Plain Bearings

Plain bearings are mechanical components that allow for angular rotation around a central point. These bearings are designed to accommodate misalignment from mounting or shaft deflection, making them suitable for a wide variety of applications.

Plain bearings can be made from various materials, featuring an outer and inner ring, and are often self-lubricating, corrosion, and chemically resistant.

RS has a range of high-performance spherical bearings with bore sizes ranging from 3 mm to 140 mm and various outside diameters from 12 mm to 225 mm to meet a number of bearing solution requirements.

How Do Plain Bearings Work?

Plain bearings function by accommodating a rotating shaft within an inner ring, allowing it to rotate and move at an angle without the use of rolling elements. The inner ring (often referred to as a spherical bush) has a convex outer moulding that fits perfectly within the concave moulding of the outer ring. This design creates a smooth sliding surface, enabling angular movement and accommodating misalignment. Self-lubricating materials are often used to reduce friction between the inner and outer rings, ensuring smooth operation and a long lifespan.

Applications of Plain Bearings

Plain bearings are used in countless applications, wherever rotational motion must be allowed to change the alignment of its rotation axis. They are used in machinery and applications like:

• Engines: Plain bearings are used in engine systems to support rotating shafts, such as in crankshafts and connecting rods. They accommodate high loads and provide a smooth sliding surface, ensuring reliable engine performance.
• Car Suspension Systems: Spherical plain bearings are used in car suspension systems to accommodate the movement of the drive axle and control arm. They allow for angular rotation and misalignment, ensuring a smooth and comfortable ride.
• Heavy Machinery: In heavy machinery, plain bearings are used to support rotating shafts in excavators, cranes, and construction equipment. They can withstand high loads and provide a durable and reliable solution for demanding applications.
• Robotics: Plain bearings are used in robotics to provide angular movement and support for robotic arms and joints. They allow for smooth and precise movements, making them essential for a wide range of robotic applications.
• Wind Turbines: In wind turbines, plain bearings are used in the yaw and pitch systems to accommodate the angular rotation of the blades and the nacelle. They provide a durable and reliable solution for these demanding and high-load applications.

Types of Plain Bearings

Plain bearings are available in different types, each designed for specific load and movement requirements. They can be categorised by their construction, load direction, and material.

By Construction

• Spherical Plain Bearings: These bearings consist of an inner ring with a convex spherical outer surface and an outer ring with a corresponding concave spherical inner surface. This design allows for angular movement in all directions.
• Plain Bushes: These are cylindrical bearings that support a rotating or sliding shaft. They are simple in design and are used in applications where angular movement is not required.
• Flanged Bearings: Flanged bearings feature a flange at one end, enabling them to be securely mounted and support axial loads. They are commonly used in conveyor systems and industrial machinery.

By Load Direction

• Radial Spherical Plain Bearings: These bearings accommodate radial loads and misalignment. A radial plain bearing supports a rotating shaft within the inner ring, allowing it to move at an angle.
• Spherical Plain Thrust Bearings: Designed for axial loads and misalignment, a plain thrust bearing supports a rotating shaft and allows it to move at an angle.
• Angular Contact Spherical Plain Bearings: These bearings accommodate a combination of both radial and axial loads, as well as misalignment.

By Material

• Metal Bearings: Made from metals like steel or bronze, these bearings are used in applications where high loads and speeds are required.
• Plastic Bearings: Made from composite materials, they are often self-lubricating and resistant to corrosion and chemicals. These are ideal for applications where low friction and chemical resistance are important.

How to Install Plain Bearings

The proper installation of spherical plain bearings is crucial for their performance and longevity. Here is a general guide on how to install them:

• Preparation: Before installation, ensure the bearing and the housing are clean and free from any dirt or debris. Check for any damage or burrs on the shaft or housing and remove them.
• Mounting: Use a press or a hammer with a soft punch to gently tap the bearing into the housing. Do not use excessive force, as it can damage the bearing. Ensure the bearing is seated correctly and is flush with the housing.
• Lubrication: For bearings that require maintenance, apply a suitable grease to the bearing before installation. Re-lubricate the bearing as needed, depending on the operating conditions and manufacturer's recommendations.
• Shaft Installation: Insert the shaft into the inner ring of the bearing, ensuring it is aligned correctly. Do not use excessive force, as it can damage the bearing.

How to Choose the Right Plain Bearings

Choosing the right plain bearings is essential for ensuring optimal performance and longevity in your application. Consider the following factors when selecting a bearing:

• Load Direction: Determine the direction of the load, whether it is radial, axial, or a combination of both. This will help you choose between radial plain bearings, plain thrust bearings, or angular contact bearings.
• Operating Conditions: Consider the operating conditions, such as the speed, temperature, and environment. For high-speed and high-load applications, metal bearings are a good choice. For applications with chemical exposure, plastic bearings are a better option.
• Material: Choose a bearing material that is suitable for your application. Self-lubricating plastic bearings are ideal for applications where maintenance is difficult, while metal bearings are suitable for high-load and high-temperature applications.
• Size and Dimensions: Ensure the bearing's bore size and outside diameter are compatible with your shaft and housing dimensions.
• Compliance Standards: Ensure the bearing complies with relevant industry standards and regulations for safety and performance.
• Price and Availability: Consider the price and availability of the plain bearing.

Buy Plain Bearings Online from RS

As your trusted supplier and distributor, RS offers a vast and high-quality range of spherical plain bearings for any project in Australia. You'll find a comprehensive selection from renowned brands such as Igus, SKF, and INA, with various types and sizes available at a price to suit your budget. We also offer products such as roller bearings and pipe sealants. Our seamless online ordering process ensures efficient and fast delivery of your order. To get complete details on our delivery services and charges, please visit our Delivery Page.