Small powerhouses off the main tracks: Starting in the 1930s, small locomotives became a staple of light switching operations at German rail stations. Designed as economical standard-series locomotives, they made it possible for a single train conductor to perform the time-consuming task of switching operations. Whether the legendary Köf-I and Köf-II models or their more powerful successors—these versatile workhorses ensured smooth operations at countless rail yards and industrial tracks.

Performance Group	Engine power	Typical Series (DB / DR)	Characteristics & Applications
Performance Group I	Up to 39 PS (approx. 29 kW)	Class 311 (Kö I)	Early, lightweight two-axle cars for light shunting operations at small stations.
Performance Group II	40 to 150 PS	Class 321, 322, 323, 324 (Köf II), DR class 100	The tried-and-true standard model with a mechanical transmission.
Performance Group III	150 to 250 PS	Class 331, 332, 333, 335 (Köf III)	Subsequent, more extensive upgrades to the Federal Railroad for heavier shunting operations.
Special Designs	Variable (battery-powered / narrow-gauge)	Class 381 (battery-powered), Class 399 (narrow-gauge)	Special-purpose vehicles for emission-free indoor operations or narrow-gauge rail networks.

Series DB	Numbers	Series DR	Numbers	built
311	185 … 281	100.0	001-099	1934-1935
321	001 … 626	100.1-8 / 310	101-799; 801-899	1934
322	001 … 663			1952
323	001 … 999			1954
324	001-060			1959
		101.1 / 311	101 … 342; 501 … 677	1960
		102.0 / 312.0	001-081	1968
		102.1 / 312.1	101 … 257	1970
329 / 399 (1.000 mm)	501-504			1952-1971
331	001-003			1959
332	002 … 902			1959-1965
333 / 335 mit automat. Kupplung	001-251			1968-1978
333.9	901-902			1958, ex Kerkerbachbahn V 18 und V 19