Pillow block bearings are one of the most widely used mounted bearing units in industrial applications for good reason. They provide simple installation and long-lasting performance in both light-duty and heavy-duty environments.
This article explains what pillow block bearings are and where they are most commonly used. We also cover best practices for maintenance and signs of failure to be on the lookout for.
Let’s get started.

What Is a Pillow Block Bearing

A pillow block bearing is a bearing that comes pre-mounted in a housing. The housing is designed to be bolted onto a flat surface. Inside the housing sits a ball bearing or roller bearing that supports a rotating shaft.
The purpose of a pillow block bearing is to allow the shaft to rotate while keeping it stable under load. It also protects the bearing insert from vibration and misalignment. Pillow blocks are easy to install and maintain.

Key Features

Self-contained unit. Bearing and housing come together as one part.
Mountable to flat surfaces. Can be installed on machines, conveyors, and structural frames.
Supports radial and axial loads. Great for applications with both downward and side loads.
Replaceable insert. When the bearing wears out the insert can be replaced without changing the housing.
Standard sizes. Available in metric and inch dimensions for a wide range of shaft diameters.

Types of Pillow Block Bearings

Pillow block bearings come in several designs. The most common types include:
Standard cast iron units
These use deep groove ball bearings in heavy-duty cast housings. They are used in general industrial equipment and manufacturing lines.
Pressed steel housings
Lighter and more compact than cast iron versions. Used a lot in low-load or space-constrained applications.
Thermoplastic housings
Corrosion-resistant and food-safe. Common in food and beverage industry where washdowns are required.
Stainless steel housings
Strong and highly resistant to rust. Used in clean or wet environments like chemical plants and dairy facilities.
Split housing pillow blocks
Larger units that can be opened for easy service. Used in applications with big shafts or limited access.

Applications

Pillow block bearings are used in nearly every industry. Some common examples include:
Agricultural machinery
Food processing lines
HVAC systems and fans
Mining and construction equipment
Automotive assembly lines
Material handling systems
Woodworking and sawmill machines
The simple design and ease of replacement here makes them popular in systems that require regular maintenance (or where uptime is important).

Installation Steps

Clean the shaft and mounting surface. Remove debris or rust.
Position the bearing. Slide the pillow block onto the shaft.
Align the shaft. Make sure it is centered and parallel to the mounting surface.
Bolt the housing down. Do not tighten fully until the final alignment is confirmed.
Lock the bearing to the shaft. Use the set screws or eccentric locking collar.
Tighten the housing bolts. Make sure the base is flat and secure.
Test for free rotation. The shaft should rotate smoothly with no binding.
Avoid over-tightening or misalignment. This can reduce bearing life.

Maintenance

Even though many pillow blocks are pre-lubricated ongoing maintenance is still necessary for long service life.
Lubricate on schedule. Use the grease fitting if available.
Inspect for leaks or dirt. Contamination causes early failure.
Check the shaft fit. Loose shafts damage the bearing bore.
Listen for unusual noise. Grinding/squealing indicates wear.
Monitor temperature. Overheating signals poor lubrication and overload.
With proper lubrication and inspection pillow blocks can last thousands of operating hours.

Signs It’s Time to Replace

Pillow block bearings should be replaced before they fail completely. Look for these warning signs:
Increased noise/vibration
Movement between shaft and bearing
Leaking grease
Rust or corrosion on the housing
Surface cracking or chipping
Shaft misalignment or bending
If these issues are found replace the bearing insert or the entire unit ASAP depending on condition.
Pillow block bearings offer shaft support in a wide range of conditions. Choosing the right type for your application leads to better performance and long-term reliability.
At NSAR Bearings we have a full selection of pillow block bearings for light and heavy-duty use. We carry corrosion-resistant units and customizable OEM solutions.
Our team can help you find the correct fit if you’re still not sure. Get in touch today and let us help you keep your machines running at top-speed.