loco-info.com - Royal State Railways of Siam No. 311 and 312

flickr/Historical Railway Images

In the twenties, the Royal State Railways of Siam (Thailand) got Mikado locomotives from different manufacturers. Beside some from the USA and France, two were delivered in 1924 by Nasmyth, Wilson & Co. in Britain. These were numbered 311 and 312 and used wood as fuel. According to contemporary reports, they performed very well.

General
Built	1924
Manufacturer	Nasmyth, Wilson & Co.
Axle config	2-8-2 (Mikado)
Gauge	3 ft 3 3/8 in (Meter gauge)

Dimensions and Weights
Length	58 ft 8 in
Wheelbase	27 ft 2 5/8 in
Rigid wheelbase	12 ft 9 3/8 in
Total wheelbase	48 ft 2 5/8 in
Service weight	129,091 lbs
Adhesive weight	88,659 lbs
Total weight	209,059 lbs
Axle load	22,221 lbs
Water capacity	3,603 us gal
Fuel capacity	18,300 lbs (wood)

Boiler
Grate area	32.7 sq ft
Firebox area	145 sq ft
Tube heating area	1,130 sq ft
Evaporative heating area	1,275 sq ft
Superheater area	280 sq ft
Total heating area	1,555 sq ft

Power Plant
Driver diameter	43.5 in
Boiler pressure	170 psi
Expansion type	simple
Cylinders	two, 18 1/4 x 23 3/8 in

Power
Power source	steam
Estimated power	1,100 hp (820 kW)
Starting effort	25,862 lbf

Calculated Values
Factor of adhesion	1 : 3.43
Optimal speed	27 mph
Power-to-weight ratio	0.0085 hp/lb
Heating Area Equivalent	2,560 sq ft
Cylinder volume/HAE	1 : 842.61
Adhesive weight/Total	1 : 1.46
Tractive force/Heating area	1 : 3738.92
Grate area/Heating area	1 : 43.12
Firebox/Tube area	1 : 9.72
Total/Superheater	1 : 4.55

steam locomotive

freight

last changed: 11/2024

Schematical drawing with dimensions

flickr/Historical Railway Images

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