UK Maybachs - The "Hymeks"

British Railways operated these Maybach engined locomotives between May 1961 and March 1975. All were built to operate on standard gauge railways. (4ft 8½inches, 1435mm)

These locomotives were designed and constructed by a private consortium consisting of Beyer-Peacock, Bristol-Siddeley Engines and J.Stone & Co. The members of the consortium formed a separate company called "Beyer-Peacock (Hymek) Limited" which was displayed proudly on the builders plates along with the builders number. The "Hymek" part of the name, which very quickly came to be the nickname of the locomotives, was derived from the words "Hydraulic" and "Mekydro", which was the transmission used in these locomotives.

The reason such a powerful consortium bid to construct the Hymeks was because originally the British Railways Modernisation Plan had called for over 300 locomotives of the same type in the 1500-1750hp range, which would have been very lucrative for all concerned. Beyer-Peacock built the locomotive bodies and out shopped the finished product from their works in Manchester. J.Stone & Co as Maybach licensee, produced 91 Mekydro K184u transmissions, all C33 & C33v final drives, 45 Vapor train heating boilers and acted as the UK agent for the Gelenkwellenbau transmission cardan shafts used. Finally Bristol-Siddeley Engines licence manufactured the MD 870 engines. In the event, British Railways decided that the rest of the 300 locomotives would be heavy diesel-electrics which were better suited to working heavy unbraked freight trains.

The locomotives themselves were probably the most sound of the British Maybach-Hydraulic locomotives; the design was simplicity itself, being a heavy under frame with a light non stressed skin bodywork resting on two standard design Commonwealth bogies. The cabs had a lightly forward raked appearance from the buffer beam to the bottom of the windscreen, which was formed of two large panes. Right from the beginning of the class, the frames surrounding the cab windows were picked out in a colour that was a perfect contrast to the main paint scheme: Initially the surrounds were light grey against green body with a light green band at waist level, then warning yellow against BR Blue. Whatever paint scheme was applied to the Hymeks, it looked good, although some would say that the best was green with full yellow ends.

In service, the Hymeks were reliable and capable of tackling any task put to them - on occasion putting in creditable performances in place of failed Warships or Westerns on expresses, as well as operating their own diagrammed expresses from Worcester to Paddington. While there were early teething problems with the MD870 engine, caused by poor licensed manufacture which resulted in some members of the class being de-rated to 1350hp for a time, the locomotives were not as highly stressed as they could have been - the MD870 was capable of producing 2000hp if need be, which could have produced a single engined locomotive of similar power and performance as twin engined Warship locomotive and significantly higher performance than the 2000hp English Electric D200 locomotives. The only real flaw in the Hymek as a mixed traffic locomotive, was that it was too light to work unbraked freight trains.

Ultimately, however, the BR National Traction plan in 1968 decreed that the less successful and non standard types of locomotive would be phased out and in future all standard classes of locomotive would be based around electric transmission and medium speed diesel engines. This was the death knell for all of the Maybach engined locomotives on British Rail (including electric transmissioned "Falcon").

Much has been discussed and written about this decision, but my personal opinion is: If the Hymeks had been built with electric transmission, they would almost certainly have survived much longer than they did, possibly into the mid 1980's. Alternatively, if the 1968 plan had the survival criteria based on performance rather than pressure to reduce overseas competition for a once strong but rapidly decaying British locomotive building industry, the Hymeks would have again lasted later than their final withdrawal date in February 1975.

Hymeks in preservation

Four Hymeks have been preserved - D7017 & D7018 by the Diesel & Electric Preservation Group at Williton on the West Somerset Railway, D7029 by privately  at Kidderminster and D7076 privately at Bury on the East Lancashire Railway, where it is maintained by the Bury Hydraulic Group.

Current status at 10th January 2009:

D7076 has a train heating boiler fitted but currently not working