The crankshaft is an important moving part in the air compressor. Its function is to transfer the energy of the motor to the connecting rod and the piston, and convert the rotational motion into the reciprocating motion of the piston. When designing the crankshaft, it is necessary to consider the periodic load and friction and wear it bears, so there are high requirements for fatigue strength and wear resistance.

The basic structural forms of crankshafts are mainly crankshafts and crankshafts. Crankshafts are mostly used in old single-row or double-row horizontal air compressors and are now obsolete. The crankshaft consists of a crankshaft neck, crank pin, crank and shaft body, and is widely used in symmetrical balanced, angle and piston air compressors. The crankshaft is usually designed as an integral unit, but in some cases it can also be a combined crankshaft, which is composed of several parts and assembled into one.

Crankshafts are generally made of forged and cast materials. Forged crankshafts are usually made of 40# and 45# high-quality carbon steel, while cast crankshafts are usually made of rare earth-magnesium ductile iron. Cast crankshafts are widely used due to their good castability and processing properties, as well as good vibration absorption, high wear resistance, and low manufacturing cost.

In order to improve the fatigue strength of the crankshaft, some measures can be taken, such as increasing the fillet radius to reduce stress concentration, rolling or high-frequency quenching of the crank fillet, and surface nitriding. The crankshaft of a large air compressor is often designed as a hollow structure to reduce weight, reduce inertia force, and improve fatigue resistance.

In terms of maintenance, crankshaft fracture may be caused by a variety of reasons, such as too small transition radius, irregular processing, long-term overload operation, material defects or cracks in the oil hole, etc. Treatment measures include increasing the transition radius, improving processing quality, avoiding overload operation, improving the casting process level and strictly controlling the oil hole processing process.