Class 37s turn 60
To mark 60 years of operation, DAVID CLOUGH looks at important milestones in the history of the class
Important milestones in the history of the great survivors, as they enter their seventh decade of operation.
As dieselisation on BR gathered pace, in 1957 the Southern Region (SR) was the first to specify a design of between 1,500-1,750hp, power class Type 3.
Several manufacturers, including the English Electric Co Ltd (EE), tendered for the order and the Birmingham Railway Carriage & Wagon Co Ltd (BRCW) was successful for what became the Class 33s.
British Railways’ Regions prepared dieselisation schemes for steam replacement in discrete geographical areas, and tenders were invited from manufacturers for 130 Type 3s for submission by June 1958. BRCW again submitted the lowest tender.
However, BR was concerned at the company’s ability to fulfil deliveries without jeopardising the supply of Class 33s to the SR in the required timescale. In January 1959, this led to the decision to opt instead for the next lowest tender, which was from EE, although the quantity now required was just 42 - 30 for the Eastern Region (ER) and 12 for the North Eastern Region (NER).
In EE’s favour was the commonality of some components with Type 1 and Type 4 locomotives already on order from the company. The new Type 3s received numbers from D6700 and eventually became the Class 37s.
Parliamentary and government scrutiny of the modernisation plan during 1960 created something of a hiatus in the placing of further orders for diesel traction, and it was not until February 1961 that BR ordered 37 more Type 3s - 13 for the ER and 24 for the NER.
The interruption to new supply contracts had put jobs at risk in the manufacturing industry, and representations were made to BR to maintain continuity of construction.
However, BR was no longer allowed to order locomotives without a clear, costed proposal for their use, whereas previously it had been the practice to place some orders and decide later where these should be allocated.
On February 11 1960, the Technical Committee had recommended standardising on as few diesel types as possible, and Class 37s were selected as the standard Type 3.
Class 33s had provision for electric train supply (ETS) to meet the SR’s requirements, but the new standard Type 3 would have to have a steam heating capability.
Even though BRCW’s tender was again the lowest, the cost of redesigning Class 33s to provide this supply was said to be prohibitive. Moreover, BR was concerned that ordering more ‘33s’, which had Sulzer engines, could slow down the supply of these units for fitting into several Type 2 and Type 4 designs already in production. EE therefore won the order for the extra 37 Type 3s.
This procurement was followed two months later, in April, by an order for 17 ‘37s’ for the NER, at a reduced price of £ 89,400. When an expanded Sheffield area dieselisation scheme on the ER was approved, on December 13 1961, 23 EE Type 3s were sanctioned at
an even lower price of £ 89,300, with a minimum delivery of 15 during 1962.
By April 1962, EE reported that a gap in its production schedule was again likely to result in job losses. The Western Region’s ( WR’s) general manager told the Supply Committee his Region was preparing schemes that envisaged a requirement for a further 200 Type 3s, beyond the 100 already ordered from Beyer Peacock (‘Hymek’ Class 35s).
He claimed these latter were more expensive than the EE design and suggested that
British Railways should intimate to EE that a requirement for 200 more Type 3s was emerging. Breaking with the usual practice of only approaching suppliers once expenditure was authorised, the Supply Committee accepted the general manager’s suggestion.
On July 10, the WR produced outline scheme details for its dieselisation Areas 4 and 5, which covered part of Wales and the Welsh borders. The general manager wanted to produce a Region-wide scheme to better assess the diesel requirements, but time pressure ruled this out.
While 74 of the estimated 200 Type 3s were now being sought for the two schemes, the Supply Committee suggested an additional 26 for WR Area 3, which had not yet been finalised. This was in view of EE’s advantageous price, and provisional approval for 100 came on August 7.
No doubt to help EE maintain continuity of production, the following month a tranche of 20 out of the 100 was actually ordered. However, closure of BR workshops at the time made this a sensitive issue. BR therefore told EE to give no publicity to this order, but that if there was a leak, criticism should be countered by a statement that the order was an extension of an existing contract and was not for a type of locomotive which BR workshops were equipped to build.
In February 1960, EE had offered a quantity rebate, which explains the reason for successive orders leading to a decline in the cost per locomotive. With the above 20 approved, in November 1962, the Contracts Officer reported that if an extra 40 were ordered by the year end, an increase of £ 270,000 would be obtained in the rebate payable. But instead, the remaining 80 of the proposed 100 was added to the order.
Two further orders came in early 1964, following provisional authority on December 19 1963. On January 23, the quantity was 20 at a price of £ 88,718 each, while on February 27 it was 50 at £ 86,858.
These were D6939-99 and D6600-08, all bound for the WR except D6959-68 for the ER. In view of the WR not using the steam heating equipment, a recommendation was not to fit it on the latest batch.
Allocation of some examples to the London Midland Region was under consideration, and these could come from earlier builds with this equipment already on the WR, if required. By the conclusion of these deliveries with D6608 on November 9 1965, the class total was 309.
Turning to the design itself, whereas the earlier EE Type 4 ‘D200s’ were heavy (at over 130 tons) and used a four-axle bogie to lower the axle load, the Type 3s could be accommodated on the company’s own design of three-axle bogies for an overall weight of 105 tons.
A comprehensive review of BR’s diesel fleet in April 1967 showed the class to be one of the star performers, alongside EE’s Type 1 design. The rate of failure during 1966 was an excellent 50,000 to 60,000 miles per casualty.
The well-proven EE ‘SVT’ diesel was improved by the addition of charge-air cooling in order to raise output, and when built in 12-cylinder form it could deliver 2,025bhp at 850rpm.
For Class 37s, BR specified a lower rating of 1,750bhp instead. Six EE538 traction motors had a gear ratio of 53:18. Maximum speed was 90mph, although these motors and this gear ratio was also used in the company’s Class 55s and ‘50s’, which were permitted 100mph.
Changes were made in the design during construction, based on service experience and to assist with maintenance.
The original design, Series 1, comprised D6700-6818 and had front-end gangway doors with two-position route indicator boxes on each side of the doors. D6819-6958 were Series 2, had no gangway doors, and a four-character route indicator box in the front end.
While the warning horns were located in the nose end in Series 1, these were moved to the cab roof in Series 2. D6959-99 and D660008 benefited from a significant upgrading of control equipment, which included improved wheelslip correction.
External appearance was very similar to the EE Type 4 ‘D200s’, with the inclusion of a cab front nose end, and BR was content with this at first. But in March 1959, Ted Wilkes was appointed to advise on styling.
By 1963, nose ends were out of favour with BR and Wilkes produced a revised outline that was very similar to his styling for Class 47s, in anticipation of further orders. But over several months, a dialogue involving different parts of BR, Wilkes and EE failed to reach a meeting of minds and the use of a nose end persisted.
BR locomotive green was applied to the bodysides, and unusually for the period there was no lining out using horizontal stripes - creating a drab appearance. The roof was mid-grey and the undergear was black, while the bufferbeam was red.
EE divided construction between its workshops at Vulcan Foundry and Darlington, which at times meant both were manufacturing concurrently. Darlington produced D6769-95, D6819-28, D6859-68 and D6879-98, while Vulcan constructed the rest. Delivered in November 1965, D6988 had the 2,000th diesel engine of EE manufacture supplied to BR (a world record at the time).
D6700 went to Doncaster for acceptance testing on December 2 1960. The ER based its early deliveries in East Anglia on a mix of passenger and freight work. One particularly interesting job was the ‘North Country Continental’ from Harwich Parkeston QuayLiverpool Central. From September 9 1963, when the working was cut back to Manchester Piccadilly, this became the longest-ever daily Class 37-hauled passenger service.
Sheffield’s fleet was employed on the York-Bournemouth service and the ‘Sheffield Pullman’, but was generally found powering freights.
Hull received the NER’s first allocation and subsequent arrivals were based in the North East and at Healey Mills - mainly for use on freight, although Summer Saturdays could find examples powering passenger trains to holiday resorts.
Coal and steel traffic in South Wales kept
English Electric types posed at Stratford depot in east London, with Class 40 D200 and Class 37s D6723 and D6717 showing the similarity of styling. All have acquired small front-end yellow warning panels.
the WR’s stud occupied. The class was preferred to the Region’s Type 3 ‘Hymeks’ on mineral trains, because the latter had insufficient brake force.
Did the WR over-order the type? A memo to the BR Board in December 1963 refers to several Regions ordering too many locomotives of several classes, and the ‘37s’ were among these.
However, reference was made to buying more examples to replace the ill-starred North British Class 21s, rather than fitting the latter with a replacement engine. Belatedly, BR gradually introduced the concept of a national traction plan by 1965, to ensure best use of its diesel fleet.
Over the following years, the WR shed nearly half of its ‘37s’ - mainly to the NER, although the Scottish Region (ScR) indicated it would take Type 3s instead of Type 4s and the Region received some examples. South Wales coal mining was in decline at the time, and the Division required Type 4s with slow speed control for some duties in place of Type 3s.
Although the class did not suffer the same major technical problems that beset most BR diesels apart from those of EE and BRCW manufacture, fractures in the bogies began to appear in 1961 and also affected the Type
While based at Landore depot in Swansea, 37180 departs Carmarthen after being named Sir Dyfed/
County of Dyfed on May 28 1981. The train was the 1115 Swansea-Milford Haven, and this was the first official Class 37 naming. BRITISH RAIL. 5 ‘Deltics’. Modifications to D6708 in 1963 were not fully satisfactory, and EE changed to a cast steel version for later builds. The main generator went through several modifications to improve performance but was never entirely satisfactory.
A comprehensive review of BR’s diesel fleet in April 1967 showed the class to be one of the star performers, alongside EE’s Type 1 design. The rate of failure during 1966 was an excellent 50,000 to 60,000 miles per casualty (mpc). Demonstrating the way that they were deployed, 90% of the duties were on freights. There were no major problems requiring modifications, although the issue of fractures of the fabricated bogie had yet to be resolved fully.
By 1971, reliability had dropped to 43,000mpc, although availability remained very high at 88%. Freight work now accounted for 94% of duties, which explains the modest annual mileage per locomotive of 52,000.
With the ban on locomotive naming overturned in 1977, 37180 became the first of the class to be named officially when it became
Sir Dyfed County of Dyfed on May 28 1981.
This just preceded a number of Eastfield’s fleet receiving names linked to the West Highland Line, over which the class now worked.
During the second half of the 1970s, BR’s diesel fleet had reached the point where attention beyond the usual works overhauls was needed, in order to improve reliability.
Classes deemed to have an expected future life of at least ten years were selected to be put through a life extension or refurbishment programme. The work comprised a heavy general works overhaul, involving reliability improvements and a standard works overhaul to other components.
By the start of the 1980s, Classes 45/1, ‘47’ and ‘50’ were undergoing bespoke HGR programmes, and attention next turned to the Class 37s.
While the class was performing well, reliability had dropped to between 20,000 to 40,000mpc, depending on Regional allocation. A heavy general works overhaul was an opportunity to upgrade the class, while business cases emerged for specialist subclasses for particular applications.
The Provincial Sector wanted examples fitted with an electric train supply (ETS) in order to eliminate steam heating, while the Freight Sector wanted a locomotive of 120 tonnes that would have a starting tractive effort equal to Class 56, to enable the haulage of heavier trains.
English Welsh & Scottish Railways (EWS) took over all the class on privatisation, but the company’s acquisition of Class 66s rendered virtually all its ‘37s’ redundant.
The accompanying table (above) explains the differences between the various subclasses.
The fitting of ETS equipment during refurbishment would divert power away from hauling the train, so uprating the engine to EE’s nominal value of 2,000hp was considered to compensate for the impact on haulage capability.
In May 1981, 37292’s engine was set to 2,000hp to assess any technical impact, and it was transferred to Eastfield depot for West Highland Line work. 37292 lacked steam heating equipment, and in October it moved to Motherwell and the 2,000-tonne mineral train circuits between Hunterston and Ravenscraig to continue the uprating trial, with its extra power appreciated by drivers.
For several reasons, Provincial Sector management decided to retain the usual 1,750hp engine setting, and 37292 eventually became 37425 after going through the life extension programme.
Refurbishment covered several aspects beyond a standard works overhaul. Each locomotive was stripped internally and rewired, including provision for fitting slow speed control later.
Modifications were made to the bodywork, including plating over the front end doors on Series 1 examples and improving cab insulation. Train air brake equipment was fitted where this had not been done already.
The Freight Sector decided the quantity of locomotives of 120 tonnes it required, and ballast was added to those concerned to increase their weight. Fuel tank capacity was increased to 1,690 gallons by converting the steam heating water tanks. Where fitted, steam heating equipment was removed. Engine room air management and filtration also received attention.
A temperature-controlled clutch was added to the radiator fan drive, which helped prevent overcooling when the diesel was idling. Brushmanufactured alternators and starter motors replaced the main and auxiliary generators, except for ten sets which came from GEC.
All refurbished locomotives were fitted with
CP7 bogies, which had lower traction motor gearing and Class 50 type axles. The lower gearing meant maximum speed had to be cut to 80mph but gave a traction characteristic better suited to freight work. To avoid driver confusion, the 80mph limit was imposed across all the fleet.
The class had taken over West Highland duties from May 1981 and those north of Inverness the following May. The Provincial
Sector wanted to eliminate steam heating on these services as soon as possible, and so the first refurbished examples were of subclass ‘37/4’ and went to Eastfield, followed by Inverness.
37268 entered Crewe on June 22 1984 and emerged as 37401, painted in large logo livery. Provincial later decided to switch the last six ‘37/4s’ (37426-31) to Cardiff Canton for use on the Cambrian and North & West routes. Freight Sector units received Railfreight grey, later embellished with a horizontal red stripe.
In 1985, both GEC and Brush offered new engines to prove these for possible application in the proposed but stillborn Class 38.
Ruston’s RK270T went into 37905/906, while 37901-904 had the Mirrlees MB275T.
Both types of diesels had just six cylinders and were set to deliver 1,800hp, which was well within their potential. Service performance was satisfactory.
The life extension programme was terminated when Railfreight ordered Class
60s, and 37719 was the last to return to traffic on March 20 1989, with 135 locomotives having been dealt with and the planned performance improvements achieved.
Subsequently, a number of unrefurbished ‘37s’ received CP7 bogies, becoming Class 37/3s and so benefiting from the improved tractive characteristic offered by lower gearing.
Renumbering associated with refurbishment took account of whether they were Series
1 or Series 2 or ‘3’, to help identification for maintenance staff.
In 1976¸ the mineral train flows between
Port Talbot and Llanwern in South Wales went over to triple-headed ‘37s’, hauling a load increased to 2,700 tonnes.
Pairs of Class 56s displaced the ‘37s’ when the Type 5s became available, but these in turn gave way to Class 37/7s or ‘37/9s’ from May 1988, once these had been put through the refurbishment programme. This demonstrates the benefit of increasing the starting tractive effort by raising the locomotive weight to
120 tonnes and fitting lower traction motor gearing.
Benefiting from increased fuel capacity following refurbishment, pairs of Lairaallocated Class 37/ 5s began the longest through working ever diagrammed -between Burngullow (Cornwall) and Irvine (South West Scotland) during 1989.
In 1995, 12 Class 37/ 5s were modified to operate European Passenger Services Nightstar services as far as the Channel Tunnel. The plan was to use these in pairs, separated by a generator van that would provide an electric train supply, and the locomotives received additional internal wiring and front end connection equipment.
The Nightstar project was eventually cancelled without being completed, and the locomotives were sold but remained as 37601612.
English Welsh & Scottish Railways (EWS) took over all the class on privatisation, but the company’s acquisition of Class 66s rendered virtually all its ‘37s’ redundant. The company then hired some for use in Europe, for work associated with the construction of high-speed lines (see panel, page 55).
EWS eventually disposed of the class. Today Direct Rail Services has the largest holding among main line operators, while some are confined to heritage lines.