Steam Locomotive Classes


Note: This FAQ section was not meant to be a comprehensive list of features or history of locomotive classes. Some classes have been selected for railfan interest, and in the case of locos that are restricted to certain areas, information on where they may be seen today has been provided. Detailed information on dimensions and operating figures, makers' lists, lines worked, etc., can be found in standard reference works on this topic such as the Hugh Hughes books (see the bibliography section).

Much background information on steam can be found on our web site at the Indian Steam Pages which include articles on the history of steam, newsletters of the Indian Steam Railway Society, and much more.

Some relevant sites on the web include the Diesel Loco Works' product web page, Chittaranjan Loco Works' web page and a page at IRIEEN on CLW's product range. You can see pictures of many classes of locomotives at the IRFCA Picture Gallery, and other sites such as RailInIndia.

Also see Chittaranjan Loco Works' electric loco production figures.

Q. What are the technical specifications for the various loco classes?

The section on diesel and electric loco specifications has information on most diesel and electric locomotives of IR, and includes figures on power, max. speed, serial numbers, etc. The information is drawn mostly from Jal Daboo's book, with updates and additions from IRFCA members.

Also see the section on additional electric loco specifications which has comparisons of the passenger AC electrics, the freight AC electrics, and the WCAM series of AC-DC electrics.

For more complete information, see Jal Daboo's book or Hugh Hughes' books (see the book listing) or other such reference material on locos of IR. Loco specs can also be found at DLW's diesel locomotive products page and CLW's web page. There is some data on 3-phase locos such as WAP-5 and WAG-9 at IRIEEN's web site; and you can also find specs for WAG-7, WAP-4, etc. on that web site.

Steam Locomotives

See the articles section for an overview of steam locomotive development in India.

SG, HP, HG These early classes were BESA designs from 1903-1910, used in many areas, but performed poorly because they were British designs not well-adapted to Indian conditions. They had narrow grates and fireboxes meant for high-grade coal, inside cylinders, and other such typical British features of the period.
XA Branch line passenger, 4-6-2, BG. The smallest of the 3 Pacific IRS types, with an axle load of 13 tons. 113 of these were built. A few are preserved.
XB Light passenger, 4-6-2, BG, with an axle load of 17 tons. 99 were built. This class had problems with stability and sideways oscillation, which led to the Bihta accident (see below) where over a hundred lives were lost when a passenger train derailed at speed. No locos of this class have survived in India. In Pakistan, an ex-EBR XB class loco, #450, was known to be in good condition at Moghulpura Works, Lahore, in 1994. It was the only one sent to the then West Pakistan from the then East Pakistan (Bangladesh today).
XC Heavy-duty passenger, 4-6-2, BG. A larger version of the XB design, with an axle load of 19.5 tons. 72 were built. Disliked by loco crew for its instability at speed. The "big brother" of the Flying Scotsman. None of these have survived. The photographer Colin Garratt recounts an attempt to hide one of the last of these locos that was intended for the scrapyard at the Bardhaman shed with the help of the shed foreman. The loco, however, was discovered and scrapped. The last XC was also extensively photographed by Garratt in repainted colours standing in for 'The Flying Scotsman'.
XD "X Dominion" loco for light freight, 2-8-2, BG. This was widely used for freight duties, with nearly 200 built in all (a second batch was built in the 1940's). Axle load of 17 tons. None have survived.
XE "X Eagle" loco for heavy freight, 2-8-2, BG. The most powerful of the IRS designs. These locomotives were huge. The boiler was 7' in diameter. Axle load 22.5 tons. Baldwin, USATC. Later the USATC locos were reclassified "AWE". These were seen working on SR as late as 1980 (at Jolarpettai). A few of these have survived. There were at least two at Korba Power Station (near Bilaspur), of which one could be fired and driven as late as 1999.
XT Light Tank, 0-4-2T, BG, Caprotti valvegear. Used for light passenger duties. In the '40s Ajmer workshops began producing this class of loco. A few of these have survived.
XA, XB, XC, XD, XE, XT, YB, YC, YD, YF, YK, ZB, ZE These classes were IRS designs from around 1925, and the first locos specifically designed for Indian conditions (in particular, they had a wider firebox and other improvements to handle low-grade coal).
XPThis 4-6-2 class was built by Vulcan Foundry for the GIPR in 1937. They were experimental locomotives, with the aim of gaining the power of the XC within the operating area of the XB. The aim was to achieve running mileages of 200,000 between overhauls, and a monthly average of 10,000 miles. These were very high figures for the time. The boiler and firebox of the XB were taken as the basis, although details were modified, and the wheels and cylinders were of the same dimensions. Boiler pressure was higher at 210lb, and the tractive effort of 31,200lb was greater than that of both the XB (26,760lb) and the XC (30,625lb).
Both locomotives were fitted with Caprotti valve gear, and both had roller bearings on all engine and tender wheels; one Timken (3100) and one Skefco (3101). They weighed 99 tons, with an axle load of 18-2/3 tons, and a grate area of 45 sq ft.
The XP class was the basis for India's renowned WP class 4-6-2.The two locos carried GIPR running numbers 3100 and 3101, and on CR the all-India numbers were 22599 and 22600.
CWD A design similar to the XD class, by the Canadian Locomotive Company and the Montreal Loco Works.
AWD A design similar to the XD class, by Baldwin. Along with the CWD's (above) the largest imported class, numerically.
AWE Baldwin variant of XE.
B The "B" class locos of the Darjeeling Himalayan Railway were unusual in having two kinds of tanks, saddle tanks and well tanks (0-4-0 SWT).
F 2-8-2 locos with bogie tenders built between 1926 and 1950 by Nasmyth Wilson, UK. Most were in service in CR.
ZB 2-6-2 NG loco built for Gaekwar Baroda State Railway.
EM 4-4-2 with 6'6" drivers, introduced in 1907 and in service until the late 1970's. EM 922 is at the NRM.
ZPAn NG 4-6-2 loco with 6-wheel tender, some built by Nippon Sharyo, Japan, around 1955. Was in service in CR, SER.
ZDThe original ZD class for 2'6" gauge was to be an IRS design of 4-6-2 (1925), based on the BNR Pacifics (class C, later CC or CS), with an axle load of 8 tons, and a loco weight of 41 tons. These were never built.
The ZD class as constructed was a modern 2-8-2 using a boiler based on the MG YL class (2-6-2) which had a pressure of 210lb. The 6 locos were built by Nippon Sharyo in 1957-58 to work trains on the two lines radiating north and south from Murtajapur. They had a 7 ton axle load.
ZEAn NG 2-8-2 loco with 6-wheel tender, some built by Kawasaki Rolling Stock of Japan, in 1955; was in service in CR, SER. This ZE class is not the same as the IRS class ZE specified in 1925. Some ZE's were imported from Germany in the 1980s. Most were based in Nainpur by the late 1980s.
WPA Pacific class introduced after World War II for passenger duties, marking the change from 'X' to 'W' for broad gauge locos. A WP at her finestIt was capable of doing up to 110km/h and remained IR's crack locomotive for many years. WP's were designed specifically for low-calorie, high-ash Indian coal, by Railway Board designers in India.
  • Tractive effort: 30,600lb
  • Axle load: 18.5 tons
  • Boiler: 5'11"
Several WP's remained in service until the '80s. Easily recognized by the cone-shaped bulging nose with (usually) a silver star device painted on it. Early prototypes from Baldwin were labelled WP/P; CLW versions after about 1965 were labelled WP/1. A few reconditioned WP's have been exported to countries in the middle East (after regauging?).
WGUntil the advent of diesels and electrics, IR's BG freight workhorse; capable of about 88km/h, and with a tractive effort of about 38,890lb. A WG exudes industrial atmosphereInitially imported (several were supplied by the North British Locomotive Co.), CLW began production of them in 1950, the first one, WG 8401 being named "Deshabandhu". More than 2,400 of these were built between 1950 and 1970 by CLW. India built her last BG steam engine in 1970, a WG, named "Antim Sitara". Sadly, WG 10560 Antim Sitara never really had a chance to do the type of jobs she was supposed to do, i.e. haul freights. The engine was in steam till about 1996 hauling coal trains to and from the coal washeries to coal mines, perhaps a dignified form of shunting.
The WG may have the distinction of being the class of loco that was manufactured in the largest number of countries, as units were built in England, Scotland, Germany, Austria, USA, Japan, Switzerland, and of course in India.
Some WG locos were marked 'WGx'. This was not a separate class of loco, but simply indicated that the loco had CBC knuckle couplers for working block freight rakes, especially on SER.
WLThere were two classes of BG 4-6-2 locomotives of the WL type. The first were 4 locomotives built by Vulcan Foundry in 1939 for the North Western Railway, and these went to Pakistan on partition. There is a Kelland photo of WL 103 ('New India'), streamlined with an aluminum casing, in Indian Locomotives, Part 4 by Hugh Hughes, hauling the 'Train of the Future'.
However, the Indian WL 4-6-2 was a new class built in 1955. Initially, 10 locomotives were built by Vulcan Foundry. They were designed to operate passenger trains on lines denied to the WP class; and so are lighter and smaller. While the new standard express WP class weighed 102 tons, the WL weighed 89 tons, giving an axle load of 16 tons, against the WP's 18.5t. Five WLs were allocated to the Southern Railway, and five to the Northern Railway. Ten years later, production began at CLW, and WL 15014-15107 were built there in the years 1966-1968.
NR WL #15005 (VF, 1955) hauled the last regular BG steam service in November 1995, and this loco is now in the Rail Transport Museum.
WT The broad-gauge WT was a 2-8-4T tank loco built for the busy and heavy suburban trains around Calcutta, before those lines were electrified. It is a noteworthy design for two reasons. It was the first locomotive to be fully designed at CLW; and it is probably the world's last new design of main line steam locomotive to go into series production. Ten were built by CLW in 1959-1960; and a further 20 in 1965-1967 -- these went to Madras. The last WTs were operating in the Rajahmundry area in the early 1980s.
They were large and powerful tank locomotives: they had the boiler and grate area of the WL class, with the WP's larger cylinders. Total weight of the WT was 123t, with an axle load of 18t. All of the post-war classes had a common boiler pressure of 210lb.
Much smaller were the six WT class 0-6-4T tanks built in 1925/6 for the Gaekwar's Baroda State railways. These locomotives had an axle load of 6t. In 1979, four WT were based at Nadiad, along with 1 W and 6 ZB and the other two were the sole power allocated to Devgadh Bariya.
A YP, workhorse on the metre gauge railsYPThe YPs were adapted Baldwins ordered for the Jodhpur MG network in 1948; some were later built in India. These locos had a tractive effort of about 18,400lb.
YG YG's were also imported at first (some from Germany; others were Baldwins) but later built in India by CLW and Telco. The last MG steamer built was a YG, simply named YG 3572. This last MG steamer was outshopped in 1972. Reconditioned YG's were also sold to Tanzania in the '70s. Tractive effort: 23,450lb.

Also see the sections on general information on IR locomotives, and lists of preserved and named locomotives.

Giesl Ejectors

Giesl ejectors, developed by the Austrian engineer Dr. Adolph Giesl-Gieslingen in the 1940s, consisted of a prefabricated nozzle and chimney with seven or more steam jets inline with the main nozzle and directed along it. The idea was to greatly improve the pumping efficiency of the exhaust within the loading gauge by using an oblong chimney (most of the length is below the boiler top line): depending on the original state of the loco, the Giesl ejector with superheater booster, produced notable fuel economies, and gains in available power.

IR ordered four Giesl ejectors in 1957: two were for WP locos, and two for AWE locos. The WP's were #3036 and #3037 (built by Wiener Lok, 1957); later WP's #7036 and #7037 were also fitted with Giesl ejectors. This was an unusual order -- in 1957, very few non-Austrian railways used Giesl ejectors. In 1964, 20 more ejectors were ordered, for WP/WG locos. In 1965 four more were ordered, two for WM locos and two for HPS locos. Finally, in 1966-67 85 were ordered for WG locos, and 45 for WP locos.

Seen here is a WP #3036 with a Giesl ejector. This is an AWE with a Giesl ejector.

The first fully developed Giesl ejector went into operation on an Austrian express 4-8-0 in 1951, and over 2400 ejectors were built by 1966. They were widely used in the last years of steam: the East African Railways equipped most of their modern steam fleet with them.

Boiler Numbers

In the days of steam, each steam boiler had an identifying number and its own schedule of maintenance. Boiler numbers were quoted in many ways, but a common format was something like '37/L/NG/1962'. In this, the 37 is the serial number, the L stands for a steam locomotive (although diesels and electrics don't have boilers, their equipment would use DL and EL instead), the NG refers to narrow gauge, and the 1962 refers to the year of manufacture.

The Bihta Accident The Locomotive Standards Committee set up in 1924 to update the BESA locomotive designs proposed several new designs for locomotives to be used in India. Among these designs known as the Indian Railway Standard or IRS classes was a 17 ton 4-6-2 locomotive design known as the 'XB' class.

These locos as well as the lighter 12.5 ton 4-6-2 'XA' class locos were involved in a number of minor derailments right from the beginning. On 17 July 1937, an XB loco hauling a mail train derailed at Bihta at an estimated speed of 96.5km/h, and over a hundred people died as a result. This tragedy received wide publicity. Although heavy monsoon rains had a role to play in undermining the track structure at the site of the derailment, it was determined that the tragedy was really caused by poor damping of lateral oscillations of the locomotive and its tender, which had over time also dangerously damaged the tracks. The investigation committee set up to look into the accident recommended that a deeper study be done into the design of the locomotive and ways to prevent such disasters.

As a result, in 1938, the Pacific Locomotive Committee was appointed and in its report published in 1939 recommended several significant changes to the loco design, such as modifications to the front bogie spring controls to damp the lateral oscillations, hind truck slides, and improved drawgear to couple the engine to its tender. Emphasis was also given to running these locos, even with the modifications, under strict speed limits.

However, World War II resulted in these plans for modified locomotives never materializing, and no purchase orders were placed with British manufacturers for any new XB locomotives. British manufacturers were fully occupied supplying required wartime locomotives. Instead, as the war progressed, India started receiving large numbers of locomotives from the USA and Canada (e.g., the X-Dominion or CWD 2-8-2, the AWD, AWE, etc.), which established a whole new set of loco designs in India, with their cast frames, integrated cylinders, and many other features including robustness in operation, and eventually this spelled the end of the old IRS set of loco designs in India.

For an alternative account of the accident, read Ken Staynor's article on the Bihta derailment.

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