Indian locomotive class ZDM-2

The Indian locomotive class ZDM-2 is a series of narrow gauge diesel-hydraulic locomotives built for Indian Railways by the German company Maschinenbau Kiel. In the 1980s and 1990s, several of the type were fitted with KPC engines, these were reclassified as the ZDM-2R.

History
The ZDM-2 class was designed and manufactured by Maschinenbau Kiel (MaK). The type was specially developed for the Indian 762 mm railway lines. Locomotive No 600488 was tested on the Kreisbahn Osterode-Kreiensen 750 mm gauge railway line before delivery. The class was initially used on the Kalka–Shimla Railway and the Kangra Valley Railway, then later in Nagpur. On the Kalka-Shimla line, ten ZDM-2 locomotives partly replaced the ageing steam locomotives and partly the inefficient and failure-prone ZDM-1 diesel locomotives for passenger transport. On the Kalka–Shimla line, ZDM-1 locomotives pulled only three passenger coaches, while ZDM-2 locomotives often pulled seven. The ZDM-2 and ZDM-1 locomotives that remained on the line were completely replaced by ten ZDM-3 locomotives delivered between 1970 and 1972, the former being transferred to the South Eastern Railway in 1971–1972 and the latter to the Matheran Hill Railway in 1976. The ZDM-2s were fitted with a hydraulic transmission of the Indian "Suri" type, which proved to be highly failure-prone. The series was equipped with the Maybach "MD 435" diesel engine. On the first ten units these operated at the speed of 1400 min⁻¹ for a power output of 650 PS, while on the latter fifteen at 1700 min⁻¹ for a power output of 700 PS.

Several members of the type were modified in the 1980s and 1990s; they were fitted with KPC hydraulic transmissions and MaK diesel engines.