British Rail Class 35

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British Rail Class 35
WSR 7017 79-08.JPG
Preserved D7017 at Minehead in 1979
Type and origin
Power typeDiesel-hydraulic
BuilderBeyer Peacock (Hymek) Ltd
Serial number7894–7938, 7949–8004
Build date1961–1964
Specifications
Configuration:
 • WhyteB-B
 • UICB'B'
Gauge4 ft 8 12 in (1,435 mm) standard gauge
Wheel diameter3 ft 9 in (1.143 m)
Wheelbase36 ft 0 in (10.97 m)
Length51 ft 8 12 in (15.761 m)
Width8 ft 10 in (2.69 m)
Height12 ft 10 in (3.91 m)
Loco weight75 long tons (76.2 t)
Fuel capacity800 imp gal (3,600 l; 960 US gal)
Prime moverBristol-Siddley / Maybach MD870
TransmissionHydraulic. Stone-Maybach Mekydro type 6184U
MU workingYellow Triangle
Train heatingSteam generator
Train brakesVacuum
Performance figures
Top speed90 mph (145 km/h)
Power outputEngine: 1,700 bhp (1,270 kW)
Tractive effortMaximum: 46,600 lbf (207.3 kN)
Brakeforce57 long tons-force (568 kN)
Career
Railroad(s)British Railways
NumberD7000–D7100
NicknamesHymek
Axle load classRoute availability 6
Retired1971–1975

The British Rail Class 35 is a class of mixed traffic B-B diesel locomotive with hydraulic transmission. On account of their Mekydro-design hydraulic transmission units, the design became known as the Hymeks.

The type 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 Withdrawal from service began in 1971, and by 1975 all had been withdrawn. Their early withdrawal was caused, primarily, by BR classifying the hydraulic transmission as non-standard. Four examples survived into preservation.