All the articulating use two (or occationally three) 'engines' ie cyinders, wheels and frames. The differences between them, and the patent they are named after, usually had to do with with mechanics of the suspention of the boiler /cab frame on the engine frames
The major sytems are:
Rear engine fixed front one on a sliding pivot. Eariest ones compound later simples.
Boiler frames supported on both engines by pivots. Fuel and water carried on the engine frames
Boiler frames supported on the front frames with a pivot and on the rear frames with hemi-spherical side bearings. Fuel and water carried on the engine frames
Similar to the Meyer type but with the fuel and water carried on the boiler frames and oftern with the cylinders on the inner ends of the engine frames. Both this and the proceding type had a second chimney for the rear cylinders.
Two boilers with (usually) one firebox and two pivoted engine units. There was also a single Fairley with one boiler and one power unit and a trailing bogie, and an "Improved Fairley" which looked like a garret but with the fuel and water tanks at the ends of the boiler frames.
The Mallets and Faileys were early designs (1870) and the patentes had lapst by the begining of the this century. This enable them to be built by a number of different comanies. Beyer Peacock held the patents to the Beyer Garrets though they were also built under licence in Belgium. Meyers, of both types seem only to have been built by Kitsons in Leeds and most seem to have gone to South America.
There were also a number of systems articulating the axles within the frames.
---------------------------------------------------------------- Bill Bedford Designer of Photo-Etches billb@mousa.demon.co.uk ----------------------------------------------------------------
