With the exception of South Indian Railway (SIR) all the early metre gauge railways systems were state owned railways. Within six years of the adoption of metre gauge as economical alternate to broad gauge, 400 locomotives had been imported. The vast majority of the initial lot of MG locomotives imported were of British origin with the exception of a few German locomotives. (See table below)
The A class 2-4-0 tank locomotive was largely utilised for construction work on the metre gauge. One example of this class LORD LAWRENCE can be seen displayed at the North Eastern Railway (NER) Works at Gorakhpur. One of the earliest MG pug locomotive imported was the BLACK HAWTHORN , 0-4-0ST locomotive that was imported in 1873 for an irrigation project but shunted at Ajmer for several years in the later part of its working life. It can now be seen plinthed outside the Ajmer works. The other two locomotives of the same era that have survived to date are MERSY and TWEED both 0-4-0 tender engines of the D class which are still in working order at private sugar works in Bihar and Uttar Pradesh. SATURN was the third locomotive of D class from a total batch of ten engines built, which is known to have completed its eightieth birthday and was displayed at the 1953 centenary celebrations in Delhi. Its whereabouts thereafter are unknown and it probably met the same fate as SINDH (see the Broad Gauge section)The most successful locomotive class of its time however was the F class of 0-6-0 tender engines which constituted nearly 3/4th of total populace at its peak. F class derivative F1 734 was the first locomotive to be fully assembled in India (from imported parts) at the Ajmer Works and can be now seen resting at the National Rail Museum (NRM) in Delhi. Equally commonly seen engine was O class 4-4-0 outside cylinder tender engine on the passenger and mixed traffic. The O class was an outside cylinder derivative of the much admired M class 4-4-0 with inside cylinders, the only MG locomotive ever on Indian Railways with such arrangement. The M class engines were specifically designed to work the mail trains on the Delhi – Ahmedabad trunk route. These were so much loved by their crews that that when the original batch of 35 locomotives built by Dubs was worn out they were either rebuilt of replaced at Ajmer works with larger cylinders and superheated boilers. M2 162 is one such example of rebuilt M class built at Ajmer in 1923 and is preserved at NRM.In less than 30 years of coming to fore, the metre gauge milage touched the 10000 Kilometre mark. With the increased traffic towards the end of the nineteenth century the need for more powerful locomotives was felt and 3 new 4-6-0 designs with inside frames and up-to-date proportions were therefore evolved. These designs were radically different from what was already in use then and predicted the shape of locomotives to come.
The three typed designs were: –
When BESA committee was formed in 1903 to standardise the Metre Gauge locomotive types, they drew heavily from the above designs and the following prototypes evolved:
These standard designs (mainly the standard 4-6-0 and its variants) were widely used on the MG network. There were however many modifications to the typed designs and many railways while accepting the basic designs, manufactured to their own standard details to avoid multiplicity of spare parts. Local conditions particularly the quality of water supply affected the tender and boiler specifications and the latter were further varied with the introduction of superheating from 1912 onwards. No uniform classification could ever evolve due to the variants and each railway used their own unique notation to define a particular class.
In the subsequent attempt at locomotive standardisation in 1924, the Indian Railway Standard (IRS) series evolved to cater for the increase in traffic and also too cope with the much inferior coal allotted to the railways that necessitated a wider firebox on the mainline locomotive. The standard practice before the WW I was to import vastly superior Welsh coal and the compulsion to use inferior Indian coal after the War necessitated many changes in the locomotive designs. The full list of these classes can be seen in the table below.
Later modified to 2-6-2 due to unsteadiness in working.Other designs, a light passenger Pacific (YA), heavy goods 2-8-2 (YE) and a light 4-4-2 (YJ) were also considered but did not materialise. A unique variation was the GR class 2-8-0 built by W.G. Bagnall in 1934 for the Khamblighat section of BBCIR. The BBCIR and BNWR also carried out some other interesting experiments in this period by using various types of valve gears and feed water heaters.During World War II, traffic increased enormously, particularly on the strategic Bengal Assam Railway had to cope with this need and a number of wartime 2-8-2 locos were obtained from America and called MAWD, later simplified to WD. (War Department) and also referred popularly as McArthurs. No. 1798 built by Baldwin Locomotive Works, Philadelphia is from the last batch of 33 locomotives purchased by Indian railways in 1948 and has recently been restored by Northeast Frontier Railway to work excursion specials. Garratt locomotives of various wheel configurations were also used on hill sections in Assam by Assam Bengal Railway (ABR) with limited success. One of these rare metre gauge Garratt has survived the ravages of time and is lying at Guwahati diesel shed awaiting restoration attempts bay the new management.
The post-war MG designs, totalling four in number were built in large quantities to cope with the increased traffic and to replace the over aged locomotives used extensively during the war years. By 1972, when MG steam loco production stopped, 871YP 4-6-2 passenger engines and a staggering 1074 YG 2-8-2 goods locomotives had been produced, a vast majority of these at home by TATA and CLW. In addition 264 locomotives of YL class, a mixed traffic 2-6-2 design with a lighter axle load and 12 YM class 2-6-4 tank locomotives for short distance passenger trains were built, the latter being a corresponding class of its BG counterpart, the WM class.
Their crews loved the YP and the YG and immaculately maintained them well into the 1990s by when the decline of not just steam metre gauge itself and set in. Many consider these classes to be some of the most aesthetically pleasing locomotive designs in Indian Railway steam locomotive history. They looked especially pleasing with their large high-pitched boilers and smoke deflectors often painted with slogans and insignias of the concerning shed.
A unique exception to the other Hill Railways in India is the Nilgiri Mountain Railway that employs metre gauge rather than a narrow one and also a rack and pinion system for climbing the 1:12.25 gradient. The rack and pinion section has always been the exclusive domain of X class rack locomotives built by SLM of Switzerland originally in 1914, the last one coming in 1952. Eight locomotives from the original lot of twelve still work all the traffic between Mettupalaiyam to Coonoor, the subsequent non-rack section till Udgamandalam (Ooty) having gone to diesels since the mid 1990s. Built to metric dimensions, these are compound locomotives with all four cylinders outside the frames. On the easier section of the line, these locos work as two cylinder simple engines. The two low-pressure cylinders driving the rack wheels are immediately above the high-pressure cylinders and the working of the complicated Walschaerts type valve gear is really amazing. Most of the moving parts are placed on the outside making life of the maintenance staff very easy.