A crankshaft is a mechanical part able to perform a conversion between reciprocating motion and rotational motion. In a reciprocating engine, it translates reciprocating motion of the piston into rotational motion. Whereas in a reciprocating compressor, it converts the rotational motion into reciprocating motion
Crankshafts are found in many different machines. For example: piston engine, a steam piston engine, a reciprocating compressor, a piston pump, an eccentric press or a sewing machine. The load on the whole crankshaft is really very large, so it must be made of the highest quality materials.
Crankshafts are used in cycloidal gears. The operation of the cycloidal gear consists in forcing the rotation of the cycloid gear wheel with an eccentric bearing.
Movement of the system is enforced by the rotation of the eccentric bearing, which drives the cycloidal gears. The amount and the outline of the teeth force the movement in such a way that 1 full rotation of the input shaft causes the cycloid circle to rotate 1 scale in the opposite direction. Thus, the cycloidal wheels perform rotary motion at reduced speed. The turnovers are transferred to the output shaft by means of pins cooperating with holes in the wheels. This connection is also made using rotating elements.
An eccentric bearing is a very common type of bearing. It mainly includes the outer ring, inner ring, basket and rolling body. The eccentric bearing design is very simple and easy to use.
Connecting rod – how to recognize its wear?
An effective method of checking the slack on the crankshaft is … listening with a significant load. For example, we can enable a higher gear for a given speed and accelerate. It is also worth remembering to regularly check the condition of greases and oils. In this way we can avoid unnecessary machine breakdown. Insufficient lubrication can lead to their seizure – steel filings in the engine oil will lead to defect.
Excessive looseness or damage to the crank and main bearings is usually a consequence of normal wear. Despite the considerable hardness of rolling elements as a result of long-lasting work, these parts wear out and fatigue wear of the surface due to the constantly changing, very high pressure. The result of friction is the increase in clearances and the result of variable pressures – cracking and flaking of the bearing race.
An additional factor is the corrosion, leading to the occurrence of pitting on rolling surfaces.
Among the most frequent failures we can distinguish:
- excessive slack or damage of the crank bearing,
- excessive slack or damage to the main crankshaft bearings,
- non-centricty or other deformations of the crankshaft,
- connecting rod deformation.