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LMS Route: Nuneaton to Birmingham New Street

LMS Route: Birmingham New Street to Tamworth

Saltley Shed: mrsalt1246

British Railways Western Region Hymek D7051 is seen standing alongside Saltley shed's amenities block

British Railways Western Region Hymek D7051 is seen standing alongside Saltley shed's amenities block. The 'Hymek' class were unique by the fact that they were the only Type 3 diesel-hydraulics to be built as this design was not part of the Modernisation Plan for Britain's railways. Beyer Peacock were hoping for a share of the diesel orders then being placed for Britain's railways and were in fact building shunting locomotives plus 200 sets of underframes for the Brush Type 2 locomotives. With an intention of supplying complete locomotives for future orders, Beyer Peacock looked into the possibility of building main-line diesel-hydraulics, and although BR employed Type 2 D6300 class and Type 4 Warship class, no plans were announced for a Type 3 machine of 1501 to 1750 hp. In response, Beyer Peacock formed a consortium in 1958 with Bristol Siddeley Engines and J Stone of Deptford, named Beyer Peacock (Hymek) Limited. Their design for a Type 3 locomotive featured a 16-cylinder Maybach MD870 engine capable of 1,920 hp, coupled with the Mekydro K184U transmission. Construction was to based at Beyer Peacock's Gorton works in Manchester.

In June 1959, the BTC ordered an initial batch of 45 'Hymeks' at a cost of £80,000 each, but in July 1960, ten months before the first 'Hymek' entered traffic, the BTC ordered a further 50 locomotives, such was the confidence in the design. A final batch of 6 locomotives was ordered in December 1961. The Maybach MD870 engine was basically a stretched version of the MD655 engine to be used in the 'Western' class, but with four intercoolers and two turbochargers. Power was reduced to 1,740 hp at 1500 rev/min to bring it in line with the Type 3 specification. Manufacture of the engine was to be at Bristol Siddeley's engine plant at Ansty, near Coventry although the first 20 units contained a number of parts from Germany. Similarly, of the 116 sets of Mekydro transmissions, 91 were made by J Stone with the remaining 25 built in Friedrichshafen. The stretched-skin type of body construction so successfully used by the 'Warship' and 'Western' classes was not required for the 'Hymeks'. With conventional construction and, of course, a single engine and transmission, an adhesion weight of 75 tons was perfectly satisfactory. In addition, the absence of special construction methods removed the need for training of Beyer Peacocks workforce as well as entering into a licencing agreement with the Germans.

The main load-bearing members of the 'Hymek' underframes were longitudinal rolled steel joists to which lighter angle sections were added to form the body framing. The body panels themselves were made from lightweight sheets as they were non-loadbearing as shown by the use of fibreglass mouldings for the cab roof. The bogie used on the 'Hymeks' was the tried and trusted Commonwealth design, to which, wheels of 45 inches diameter were fitted. This was an odd size for the Western Region as previous diesel-hydraulic locomotives used wheels of 39½ or 43 inches diameter . The first 'Hymek', number D7000, was handed over to the Western Region on the 16th May 1961 in a ceremony at Paddington station, almost two months ahead of schedule, however, the last 'Hymek' number D7100 was held up until February 1964, after problems at Gorton caused a delay in delivery for almost twelve months.

There were two main differences between the first and last members of the class in that D7000 to D7044 were fitted with the Stone-Vapor train heating boiler and brakes were of the Knorr straight air type together with Laycock-Knorr compressors. Numbers D7045 to D7100 used the Spanner Mk. IIIa train heating boiler and brakes and compressors were supplied by Westinghouse. The location of the air horns on the first three members, which was under the buffer beam, was moved to the cab roof on the remainder of the class and those first members had their horns repositioned to the cab roof also. Livery on all members of the class when delivered was Brunswick Green with a light green band band running the full length of the locomotive at waist height. In addition, the window surrounds were painted white. The running numbers were an unusual feature of the class in that the cabside numbers where made from cast aluminium. The 'Hymeks' did not receive the "TOPS" style of numbering which would have been 'Class 35'.

Courtesy www.greatwestern.org.uk