History
A History of 2-6-4Ts and our Locomotive in Particular
This type had appeared on the Great Central in 1916 with some inside cylinder
engines but these were designed for freight duties. In 1917 R E L Maunsell
brought out a solitary example. Another 20 were built in 1925/26 (one with three
cylinders in lieu of two ) and intended for express passenger work on the South
Eastern section, but after an unfortunate derailment at Sevenoaks in 1927
resulting in a severe accident they were taken out of service and later rebuilt
as 2-6-0 tender engines. Meanwhile Sir Henry Fowler on the LMS had introduced
the type which was to prove extremely successful. 125 were built to his original
design and Sir William Stanier who succeeded Fowler in 1932 continued with his
own modifications. The principal of which was the substitution of a taper boiler
for the original parallel one. The design was also continued by his successors C
E Fairburn and H G Ivatt. Ultimately the whole class consisted of 545 engines.
What was to become the third most numerous of the Standard classes, after the 9F
2-10-0 and the 5MT 4-6-0, was introduced in 1951. Designed at Brighton (and, in
the main, constructed there), the Class 4 2-6-4 tank was firmly based on the
proven Stanier and Fairburn designs for the LMS, but with a number of changes to
bring it within the newly-introduced L1 universal loading gauge. The
distinctive, and stylish-looking inward curves of the cab sides, bunker and side
tanks of the Standard engines was a result of meeting the dictates of the L1
specification.
Although Brighton took overall responsibility for the design, detail work - as
with most of the Standard classes - was contracted out to other BR workshops, in
the case of the MT 2-6-4 tank to Derby, Doncaster, and Swindon. All but
twenty-five of the 155 strong class were also built on the south coast; of the
remainder, Derby turned out fifteen and Doncaster ten.
The demands of the L1 loading gauge further required a reduction in cylinder
size over the Fairburn engines (18 in diameter by 28in stroke as opposed to 19
and five eighths in by 26in). Another difference between the classes saw the
Stanier-pattern top feed substituted by Southern type clack valves and external
rather than internal rodding linked the cab regulator handle with the regulator
in the dome.
The Class 4MT was regarded as the tank engine equivalent of the Class 4 4-6-0
tender class (Nos 75000-79) and shared the same boiler type (BR5). Most of the
motion components were duplicated between the two classes, although the tanks
were equipped with two sidebars to support the crosshead.
In the original scheme of things, the Class 4 tanks were to have been
principally divided up between the Scottish, Southern and London Midland
Regions. Initially, the North Eastern Region was allocated just three and the
Eastern and Western Regions none at all. Eventually, the Eastern region became
home to some forty of the class and they became the mainstay of the commuter
services on the London, Tilbury and Southend line prior to electrification. The
NER also received its quota, but it was a while before Western Region sheds
received an allocation, chiefly locomotives displaced from the LT&SR route.
Presumably the WR was considered well-subscribed with Churchward/Collett Prairie
tanks.
The class 4 tanks became a familiar sight at London terminuses other than
Fenchurch Street: they worked out of Euston to Bletchley, from St Pancras to
Bedford and from Marylebone through the Chilterns. They found work out of
Victoria on the non-electrified outer suburban services to the likes of Oxted
and in their later years handled parcels and empty stock workings out of
Waterloo.
The sharp acceleration of the Standard 4 tanks, and the fair turn of speed
obtainable from the 5 ft 8 in diameter driving wheels, made them ideal suburban
tank locomotives, as was proved in and around Glasgow. Yet they also established
their usefulness on branch workings in the West Country and on the ex-Cambrian
lines in Wales. The North Eastern Region employed them between Whitby and
Scarborough, and the class even made a belated appearance on the Somerset and
Dorset. The tank's duties on the Scottish Region extended to the
Dumfries-Stranraer line and to banking on the climb to Beattock. Their
versatility made them popular locomotives, a popularity which has extended into
preservation. With fifteen survivors, the Class 4 tank is now numerically the
largest of the preserved Standard classes. The story of one of the most
successful of the Riddles Standard designs is set to continue.