The 1938 rebuilding programme, which included the fitting of tapered boilers to the 344Ds and 433Ds, did not entirely live up to its promise of improved steaming and performance. The locomotives appeared slimmer and more racy but technical success stayed just out of reach, it seemed. The problem of the trailing bogie's tendency to derail was not solved, although the weight distribution was shifted slightly to the rear. The non-standard 2000-mm driving wheels were still bothersome to the workshop men and the ashpans still got clogged after a run of more than 100 kilometres. It was only the 1950 rebuild that really brought the 344Ds and 344DDs up to scratch.

Text and graphics © Norman Clubb 2012