title: Jean-Jacques Meyer
text: # Jean-Jacques Meyer
  
  Jean-Jacques Meyer (1805–1877) was a French engineer, noted for his work with steam engines and steam locomotives.
  
  ## Innovations
  
  ### Background
  
  He was trained at the engineering school Arts et Métiers ParisTech.
  
  ### Expansion valve
  
  His first major invention was the Meyer expansion valve, used to improve efficiency in stationary steam engines. The first locomotives to use this invention were a pair of 2-2-2 locomotives Mayer built for the Chemin de fer de Strasbourg à Bâle [fr] in 1842. Named L'Espérance (Hope) and Le Succès (Success), they continued in service for S-B's successor, the Chemins de fer de l'Est until 1859.
  
  ### Articulated locomotive
  
  He was the originator of the articulated locomotives which bear his name. Meyer registered his first patent describing the system in 1861. The Meyer locomotive comprised:
  
  * a rigid single frame supporting cabin, and boiler;
  * two revolving units like bogies made up each one of a steam engine involving a group of driving wheels and possibly comprising carrying wheels.
  
  The first engine of this type built by the Société J. F. Cail & Cie. [fr] in 1868 was a 0-4-0+0-4-0 named L'Avenir (Future). The design was developed by Gaston du Bousquet, who designed a class of 0-6-2+2-6-0 tank locomotives for hauling heavy goods trains on the Chemins de fer du Nord and the Chemins de fer de Ceinture de Paris.
  
  ## Sources
  
  The above information is taken from the French Wikipedia article on the subject.
  
  