| LNWR Experiment Class (Whale) | 
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| | Type and origin | 
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 | Power type | Steam | 
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 | Designer | George Whale | 
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 | Builder | Crewe Works | 
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 | Serial number | 4505–09, 4550–59, 4620–39, 4680–89, 4770–89, 4830–69 | 
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 | Build date | 1905–1910 | 
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 | Total produced | 105 | 
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 | Rebuild date | 1915 | 
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 | Number rebuilt | 1 | 
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 | 
| | Specifications | 
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 | Configuration: 
 |  | 
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 | • Whyte | 4-6-0 | 
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 | • UIC | 2′C n2 (rebuilt: 2′C n4) | 
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 | Gauge | 4 ft 8+1⁄2 in (1,435 mm) | 
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 | Leading dia. | 3 ft 9 in (1.143 m) | 
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 | Driver dia. | 6 ft 3 in (1.905 m) | 
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 | Loco weight | 65.75 long tons (66.81 t) | 
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 | Fuel type | Coal | 
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 | Boiler pressure | 175 psi (1.21 MPa) | 
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 | Heating surface | 2,041 sq ft (189.6 m2) | 
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 | Cylinders | Two (rebuilt: four) | 
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 | Cylinder size | 19 in × 26 in (483 mm × 660 mm); rebuilt: 14 in × 26 in (356 mm × 660 mm)
 | 
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 | Valve gear | Joy; rebuilt: Dendy-Marshall | 
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 | Valve type | Slide valves | 
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 | 
| | Performance figures | 
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 | Tractive effort | 18,616 lbf (82.8 kN); rebuilt: 20,232 lbf (90.0 kN) | 
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 | 
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The London and North Western Railway (LNWR) Experiment Class was a class of 4-6-0 steam locomotive designed by George Whale.