NER Class 66 & LNER Class X1  2-2-4T  Aerolite  

 66 1 As built in 1869 as a 2-2-2T but with the sidetanks added in 1886
 66 2 As a 4-2-2T following the rebuild in 1892
 66 3 As a 2-2-4T following 1902 rebuild
Power Classification  
Introduced 1869
Designer Fletcher but with subsequent rebuilts
Company NER
Weight As a 2-2-2T – 37t 0cwt

As a 4-2-2T – 38t 15cwt

As a 2-2-4T – 44t 10cwt

Driving Wheels 5ft 8ins
Boiler Pressure As a 2-2-2T – 140lbf

As a 4-2-2T – 160lbf

As a 2-2-4T – 175lbf

Cylinders Inside – High Pressure -13in x 20in

Low Pressure – 18½in x 20in

Tractive Effort In final form – 6,390lbf
Valve Gear In final form – Stephenson (slide valve)

An outside cylinder 2-2-2WT named Aerolite was built by Kitson, Thompson and Heitson (Leeds) in 1851, originally for display at the Great Exhibition of that year. It was purchased by Leeds Northern Railway in April 1852’ and became NER 369. It was damaged beyond economic repair at Otterinton in 1868, although no such incident was reported upon by the Board of Trade. 

A new inside cylinder 2-2-2WT was built by Edward Fletcher at Gateshead in September 1869. It was numbered 66 given nameplates from the earlier Aerolite. It has been suggested that the name was removed in May 1883 prior to the engine being rebuilt.

In May 1886 the engine was extensively rebuilt which included being fitted with a new boiler and side tanks, in the T W Worsdell style as a side tank. 

In November 1892 it was rebuilt again to be a two-cylinder compound and with a leading bogie to form a 4-2-2T.

In the April 1902 rebuild it acquired a larger bunker at this rebuild.t yet again. This time as a 2-2-4T and again it acquired a new boiler but still as a two-cylinder compound.

New Aerolite nameplates were fitted in 1907, together with new number plates proclaiming Kitson origin 1851, at the behest of Lord Airedale (the former Sir James Kitson, and head of the eponymous Leeds locomotive building firm) an NER director possibly in celebration of his recent elevation to the peerage.

In August 1910 new cylinders were fitted and in March 1919 it had a new crank axle. In February 1921 it was again fitted with a new boiler.

Westinghouse brakes and vacuum ejector were fitted December 1928 which enabled it to participated in the Stockton and Darlington Centenary procession.

This locomotive was thus much rebuilt, but why it was rebuilt as a (two cylinder) compound as late as 1892 (then as a 4-2-2T) is something of a mystery, which it also remained when in 1902 it was rebuilt from 4-2-2T to 2-2-4T, and new cylinders were even fitted in 1910. As such 66 was the last two-cylinder compound to remain in service in Great Britain (as opposed to Ireland) by many years.

Following Grouping in 1923 the engine became LNER 1478. Throughout its life under LNER ownership it was based at Darlington.

Latterly it was used to haul the inspection saloon of the Deputy CME at Darlington, Arthur Stamer. After he retired in 1933 66 was restored for York LNER Railway Museum (January 1934) which it entered in June 1934, which was its official withdrawal date.

Home Base Current Status Owner
National Railway Museum – York On static display National Railway Museum NRM Object Number{1975-7013}
66 Aerolite
This image has an empty alt attribute; its file name is 66-aerolite-in-doncaster-works-may-1979.jpg
66 Aerolite in Doncaster Works – May 1979
66 Aerolite in the National Railway Museum at York-1992
66 Aerolite in the National Railway Museum at York – September 2010
66 Aerolite in the National Railway Museum at York – May 2018

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