Journal bearings, also known as sliding bearings or sleeve bearings, support a rotating shaft through a cylindrical bearing surface. This allows relative motion without rolling elements (such as in ball bearings). In a plain journal bearing, the shaft rotates within a bearing shell housed within a bearing housing, relying on an oil film to separate surfaces and prevent metal to metal contact. Journal bearing designs focus on load capacity, shaft radius and operating conditions. SBS – Singa Bearings Solutions®️ provides high-performance journal bearing solutions operating under demanding requirements!
Why Journal Bearings?
Journal bearings or plain bearings are an excellent choice when your application requires handling of high loads and high leads. Journal bearings are also key to long-term durability at a lower cost!
Ball Bearings vs Journal Bearings
Ball bearings, including angular contact ball bearings, are rolling element bearings that use balls as rolling elements to reduce friction at a contact point. While ball bearing design supports high rotational speeds, these bearings have limited load carrying capability compared to sliding bearings. In applications with high load capacity requirements, oil whip risk, or critical speed concerns, SBS recommends journal bearings over ball bearings, especially in high speed machinery and relatively low speed applications with heavy loads.
The point-contact design of ball bearings result in lower load capacities, making them unsuitable for heavy, high-load applications. Additionally, ball bearings are highly vulnerable to contamination, corrosion and improper lubrication. Ball bearings are also not ideal due to their susceptibility to premature failure under high-impact, shock or vibrating loads. As such, ball bearings can cause fatigue and surface cracking.
Angular contact ball bearings have limitations, making them unsuitable for high-load, low-cost applications. They require complex and precise installation and are sensitive to misalignment. Angular contact ball bearings are also very costly compared to simpler bearings!
Rotating Shaft in Journal Bearings
In journal bearings or plain bearings, the rotating shaft plays a central role in forming the hydrodynamic fluid film. As the shaft rotates, shaft motion and shaft rotation create an oil wedge that generates oil pressure. Factors such as bearing speed, rotational speed and relative motion directly influence minimum film thickness and operating temperature. As a trusted partner, SBS engineers are able to carefully monitor and evaluate shaft rotation behaviour.
Tilt Pad Journal Bearings
Tilt pad journal bearings, also known as tilting pad bearings, are advanced hydrodynamic bearings designed for high speed machinery and critical rotating equipment. These bearings use individual tilting pad elements that pivot to form a stable hydrodynamic fluid film, improving load carrying capability and controlling fluid forces. SBS tilt pad journal bearings are ideal for applications operating near critical speed or under variable operating conditions, offering high load capacity and enhanced stability.
Tilting Pad
Each tilting pad in a tilt pad journal bearing automatically adjusts to shaft motion, optimizing oil film thickness and reducing vibration. Design features such as pressure dam, lemon bore geometry, and one direction loading improve bearing properties and operational stability. SBS uses precision engineering to ensure optimal film thickness, minimum film thickness control, and reliable performance across a wide operating temperature range.
Plain Bearings and Journal Bearings. What’s the difference?
Plain bearings, including sleeve bearing, plain journal, circular bearing, and thrust bearing designs, operate through sliding contact rather than rolling elements. Plain bearings are well-suited for high load capacity, shock loading, and continuous operation. SBS plain bearings are used extensively in rotating machines where radial loads, axial loads, and fluid film lubrication are required to achieve long service life and stable performance.
Hydrodynamic Journal Bearings
Hydrodynamic journal bearings rely on hydrodynamic bearings principles, where a hydrodynamic fluid film separates the bearing surface from the shaft. As lubricating oil is drawn into the oil wedge, oil pressure builds and supports load carrying without direct contact. SBS hydrodynamic journal bearings are designed to manage oil film thickness, oil viscosity, lower viscosity base oil or higher viscosity base oil selection, and operating temperature to ensure reliable operation in high speed applications.
Roller Bearings vs Journal bearings
Roller bearings are rolling element bearings that use cylindrical or tapered rollers to support load carrying through line contact. While suitable for certain bearing speed ranges, roller bearings are more sensitive to shock loading, lubrication methods, and misalignment. In contrast, SBS sliding bearings provide superior performance in applications requiring high load capacity, high rotational speeds, and resistance to fluid forces.
Integral Bearings
Integral bearings combine the bearing shell and bearing housing into a single bearing unit. These designs are commonly used in single bearing arrangements for industrial machinery. SBS integral bearings are engineered to optimize oil supply, film thickness, and load capacity while maintaining consistent performance under varying operating conditions.
Cast Iron
Cast iron is a widely used material for bearing housing and bearing shells due to its damping properties and thermal stability. In babbitt bearings and plain journal bearing systems, cast iron housings support hydrodynamic bearings by maintaining alignment and controlling vibration. SBS carefully selects materials such as cast iron to match bearing properties with application requirements.
Lubrication Methods
Effective lubrication methods are essential for journal bearing performance. Hydrodynamic bearings depend on continuous oil supply to maintain oil film thickness and avoid boundary lubrication regime conditions. SBS designs lubrication systems with operating conditions in mind, and ensure high load capacity across high speed and low speed conditions.
Contact Point
Unlike ball bearings or roller bearings where load is transferred at a contact point, journal bearings distribute load across the bearing surface through a fluid film. This eliminates direct contact during normal operation and significantly improves load carrying capability. SBS sliding bearing solutions are designed to maintain stable fluid film conditions, minimize wear, and deliver reliable performance in demanding industrial applications.
Contact Us Today for Journal Bearings
Curious and want to learn more? Contact us now at info@sbs-bearings.com.sg . Work with SBS today.
