The 240 B and 240 C models are the smallest locomotives of the first generation from Maschinenfabrik Kiel. They were introduced in 1954, shortly after the first four-axle models, and were available with either two or three axles. While the two-axle variant with an axle load of around 14 to 16 tonnes was primarily used in companies in the mining industry, the axle load of the three-axle variant was around ten tons, which also allowed it to be used on small railways with a lighter superstructure. Depending on the requirements, many locomotives were weighed down by additional weights on the buffer beams. In contrast to most of the smaller diesel locomotives of their time, these models also had a relatively central driver's cab with good visibility in both directions.

While the larger front structure housed the engine, the rear structure housed a generous 1,000 liter tank. Unlike the other MaK locomotives, the engine was a smaller six-cylinder with a rated speed of 1,000 rpm. The power was transmitted to the Voith converter transmission, which was located under the driver's cab and first acted on a jackshaft and finally on the axles via coupling rods. A total of 55 two-axle and 14 three-axle vehicles were built, a few of which are still operational today.