Under the
Whyte notationThe Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte and came into use in the early twentieth century encouraged by an editorial in American Engineer and Railroad Journal...
for the classification of
steam locomotiveA steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
s, a
2-8-8-8-2 has two
leading wheelThe leading wheel or leading axle of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the leading wheels are normally located in a truck...
s, three sets of eight
driving wheelOn a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...
s, and two
trailing wheelOn a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle located behind the driving wheels. The axle of the trailing wheels was usually located on a trailing truck...
s. Because of its length, such a locomotive must be an
articulated locomotiveArticulated locomotive usually means a steam locomotive with one or more engine units which can move independent of the main frame. This is done to allow a longer locomotive to negotiate tighter curves...
. It is not longer than a normal articulated; the third set of drivers is located under the tender. All of the examples produced were of the Mallet type.
Other equivalent classifications are:
UIC classificationThe UIC classification of locomotive axle arrangements describes the wheel arrangement of locomotives, multiple units and trams. It is set out in the International Union of Railways "Leaflet 650 - Standard designation of axle arrangement on locomotives and multiple-unit sets". It is used in much...
:
1-D-D-D-1 (also known as German classification and Italian classification)
AAR classification:
1-D-D-D-1
French classification:
140+040+041
Turkish classificationIn the Turkish classification system for railway locomotives, the number of powered axles are followed by the total number of axles. It is identical to the Swiss system except that the latter places a slash between the two numbers.Thus0-6-0 becomes 33...
:
45+44+45
Swiss classification:
4/5+4/4+4/5
The equivalent
UIC classificationThe UIC classification of locomotive axle arrangements describes the wheel arrangement of locomotives, multiple units and trams. It is set out in the International Union of Railways "Leaflet 650 - Standard designation of axle arrangement on locomotives and multiple-unit sets". It is used in much...
is to be refined to
(1'D)D(D1') for these Triplexes.
BaldwinThe Baldwin Locomotive Works was an American builder of railroad locomotives. It was located in Philadelphia, Pennsylvania, originally, and later in nearby Eddystone, Pennsylvania. Although the company was very successful as a producer of steam locomotives, its transition to the production of...
built the only three examples of the type for the
Erie RailroadThe Erie Railroad was a railroad that operated in New York State, New Jersey, Pennsylvania, Ohio, Indiana, and Illinois, originally connecting New York City with Lake Erie...
between 1914 and 1916. The first was named
Matt H. Shay, after a beloved employee of that road. All three, as well as the lone
2-8-8-8-4Under 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:...
and several
Virginian RailwayThe Virginian Railway was a Class I railroad located in Virginia and West Virginia in the United States. The VGN was created to transport high quality "smokeless" bituminous coal from southern West Virginia to port at Hampton Roads....
electrics, shared the nickname "Triplex" because of their three sets of drivers. (Compare
DuplexesA 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...
, which had two sets.)
An overview of Triplex engineering is given at
Triplex (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...
External links