6P5F  72000 – 72009  4-6-2  BR Standard Clan

clan

Power Classification 6P5F/6MT
Introduced 1951 – 1952
Designer Riddles, designed at Derby
Company BR
Weight – Loco 86t 19cwt
               Tender 49t 3cwt
Driving Wheels 6ft 2ins
Boiler Pressure 225psi superheated
Cylinders Outside – 19½in x 28in
Tractive Effort 27,520lbf
Valve Gear Walschaert (piston valve)

These ten locomotives, which were built at Crewe, were lighter versions of the Britannia class, with higher running plates, smaller diameter boilers and taller domes and chimneys. As often happens when the proprtions of a good design are altered, the result was far from satisfactory. The Clans were generally poor machines, lacking the punch of the Britannias.

 brit small Britannia class
 clan Clan class

Under the initial scheme for the creation of a series of British Railways standard locomotives, larger passenger and mixed traffic types were intended to be of the 4-6-2 Pacific wheel arrangement, the main advantage of which was that it could be fitted with a wide firebox capable of burning a range of types and qualities of coal.

It was further appreciated that a pacific of 6MT power could be built with a high enough route availability to fulfil all remaining requirements; this had been amply demonstrated by the West Country and Battle of Britain light pacifics which were capable of operating on almost 90% of the Southern Regions rail network.

 wcbb small West Country/Battle of Britain class as originally introduced between 1945 and 1951 weighed 86 tons. 50 of the 110 built were not rebuilt

West Country/Battle of Britain class as rebuilt between 1957 and 1961 weighed 90 tons

 clan Clan class introduced in 1951 weighed almost 87 tons.

The advantages of such a locomotive for use on some of the heavily restricted main lines in Scotland, such as the Dumfries to Stranraer line, had been further demonstrated by the remarkable performance of West Country class pacific 34004 Yeovil on the ex Highland Railway line to Inverness during the British Railways 1948 Locomotive Exchange Trials. During these trials the locomotive showed that a light pacific had the potential to revolutionise the timetable over this difficult trunk route. As the general policy of the Railway Executive was to eliminate as far as possible the perceived complication of multi-cylinder locomotives, an equivalent 2-cylinder pacific was produced by mounting a smaller and lighter boiler on the standard 7MT chassis.

The arrangement consisted of a modified Britannia Standard boiler, with smaller steel cylinders and other modifications to save weight and hence increase route availability. The wider firebox, designed for use with cheaper imported coal, was also utilised to spread its weight evenly over the axles, whilst the standard smokebox completed the boiler, which at 225 lbf was rated at a lower working pressure than that of the Britannias. A single chimney was incorporated into the design. This was to create problems later on, due to its small diameter, which reduced the choke area that allowed the fierce exhaust blast to escape, reducing the overall efficiency of the locomotive. Similarities with the Britannias rested with the frames, tenders and running gear, allowing easy standardisation of parts common with other classes. The design was fitted with a standard set of two Walschaerts valve gear systems, and all members of the class were equipped with 4,200 gallon BR 1 tenders.

Unlike the smaller BR Standards engines, the exhaust steam manifold within the smokebox saddle was a steel casting that was welded into the saddle. Other original drawings confirm the exhaust steam manifold was a steel fabrication in the smaller BR standards.

Designed at the drawing offices of Derby Works, the new class was constructed at Crewe Works between 1951 and 1952. 72000 Clan Buchanan was completed in December 1951 at Crewe Works at a cost of £20,426. The final engine of the batch of ten, 72009 Clan Stewart entered service in April 1952. The BR plan was to build 118 of the Clan class locomotives. The initial order was for 25 locomotives, but such was the immediacy of demand regarding a smaller version of the Britannias that a batch of 10 was rushed through construction before teething problems had been ironed out at the British Railways testing station at Rugby.

Some modifications to the locomotives were carried out to try to overcome the problems identified. Most notably to the diameter of the blastpipe, resulting in better steaming and increased power. Initially, the return cranks on the main driving wheels were of LNER block-type as seen on Arthur Peppercorn’s A1s and A2s, but this was changed to the simpler LMS four-stud fitting.

A further fifteen were ordered (five for use on the Southern Region and ten for use on the Scottish Region). These additional engines would have incorporated the improvements identified for the first ten locomotives. However, due to worldwide acute steel shortages in 1954 which almost halted locomotive production in Britain. During this period the government decided to bring dieselisation forward, cancelling orders for new steam railway locomotives, starting with express passenger types. The order for more Clan locomotives was cancelled as a result.

The choice of locomotive names came from engineer and future railway historian Ernest Stewart Cox’s desire to replicate the near extinct Ex-Highland Railway 4-6-0 Clan class introduced in 1919, therefore representing Scotland in the new organisation. The first of the class, 72000 Clan Buchanan, was treated to a special ceremony at Glasgow Central station in January 1952 at which the Lord Provost unveiled its nameplates. Five of these names had previously been used on Highland Railway locomotives. The first five of the planned second batch of 15 locomotives were intended for use on BR’s Southern Region; these were allocated names Hengist, Horsa, Canute, Wildfire and Firebrand, which had all been previously used on locomotives in southern England. The following ten were to be allocated to Scotland and were allocated further new Clan names.

The Clan Class had a mixed reception when first introduced to British Railways locomotive crews because there were only 10 locomotives in a class that was mostly confined to the North West of the railway network. This was due to the fact the low number of class members prevented effective training of locomotive crews throughout the nationalised network, and a degree of partisanship amongst crews towards newer locomotives further ensured this. The entire class was also based predominantly at two depots throughout their working lives, these being Glasgow Polmadie and Carlisle Kingmoor, compounding their restricted circulation. Crews that used them on regular duties displayed their liking for the locomotives, and as such, could produce good work. However, the predominant number of crews who were unfamiliar with the Clans found them difficult to handle, leading to an undeservedly bad reputation.

The poor steaming characteristics of the class had been the result of rushed production, which was another factor that led to the bad reputation of the Clan class. Furthermore, they suffered from complaints regarding a lack of pulling power, although this can be attributed to indifferent handling and firing techniques, which certainly did not help the situation. However, had the Modernisation Plan been delayed, and the correct amount of investment made for undertaking the relevant modifications, such as streamlining of the steam passages and increased diameter blastpipe in a double-chimney layout, the clans would have been free-steaming locomotives worthy of complementing the Britannias. Without modification, they were still capable machines when handled properly, as various feats testifying this included regular ascents of Shap and Beattock with 14 carriages without the assistance of a banking locomotive. Other arduous duties that the class frequently undertook were the regular turns on the Settle to Carlisle route, which has some of the steepest gradients and harshest working conditions of any British mainline. The Midland region was always short of top-link motive power and the Clan class proved to be a very welcome addition to the fleet.

The engines also performed on Glasgow–Crewe, Manchester and Liverpool services, Edinburgh–Leeds services, Carlisle–Bradford services, and finally the Stranraer Boat Train workings. Clan number 72001 remains the only pacific locomotive to have worked over the West Highland Line, the result of a successful trial held in early 1956 to ascertain whether a pacific type could traverse this steeply graded line. Having passed that test, a tribute to the versatility of the class, Clan Cameron was allowed to work special trains for the Clan Cameron gathering that took place in June of that year.

In August 1958, number 72009 was tested on the Eastern Region, being based at Stratford depot, though a preference for the Britannias meant that this sojourn was short-lived, lasting only a month. The locomotive was utilised on services from London Liverpool Street to Norwich, Clacton, and Harwich. At first they were mistakenly allocated class 7 duties, in which the Clans, although capable, were not able to keep to their allotted timings. This was part of the trials for the West Highland Line services mentioned earlier, but the locomotive was rejected for such duties on the grounds that they were no better than a good B1. The result of these trials was that as the Britannia locomotives were moved north in 1961 after dieselisation started in earnest, the Clans were downgraded to secondary work. Maintenance was initially undertaken at Crewe Works, but responsibility was transferred to Cowlairs Works in the spring of 1958. More varied work was allocated to them as their reliability improved, including working portions of the Thames-Clyde Express and the Queen of Scots Pullman. They also deputised for the many failed diesel locomotives that plagued the network at the time, and were extensively used on freight workings.

The first locomotives to be withdrawn from service were the Polmadie locomotives 72000-72004 en masse in December 1962, where after being moved first to Glasgow Parkhead and stored, they were eventually moved to Darlington for scrapping in 1964. Of the Kingmoor allocation, the first, number 72005, was withdrawn in April 1965, whilst the final engine was 72008 on 21 May 1966 from Carlisle Kingmoor shed. When 72008 Clan MacLeod was finally scrapped in August 1966, it rendered the class extinct. Though this locomotive served British Railways for only fourteen years and three months, it was the longest serving Clan.

Allocation of locomotives in service as at 1st of January.

Carlisle Kingmoor Haymarket Polmadie

St Margarets

1952

2

1953

5

5

1954

5

5

1955

5

5

1956

5

5

1957

5

5

1958

3

4

3

1959

5

5

1960

5

2

3

1961

5

5

1962

5

5

1963

5

1964

5

1965

5

1966

2

 

72006-Perth-July 1965a.jpg

72006 Clan Mackenzie at Perth-July 1965. This locomotive spent almost its entire working life based at Carlisle Kingmoor. The exception was a six month spell based at Haymarket (Edinburgh) from October 1957.

 

72006-Perth-July 1965.jpg 72006 Clan Mackenzie at Perth-July 1965. This locomotive spent almost its entire working life based at Carlisle Kingmoor. The exception was a six month spell based at Haymarket (Edinburgh) from October 1957.
72008-Carlisle-October 1965.jpg 72008 Clan MacLeod at Carlisle-October 1965. 72008 spent all of its working like based at Carlisle Kingmoor. It was withdrawn from service in April 1966
72006_kingmoor-July 1966.jpg 72006 Clan Mackenzie on Carlisle Kingmoor shed-July 1966. The locomotive was withdrawn from service at Kingmoor in May 1966 and has already had some parts removed.

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