Following his world tour of foreign railways, Karel Belčamin set about upgrading a number of existing RSR locomotive classes. One candidate was his class C6 4-6-0 of 1900, which was strange, for the engines were fairly new and performing quite well. The rebuild of the C6 applied mainly to the cylinders and valve gear. A new 4-cylinder compound layout was installed, with high-pressure cylinders outside and retaining the eccentrics behind the cranks to operate outside-admission piston valves. The larger, horizontal outside cylinders made it necessary to move the front bogie frames inside the wheels, the original springs being retained. The boiler was the same as that fitted to the C5B 4-6-0s and D6 4-8-0s, which was known to be free-steaming and economical, although, here again, the original C6 boiler was also quite satisfactory. The mystery deepens when we see that only four engines were rebuilt before construction of the B14 4-4-0s began. In the event, the C6AAs were quite good engines, although not to a sufficient degree to justify the expense of the rebuild. All C6AAs were withdrawn by 1924, their unrebuilt sisters outliving them by over ten years.

Text and graphic © Norman Clubb 2009