Indian State 2-8-4 Locomotives in India

Class Details by Steve Llanso of Sweat House Media

Class IGR/WT (Locobase 4293)

See [], last accessed 3 July 2006. (Thanks to Phil Atkins for his 10 April 2023 comment on the actual origins of the WT design. Phil wrote the article for Steam Railway, issue No. 541, for February 3 to March 2, 2023, pp. 60-69, which he states is the only source he's seen to offer an article considering the WT. Thanks as well for Phil's very helpful 18 June 2023 reply to a request for the WT's locomotive diagram; Locobase could not find the specifications anywhere else.)

The 2006 description commented that these Berkshire tanks used the boiler of the WL Pacific design and the WP Pacific's running gear. In any case, note the typically high boiler pressure and consequent high boiler demand factor, but the generous grate. 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.

The IRFCA site notes two reasons why the WT was a noteworthy design. "It was the first locomotive to be fully designed at CLW [Chittaranjan Locomotive Works]; and it is probably the world's last new design of main line steam locomotive to go into series production.

IRFCA's note that this was the first design wholly laid out by the CLW is consistent with Phil Atkins's claims, which Locobase quotes in full:

"It is incorrect to state that these locomotives incorporated the same (round

top/wide firebox) boiler as the IGR Class WL light 4-6-2s, that were introduced

in 1955. The WT actually utilised the basic boiler design with narrow Belpaire

firebox of the two Class GSM 4-6-0s built for the Bengal Nagpur Railway in 1937,

only modified to provide higher superheat. The narrow firebox dictated the use

of British style plate frames rather than American style bar frames that

otherwise characterised the other post-war Indian standard locomotive classes.

All of these shared a standard boiler pressure of 210psi, which was not unduly

high by contemporary standards. The preceeding 4-6-0s were the ultimate

development of the classic 'Indian Mail' 4-6-0, and were designed in England,

where they were built by Robert Stephenson & Co. in Darlington."

Its outside constant-lead radial valve gear actuated 12" (305 mm) piston valves.

The first 10 left CLW in 1959-1960 for suburban service around Calcutta. In 1965-1967, CLW supplied 20 more for Madras State operation. Phil Atkins noted that the original authorizations added to 136, but the balance never materialized as the state railways ordered more WG 2-8-2s and some WL 4-6-2s.

"The last WTs were operating in the Rajahmundry area in the early 1980s", the site's summary of service concludes.

Heating surface data originally from tables created by Dr. Jonathan Smith of Iowa State and hosted on [] ...(10 December 2004).

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID4293
RailroadIndian State
Number in Class30
Road Numbers
Number Built30
BuilderChittaranjan LW
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)18 / 5.49
Engine Wheelbase (ft / m)42 / 12.80
Ratio of driving wheelbase to overall engine wheelbase 0.43
Overall Wheelbase (engine & tender) (ft / m)42 / 12.80
Axle Loading (Maximum Weight per Axle) (lbs / kg)40,208 / 18,238
Weight on Drivers (lbs / kg)154,560 / 70,107
Engine Weight (lbs / kg)275,408 / 124,923
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)275,408 / 124,923
Tender Water Capacity (gals / ML)3600 / 13.64
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 6.60 / 6
Minimum weight of rail (calculated) (lb/yd / kg/m)64 / 32
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)67 / 1702
Boiler Pressure (psi / kPa)210 / 14.50
High Pressure Cylinders (dia x stroke) (in / mm)20.25" x 28" / 514x711
Tractive Effort (lbs / kg)30,589 / 13874.95
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.05
Heating Ability
Tubes (number - dia) (in / mm)124 - 2" / 51
Flues (number - dia) (in / mm)30 - 5.25" / 133
Flue/Tube length (ft / m)13.49 / 4.11
Firebox Area (sq ft / m2)208 / 19.32
Grate Area (sq ft / m2)38 / 3.53
Evaporative Heating Surface (sq ft / m2)1637 / 152.08
Superheating Surface (sq ft / m2)409 / 38
Combined Heating Surface (sq ft / m2)2046 / 190.08
Evaporative Heating Surface/Cylinder Volume156.84
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7980
Same as above plus superheater percentage9576
Same as above but substitute firebox area for grate area52,416
Power L114,285
Power MT815.04

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