The British Rail

British Rail

British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...

 (BR) Class 35 is a class of mixed-traffic B-B diesel locomotive

Diesel locomotive

A diesel locomotive is a type of railroad locomotive in which the prime mover is a diesel engine, a reciprocating engine operating on the Diesel cycle as invented by Dr. Rudolf Diesel...

 with hydraulic transmission

Hydraulic transmission

Hydraulic transmission may refer to:* Hydrostatic transmission, see Hydraulic drive system and Hydraulic machinery* Hydrokinetic transmission, see Torque converter...

. Because of their Mekydro-design hydraulic transmission units, the locomotives became known as the Hymeks.

The class was developed for the Western Region of British Railways

Western Region of British Railways

The Western Region was a region of British Railways from 1948. The region ceased to be an operating unit in its own right in the 1980s and was wound up at the end of 1992...

, 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.