LINKAGE MECHANISMS

Linkage Mechanisms Linkages are mechanical mechanisms which allow force or motion to be directed in either a rotary or a linear motion. These can also change the direction of motion of the force being exerted. A linkage system is made up of a mechanical system such as rods or arms joined together with mechanical fasteners. This system will include points where the parts will pivot. Depending upon the type of linkage system used, the input motion will transmit a different motion to the output.

Reverse-motion Linkage This Linkage moves in opposite directions. Top rod moves to the left, bottom to the right A linkage which makes the output move, just as the input is a ‘push-pull linkage’ The following link will take us to a animation which shows the mechanism in action. http://www.bbc.co.uk/schools/gcsebitesize/design/systemscontrol/me chanismsrev3.shtml

Parallel-motion Linkage Large rod at the top moves to the left Two small rods at the bottom move to the right All rods are parallel to each other These can be used as a tool box drawers mechanism The following link will take us to a animation which shows the mechanism in action. http://www.bbc.co.uk/schools/gcsebitesize/design/systemscontrol/me chanismsrev3.shtml

Bell-crank Linkage Horizontal movement converted to vertical movement This also works the opposite way around A practical example of this is the brake mechanism on a bicycle The following link will take us to a animation which shows the mechanism in action. http://www.bbc.co.uk/schools/gcsebitesize/design/systemscontrol/me chanismsrev3.shtml

Treadle Linkage Linkages can be used to change one type of motion into another Rotary motion of the cam moves a parallel-motion linkage The parallel-motion linkage controls the identical side-to-side, or oscillating motion A practical example of this is the mechanism on a car windscreen wipers. The following link will take us to a animation which shows the mechanism in action. http://www.bbc.co.uk/schools/gcsebitesize/design/systemscontrol/mechani smsrev3.shtml

Crank and Slider Linkage The rods move forwards and backwards in slider The fixed pivot anchor the linkages to one place An everyday example of this is a piston crankshaft. The following link will take us to a animation which shows the mechanism in action. http://www.technologystudent.com/cams/link1.htm