Southern Electric Group Kent Coast Electrification Scheme (Part 4)

Express Rolling Stock—4Cep and 4Bep (later Class 411 and 410)

The Kent Coast electrification scheme involved the building of rolling stock to cover both express and semi-fast services, and motor luggage vans for use on continental boat trains. For all these the electric multiple-unit principle was adhered to. In addition, the scheme involved the construction of 24 electric locomotives.

The express rolling stock design was the culmination of the development of the 4Cor units introduced for the 1937 Portsmouth electrification but using electro-pneumatic brakes and BR standard carriage designs. The units were of two types, one incorporating a buffet car. Buffet units were designated 4Bep (originally 4Buf(EPB)), whilst the remainder of the fleet were designated 4Cep (originally 4Cor(EPB)). The designations stand for Buffet EP brake and Corridor EP brake. Prototypes of the new designs had entered service on the Central Division in 1956. These were 4Cep 7101-7104 and 4Bep 7001-7002.

The 4Cep had a Motor Brake Second Open (MBSO) with driving position at each end of the unit, with a Trailer Composite (TC) and Trailer Second (TS) as intermediate vehicles. In the 4Bep units, the Trailer Second coach was replaced by a Trailer Buffet (TRB). All units were gangwayed throughout. Weight and seating capacity of the coaches of the prototype units was as follows:

The motor coaches at each end of the unit differed slightly, in that only those adjacent to the TS (TRB in 4Bep) were equipped with motor generator sets and batteries these being the higher numbered coach in each unit. All vehicles were 64ft 6in long over bodywork, 9ft 3in overall width, and 12ft 9in high from the top of the running rail. Each unit was 265ft 8˝in long overall, and was equipped with Mk 4 bogies.

The units used English Electric 250 hp EE507 traction motors, two being mounted on the nose end axle of each MBSO. The prototype units employed a contactor control system operating at 70V, incorporating field weakening. This system was also used to control the heating and lighting circuits, the buffet cars having their own motor generators providing a 200 watt output for supplying cooking equipment.

The motor coaches incorporated a 10ft long guards van, situated immediately behind the driving position, and able to accommodate up to 1 ton of luggage, mails or parcels. Situated to the left of the gangway was the motorman’s (driver’s) compartment, access to which was from the guards (conductors) van. The gangway connection were the first on the Southern to incorporate the headcode panel while still permitting passage between two units.

Accommodation in the MBSO was in a single 56-seat saloon, although there were glazed partitions between one pair of seat-backs adjacent to the centre doors. There were also doors at both ends of the coach. Seating was in 7 bays of 2+2 seating. The 64 seats of the TSK were arranged in 8 compartments, with doors on both sides of the coach at both ends of the car, and also at the centre of the car. A corridor ran the length of the vehicle. There were two lavatories at one end of the coach, one on either side of the gangway connection.

The TCK consisted of 4 first and 3 second class compartments, seating 6 in each first class compartment and 8 in the second class. A corridor ran the length of the vehicle, lavatories being located at either end of the vehicle, on the same side as the compartments. There was a dividing door in the corridor between the two classes of accommodation. There were 3 doors on the compartment side of the coach (at each end and in the centre) while the corridor side had 4 (at each end and two along the side of the coach). In both types of trailer coach there was a central vestibule; that on the TSK was adjacent to the centre pair of doors while on the TCK the compartment side centre door gave access to the vestibule from one side only.

The trailer buffet coaches of 4Bep had 21 loose seats for the use of those obtaining refreshment. These were arranged 2+1 in pairs facing across tables. The kitchen equipment in the cars comprised an electric cooker with grill and hot closet, a refrigerator and a freezer for keeping ice cream. A bottle cooler was situated under the buffet counter end. Water used for catering purposes was carried in a 120 gallon tank mounted on the underframe of the coach, and was raised to service taps at a pressure of between 5 and 12 psi. In addition to the motor generator for catering equipment, the underframes also carried condensing units for the refrigerator, ice freezer and bottle cooler.

The 6 prototype units were finished in wood panelling, but this was replaced by laminate in the production units. The colour scheme employed was steel blue, black and light grey panelling in the motor coaches, red plastic matt bodyside panels in the corridor second and green plastic matt panels in the corridor composite. The buffet coaches had white bodyside panels. with gangway entrances finished in stardust brown. All coaches employed sycamore framing. Prototype and phase 1 units were fitted with double glazing when built.

Apart from the differences in interior finishing, the production units differed from the prototypes in that they were equipped with electro-pneumatic camshaft control, and a series switch was incorporated. This ensured that the automatic acceleration equipment did not notch up from the series position whilst ascending the 1 in 30 gradient from Folkestone Harbour, while allowing the current limit relay to switch to the parallel setting and so increase tractive effort. (The prototype units could not, therefore, be formed at the head of a train from Folkestone Harbour.)

The Phase 2 units saw slight modifications to earlier designs. These included a reversion to single glass panes, since it was found that the double glazed units were not watertight, and subsequently were replaced by single pane windows. The final batch of units (7205-11) were fitted with small headcode panels and tapering windscreens.

Unit numbers were as follows:

4Bep

4Cep

Units 7205-11 were originally intended for operation on South Western Division services, but when introduced went to the South Eastern Division. All the vehicles were built at Eastleigh Works, using underframes constructed at Ashford. Coach numbers, and date of build, were as follows: