each. Maximum tractive effort: Driving wheel diameter: Coupling code: Standard "Buckeye" compatible with contemporary Class 20x and 4xx units. Train heating: Electric Number 1129 was experimentally fitted with a Dorman 12QTCW V-12 diesel engine of Operations The first examples of the class entered service in September 1957 after a month of testing. They were initially used on services linking Portsmouth and Southampton to Salisbury, as well as those between Southampton and Portsmouth Harbour and from Southampton to Alton/Andover. Journey times were around two-thirds of those required by the steam locomotives which the units replaced. The new services proved so popular that the class was temporarily taken off the route to Alton and Andover to provide extra capacity on the other lines prior to the fitting of a third carriage to the first 18 units. The delivery of the second batch of four units saw the class introduced to the Marshlink Line between Ashford and Hastings. These units also ran on the Bexhill West Branch Line and the short line to , and a Sunday-only service on the Fawley Branch Line. All of these routes except for the Marshlink Line had been closed by 1967, by which time the route between Reading and Salisbury was also operated by the class. The units also operated on the to route from 1966 until its closure in 1972. Other routes served included the Steyning Line between and , which closed in 1967; the Cuckoo Line, which closed in 1968; the Lymington Branch Line, which was served by the units for two months in 1967 prior to its electrification; and some journeys on the Oxted Line, which was also served by the newer units. In 1973 some services from Portsmouth to and were converted to Class 205 operation. Soon after introduction, an orange "V" shape was painted on the motor-coach in order to provide an early visual indication to station staff that there was no brake van at the other end of the unit. With the introduction of yellow warning panels the orange V was replaced by an inverted black triangle; this being extended at this time to all Southern Region 2 & 3-car multiple units. The electrification of the line to in 1987 saw the majority of the class withdrawn. Those which survived largely operated on services from Ashford to Hastings and from London to Uckfield. The privatisation of British Rail in 1995/6 saw