Under the

Whyte notation Whyte notation is a classification method for steam locomotives, and some internal combustion locomotives and electric locomotives, by wheel arrangement. It was devised by Frederick Methvan Whyte, and came into use in the early twentieth cen ...

for the classification of steam locomotives by

wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...

, the is a Garratt

articulated locomotive An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to neg ...

. The wheel arrangement is effectively two

4-8-0 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels on two axles, usually in a leading truck or bogie, eight powered and coupled driving wheels on four axles and no ...

locomotives operating back to back, with the

boiler A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, centr ...

and cab suspended between the two engine units. Each engine unit has two pairs of

leading wheel The leading wheel or leading axle or pilot wheel 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 on a leading truck. Leading wheels are used ...

s in a leading bogie, followed by four coupled pairs of driving wheels and no

trailing wheel On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle ( wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, ...

s. Since the 4-8-0 type is known as a Mastodon type, the corresponding Garratt type would be referred to as a Double Mastodon. A similar wheel arrangement exists for the

Union Pacific Big Boy The Union Pacific Big Boy is a type of simple articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service until 1962. The 25 Big ...

, but is referred to as 4-8-8-4 since only the front engine unit swivels.

Overview

The was the fifth rarest Garratt wheel arrangement, with a total of 26 locomotives constructed.

Usage

All the 4-8-0+0-8-4 Garratts were built by Beyer, Peacock & Company for the gauge

Bengal Nagpur Railway The Bengal Nagpur Railway was one of the companies which pioneered development of the railways in eastern and central India. It was succeeded first by Eastern Railway and subsequently by South Eastern Railway. History The opening of the ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. The first 16 were designated Class N and were delivered in 1929, while 10 more arrived in 1931 and were designated class NM. The locomotives had

Belpaire firebox The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium in 1864. Today it generally refers to the shape of the outer shell of the firebox which is approximately flat at the top and sq ...

es and

piston valves Piston valves are one form of valve used to control the flow of steam within a steam engine or locomotive. They control the admission of steam into the cylinders and its subsequent exhausting, enabling a locomotive to move under its own power ...

. Two of the type survive, both of Class N. No. 811 is staged at Kharagpur Workshop, while no. 815 is on display at the

National Rail Museum, New Delhi The National Rail Museum in Chanakyapuri, New Delhi, displays exhibits on the history of rail transport in India. The museum was inaugurated on 1 February 1977. The museum spans over an area of over 11 acres and the indoor gallery compris ...

References

External links

{{Whyte types 8,4-8-0 88,4-8-0+0-8-4