Forester1,
The Garratts are 4-cylinder simple locos, with steam being delivered to and exhausted from the forward and rear cylinders by a complex series of pipes. Both sets of drivers are articulated, with each respective bunker (coal on the rear or water up front) moving with the drivers, unlike U.S. mallets and articulated engines where only the front set was articulated. So these Welsh Highland locos would be 2-6-2+2-6-2. The concept was very effective, allowing for very tight radii. Also equally effective going forward or reverse. These locos originally went to South Africa, circa 1958, now back in the UK. Both the model and Ken's reskins are terrific.
Best,
smyers