Watt's linkage
（重定向自Parallel linkage）
![Animated depiction of Watt’s linkage](/Images/godic/202502/01/Watts_linkage0808.gif")
![Hand-drawn diagram by James Watt (1808) in a letter to his son, describing how he arrived at the design.[1]](/Images/godic/202502/01/The_Kinematics_of_Machinery_Fig_10808.png")
![Figure 9 from James Watt's patent application (top left part) showing the straightline linkage](/Images/godic/202502/01/James_Watt's_straight-line_linkage0808.jpg")
![Watt's linkage as part of an automobile suspension](/Images/godic/202502/01/Wattslinkage.svg0808.png")
Watt's linkage (also known as the parallel linkage) is a type of mechanical linkage invented by James Watt (19 January 1736 – 25 August 1819) in which the central moving point of the linkage is constrained to travel on an approximation to a straight line. It was described in Watt's patent specification of 1784 for the Watt steam engine. It is also used in automobile suspensions, allowing the axle of a vehicle to travel vertically while preventing sideways motion.