Charles Collett
Charles Benjamin Collett was Chief Mechanical Engineer of the Great Western Railway from 1922 to 1941. He designed the GWR's Castle and King Class express passenger locomotives.
Education and early career
Collett was educated at the Merchant Taylors' School and the City and Guilds College of London University. He then became an engineering pupil at Maudslay, Sons and Field, a firm that built marine steam engines. In 1893 he entered the GWR Drawing Office at Swindon as a junior draughtsman. Four years later he was put in charge of the buildings section, and in 1898 became assistant to the Chief Draughtsman. In June 1900 he was appointed Technical Inspector, and soon after Assistant Manager, at the Swindon Works. In 1912 he rose to be Manager of the Works, then in 1919 he was made Deputy Chief Mechanical Engineer of the GWR.Chief Mechanical Engineer
Collett's predecessor, George Jackson Churchward, had delivered to the GWR from Swindon a series of class-leading and innovative locomotives, and arguably by the early 1920s the Great Western‘s 2-cylinder and 4-cylinder designs were substantially superior to the locomotives of the other railway groupings.In 1922 Churchward retired, and Collett inherited a legacy of excellent standardised designs. But, with costs rising and revenues falling, there was a need to rationalise the number of pre-grouping designs and to develop more powerful locomotives. Collett was a practical development engineer and he took Churchward's designs and developed them – notably the Hall from the Saint class, and the Castle from the Star. He was also responsible for more humble locomotives, such as many of the pannier tank classes.
4-cylinder engines
By the time Churchward retired, his 4-cylinder Star class locomotives were becoming inadequate for the increasing loads and speeds expected of express passenger trains. To solve this, Churchward had proposed fitting a No 7 boiler onto a Star. This was not possible, because the weight would be too great for the track. Instead, Collett enlarged the Star design, leaving the wheels the same but with bigger cylinders and a new standard boiler that would not exceed the ton permitted axle load. He also fitted a more comfortable cab. The result was christened the Castle class, and the first engine, No 4073 Caerphilly Castle, was soon proudly paraded at the British Empire Exhibition, with the claim that it was 'Britain's most powerful passenger locomotive'.One result of this provocative claim was an agreed exchange of locomotives between the companies. Castle class No 4079 Pendennis Castle went to the LNER in exchange for A1 class No 4474 Victor Wild. Both engines acquitted themselves well, but the performance of the smaller Castle led Gresley to investigate the cause and redesign the A1's valves, as well as give them a higher boiler pressure.
As well as rebuilding several Star class locomotives into Castles, Collett shocked some people by rebuilding the GWR's flagship locomotive No 111 The Great Bear into a Castle. This at least drew the attention of General Manager Sir Felix Pole to the restrictive permitted axle loads, which had constrained the usefulness of this prestige symbol. When larger locomotives were needed, Sir Felix instructed the Civil Engineer to ensure that the main lines could carry a ton axle load. This was quickly done, since work was already underway to meet this standard.
By 1926, the other railway companies were catching up with the GWR, with designs such as the LNER Pacifics, SR Lord Nelson class, and the imminent LMS Royal Scot Class. Better locomotives were needed not only for faster and heavier trains, but also for to uphold the prestige of the GWR. Collett started by testing driving wheels on No 5001 Llandovery Castle. When this proved satisfactory, he spread these wheels out under a larger and higher-pressure boiler, and increased the piston stroke to 28 inches, pushing the design to the limit both of the loading gauge and the newly increased axle load. Fitting these increased dimensions together required an unusual front bogie, with outside bearings on the front axle but inside bearings on the rear, to clear the inside and outside cylinders respectively. Finally, the first loco had cylinders bored out to inches. The significance of this small change was that it pushed the calculated tractive effort over 40,000 lbs, as required by Sir Felix Pole, thereby emphasising the locomotive's status as the most powerful passenger locomotive in the country. It was named the King class.
Like the Castle class, the King class was exploited for its publicity value. The very first one, No 6000 King George V, was shipped off to America where it led the parade of engines at the Baltimore and Ohio Railroad Centenary Exhibition, and whence it returned carrying a commemorative bell on its front buffer beam. The King class remained the heaviest and most powerful engine in Britain. Stanier paid it the compliment of using its principal dimensions in his first design, the LMS Princess Royal Class.
However, while it has been described as Collett's masterpiece, the suggestion has also been made that it was largely the responsibility of Hawksworth, Collett's eventual successor, who was then Chief Draughtsman.
Streamlining
A curious event in the story of the 4-cylinder designs was the appearance of two streamlined locomotives. In the 1930s there was a vogue for streamlining, and Collett came under pressure to produce a streamlined locomotive for the GWR, particularly in view of the forthcoming centenary of the company in 1935. The story goes that Collett took a paperweight model of a King, and smeared plasticine over it to produce an outline for the drawing office to work from. Although probably apocryphal, this may have been as good a way of designing a streamlined loco as any, short of carrying out tests in a wind tunnel. Collett was certainly aware of the many other factors causing drag. As The Great Western Railway Magazine put it, "Rigorous application of the principles of scientific streamlining becomes not only difficult but practically inexpedient, as the net reduction in the total resistance may be relatively small." In March 1935, locomotives 5305 Manorbier Castle and 6014 King Henry VII were outshopped with a hemispherical dome over the front of the smokebox, fairings covering the front buffer beam, cylinders, and splashers, fairings behind the chimney and dome, a vee-shaped cab front and a tapered roof over the tender. Both of these engines, and no others, were given a full-page photograph in the GWR's 1935 publication Swindon Works and its place in Great Western Railway History, but without any further descriptive text. The locomotives gradually lost the streamlined features as they passed through the shops in following years.Absorbed locomotives and the 5600 class
Collett became CME just before the grouping of British railway companies took effect on 1st January 1923. Although the GWR retained its identity by virtue of being grouped with many much smaller railways, it did make Collett responsible overnight for over 800 locomotives, of a wide variety of designs, many in a state of disrepair. The ones in the worst condition could only be scrapped; those in a better condition were surveyed to establish which could be refitted with boilers from the GWR standard range, including three new boilers modified for the purpose. The scrapping of so many unmaintainable engines left a shortfall in power, especially in the Welsh valleys where the widely-used compact inside-cylinder engines were hard to replace with standard GWR classes. Collett decided to build a new class, based on the Rhymney Railway R class. Although it used a standard No. 2 boiler, and as many other standard parts as possible, the cylinder castings, wheels, hornblocks, valve gear and three-bar motion crosshead were all new designs. The 5600 class was powerful and versatile, working both passenger and freight trains in the Welsh valleys in a characteristic 'facing up the valley' direction, so that on the faster descending services, the pony truck helped to keep them stable.However, one story indicates that the development of these engines was not without problems. According to Hurry Riches, the son of the last Locomotive Superintendent of the Rhymney Railway, who had been taken on by the GWR and worked on the new class, the first engine of the class stalled dramatically when it was first steamed. Investigation showed that in the transfer of the standard Stephenson valve-gear arrangement from outside-cylinder use to an inside-cylinder design, the function of the rocker shaft in withstanding off-axis forces was not appreciated, and inadequate support was provided for the end of the valve spindle. The result was that when steamed, the valve spindle bent under the strain, throwing the whole motion out of alignment. A quick fix had to be developed before any of the locomotives could be rolled out, and the story was apparently suppressed to avoid embarrassment at a senior level.
2-cylinder standard tender classes
Collett built no more of Churchward's Saint class locomotives, but he did build further batches of the 2-6-0 'Moguls' in 1925 and 1932. The Running Department asked him to build an enlarged version of this engine, as crews had a tendency to expect too much of it. However, Collett preferred to modify a Saint. He took No 2925 Saint Martin, and fitted it with smaller wheels. Over three years of testing, it proved itself a useful and popular mixed-traffic engine. In 1928 a batch of 80 engines of the new Hall class was ordered, differing from the Saints only in having the smaller wheels and a more generous side-window cab. Further batches totalling 259 locos were built up till 1943, and—together with his successor Hawksworth's 71 Modified Halls—made up the largest class of named locomotives on the GWR. Later testing showed that the Hall class suffered a marked reduction in drawbar horsepower when running over 50mph, as the boiler and cylinders designed for the Saint's wheels struggled to keep up with the faster revolving smaller wheels. Apart from one war casualty, and the prototype Saint Martin, none were withdrawn from service until 1960.In 1901 Churchward had proposed, as part of his set of standard locomotive classes, a two-cylinder with wheels, but never developed one. In 1936, seeking to replace the older 4300 'Moguls', Collett produced such a locomotive as the Grange class. Indeed, he withdrew 80 of the 'Moguls', and used the wheels and motion as part of a with the same No 1 boiler as the Halls. One disadvantage was that the Granges were heavier than the 'Moguls' and thus had more limited route availability. To answer this, in 1938 Collett withdrew another 20 'Moguls', and again used the wheels and motion to build a, this time with the specially developed, lightweight, No 14 boiler. These were the Manor class. Even though they were indifferent steamers until the draughting of the boiler was investigated and modified in 1951–52, British Rail still built another ten Manors in 1950.
Collett continued to build more in the form of the 2884 class, which differed only in detail, not in the principal dimensions, from Churchward's 2800 class of 1903. The last of this class was built by Collett's successor Hawksworth in 1942, and this class was represented in the 1948 Locomotive Exchange Trials.