The reference for locomotives and railcars
London & North Eastern class W1 “Hush-Hush”
Great Britain | 1929 | only one produced

In 1929, Gresley attempted to build a high-pressure locomotive using the Yarrow boiler from shipbuilding. This boiler consisted of three barrels arranged in a delta shape and was not divided into a firebox and a boiler barrel. It was faired with a streamlined mantle and operated at 450 psi. The chassis came from an A1 Pacific and was expanded to include an additional, independently movable trailing axle. A four-cylinder compound engine was used, which had relatively small cylinders due to the high pressure. Since the boiler did not meet the expectations placed upon it, the locomotive was rebuilt with a conventional boiler in 1936 and was given three cylinders of the same size.

Variantas builtrebuilt
Axle config4-6-4 (Hudson) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Service weight241,920 lbs
Adhesive weight147,840 lbs
Water capacity6,005 us gal
Fuel capacity20,160 lbs (coal)
Power sourcesteam
Estimated power3,000 hp (2,237 kW)2,500 hp (1,864 kW)
Optimal speed73 mph38 mph
Starting effort26,325 lbf41,438 lbf
with start valve31,590 lbf
Power Plant
Driver diameter80 in
Boiler pressure450 psi250 psi
Expansion typecompoundsimple
Cylindersfour, HP: 12 x 26 in
and LP: 20 x 26 in
three, 20 x 26 in
Grate area35 sq ft50 sq ft
Firebox area1,114 sq ft
Tube heating area1,484 sq ft
Evaporative heating area2,598 sq ft
Superheater area750 sq ft
Total heating area3,348 sq ft
Calculated Values
steam locomotive
high pressure
Herbert Nigel Gresley
last changed: 03/2023

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