Mallard is the holder of the world speed record for steam locomotives at 126 mph (203 km/h). The record was achieved on 3 July 1938 on the slight downward grade of Stoke Bank south of Grantham on the East Coast Main Line, and the highest speed was recorded at milepost 90¼, between Little Bytham and Essendine. It broke the 1936 German (DRG Class 05) 002’s record of 124.5 mph (200.4 km/h). The record attempt was carried out during the trials of a new quick-acting brake (the Westinghouse “QSA” brake).
Mallard was a very good vehicle for such an endeavour. The A4 class was designed for sustained 100+ mph (160+ km/h) running, and Mallard was one of a few of the class that were built with a double chimney and double Kylchap blastpipe, which made for improved draughting and better exhaust flow at speed. (The remainder of the class were retro-fitted in the late 1950s.) The A4’s three-cylinder design made for stability at speed, and the large 6 ft 8 in (2.03 m) driving wheels meant that the maximum revolutions per minute (529.4/min at 126 mph) was within the capabilities of the technology of the day. Mallard was just four months old, meaning that it was sufficiently broken-in to run freely, but not overly worn. Selected to crew the locomotive on its record-breaking attempt were driver Joseph Duddington (a man renowned within the LNER for taking calculated risks) and fireman Thomas Bray.
| Type and origin |
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| Power type | Steam |
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| Designer | Sir Nigel Gresley |
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| Builder | LNER Doncaster Works |
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| Serial number | 1870 |
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| Build date | 3 March 1938 |
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| Specifications |
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| Configuration: | |
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| • Whyte | 4-6-2 |
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| • UIC | 2’C1’h3 |
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| Gauge | 4 ft 8 1⁄2 in (1,435 mm) standard gauge |
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| Leading Wheel dia. | 3 ft 2 in (0.965 m) |
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| Driving Wheel dia. | 6 ft 8 in (2.032 m) |
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| Trailing Wheel dia. | 3 ft 8 in (1.118 m) |
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| Length | 70 ft (21.34 m) |
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| Loco weight | 102.95 long tons (104.6 t; 115.3 short tons) |
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| Total weight | 165 long tons (167.6 t; 184.8 short tons) |
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| Boiler pressure | 250 psi (1.72 MPa) |
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| Cylinders | Three |
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| Cylinder size | 18.5 in × 26 in (470 mm × 660 mm) |
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| Loco brake | Steam |
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| Train brakes | Vacuum |
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| Performance figures |
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| Tractive effort | 35,455 lbf (157.7 kN) |
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Further information at Wikipedia
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