A Scott Russell linkage is a linkage which translates

linear motion Linear motion, also called rectilinear motion, is one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion, with co ...

through a right angle. The linkage is named after

John Scott Russell John Scott Russell FRSE FRS FRSA (9 May 1808, Parkhead, Glasgow – 8 June 1882, Ventnor, Isle of Wight) was a Scottish civil engineer, naval architect and shipbuilder who built '' Great Eastern'' in collaboration with Isambard Kingdom Brune ...

(1808–1882), although watchmaker William Freemantle had already patented it in 1803. A different form of the linkage has been used in a

front-wheel-drive Front-wheel drive (FWD) is a form of engine and transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longi ...

vehicle with solid rear axle to control lateral movement, and with a flexing elastomeric connection instead of the rolling or sliding connection. The linkage does not share the disadvantages of the asymmetric

Panhard rod A Panhard rod (also called Panhard bar, track bar, or track rod) is a suspension link that provides lateral location of the axle. Originally invented by the Panhard automobile company of France in the early twentieth century, this device has been ...

, and although more compact than Watt's linkage, it has all the forces concentrated in one link.

Construction and related linkages

The linkage is composed of two links. One link is double the size of the other, and is connected to the smaller link by its midpoint. One of the ends is then connected to something that can generate linear motion, such as a

rolling Rolling is a type of motion that combines rotation (commonly, of an axially symmetric object) and translation of that object with respect to a surface (either one or the other moves), such that, if ideal conditions exist, the two are in contact ...

or sliding connection, or another straight line mechanism. The Evans 'grasshopper' linkage is a variant of a Scott Russell linkage which uses a long link to create a large enough arc to approximate a line. The Bricard inversor directly incorporates the Scott Russell's links, replacing the previously required straight line connection and allowing for two exact straight line outputs at right angles. If both ends are turned into sliding connections, you get a Trammel of Archimedes.

References

External links

Animation of a Scott-Russell linkage in action
Automotive suspension technologies Linkages (mechanical) {{automotive-tech-stub Straight line mechanisms