LNER B17

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======================================================================The B17's (Sandringham or Footballer) worked on the LNER, designed by Gresley for hauling passengers on The Great Eastern Mainline.

Background
By 1926, the former GE B12 class locomotives were no longer able to cope with the heaviest express passenger trains on the Great Eastern Main Line between London and Cambridge, Ipswich and Norwich. Yet Gresley was unable to use his larger classes due to severe weight restrictions on the line. The requirement for a lightweight yet powerful 4-6-0 proved to be difficult to achieve.

Design
After several unsuccessful attempts by Doncaster Works to satisfy Gresley's specification, the contract for the detailed design and building of the class was given to the North British Locomotive Company in 1927. They used several features from a batch of A1 Pacifics they had built in 1924. The cab, cylinders, and motion had all been copied directly or slightly modified. Most of the boiler design was taken from the LNER Class K3 2-6-0 and LNER Class O2 2-8-0 designs. Darlington Works provided drawings for the bogies, and Stratford Works designs for the GE-type 3,700-imperial-gallon (17,000 l; 4,400 US gal), 4-long-ton (4.1 t) tender.

Due to weight restrictions it proved to be impossible for all three cylinders to drive the middle coupled axle, the design used divided drive with the middle cylinder driving the leading axle and was positioned forward above the front bogie. The LNER also ordered some modifications, including an increase in cylinder size from 17 in (432 mm) to 17 1⁄2 in (444 mm), and a lengthening of the firebox by 5 in (127.0 mm) with longer frames, and lighter springs. The design continued to prove problematic and the LNER eventually cancelled a penalty clause in the original contract. The first locomotive, No. 2802 Walsingham was delivered 30 November 1928, thirteen weeks late.