Crankshaft is one of the important parts of engine. is to the piston connecting rod Group of the gas force transferred to the ISS axis of the rotation torque external output, and drive the engine valve and other auxiliary devices (such as generators, pumps, fans, oil pumps, diesel engine injection pump, etc.) work. In order to ensure the reliability of the work, the crankshaft is required to have sufficient stiffness and strength, Crankshaft and the working surface should be wearable and well lubricated. The crankshaft’s spindle neck is installed on the cylinder body, the connecting rod axle neck is used to install the connecting rod, and its machining precision and dynamic balance degree play a vital role in the smooth running of the engine.

The crankshaft is subjected to the force of the connecting rod and converts it to torque through the crankshaft to output and drive other accessories on the engine to work. Crankshaft is subjected to the action of bending torsional load by centrifugal force of rotational mass, Crankshaft periodic variation of gas inertia force and reciprocating inertia force. Therefore, the crankshaft is required to have sufficient strength and stiffness, the surface of the axle neck wear, uniform, good balance.

The crankshaft is usually composed of a spindle neck, a connecting rod axle neck, a crank, a balance block, a front end and a back end. A spindle neck, a connecting rod axle neck and a crank form a flexure, the crank number of the crankshaft is equal to the number of cylinders (straight row engine); The crank number of the V-type engine crankshaft is equal to half of the cylinder number.

The crankshaft has a number of spindle necks more than the number of cylinders, that is, Crankshaft each of the connecting rod axle neck has a spindle neck. such as six-cylinder engine fully supported crankshaft has seven spindle necks. Four-cylinder engine fully supported crankshaft has five spindle necks. This kind of support, the crankshaft strength and the rigidity are good, Crankshaft and reduces the main bearing load, reduces the attrition. Diesel engines and most petrol engines use this form more than once.

The function of the crankshaft is to turn the thrust of the piston connecting rod into a rotating torque, turn the reciprocating linear motion of the piston into the crankshaft circular rotation, then transmit the engine torque to the transmission system through the flywheel, Crankshaft and also drive the engine’s valve distribution mechanism and other auxiliary devices.

The crankshaft is mainly composed of the crankshaft front end (or the free end), the connecting rod axle neck, the spindle neck, the crank, the balance block and the crankshaft back end flange (or the power output end). The crankshaft is fitted with a crankshaft timing gear, and the rear end is fitted with a flywheel (some engines also have balance blocks).

According to the number of spindle necks of crankshaft, the crankshaft can be divided into two kinds: fully supported crankshaft and non-fully supported crankshaft, Crankshaft according to its structure, it can be divided into three kinds: whole forging, whole casting and combined type. According to the material, it can be divided into ductile iron and steel.