DRG Kleinlokomotive Class II

German Kleinlokomotiven (literally: small locomotives) like the DRG Kö II (later: Köf II) were developed as locomotives with a low weight and driving power for light shunting duties. There were two classes, based on engine power. The Class II were engines which developed more than 40 (later 50) HP.

After tests with several trial locomotives, they were placed in service from 1932 onwards by the Deutsche Reichsbahn (DRG) and used on small stations for light shunting and marshalling work. They were intended to make the handling of goods traffic more economical. To do that, an appropriately trained controller had to be able to handle shunting duties using the locomotive. Accordingly, the locomotive was designed to be robust and easy to operate.

Light locomotives mainly used diesel motors (originally classified as Kö/Köf/Köe by the DRG), as their source of energy, but there were also versions with Benzolmotors, designated as Kb/Kbf/Kbe, and with electrical batteries (accumulator cars: Ks/Ka), as well as one locomotive with a steam engine. The third letter, if present, indicated the type of power transmission. If there was none, the locomotive had a mechanical gear system with a dry clutch. An f stood for an hydraulic drive and an e for electric traction motors, that were fed by a generator. Köf, therefore, stood for a light locomotive (Kleinlok) with diesel engine (Öl-(Diesel-)Motor) and hydraulic transmission (Flüssigkeitsgetriebe). Power is transmitted to the axles using a chain linkage.

The locomotive is very small and yet of 1,435 mm (4 ft 8 ¹⁄₂ in), standard gauge, width, but only fills about half the loading gauge profile. As a result, it can be loaded onto flat wagons. That was necessary, because if it had to move under its own power, its top speed of only 30 km/h (19 mph) would have seriously held up rail traffic.

The light diesel locomotives were the first German diesel engines that were built in batches by several manufacturers. They were initially divided into two power groups:

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