Indian Railways 2-6-2 Locomotives in India


Class Details by Steve Llanso of Sweat House Media

Class IRS/YF (Locobase 4270)

Part of a series of designs created in the mid-1920s to meet Indian railway requirements. This narrow-gauge Prairie used the same boiler and driver set as the 0-6-2 YF, but added a leading truck. It also put more weight on the drivers.

[] notes that these had "...a wider firebox and other improvements to handle low-grade coal."

Dr. Jonathan Smith of Iowa State ([] ) for data on this design.


Class IRS/ZB (Locobase 4271)

Part of a series of designs created in the mid-1920s to meet Indian railway requirements. Smaller than the YF Prairie, this class operated on an even narrow gauge.

[] notes that these had "...a wider firebox and other improvements to handle low-grade coal."

Dr. Jonathan Smith of Iowa State ([] ) for data on this design.

[] -- the website of India's National Rail Museum and edited by S. Shankar -- shows the RD, which looks very much as if it could be related to this design. It has low drivers, but is described as "non-standard". (The RD meant Raipur-Dhamtari, the stretch of the Bengal Nagpur Railway on which it ran.)


Class IRS/ZF (Locobase 4272)

Part of a series of designs created in the mid-1920s to meet Indian railway requirements.This little Prairie tank had some useful power for its narrow gauge.

See [] -- the website for India's National Rail Museum -- where it comments: "Derived from an earlier very popular KC class, the ZFs were compact and powerful engines, used extensively on the hill lines of the Kalka-Simla line and Kangra Valley (Pathankot-Jogindernagar). The formidable looking machines were utilized primarily for passenger operations, and some of them survived well into the late 1980s. One unusual feature of these engines is the absence of the familiar driver's lookout when the boiler was leading. This was largely because of the large size of the side tanks, and heightened coal bunkers.Nonetheless, despite this, several drivers preferred to drive the engines boiler forward due to easier accessibility to the controls. The ZFs were fitted with Caprotti valve gear. However, later variants of this class were fitted with Walschaert's valve gear, and several of them were classed ZF/1."

[] notes that these had "...a wider firebox and other improvements to handle low-grade coal."

Dr. Jonathan Smith of Iowa State ([] ) for data on this design.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassIRS/YFIRS/ZBIRS/ZF
Locobase ID4270 4271 4272
RailroadIndian RailwaysIndian RailwaysIndian Railways
CountryIndiaIndiaIndia
Whyte2-6-22-6-22-6-2T
Number in Class
Road Numbers
GaugeMetre2'6"2'6"
Number Built
Builderseveralseveralseveral
Year192519251925
Valve GearCaprotti
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)56,000 / 25,40140,320 / 18,28964,960 / 29,465
Engine Weight (lbs / kg)80,640 / 36,57864,960 / 29,46594,080 / 42,674
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)94,080 / 42,674
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)31 / 15.5022 / 1136 / 18
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)43 / 109234 / 86430 / 762
Boiler Pressure (psi / kPa)160 / 11160 / 11160 / 11
High Pressure Cylinders (dia x stroke) (in / mm)14" x 22" / 356x55912" x 18" / 305x45714" x 16" / 356x406
Tractive Effort (lbs / kg)13,638 / 6186.1010,368 / 4702.8514,217 / 6448.73
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.11 3.89 4.57
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)
Grate Area (sq ft / m2)18 / 1.6714 / 1.3016 / 1.49
Evaporative Heating Surface (sq ft / m2)641 / 59.57587 / 54.55
Superheating Surface (sq ft / m2)136 / 12.64125 / 11.62
Combined Heating Surface (sq ft / m2)777 / 72.21712 / 66.17
Evaporative Heating Surface/Cylinder Volume163.53249.13
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation288022402560
Same as above plus superheater percentage339826432560
Same as above but substitute firebox area for grate area
Power L1
Power MT

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