Indian locomotive class XB
| Company type | Steam locomotive |
|---|---|
| Industry | Rail transport |
| Founded | 1920s |
| Headquarters | India |
| Products | 4-6-2 steam passenger locomotives |
Template:EngvarB Template:Multiple issues Template:Infobox locomotive
The Indian locomotive class XB was a 4-6-2 steam passenger engine, commonly referred to as a Pacific, featuring an axle load of approximately 17 long tons (17 t; 19 short tons). This model was among several standardized locomotives developed during the early 1920s under the Indian Railway Standard (IRS) initiative. Initially, the class encountered various operational challenges; however, after implementing certain adjustments, the XBs remained active in service until the 1980s.
Background and design
During 1924, the Indian Railway Board established the Locomotive Standards Committee to create new locomotive models in response to increased traffic following the First World War and the anticipated use of lower-grade coal, which previous designs were ill-suited to handle. Building upon the BESA concepts from the early twentieth century, a series of three 4-6-2 passenger locomotives and two freight 2-8-2 types were formulated.
The XB represented one of these Pacific-type configurations and was developed through collaboration between multiple manufacturers and the British Engineering Standards Association (BESA), coordinated by the Indian Railway Board. Its design bore similarities to contemporary British locomotives, incorporating American-style three-point suspension with compensating levers tailored to withstand India's variable track conditions. The trailing wheels utilized a Cartazzi axle, consistent with other British Pacific locomotives of that period. Additionally, Goodall-type drawgear connected the engine to its tender, allowing enhanced freedom of movement. The locomotive featured a copper firebox extended by a combustion chamber for improved efficiency.
Problems
Similar to other locomotives in the X series Pacific category, the XB model frequently experienced frame fractures. One particular locomotive underwent nine frame breaks within a span of nine years. Among the eighteen XBs operated by the East Indian Railway Company (EIR), the locomotives collectively spent three out of eight years undergoing repairs. Additionally, as a member of the X series Pacifics, it suffered from persistent coupling rod breakdowns. The radius of the tubeplate flanges was susceptible to cracking, necessitating frequent replacements. The boiler was substandard, operating at pressures below 150 pounds per square inch (1,000 kPa), and its diameter was insufficient to handle the volume of flue gas produced by the firebox. The ratio of tube cross-sectional area to grate area was only 9%. Performance tests revealed that this engine could not manage hauling a 350-long-ton (360 t) load at 60 mph (97 km/h) with a 33% cylinder cut-off. It exhibited lateral oscillations perpendicular to the track, which caused track damage. Over nine years, there were 68 incidents attributed to XB and XC class engines involving such oscillations.
Remediation attempts
To address these issues, the trailing bogie was repositioned 30 inches (760 mm) rearward, and an American-style drawgear was installed,[1]Template:Fix/category[better source needed] while speed limits of 45 miles per hour (72 km/h) were imposed on many routes.[2] In 1937, the Bihta accident occurred when the locomotive derailed at approximately 60 mph (97 km/h), resulting in over 100 fatalities.[2] This tragedy prompted public demand leading to the formation of the Pacific Locomotive Committee, which included representatives from Britain, France, and India.[2]
Robert Leguille proposed equipping both leading and trailing bogies with firmer side springs and enhanced damping mechanisms—an approach validated through testing. Following his recommendations, both the Bombay, Baroda and Central India Railway and Madras and Southern Mahratta Railway implemented these improvements, while EIR limited these locomotives to slower services. The alterations made in India were subsequently adopted by the London, Midland and Scottish Railway in Britain.[3]
| Technical specifications | |
|---|---|
| Length between tube plates | 18 ft 6 in (5.64 m) |
| Diameter of small tubes (95) | 2.25 in (57.15 mm) |
| Diameter of smoke tubes (22) | 5.5 in (139.7 mm) |
| Number of arch tubes | 4 (3 inches (76 mm) diameter) |
Preservation
None of the Indian Railways' XB class locomotives have been retained in preservation. However, locomotive No. 450, originally from the East Bengal Railway, has been preserved and is housed at the Lahore workshops in Pakistan.
Trains hauled by XB
See also
References
- ↑ Hughes 1979, p. 36.
- ↑ 2.0 2.1 2.2 Hughes 1979, p. 21.
- ↑ "XB 4-6-2". Archived from the original on 2 October 2013. Retrieved 30 September 2013.Template:Fix/category[better source needed]
Bibliography
External links
- Steam Locomotive Classes - Indian Railways Fan Club