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![]() photograph by Keith Harwood
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To replace steam hauled stock in the Hampshire area in
1957 eighteen two coach Diesel Electric Multiple Units to a BR standard design
were built. The first batch of units, numbered 1101-1118, was built in 1957 as
two-car units and classified as 2H. In 1958 and 1969 all eighteen units were
strengthened to three cars, with the addition of a centre trailer, and therefore
were reclassified as 3H units. All these units were subsequently denoted as
Class 205 under TOPS.
Unlike most diesel multiple units (which have mechanical drives) the power cars on DEMUs are effectively mini diesel-electric locomotives with final drive by electric traction motors. This was the Southern's preferred form of multiple unit away from the third rail juice, governed by commonality with the EMU fleet of many components for maintenance purposes. Designated 2H (for Hampshire) they consisted of a motor brake second saloon (MBSO) and a driving trailer composite (DTC) - the DEMU equivalent of a 2 Hap. A further four units were built in 1958 for use in East Sussex and Kent. Between 1958 and 1959 the original eighteen units were augmented to 3 car by addition of a trailer second semi-saloon (TSO) and four more 3 car units were built. The new designation became 3H. A final batch of seven units was built for service between Salisbury and Reading. These were different in that they had larger guards vans and were designated Berkshire units, although still 3H/class 205. As some branches in Hampshire closed surplus units were drafted for use on the Oxted line. Rebuilding of most of the non Berkshire units to create a luggage compartment in the DTC occurred between 1963 and 1964 however this work was reversed in 1975/76 on most of the units used on the Oxted line. In 1979 driving trailers from disbanded 3R Tadpole units were used to augment the remaining 2 car units to 3 car. These units were re-designated 3T (class 204). In 1979 one unit underwent an experimental refurbishment much modernising the passenger accommodation and becoming class 3H(M). This rebuilding remained an experiment and it was not repeated on the rest of the class. With the electrification of lines in the Fareham area further reducing their original service requirement, and prior to the introduction of Sprinter DMUs, the scope of operation of these units increased to regional services working between places such as Portsmouth and Bristol. Withdrawal and reformation of units has happened during the class's later life, although until replacements arrive in 2004 the survivors were still in service working for South Central alongside the remaining class 207 units down to Uckfield or across the Kent marsh. |
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This page was last updated 28 December 2008