Linkage

Linkage is a mechanical device with a series of firm links that are coupled with joints to form a closed chain. Each and every link may have two or more joints. The degrees of freedom are different for each link. Linkage is also referred as mechanical mechanism which has two or more flexible parts which move with respect to fixed link. By changing motion of link, velocity and acceleration each input produces different output.

History

The mechanical linkages became evident only in 19^th century. Golden age of linkages led to industrial revolution. Leonhard Euler, a mathematician was the first to study the effect of linkage synthesis. James watt introduced watt linkage to bear steam engine piston. Chebyshev introduced polynomials with the help of mechanical linkages. It was used in conversion of power, cloth making process and also in regulation of speed. Much of electronic technology has replaced mechanical linkages.

Types of mechanical linkages

Based on bar linkage

• Four bar linkages
  • Pantograph
  • Grashof
  • Crank slider
• Five bar linkages
• Six bar linkages
• Watt  & Stephenson kinematic chain
• Watt I & II
• Stephenson I,, II & III

Based on mechanical linkage mechanism

• Chebyshev linkage
• Sarrus linkage
• Hoekens linkage
• Scott Russell linkage
• Peaucellier linkage
• Watt linkage

Questions:

• What are linkage applications?
• Describe biological linkage in detail.
• What are the types of mechanical linkages?
• What is the theory behind mechanical linkage?