Steam Locomotives of a Leisurely Era
1941 – Bulleid ‘Merchant Navy’ Pacifics
The first engine of the 4-6-2 type to run on Southern Railway metals appeared under conditions of some secrecy owing to war conditions during 1941. It was a 3-cylinder engine incorporating many novel features, including a thermic siphon, only once before used in this country, and a patent valve gear of O.V.Bulleid’s own design in which the primary drive is by means of chains enclosed in an oil bath. The novel design of wheels, reminiscent of Hackworth’s engines of early days may also be noted. It was fully streamlined, or air-smoothed, as it was referred to at the time. A new and somewhat peculiar numbering scheme was also introduced, in which the prefix 21C indicated the wheel arrangement – two pairs of bogie wheels, a trailing axle, with the C designating the three pairs of coupled wheels. The first engine, No.21C1 was named ‘Channel Packet’ and they were known as the ‘Merchant Navy’ class. Nos.21C2-10 all appeared in 1941-2, followed by Nos. 21C11-20 in 1944-5. Ten more came out after Nationalisation in 1948 with rational numbers, 35021-30, when the original batches were altered to 35001-20.
These engines have done a great deal of heavy main line service on the SR, but the valve gear was not entirely satisfactory, and commencing with No.35013 in 1956 this was replaced by the Walschaert type and at the same time the streamlined casing was removed, with considerable improvement to the looks of the locomotives. Their original boxed-in appearance gave rise to their being somewhat irreverently described as ‘spam-cans’.
All of the class were rebuilt by 1959 and seemed likely to see a good many more years’ service.
Driving wheels – 6’ 2”, Cylinders (3) 18”x 24”, Pressure – 250 lb., Tractive effort – 33495 lb., Weight – 94 tons 15 cwt (as built), 97 tons 18 cwt (as rebuilt), BR classification – 8P.