The British Rail Class 205 (3H) diesel-electric multiple units were built by BR at Eastleigh from 1957 to 1962, and in service for 47 years from BR Southern Region to Connex South Central and finally to the Southern franchise. They were eventually replaced by Class 171 Turbostar units. Description This class of unit was built in four different batches for use on different lines. The Southern Region class 201 to 207 DEMUs are nicknamed 'Thumpers' owing to the noise they made while in motion. The first batch of units, numbered 1101–1118, was built in 1957 as two-car units and classified as 2H. They were built for services in Hampshire on the non-electrified routes between , and and between , and . The first units entered service in September 1957. However, owing to increasing passenger numbers, all eighteen units were strengthened to three cars in 1958 and 1969, with the addition of a centre trailer, and therefore were reclassified as 3H units. Upon the introduction of TOPS they were reclassified as Class 205. Some of these were later converted back to 2 car sets, but they retained their Class 205 designation. The second batch of 2H units, numbered 1119–1122, was built as 2-car units in 1958. These units were built for services on the Marshlink Line from to Ashford, and associated branch lines. These units remained as two-car sets until 1979, and were reclassified as Class 204 upon the introduction of TOPS. In May 1979, following the disbandment of the four Class 206 units, they were strengthened to three cars and redesignated as Class 205s. The third batch of units was built as three-car sets in 1959, and numbered 1123–1126. These units were built to supplement the first batch on services in Hampshire. Collectively, the first and third batches are often called Hampshire sets. The final batch of units, numbered 1127–1133, was built in 1962 as three car sets. These units have some detail differences from the earlier batches, such as a different internal layout, and smaller route indicators (compare the two photos). They were built for services from to Salisbury, and other services in Berkshire. The final batch of units is sometimes referred to as Berkshire sets. Technical details Power car (one per set) Introduced: 1957 Weight: Engine: English Electric 4-cylinder type 4SRKT Mark II of at 850 rpm Transmission: Electric, two English Electric type EE507 traction motors rated at