later. In the 1990s, the fabrication of newly developed products started, for example the air-cooled one-cylinder diesel engines of the series 1B with vertical shaft. Due to their low weight, Hatz diesel engines are also mounted in motorcycles. The motorbike manufacturer Sommer based in Eppstein uses the one-cylinder four-stroke Hatz diesel engine 1B40 (462 cm³, 8 kW/11 PS) for retrofitting of the Indian motorbike series Royal Enfield. Products The product portfolio of Motorenfabrik Hatz comprises 3 business fields: manufacture of diesel engines, of systems and components for the automotive and commercial vehicle industry. Diesel engines The product portfolio of Hatz Diesel currently includes six engine series in a power range from 1.5 to 56 kW. Since 2014 a new water-cooled engine, the H-series, is on sale. B-series With the slogan “The challenger“, the HATZ 1B-series was presented in 1996, showing a number of technical highlights. In a minimum of space, all the important functional components of the engine such as decompression device, injection pump drive, oil pump with oil pump pressure regulator, valve train system for inlet and outlet valve, governor, speed control lever with governor spring and the multi-functional mechanical control system are integrated in the governor housing. Due to these technical features, the B-series scores with a light-weight and compact design. Depending on their cylinder capacity, the air-cooled one-cylinder diesel engines of B-series are available at power ranges from 1.5 to 7.6 kW and a maximum speed of 3600 rpm. Furthermore, models with vertical or horizontal crankshaft are available. The B-series complies with the strict requirements of EPA (Environmental Protection Agency) Tier IV final in the US. D-series The D-series, also referred to as SUPRA offers an even more robust design than the B-series. Therefore, the air-cooled one-cylinder diesel engines of this series are frequently mounted in compaction machines but are also used for other application fields such as generating sets for example. They have a power range of 3.5 to 15.2 kW at a maximum speed of 3600 rpm. The maximum torque is at 40.7 Nm. The SUPRA series particularly excels in its high running smoothness. This is achieved by a new design of the balance weights as well as the optimum use of two counter-rotating balance shafts and consequently a 100% first-order counterbalance. On demand, the engine may be equipped with the patented SILENT PACK ©, which reduces the noise emission by up to 90%. In