The Crankshaft Is The Most Important Component in An Engine

The most important component in an engine. It bears the force transmitted from the connecting rod and converts it into torque, which is output through the crankshaft and drives other accessories on the engine to work. The crankshaft is subjected to the combined action of the centrifugal force of the rotating mass, the periodically varying gas inertia force, and the reciprocating inertia force, making the crankshaft withstand the bending and torsional load. Therefore, the crankshaft is required to have sufficient strength and stiffness, and the surface of the journal should be wear-resistant, work evenly, and have good balance.

In order to reduce the mass of the crankshaft and the centrifugal force generated during movement, the crankshaft journal is often made hollow. An oil hole is opened on each journal surface to introduce or lead out oil for lubrication of the journal surface. To reduce stress concentration, the main journal, crank pin, and crank arm are connected by a transition arc.

The function of crankshaft counterweight (also known as counterweight) is to balance the rotating centrifugal force and its torque, and sometimes it can also balance the reciprocating inertial force and its torque. When these forces and moments balance themselves, the counterweight can also be used to reduce the load on the main bearing. The number, size, and placement position of the counterweight should be considered based on factors such as the number of cylinders in the engine, the arrangement of the cylinders, and the shape of the crankshaft. The counterweight is generally cast or forged into a whole with the crankshaft. The counterweight for high-power diesel engines is manufactured separately from the crankshaft and then connected together with bolts.