Institute for Advanced Studies all rights reserved
Straight Line Generators
Return to the table.
The Peaucellier (Po-sel-yea. Sorry, Francophones. That's the best I can do) produces an "exact" straight line over its range. For straightline motion, link BC = AB. The geometry shown here is from Ref 1: AB = BC = 150. CD = DF = CE = EF = 200.
This mechanism was devised in 1873 (a hundred years after Watt's work) by Captain Charles-Nicolas Peaucellier of the French corps of engineers. Its general function as a generator of an arc of any radius is specialized here by choosing link lengths to make that radius infinite (a straight line.)
When Lord Kelvin worked a model of the device, he is reputed to have remarked that it was the most beautiful thing he had ever seen. [Ref 3]