710 units, some of which would displace the Class 378s in use on the Watford DC line. These displaced units will then be cascaded to strengthen services on the other lines the units are used on. Three years later, London Overground began a programme to refresh the Class 378 fleet, giving them a livery and moquette similar to that of the newer Class 710 fleet. During January 2018, the Class 378 fleet was temporarily withdrawn from service for urgent safety inspections after one unit suffered a failed brake caliper. Fleet The Class 378 fleet is currently formed of two separate subclasses, DC-only 378/1 and dual-voltage (AC and DC) Class 378/2: Class 378/1 – 20 four-car units were ordered. These units operate services on the extended East London Line, and are 750 V DC only. These trains, which are designated Class 378/1, replaced the A60/A62 Stock previously used on the line. They entered service on 27 April 2010, on the preview service between Dalston Junction and New Cross / New Cross Gate. The service was extended to Crystal Palace and West Croydon on 23 May 2010. In common with all trains in the Electrostar family, these DC-only 378/1 units have a recessed roof space for the fitting of a pantograph and other equipment for dual-voltage working in the future if necessary. The Southern services on the South London line were withdrawn in 2012 and replaced by a new London Overground service operated using new air-conditioned 4-car Class 378 units. Class 378/2 – 37 dual-voltage four-car units ordered for the North London, West London, Watford DC, East London lines. These units have dual-voltage capability, taking current at 25 kV AC from overhead wires or 750 V DC from third rail. These trains replaced the Class 313 and Class 508 units in 2010. The first 24 units were originally three-car units designated Class 378/0 (378001-378024) and were redesignated Class 378/2 (renumbered 378201–378224) as each unit received its additional carriage in late 2010. The remaining 13 units (378225-378234 and 378255–378257) were built as four-car Class 378/2s from the outset. Illustration Named units Named units are as follows: 378135: Daks Hamilton 378136: Transport for London 378204: Professor Sir Peter Hall 378211: Gary Hunter 378232: Jeff Langston 378233: Ian Brown CBE See also London Underground S7 and S8 Stock Notes References External links 378 Bombardier Transportation multiple units London Overground Articles containing video clips Train-related introductions