Edward Thompson (engineer)

Edward Thompson (engineer)
Born	25 June 1881 Marlborough, Wiltshire
Died	1954
Nationality	British
Education	Marlborough College Pembroke College, Cambridge
Engineering career
Engineering discipline	Mechanical engineering

Edward Thompson (25 June 1881 – 1954) was Chief Mechanical Engineer of the London and North Eastern Railway between 1941 and 1946. Edward Thompson was born at Marlborough, Wiltshire on 25 June 1881. He was the son of an assistant master at Marlborough College. He was educated at Marlborough before taking the Mechanical Science Tripos at Pembroke College, Cambridge. Thompson's academic background contrasts with that of his predecessor Nigel Gresley, who had also attended Marlborough, but then gained practical experience as a pupil at Horwich Works.

Career

NER, GNR, LNER

After graduation Thompson worked in both industry and the railways for a while. By 1910 he was assistant divisional locomotive superintendent on the North Eastern Railway (NER), in which capacity he gave evidence at the inquiry into the fatal accident between two goods trains at Darlington on 15 November 1910. In 1912 he was appointed Carriage and Wagon Superintendent for the Great Northern Railway (GNR). He remained at this post for 18 years until he became Workshop Manager at Stratford Works in 1930. This was his final post before becoming Chief Mechanical Engineer (CME) of the London and North Eastern Railway (LNER) in 1941 after the death of Nigel Gresley. Edward Thompson retired from the post of CME in 1946. Gresley and Thompson disagreed on a number of matters. The biggest dispute between them was on the Gresley conjugated valve gear for 3-cylinder engines. This valve gear arrangement worked well during peacetime but experienced problems due to poor maintenance during the Second World War, giving Thompson some justification for his criticism of the design.

Thompson had a number of incidents with Gresley, and given the previous heated debated between Gresley and Thompson's father-in-law, Sir Vincent Raven, it is probable that there was a degree of petulance about Thompson's choice for his prototype A1/1 engine, namely No.4470 Great Northern, both for its name (that of NER rival company the GNR) and for it being Gresley's first Pacific, though opinion on this is heavily divided. Another incident is noted by O.S. Nock that Gresley reprimanded Thompson for interfering in the actions of a driver on an engine which had failed in service.

Gresley's passing was very unexpected, and the LNER had no immediate successor in mind. The LNER board of directors first requested permission from Southern Railway to approach their chief mechanical engineer, OVS Bulleid, who had been had been Gresley's assistant until joining the Southern four years previously. Permission was granted, but he declined the offer. J.F. Harrison, the man later largely responsible for the design of No.71000 "Duke of Gloucester", was the popular choice. However, at 42 years old, it was considered inappropriate for someone so young to take the post. The LNER board then turned to Arthur Peppercorn for the CME role, but Thompson held seniority amongst other LNER officials and used this political experience to sidestep Peppercorn and take the title of CME.

Temperament

According to Col H.C.B Rogers (who in turn cites a number of the LNER Engineers, Harrison, Smedley, Spencer et al), Thompson possessed an ill temper towards his colleagues and was notoriously difficult to deal with. The Drawing office at Doncaster had full height panelling on the walls of the corridors, which Thompson had windows fitted the full length of, so that he could see all that was going on and what people were doing. Those who did not agree with him did not work with him for long. He possessed a strong dislike of his predecessor, and changed a lot of Gresley designs to his own ideas, many of which lacked foundation, and in a balanced environment, would not have been considered as acceptable to introduce onto a locomotive design.

Standardisation programme

When Thompson was appointed CME of the LNER he started a much needed standardisation programme. This programme demonstrated Thompson's dislike for Gresley's engineering practices. Many notable Gresley designs were rebuilt under this practice including the P2 Mikado, V2 Prairie and A1 Pacific locomotives. The A1 chosen for rebuilding was Great Northern, this being the original Gresley prototype for the class.

Thompson's designs

Pacific rebuilds

While Thompson criticised many of Gresley's practices, equivalent comment can be made about many of Thompson's designs. His Pacific rebuilds were not the best designs. They all retained three cylinders, but with divided drive and 3 sets of independent Walschaerts valve gear. Thompson attached great importance to having the connecting rods equal in length, which was in fact unnecessary. As a result, the outside cylinders were placed behind the front bogie with the inside cylinder well forward. This gave the engine an unnecessarily long wheelbase, created long exhaust channels, generated vibration and encouraged flexing and fracture of the locomotive frames. All of his Pacifics were particularly prone to wheel slip owing to the high power output of the engine in relation to the adhesion factor. The engines were effective, and the design had materially less maintenance demand on the internal valve gear than the conjugated locomotives, but the positives were outweighed so much by the problems, which were of such significance that they were withdrawn and scrapped before many of their older Gresley designed counterparts. The Thompson Pacifics were ultimately more maintenance intensive overall than the Gresley engines. Thompson omitted the "banjo dome" that had featured on the Gresley Pacifics since 1928. However, Thompson's successor, Arthur Peppercorn, revived the feature on the remaining batches of LNER Pacifics.

From a technical standpoint, a number of the features of the Thompson design were not considered as acceptable or reasoned principles, as they did not follow established locomotive consideration. Divided drive, although it did reduce the total stress/strain on the centre crank axle, did not lend itself to frame integrity, especially coupled with connecting rods of equal length, as the greatest point of rigidity in the frame structure itself, the Cylinders, were no longer lined up. locomotive frames are flexible to handle side to side twist, and even axial twist along their length, but fore and aft motion between the frames leads to bearing and joint failures. To arrange the engines, and maintain the equal length connecting rods, meant the inside cylinder was placed as far forward as possible, and even this meant that the outside cylinders would still be between the front driving axle and the rear axle of the front bogie, which was not to LNER practice, and subsequently resulted in a very long wheelbase.

The Front Bogie itself was common with that on the B1, but was not sufficiently strong to control yawing of the Pacific classes, nor to straighten the engine out after a curve, and the Thompson A2's all had a poor reputation for being unwieldy, especially for rolling, and yawing.

However, the steam circuit, which was based on that from the P2's and the A4's, was generally regarded as excellent, as was the 19" cylinders fitted to the later A2/3's, consequently, with their large boilers, the Thompson Pacifics had a reputation for being capable of very high speeds, often being able to hold speeds in excess of 90 mph. The steam circuit aspects of the engines was carried over into the Peppercorn designs.

Class L1

Thompson's class L1 Adriatic suburban tank locomotives were another unsuccessful design. They were powerful machines that should have been well-suited to their duties but their 5 ft 2 inch wheels were too small for the fast outer suburban services and they quickly knocked themselves apart. The axle boxes suffered, water tanks split, oil pipes broke off, and crossheads wore rapidly.

Class B1

On the other hand, Thompson built one of the most successful LNER designs, the class B1 4-6-0, which was a simple two-cylinder design mixed traffic engine. The B1 was based loosely on Gresley's class B17. The prototype for the B1 was a B17/1 modified with a higher pressure boiler and with its centre cylinder removed. More than 400 B1s were built between 1946 and 1952, British Railways having continued B1 production after nationalisation. The boiler used in the class formed the basis for the rebuilding of many pre-grouping classes, including the class O4 2-8-0 freight locos. The Thompson B1 equalled the LMS Black Five locomotives during inter-regional exchange trials in the early years of British Railways. The B1 was also cheaper to build than the Black Five. The B1 had poor and very inconsistent ride quality, unlike the relatively smooth riding qualities of Gresley designs. Poor riding remains a characteristic of B1's that have been preserved.

Other Rebuilds

Thompson also rebuilt a number of different Gresley locomotives, usually using the B1 Derived boiler (in turn developed from the B17 type boiler) and 2x20" cylinders (derived from the early Gresley A1 engines). the Robinson 8K (LNER 04) was re-boilered and re-cylindered to create the class 01. two B17's were rebuilt with 2 cylinders to create the prototypes for the B1 class, and subsequently further examples followed suit. A K4 became the prototype K1/1 and a K3 became the K5. the K1/1 was a particularly unpopular engine, its name Macailan Mor was not a good choice for the locality in which it worked, and after having its 3 cylinders replaced with 2, its performance endeared it even less to the local Scottish crews.

Coach design

Thompson improved passenger safety by introducing steel-bodied coaches to the LNER. Hitherto the LNER had Gresley-designed coaches, the most famous of which had Teak bodies but by 1940's standards these were considered insufficiently safe in a collision. Therefore, during the Second World War Thompson designed new all-steel coaches that became a forerunner of British Railways Mark 1 design.

Proposed Pacific

Shortly before Thompson's retirement the LNER was short of express passenger locomotives so Thompson initiated plans for a new Pacific design, which he intended to be based on the rebuilt Great Northern. However the LNER design office, having received reports of Great Northern's performance in service, continually delayed designing the locomotive until Thompson had retired. Even then Thompson laid down a strict set of guidelines for the new locos. The new class (LNER Class A1) was finally designed under Thompson's successor Arthur Peppercorn, who disregarded almost all of Thompson's guidelines.

Locomotive list

• Thompson A1/1
• Thompson A2/1
• Thompson A2/2
• Thompson A2/3
• Thompson B1
• Thompson B2
• Thompson K1
• Thompson K5
• Thompson L1
• Thompson O1

Family

Thompson was the son-in-law of Sir Vincent Raven, the final CME of the NER.

Retirement and death

Thompson retired from the LNER in 1946 and died in 1954.

References

Business positions
Preceded by Nigel Gresley	Chief Mechanical Engineer of the London and North Eastern Railway 1941–1946	Succeeded by Arthur Peppercorn