750 V DC. There are eight pick-up shoes per unit (twice the number of previous generation 4-car electric multiple units), and this enables them to ride smoothly over most third-rail gaps. The units in the 377/2, 377/5 and 377/7 sub-classes are dual-voltage, and are fitted with a pantograph to pick up 25 kV AC from overhead lines. On these units (and on single-voltage sub-class 377/6), the shoe mechanism is air-operated so that when powered down, or working on AC overhead lines, the shoe is raised out of the way. This is used on trains from Hemel Hempstead to Clapham Junction, which use part of the West Coast Main Line between Hemel Hempstead and Willesden Junction, and then the West London Line towards Clapham Junction. These trains change to third-rail DC supply on a dual-voltage section of the West London line north of Shepherd's Bush. Since March 2009, dual-voltage Class 377 units operated some Thameslink Bedford to Brighton, Rochester and Ashford services (see below). The Bedford to Brighton services are now run by Class 700s, while the Class 377/5s themselves are now operated by Southeastern. Among the remaining units, the trailer coach in each unit has a recess in its roof where a pantograph could be fitted, to allow for future conversion to overhead AC power. Additional units and the Thameslink Programme In April 2007, as part of the Route Utilisation Strategy for the Brighton Main Line, it was announced that Southern would procure an additional 48 Class 377 carriages to replace an identical number of carriages (12 x 4-car units) due to be transferred to First Capital Connect. Eleven further dual-voltage units were then added to the order, making a total of 23. The units were commissioned at Southern's Selhurst depot in Croydon before being transferred to First Capital Connect's Bedford Cauldwell depot. The first of these, unit 377501, was delivered to Cauldwell depot on 27 February 2009 after making its first appearance through the Thameslink Central London core. The 377/5s operated mainly on Bedford to Brighton services but in the peaks formed part of First Capital Connect's and Southeastern's joint service to places such as Rochester and Ashford. Delays in the construction of the Class 377/5s for First Capital Connect saw the temporary transfer of eight of Southern's Class 377/2s to FCC to enable it to implement the planned timetable changes on 22 March 2009. The loss of these