2-8-8-8-4

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The sole 2-8-8-8-4 locomotive 28884.jpg
The sole 2-8-8-8-4 locomotive

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 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. [1] Built by Baldwin Locomotive Works, it became the only example of their class XA, so named due to the experimental nature of the locomotive. 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 Triplex (locomotive).

The XA was unable to sustain a speed greater than five miles an hour, since the six cylinders could easily consume more steam than the boiler could produce. When operating in compound the high pressure steam was divided between the cylinders of the center engine. The exhaust from one cylinder was piped to the front articulated engine. The exhaust from the other center engine cylinder was piped to the tender engine.

The exhaust from the front engine was piped to the exhaust nozzle inside the firebox to generate draft through the firebox, through the fire tubes and out the exhaust stack. The exhaust from the tender engine went out of a stack at the rear of the tender water tank. Unfortunately it did not contribute to draft, being wasted. 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 predecessor which lasted only a few years in service, these two locomotives remained in service until 1953. However, neither of the two locomotives were preserved.

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2-8-8-4 Articulated locomotive wheel arrangement

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Pennsylvania Railroad class M1

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Under the Whyte notation for the classification of steam locomotive wheel arrangements, a 2-10-10-2 is a locomotive with two leading wheels, two sets of ten driving wheels, and a pair of trailing wheels.

2-6-6-4 Articulated locomotive wheel arrangement

In the Whyte notation for the classification of steam locomotive wheel arrangement, a 2-6-6-4 is a locomotive with a two-wheel leading truck, two sets of six driving wheels, and a four-wheel trailing truck. All 2-6-6-4s are articulated locomotives, of the Mallet or related simple articulated type.

A 2-8-8-2, in the Whyte notation for describing steam locomotive wheel arrangements, is an articulated locomotive with a two-wheel leading truck, two sets of eight driving wheels, and a two-wheel trailing truck. The equivalent UIC classification is, refined to Mallet locomotives, (1'D)D1'. These locomotives usually employ the Mallet principles of articulation—with the rear engine rigidly attached to the boiler and the front engine free to rotate—and compounding. The 2-8-8-2 was a design largely limited to American locomotive builders. The last 2-8-8-2 was retired in 1962 from the N&W's roster, 2 years past the ending of steam though steam was still used on steel mill lines and other railroads until 1983.

4-8-8-2 Articulated locomotive wheel arrangement

Under the Whyte notation for the classification of steam locomotives, a 4-8-8-2 is a locomotive with four leading wheels, two sets of eight driving wheels, and a two-wheel trailing truck.

2-6-6-2 Articulated locomotive wheel arrangement

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a 2-6-6-2 is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels and one pair of trailing wheels. The wheel arrangement was principally used on Mallet-type articulated locomotives, although some tank locomotive examples were also built. A Garratt type locomotive with the same wheel arrangement is designated 2-6-0+0-6-2.

2-6-6-6 Articulated locomotive wheel arrangement

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2-6-8-0 Articulated locomotive wheel arrangement

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A Meyer locomotive is a type of articulated locomotive. The design was never as popular as the Garratt or Mallet locomotives. It can be best regarded as 19th Century competition for the early compound Mallet and also the Fairlie articulated designs. Most single cab modern trains are of a similar design such as power cars, freight diesel locomotives, and some passenger locomotives.

2-6-6-0 Articulated locomotive wheel arrangement

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 2-6-6-0 is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels and no trailing wheels. The wheel arrangement was principally used on Mallet-type articulated locomotives. Some tank locomotive examples were also built, for which various suffixes to indicate the type of tank would be added to the wheel arrangement, for example 2-6-6-0T for an engine with side-tanks.

Triplex locomotive Steam locomotive

A Triplex locomotive is a steam locomotive that divides the driving force on its wheels by using three pairs of cylinders rigidly mounted to a single locomotive frame. Inevitably any such locomotive will be articulated. All the examples that have been produced have been of the Mallet type but with one extra set of driving wheels under the tender.

Duplex locomotive

A duplex locomotive is a steam locomotive that divides the driving force on its wheels by using two pairs of cylinders rigidly mounted to a single locomotive frame; it is not an articulated locomotive. The concept was first used in France in 1863, but was particularly developed in the early 1930s by the Baldwin Locomotive Works, the largest commercial builder of steam locomotives in North America, under the supervision of its then chief engineer, Ralph P. Johnson.

South African Class KM 0-6-0+0-6-0

The South African Railways Class KM 0-6-0+0-6-0 of 1904 was an articulated steam locomotive from the pre-Union era in Transvaal Colony.

South African Class MA 2-6-6-0

The South African Railways Class MA 2-6-6-0 of 1909 was a steam locomotive from the pre-Union era in the Natal Colony.

South African Class MD 2-6-6-2

The South African Railways Class MD 2-6-6-2 of 1910 was a steam locomotive from the pre-Union era in Transvaal.

The South African Railways Class ME 2-6-6-2 of 1912 was a steam locomotive.

The South African Railways Class MG 2-6-6-2 of 1911 was a steam locomotive from the pre-Union era in Transvaal.

CGR Kitson-Meyer 0-6-0+0-6-0

The Cape Government Railways Kitson-Meyer 0-6-0+0-6-0 of 1903 was a South African steam locomotive from the pre-Union era in the Cape of Good Hope.

References

  1. Self, Douglas. "Triplex Locomotive" . Retrieved 8 May 2016.