2-8-8-8-4

Under the Whyte notation for the classification of steam locomotives, a 2-8-8-8-4 has two leading wheels, three sets of eight driving wheels, and a four trailing wheels.

Other equivalent classifications are:

UIC classification: 1DDD2 (also known as German classification and Italian classification)

French classification: 140+040+042

Turkish classification: 45+44+46

Swiss classification: 4/5+4/4+4/6

The equivalent UIC classification is to be refined to (1'D)D(D2') for these engines.

Only one 2-8-8-8-4 was ever built, a Mallet-type for the Virginian Railway in 1916. Built by Baldwin Locomotive Works, it became the only example of their class XA, (experimental articulated). Like the same railroad's large articulated electrics and the Erie Railroad 2-8-8-8-2s, it was nicknamed "Triplex".

An overview of Triplex engineering is given at 2-8-8-8-2.

The six large cylinders' ability to outdemand the boiler prevented the XA from running any faster than five miles per hour. The tender had a four-wheel truck at the rear to help guide the locomotive into curves when drifting back downhill after pushing a train over the hill.

The XA was sent back to Baldwin in 1920 and was rebuilt as two locomotives, a 2-8-8-0 and a 2-8-2. Unlike their progenitor which lasted only a few years in service, these two locomotives remained in service until 1953.

External links

* [http://www.toytrains1.com/triplex.htm Web Site of ToyTrains1 2-8-8-8-4 Triplex Steam Locomotives]
* [http://www.steamlocomotive.com/articulated/virginianxa.shtml Virginian Class XA]