Crankshaft and Flywheel — General Information (Mercedes-Benz Sprinter 903)

The crankshaft is designed to convert the reciprocating motion of the pistons into rotary motion. For additional rigidity, each crankpin is located between two main journals (full support crankshaft). For this reason, the engines considered in this publication have a different number of crankshaft main bearings. The four-cylinder engine has five main bearings, and the five-cylinder engine has six. To further balance the crankshaft, counterweights are installed on it, the number of which is determined by the number of engine cylinders, namely: the crankshaft of the four-cylinder engine has six, and the crankshaft of the five-cylinder engine has ten counterweights. On the gearbox side, the flywheel is attached to the crankshaft, and in the case of an automatic transmission, its driven and driving disks. In both the first and second cases, these parts are equipped with a toothed rim for engagement with the starter gear. The camshaft drive chain sprocket and the oil pump drive sprocket are mounted on the front end of the crankshaft. They are not visible from the outside, as they are located under the camshaft drive mechanism cover. The only thing visible from the front end of the crankshaft is the belt pulley for the poly-V belt for driving individual vehicle units. Depending on the vehicle configuration, these units may include an electric generator, a water pump, a power steering pump, and an air conditioning compressor. Vibration damper (torsional vibration damper) installed between the belt pulley and the belt pulley hub (see subsection 2.9). As already mentioned, the cylinder block of the four-cylinder 601 engine has undergone some changes compared to previous models. These changes also affected the crankshaft - bearings and bearing cap mounting bolts, which means that parts of the same type of engines, but of different years of production, may not be interchangeable.