Class 35

The British Rail (BR) Class 35 is a class of mixed-traffic B-B diesel locomotive with hydraulic transmission. Because of their Mekydro-design hydraulic transmission units, the locomotives became known as the Hymeks. They were numbered D7000-D7100.undefined

They where classed as a Type 3 locomotive.

The class was developed for the Western Region of British Railways, which had opted for lightweight locomotives with hydraulic transmission, when allocated funds under the British Railways Modernisation Plan of 1955. One hundred and one of the class were built between 1961 and 1964, when it became apparent that there was a requirement for a medium power diesel-hydraulic design for both secondary passenger work and freight duties.

They were allocated to Bristol Bath Road, Cardiff Canton, and Old Oak Common. None of the class was named. Withdrawal from service began in 1971, and was completed by 1975. Their early withdrawal was caused, primarily, by BR classifying the hydraulic transmission as non-standard. Four examples survived into preservation.

Accidents and incidents

 * D7049 crashed though the Clevedon branch buffers and into Wymams bookstall at Yatton Station whilst hauling a 15:10pm Tavistock jct - Bristol west depot goods, December 1963.
 * On 13 July 1969, locomotive No. D7048 was involved in an accident at Spetchley, Worcestershire.undefined

Preservation
Four of the class have been preserved at three locations.
 * West Somerset Railway
 * D7017 and D7018 have been fully restored to working order since withdrawal. D7017 is now operational after a spell of four years out of traffic. D7018 is currently undergoing repairs at Williton Shed, West Somerset Railway and is unavailable for traffic. (On 9 May 2009, D7017 successfully hauled a 350ton test train on the WSR, after a four-year overhaul.undefined)
 * Severn Valley Railway
 * D7029 is still undergoing a major restoration, and recently moved from Old Oak Common shed, in west London, to the Severn Valley Railway for further restoration, before a planned return to service in BR blue.
 * East Lancashire Railway
 * D7076 survived, along with sister locomotive D7096, at the Railway Technical Centre near Derby, where they were used as dead loads for research purposes. Warship no. D832 Onslaught was additionally present at this site. Both Hymeks were in poor condition; however, it proved possible to rebuild one by using the other as a donor locomotive. D7076 was therefore restored using parts from D7096 and carries the number D7096 internally in one driving cab as a nod to the donor locomotive, which was reduced to a shell and subsequently scrapped.Having been restored to working order, and used on service trains, D7076 was taken out of traffic in late 2008 for repairs to a leaking turbo and coolant faults. The engine was subsequently found to need a complete rebuild, so in an unusual move, a Maybach MD-655 engine from D1041 (Western Prince, stopped for overhaul) was fitted into the locomotive to make it a runner. The resulting loco was nicknamed a "WesMek". However, late 2009 / early 2010 D7076 was taken out of traffic due to the Maybach MD-655 engine developing a liner seal problem. During summer 2011, two ex-Hymek MD-870 engines were discovered in a scrapyard in York, in excellent condition, having been used in a hospital emergency generator set. Both engines were purchased by D7076's owning group, and one has been fitted into D7076, which returned to service at the ELR's July 2011 diesel gala. The other engine is to be retained as a spare. On the 11th November 2013 that work started on bodywork repairs at Castlecroft Diesel Depot. In July 2014 D7076 returned to service on the East Lancs Railway in BR Blue Livery with full Yellow ends.