact stress of lower pair is less when compared to upper pair. As the stress is over surface in lower pair mechanical device has long service and has better lubrication comparatively. Below are instance or lower pair
  • Hinge joint
  • Helical joint
  • Planar joint
  • Ball joint
  • Cylindrical joint
  • Slider joint
• Higher pair: The contact at points of geometry is referred as higher pair. As contact area is very small the stress on higher pair is large. There is negligible or no sliding in between contact surface. Below are instance for higher pair.
  • Cam pair
  • Cylindrical roller

Based on relative motion

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

Based on constraint

• Unclosed pair
• Self closed pair

Questions:

• What are kinetic pairs?
• What are types of kinetic pairs based on constraint nature?
• What are types of kinetic pairs based on relative motion nature?
• What are types of kinetic pairs based on nature of contact?