What is the crankshaft made of

The crankshaft is generally composed of main journal, connecting rod journal, crank, balance weight, front end and rear end. A main journal, a connecting rod journal and a crank form a crank. The number of cranks of the crankshaft is equal to the number of cylinders (in-line engine); The number of cranks of V-type engine crankshaft is equal to half of the number of cylinders.
The main journal is the supporting part of the crankshaft and is supported in the main bearing seat of the crankcase through the main bearing. The number of main bearings is not only related to the number of engine cylinders, but also depends on the support mode of crankshaft. There are generally two ways to support the crankshaft, one is the fully supported crankshaft, the other is the non fully supported crankshaft.
Fully supported crankshaft: the number of main journals of the crankshaft is one more than the number of cylinders, that is, there is a main journal on both sides of each connecting rod journal. For example, the fully supported crankshaft of a six cylinder engine has seven main journals. The fully supported crankshaft of a four cylinder engine has five main journals. With this support, the strength and stiffness of the crankshaft are better, and the bearing load of the main shaft and wear are reduced. Diesel engines and most gasoline engines use this form.
Non fully supported crankshaft: the number of main journals of the crankshaft is less than or equal to the number of cylinders. This support method is called non fully supported crankshaft. Although the bearing load of the main shaft of this support is large, it shortens the total length of the crankshaft and reduces the overall length of the engine. This type of crankshaft can be used for some gasoline engines with small load.
The connecting rod journal of the crankshaft is the connecting part between the crankshaft and the connecting rod. It is connected with the main journal through the crank, and the arc transition is used at the connection to reduce the stress concentration. In line engines have the same number of connecting rod journals and cylinders. The number of connecting rod journals of V-type engine is equal to half of the number of cylinders.
The crank is the connecting part between the main journal and the connecting rod journal. The section is oval. In order to balance the inertial force, the balance weight is cast (or fastened) at the crank. The balance weight is used to balance the unbalanced centrifugal torque of the engine, and sometimes to balance part of the reciprocating inertia force, so as to make the crankshaft rotate smoothly.
The front end of the crankshaft is equipped with timing gear, belt pulley driving fan and water pump, starting claw, etc. In order to prevent oil leakage along the crankshaft journal, an oil slinger is installed at the front end of the crankshaft and an oil seal is installed on the gear chamber cover. The rear end of the crankshaft is used to install the flywheel. An oil retaining flange and an oil return thread are made between the rear journal and the flywheel flange to prevent the oil from leaking backward.