E84004 Class 35 Hymek D7056 BR Blue (Weathered) (Small Yellow Panel)

The British Rail Class 35 Hymek is a class of mixed-traffic 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.

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. 101 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. 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.