The most important part of the engine. It bears the force coming from the connecting rod and transforms it into a torque through the crankshaft output and drives other accessories on the engine to work. The crankshaft is subjected to the combination of centrifugal force of rotational mass, periodic variation of gas inertial forces and reciprocating inertial force, which makes the crankshaft bear the role of bending torsional load.
Therefore, the crankshaft is required to have sufficient strength and stiffness, the surface of the shaft neck needs wear resistance, uniform work, good balance. In order to reduce the quality of the crankshaft and the centrifugal force generated during movement, the crankshaft neck is often hollow. Oil holes are opened on the surface of each axle to introduce or elicit oil to lubricate the surface of the shaft neck.
In order to reduce the stress concentration, the connection between the spindle neck, the crank pin and the crank arm is connected by the transition arc. The role of crankshaft balance weight (also known as counterweight) is to balance the rotational centrifugal force and its torque, and sometimes to balance the reciprocating inertial forces and their torque. When these forces and torque themselves are balanced, the balance weight can also be used to reduce the load on the main bearing. The number, size and placement of the balance weight should be considered according to the number of cylinders of the engine, the arrangement form of the cylinder and the shape of the crankshaft. Balance weight is generally with crankshaft casting or forging into one, high-power diesel engine balance weight and crankshaft separate manufacturing, and then bolted together.