The Function And Working Principle of Crankshaft

The crankshaft is the core component of engine power transmission, known as the "backbone" of the engine. Its performance directly determines the power output and operational stability of the engine, and occupies an irreplaceable position in fuel engines.

1、 The core function of the crankshaft

The primary function of the crankshaft is to convert the reciprocating linear motion of the piston into rotational motion, providing power for vehicle operation, generator power generation, and other purposes. The piston is connected to the crankshaft connecting rod journal through a connecting rod. The reciprocating motion of the piston in the cylinder is transmitted to the crankshaft through the connecting rod, driving the crankshaft to continuously rotate. At the same time, the crankshaft also undertakes the task of driving auxiliary components such as the valve train, oil pump, and water pump, transmitting power to other systems through timing gears or chains to ensure the coordinated operation of various engine components. In addition, the crankshaft needs to withstand the periodic impact force transmitted by the piston and the centrifugal force generated by its own rotation to maintain the smoothness of engine operation.

2、 Working principle of crankshaft

The crankshaft is mainly composed of the main journal, connecting rod journal, crank arm, balance weight, and other parts. During operation, the piston moves downward under the pressure of gas, and the crankshaft connecting rod journal rotates around the main journal through the connecting rod, converting linear motion into rotational motion. Due to the periodicity of piston motion, the crankshaft is equipped with a balance weight to counteract the centrifugal and inertial forces generated by rotation and reduce vibration.

In a four stroke engine, the crankshaft completes four strokes of intake, compression, power, and exhaust every two revolutions. During the power stroke, the power of the gas pushing the piston is transmitted to the crankshaft through the connecting rod and converted into rotational mechanical energy; The other three auxiliary strokes rely on the inertia of the crankshaft to complete the cycle. The main journal of the crankshaft is supported on the cylinder block through bearings to ensure smooth rotation, and is lubricated with lubricating oil to reduce wear and extend service life.