What is a lower pair?
If a pair has a surface contact between the two elements while in motion, it a called lower pair. sliding and turning pairs are lower pairs.
It is mechanism used to create straight line motion that is used to enlarge or reduce movements given at the input side.
Hart Straight Line Mechanism
Scott Russel Mechanism
Watt Straight Line Mechanism
Modified Scott Russel Mechanism
Grass Hopper Mechansim
Tchebicheff Straight line mechanism
Robert's straight line mechanism
Straight Line Mechanisms used in Engine Indicators
Crosby indicator mechanism
Thomson indicator mechanism
Dobbie McInnes indicator mechanism