A Fairlie locomotive is a type of articulated steam locomotive that has the driving wheels on bogies. The locomotive may be double-ended or single ended.
David Lloyd George of the Ffestiniog Railway
Fairlie locomotive with two separate boilers built for Burma Railways by the Vulcan Foundry
Double Fairlie Merddyn Emrys at Porthmadog
David Lloyd George built in 1992 for the Ffestiniog Railway
A bogie is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transport. A bogie may remain normally attached or be quickly detachable. It may include a suspension component within it, or be solid and in turn be suspended ; it may be mounted on a swivel, as traditionally on a railway carriage or locomotive, additionally jointed and sprung, or held in place by other means.
A railway bogie
Experiment, the first successful American locomotive with a bogie, built in 1831 to a design by civil engineer John B. Jervis
Japanese archbar bogie with axleboxes
Diamond frame bogie, elliptical springs and American style journal boxes