R.o.B Motive Power
LNER A4's 4-6-2
Specifications: Built by the LNER and first introduced from Doncaster works in March 1935
BR numbers: 60001-60034
Tractive effort: 35,455 lbs
Driving wheels: 6 ft 3 in
Bogie wheels: 3 ft 2 in
Trailing wheels: 3 ft 8 in
Length: 71 ft 3/8 in
Total weight: 165 tons 7cwt
Fuel capacity: 8tons
Water capacity: 5,000 tons
Cylinders: (3) 18 1/2 in x 26 in (Some engines had 17 in inside cylinder)
Boiler pressure: 250 lbs psi
BR power classification: 8-P/6-f
Purpose: Express passenger
Designer: Sir Nigel Gresley
Route availability: 9
The A4's were a development of the A3, though they were entirely new engines based on the success of the A3 design rather than a re-build as the A3's had been from A1's. The A4's were developed as part of the race to the north that the LNER was competing in against the LMS, both companies wanting to gain the fastest speed/journey time to Scotland. As with the A3's and the LMS 'Coronation' class Gresley wanted a locomotive that would attract the attention and interest of not only passengers but the media. It is commonly stated that these engines were the ultimate in British steam locomotive styling with their streamlined casing, Vee fronted cab giving a smooth look and efficient running. For these engines Gresley utilised higher boiler pressure, larger diameter piston valves and the internal streamlining of steam ports and enlarged passages. These were an important factor in the locomotives performance as it allowed the smooth flow of steam from the boiler with a higher force behind it getting it in to and out of the cylinder, which achievement gave the locomotive the opportunity to often pass the 100mph mark when operating fast express services on the LNER main line as Gresley intended them to be more beneficial hauling light weight trains at high speed.
The first four of the class were introduced to haul the LNER's new service which used silver liveried specially designed streamlined coaches the train being named 'Silver Jubilee', after the coronation celebration of 1935, running from London to Newcastle. The first engine to be rolled out of Doncaster works was LNER No.2509 'Silver Link', having been given priority construction at the works and rolled out in the September the order only having been placed in the March of that year. The engine was appropriately turned out in a silver livery to match its coaches and on its first public run achieved 112.5mph. The engine was to be the sole operating locomotive of that train for the first two weeks of operation, covering 5,366 miles as it did so. Another 3 of the class followed also liveried in silver with names such as 'Silver Fox' and 'Silver King' No. 2511 which was based away from its class mates at Gateshead the other 3 engines having Kings cross top shed as their base.
With the success of these locomotives and the streamlined services the LNER decided to introduce more services such as the 'Coronation' and the 'West Riding Limited' resulting in the need for more locomotives of the class the order placed for 31 more locomotives. The new A4's arrived in Garter Blue livery which is perhaps the most famous that the engines are recognised in and with them came a number of locomotives for use on general traffic, only specific engines having been chosen for the named trains. The 21st of the A4's built also happened to be the 100th Gresley Pacific locomotive so on the 26th November 1937 it was appropriately named after its designer 'Sir Nigel Gresley'. Though it is understood that like Stanier, Gresley saw streamlining as a means of publicity the effect of streamlining was obvious when the locomotives arrived back at their sheds having used less coal than an engine of their size would normally for the type of work they were doing, though this had more to do with the valve and piston design than anything else. In March 1938 a new design to the class was added when No.4468 'Mallard' was introduced to traffic with a double blastpipe and chimney, a French idea proven to improve efficiency.
One of the problems that Gresley faced with his high speed high efficiency locomotives was braking, so high speed braking test runs were made to try out different forms of brakes on the locomotives designed by the Westinghouse company. On the 3rd July 1938 as part of the trials No.4468 took the 7 coach test train along the main line returning with a world high speed record for a steam locomotive that has never been beaten after descending Stoke Bank, south of Grantham at over 125mph! The engine having been expertly driven by Joe Duddington with Tommy Bray as fireman, there names now part of high speed railway legend. For the time the train was travelling at that speed the driving wheels had carried out 500 revolutions and by milepost 90 (90 miles from London) the dynamometer car recorded 126mph for 5 miles.
With the advent of World War 2 express services and races to the north took a back seat the engines focusing on their power to move trains hauling heavy loads of soldiers along the east coast main line, sadly the war also saw the withdrawl of No.4499 after it was bombed along with York engine shed in 1942. With the end of the war they returned to their express routes with new trains introduced though it was not to be long before they started to be transferred to slower services No.4468 'Mallard' becoming the last steam locomotive to haul the 'Elizabethan' on 9th September 1961. The first of the class to be withdrawn from BR service was 'Silver Link' in the December of 1962. Not all of the class were immediately withdrawn as some were sent north to Scotland where they handled services from Edinburgh to Aberdeen and on the Waverley route from Carlisle to Edinburgh. The final 3 A4's were withdrawn from BR service in the September 1966. Today 6 of the engines survive, 4 in Britain the other 2 in America. BR No. 60009 'Union of South Africa' was the last scheduled steam hauled train from London Kings Cross also having been the last Steam locomotive to be overhauled at Doncaster works. The most recent of the A4's to re-enter traffic was 60019 BITTERN. It was at the Mid Hants railway for many years under restoration, some parts now on it made by the author! It re-entered traffic at the end of July 2007.
No 60009 Union Of South Africa: This locomotive was completed at Doncaster works in the June of 1937 and was one of 5 of the class to be used on the 'Coronation' which was the second streamlined service to be introduced, and was one of the first to be introduced in Garter Blue. As was mentioned in the A3 article some of the A4's were given the corridor tenders used by the A3's this locomotive was one of them. On introduction to service it was based at Haymarket depot (Edinburgh) where it remained until May 1962 having received a double blast pipe and chimney in the November of 1958, the engine continuing north to Aberdeen, Feryhill from where it was withdrawn in 1966. Originally it had been intended for the class to carry the names of birds, for example BR No.60009 was to be known as 'Osprey' but became known as the 'Union of South Africa' along with 4 other of its class mates that were named to honour the dominions of the British Empire. When BR withdrew the engine from traffic it was instantly purchased by a group of businessmen who formed the Lochty Private Railway Company, near Anstruther, East Fife along the former freight line from Leven to Lochty the private railway closing in the 1980's. Today it regularly sees main line and preserved action though is based at the Severn Valley railway.