 The accepted design included two 0-6-0 steam bogies with weight-saving sleeve valves and chains to couple the driving axles.The boiler was offset to provide space for a communication corridor, allowing the driver to access both cabs without leaving the locomotive, an arrangement which led to later problems.The firebox, near the centre of the locomotive, was fed by the fireman from a third cab, linked to both driving cabs by the communication corridor.