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Why don’t they use ballbearings on crankshafts?

Why don’t they use ballbearings on crankshafts? The main reasons for using plain bearings instead of rolling bearings for engine crankshafts include the following:

Friction and Lubrication: The high speed of engine crankshafts requires the use of bearings to reduce friction and minimize drag. While rolling bearings reduce friction by means of balls or rollers, plain bearings reduce hard friction by isolating the two metal surfaces through a film of oil, which reduces wear and noise.

Noise and vibration: The large contact area between the shingles and the crankshaft provides a high average pressure and the presence of an oil film makes for smoother operation and less noise and vibration. In contrast, rolling bearings generate more noise and vibration when in motion.

Installation and maintenance: Plain bearings are easy to install and take up little space, which is conducive to reducing the size of the engine. In addition, plain bearings have greater freedom in the axial direction and are able to accommodate the displacement of the crankshaft when it is subjected to thermal expansion, which reduces the damage caused by thermal expansion.

Heat dissipation and stability: Plain bearings have a large contact area, which is conducive to rapid heat dissipation and improves the stability of engine operation. In contrast, rolling bearings are susceptible to damage under high loads and harsh environments.

Cost and maintenance: although the initial cost of plain bearings may be higher, but their maintenance costs are lower, and in the high temperature, high impact environment longer service life, reducing the need for frequent replacement of bearings.

In summary, ballbearings on crankshafts engine crankshafts use plain bearings rather than rolling bearings, mainly to reduce friction, reduce noise, facilitate installation and maintenance, and improve stability and heat dissipation efficiency.