4-8-6
Encyclopedia
Under the Whyte notation
for the classification of steam locomotives, a 4-8-6 locomotive
would have had four leading wheel
s, eight coupled driving wheel
s and six trailing wheel
s.
Other equivalent classifications are:
This wheel arrangement was proposed by Lima Locomotive Works
in 1949 as a continuation of their "Super Power" concept, essentially an expansion of the 4-8-4
. A larger firebox similar to the ones on the 2-6-6-6
locomotives built by Lima would have been fitted, allowing for greater power at speed. Despite promotion by Lima, there is no firm evidence that an example of this type was ever built and no nickname was ever assigned to the arrangement. In 1949, few railroads were interested in new steam locomotives due to steady improvements in diesel-electric locomotives.
It is possible that CB&Q 4-8-4 5601 was experimentally equipped with a six wheel trailing truck to allow use on branch lines with lighter rail, but the experiment was unsuccessful. Photographic evidence is said to have existed in the 1950s, but no photos are known to exist at present.
Despite there being no documented full size examples built, there have been some 4-8-6s built for model railroads.
Reference:
Whyte notation
The 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 locomotives, a 4-8-6 locomotive
Locomotive
A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco – "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine, first used in the early 19th...
would have had four leading wheel
Leading wheel
The 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, eight coupled driving wheel
Driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...
s and six trailing wheel
Trailing wheel
On 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.
Other equivalent classifications are:
- UIC classificationUIC 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...
: 2D3 (also known as German classification and Italian classification) - French classification: 243
- Turkish classificationTurkish 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...
: 49 - Swiss classification: 4/9
This wheel arrangement was proposed by Lima Locomotive Works
Lima Locomotive Works
Lima Locomotive Works was an American firm that manufactured railroad locomotives from the 1870s through the 1950s. The company took the most distinctive part of its name from its main shops location in Lima, Ohio. The shops were located between the Baltimore & Ohio's Cincinnati-Toledo main line...
in 1949 as a continuation of their "Super Power" concept, essentially an expansion of the 4-8-4
4-8-4
Under the Whyte notation classification of steam locomotives, 4-8-4 represents the wheel arrangement of four leading wheels on two axles , eight powered and coupled driving wheels on four axles, and four trailing wheels on two axles .Other equivalent classifications are:UIC classification: 2D2...
. A larger firebox similar to the ones on the 2-6-6-6
2-6-6-6
The 2-6-6-6 is an articulated locomotive type with 2 leading wheels, two sets of six driving wheels and six trailing wheels. Only two classes of the 2-6-6-6 type were built. One was the "Allegheny" class, built by the Lima Locomotive Works. The name comes from the locomotive's first service with...
locomotives built by Lima would have been fitted, allowing for greater power at speed. Despite promotion by Lima, there is no firm evidence that an example of this type was ever built and no nickname was ever assigned to the arrangement. In 1949, few railroads were interested in new steam locomotives due to steady improvements in diesel-electric locomotives.
It is possible that CB&Q 4-8-4 5601 was experimentally equipped with a six wheel trailing truck to allow use on branch lines with lighter rail, but the experiment was unsuccessful. Photographic evidence is said to have existed in the 1950s, but no photos are known to exist at present.
Despite there being no documented full size examples built, there have been some 4-8-6s built for model railroads.
Reference:
- Bill Withuhn, "Did we scrap steam too soon?", in Trains, Vol. 34, No. 8, June 1974, pp. 36–47.