After the Great War of 1914-18 fresh developments took place towards standardization and the recommendations for IRS designs took into account factors such as quality of water and coal used in India and a concerted effort was made to ensure that the standard designs now proposed were adopted by all Railways instead of the variations that happened in case of BESA where even nomenclature varied from System to system. Some of the IRS designs that were developed at the time served the Indian Railways for several decades. The Classes of IRS Locomotives built included the ‘YB’ a 4-6-2 Passenger Locomotive, YC a 4-6-2 Heavy Passenger Locomotive with a 12 tonne axle load, ‘YD’ a 2-8-2 Freight Locomotive, ‘YF’ a 0-6-2 Branch line Locomotive, ‘YK’ another 2-6-0 Branch Line Locomotive and the ‘YT’ a Light Tank locomotive. Brief details of some of these classes is given below: Photos: Courtesy National Rail Museum New Delhi.
YB2 CLASS: The ‘YB’ Class was the standard passenger locomotive of the IRS standardization and the engine a 4-6-2 continued to be in service for several years. The locomotive was built by several manufacturers from the late1920’s up to 1952. There were 10 YB engines on the Railway in 1953 all of which came from the Bikaner State Railway and some of them were still in service more than two decades later. Six of these YB2 Locomotives were built as recently as 1951 & 1952 (30133 – 38) by R. Stephenson & Hawthorns Ltd., Newcastle & Darlington. The balance four were YB1 built in 1939 (30129 -32) built by Berliner Maschinenbau, Berlin.
Valve Gear
Walschaerts
Cylinders (Diam X Stroke) in inches
16” x 24”
Super Heater
Yes
Diameter of Coupled Wheels
57”
Total Heating Surface
1373.5 sq ft
Boiler Pressure lb per sq in
180
Tractive Force at 85% Boiler Pressure
16492 lbs
Grate Area
23.1 sq ft
Maker’s Name
R. Stephenson & Hawthorns, Vulcan Foundry, Ajmer Works, Berliner Maschinenbau, Berlin & others
Year of Manufacture
1928 – 1952
YD CLASS: The ‘YD’ Class was the IRS Goods locomotive with a 2-8-2 wheel arrangement and an axle load of 10 tonnes. Northern Railway had 8 of these engines in 1954 which were progressively condemned as only one survived till 1967. A few of these were built by the Ajmer Workshops in 1932 viz No’s 30293-95, previous No’s 253-5.
Valve Gear
Walschaerts
Cylinders (Diam X Stroke) in inches
17” x 24”
Diameter of Coupled Wheels
48”
Total Heating Surface
1701 sq ft
Boiler Pressure lb per sq in
180
Tractive Force at 85% Boiler Pressure
23649 lbs
Grate Area
26 sq ft
Maker’s Name
Ajmer Workshops, Vulcan Foundry, Nasmyth Wilson, AEG Berlin, SLM Winterthur & others
Year of Manufacture
1927 – 1949
YF CLASS: The ‘YF’ was the IRS Branch line locomotive with a light 8 ton axle load. The wheel arrangement which was initially 0-6-2 was subsequently modified to 2-6-2. There were 9 locomotives that Northern Railway inherited, two of which were of 1929 vintage i.e. No’s 30333 & 30334 previously 107 & 108 built by J. A. Maffei AG, Munich and the balance were of 1930 built by Fried Krupp Maschinenfabriken, Essen.
Valve Gear
Walschaerts
Cylinders (Diam X Stroke)
14” x 22”
Super Heater
Yes
Diameter of Coupled Wheels
43”
Total Heating Surface
776.7 sq ft
Boiler Pressure lb per sq in
160
Tractive Force at 85% Boiler Pressure
14765 lbs
Grate Area
17.75 sq ft
Maker’s Name
J. A. Maffei AG, Munich, AEG Berlin & Fried Krupp Maschinenfabriken Essen.
Year of Manufacture
1928 – 1938
