Mounted bearings, , also known as pillow block bearings or bearing units, are among the most widely used bearing assemblies in industrial machinery. They combine an insert bearing with a bearing housing, making installation easier while allowing the shaft to compensate for minor misalignment.
However, many users are unsure which type of mounted bearing is suitable for their application. Different locking methods, housing materials, and housing designs are intended for different working conditions.
This guide explains the most common classifications of mounted bearings and provides practical advice on selecting the right bearing unit.
What Is a Mounted Bearing?
A Mounted bearings consists of two main components:Insert Bearings、Bearing Housings.
Mounted bearings use a spherical outside diameter that fits into a matching spherical housing bore.This design allows the bearing to automatically compensate for small shaft misalignment during installation and operation, helping reduce installation errors and improve running stability.
Mounted bearings are widely used in:Agricultural machinery、Conveyor systems、Food processing equipment、Packaging machines、Textile machinery、Mining equipment、Fans and blowers and Material handling systems。They can be classified in several ways depending on their design and application.
1. Classification by Housing Manufacturing Method
Housing material directly affects bearing strength, corrosion resistance, and environmental suitability.
Cast Iron Housing
Cast iron is the most common housing material. Its advantages ：
· Heavy loads
· Mining equipment
· Steel industry
· Severe operating environments
· Stainless Steel Housing
Stainless steel housings offer excellent corrosion resistance.
Cast Steel Housing
Cast steel provides higher impact resistance than cast iron.
Recommended for Heavy loads、Mining equipment、Steel industry、Severe operating environments、Stainless Steel Housing.
Common applications include:
· Lightweight
· Economical
· Easy to install
They are commonly used in light-duty machinery and agricultural equipment.
2. Classification by Bearing Locking Method
The insert bearing can be secured to the shaft using different locking mechanisms.Selecting the correct locking method helps ensure reliable shaft positioning.
Set Screw Locking Bearings
Cast housings are the most common choice for industrial applications.
This is the most widely used mounted bearing type.
Two set screws lock the inner ring directly onto the shaft.
Typical Models have UC Series、UCP Series、UCF Series、UCT Series
Suitable for General industrial machinery、Conveyors、Agricultural equipment and Fans.
Eccentric Locking Collar Bearings
This design uses an eccentric collar to lock the bearing to the shaft.
Compared with set screw locking, it provides smoother locking during normal shaft rotation.
It is commonly used in applications with :
· Constant rotational direction
· Moderate loads
· Easy to install
They are commonly used in light-duty machinery and agricultural equipment.
3. Classification by Housing Material
Housing material directly affects bearing strength, corrosion resistance, and environmental suitability.
Cast Iron Housing
Cast iron is the most common housing material.
· Advantages include:
· High strength
· Excellent rigidity
· Low cost
Suitable for most industrial machinery.
Cast Steel Housing
Cast steel provides higher impact resistance than cast iron.Recommended for:
· Heavy loads
· Mining equipment
· Mining equipment
· Severe operating environments
· Stainless Steel Housing
Stainless steel housings
They offer excellent corrosion resistance.Common applications include:
· Food processing
· Pharmaceutical equipment
· Beverage machinery
· Marine equipment
· Polymer Housing
Engineering polymer housings
They are lightweight and corrosion resistant.Typical applications include:
· Food industry
· Food industry
· Washdown environments
They also reduce equipment weight and require minimal maintenance.
4. Classification by Housing Shape
Mounted bearing units are available in many housing styles to suit different installation requirements.
Pillow Block Housing (UCP)
The most common mounted bearing unit.Used where the bearing is mounted on a horizontal base.
Typical applications:Conveyors、Motors、Fans、Agricultural machinery.
· Square Flange Housing (UCF)
Provides four-bolt mounting.Offers excellent rigidity and accurate positioning.
· Diamond Flange Housing (UCFL)
Uses two mounting holes.Ideal for limited installation space.
· Round Flange Housing (UCFC)
Provides circular flange mounting.Often used in precision positioning applications.
· Take-up Housing (UCT)
Designed for adjustable shaft position.Frequently used in belt and chain tensioning systems.
· Hanger Housing
Suspended from overhead structures.Suitable for suspended conveyor systems.
· Cartridge Housing
Designed for cylindrical mounting structures.Used where compact radial installation is required.
· Triangular Flange Housing
Three-bolt flange design.Provides flexible mounting in compact equipment.
Conclusion
Mounted bearing units combine an insert bearing with a housing to create a simple, reliable, and easy-to-install bearing solution.They can be classified according to:Housing manufacturing method、Bearing locking method、Housing material、Housing shape.
Understanding these classifications helps engineers and purchasing professionals select the most suitable bearing unit for different operating conditions.Choosing the correct mounted bearing improves equipment reliability, simplifies maintenance, and extends service life.
