The débâcle of the 564C brought the modernists at the RSR very close to convincing their bosses that steam had had its day. Ketterik, however, wasted no time in developing a new 4-10-4 without the bad aspects of its predecessor (and with a few good ones as well). A change to 5-cylinder triple-expansion drive, which required only one inside crank, brought the combined benefits of greater efficiency and lower maintenance costs. A redesigned tapered boiler consolidated the earlier departure from the time-honoured parallel type. The Wardale gas producer cumbustion system was retained. The 555As combine the good features of both 564B and (such as they were) 564C. Power, economy, speed, reliability and, last but not least, a very smooth ride have made them irresistible to both their operators and their crews. The RSR works at Akohniçe produced a total of 75 of these fine machines, all of which continue to move freight around the country with undiminished ease.

Text and graphics © Norman Clubb 2012