This locomotive has been described variously as the goods version of the 423D 4-8-4T or the tank version of the 634A. In fact, the 633A was a completely new design, but incorporating the boiler and many smaller standard components which are found in the 423D and with the addition of poppet valves, which had already become the RSR standard. The 633A is used for a variety of duties, including transfer goods workings around Bevice, banking over the back-door route from Forihv to Tormu (not often, of course, with Garratts, 4-10-4s and 4-12-4s at the front end) and helping out with suburban trains and excursions when loads are particularly heavy. With their rather small driving wheels, these engines are ideally suited to heaving long, heavy trains up the hills south of the Kroplihne valley. The works at Bevice-Akohniçe delivered 25 engines altogether, the bulk of the allocations going to Forihv, Kropčahne and Gunerad.

Text and graphics © Norman Clubb 2012