Every efficient operation inside the engine is inseparable from the support of “bearings”. As the core parts of precision machinery, engine bearings play a vital role in ensuring smooth operation between parts, reducing wear, and extending life.
The role of engine bearings
Engine bearings are mainly used to support crankshafts, camshafts, and connecting rods so that they can maintain stable and smooth rotation at high speeds, while effectively reducing direct contact between metal parts.
The main functions include:
Reducing friction: forming an oil film through lubricating oil, effectively isolating the metal contact surface and reducing the friction coefficient.
Absorbing impact loads: The high-intensity impact generated by the engine during combustion is buffered and dispersed through bearings.
Maintaining alignment and clearance: ensuring that the shaft and the hole maintain a stable position to prevent eccentric wear.
Extending the life of parts: protecting key parts such as crankshafts and connecting rods to avoid direct wear.
Common types of engine bearings
Engine bearings can be divided into the following categories according to their installation location and load-bearing form:
Main Bearings
Support the crankshaft of the engine and bear rotation and impact loads.
Connecting Rod Bearings
Installed at the big end of the connecting rod, connecting the crankshaft and the piston connecting rod.
Thrust Bearings
Bear the axial thrust of the crankshaft and prevent axial displacement.
Camshaft Bearings
Support the operation of the camshaft to ensure the normal operation of the valve mechanism.
Sliding bearings and rolling bearings
Sliding bearings are mainly lubricated by oil film and are suitable for high-speed and large loads; rolling bearings use rolling elements and are suitable for some small and medium-sized engines or accessories.
Bearing materials and manufacturing processes
The material selection and manufacturing process of bearings directly affects their performance and life.
Material type
- Bi-Metal
Composed of steel back and aluminum-based alloy or copper-based alloy, suitable for medium and high-load engines. - Tri-Metal
Includes steel back, copper-lead intermediate layer, and surface coating (such as lead-tin alloy), suitable for high load and high-speed occasions. Coated bearings
The surface is coated with PTFE or high-performance alloy coating to improve initial start-up wear resistance and anti-seizure performance.
Manufacturing process
- Sintering process: Metal powder is pressed and sintered to form a high-density and stable performance.
- Calendering composite process: Multi-layer materials are combined through high temperature and pressure to improve heat resistance and strength.
- Precision turning and grinding: Ensure the dimensional accuracy and finish of the inner surface of the bearing and improve the smoothness of operation.
Common causes and symptoms of bearing failure
- Bearing wear: Over time, continuous friction and load on the bearing will cause it to wear. Worn bearings may have symptoms such as increased engine noise, low oil pressure, and excessive bearing clearance.
- Bearing jam: Bearing jam refers to the jamming of the bearing on the crankshaft journal due to insufficient lubrication or overheating. This will cause the oil supply to other engine parts to be interrupted and cause catastrophic engine failure. Symptoms of bearing jam include overheating, knocking or clicking, and power loss.
- Bearing fatigue: Main bearings may fatigue due to high loads, improper installation, or insufficient lubrication. Fatigue cracks can lead to bearing failure and generate metal debris in the oil system. Symptoms may include engine vibration, increased bearing clearance, and obvious signs of wear or damage.
- Bearing misalignment: Improper bearing installation or crankshaft misalignment can cause uneven main bearing loading and excessive operating stress. This can cause premature wear, overheating, and increased bearing clearance.
Maintenance and care of engine bearings
Bearings are key components of internal combustion engines and require proper maintenance and care to ensure their service life. Here are some tips for maintaining and servicing main bearings:
- Regularly change lubricating oil and filters
Keep the oil clean to prevent impurities from wearing the bearing surface. - Use high-quality engine oil
Choose oil that meets the engine manufacturer’s standards to ensure oil film strength and high-temperature resistance. - Maintain a good engine cooling system
High bearing temperatures will accelerate failure, and the coolant level and water pump working status should be checked regularly. - Monitor engine operating data
If abnormal noise, vibration, or low oil pressure occurs, stop and check time. - Proper assembly and clearance control
When overhauling the engine or replacing bearings, strictly follow the technical manual to ensure that the size and torque meet the standards.
Although the bearing is small, it is one of the core components for the engine’s smooth operation. Understanding the type, material, cause of failure, and maintenance method of bearings can not only help you improve engine performance but also effectively reduce maintenance risks and costs.
As a professional engine parts supplier, Baileparts has long provided high-quality main bearings, connecting rod bearings, thrust washers, and other key bearing products, suitable for a variety of engine models such as Kubota, Yanmar, Mitsubishi, Isuzu, John Deere, etc.
For more information on bearing products and models, please visit our website baileparts.com.
