If you work in manufacturing, HVAC, or agriculture, you must have heard of pillow blocks and cartridge bearings. They're both types of block bearings, but they're not the same.

So, which one do you need for your machine? And where do you get high-quality ones?

This guide breaks it down.

Quick summary:

Pillow blocks and cartridges are mounted bearing units. The main difference? Their shape and how they mount. Knowing which fits your setup makes maintenance easier and keeps machines running smoothly.

What are block bearings?

A block bearing is a pre-assembled unit with a bearing insert mounted inside a housing. It supports a rotating shaft and is often ready to install.

And because the block bearing comes pre-mounted, you can align your shafts easily. No need for an expert, just DIY.

Who uses them?

Block bearings are go-to components for manufacturing, agriculture, HVAC, and food processing industries. Deductively, the "who" includes:

• Maintenance teams
• Mechanical engineers, and
• Machine builders

These professionals rely on block bearings to support shafts in conveyor systems, fans, motors, and more.

So, how about pillow blocks and cartridge bearings?

Are pillow blocks and cartridges block bearings?

Yes, they are two of the most common types of block bearings.

• Pillow block bearing, for a start, bolts to a flat surface.
• On the other hand, a cartridge bearing fits into machine holes.

FYI: One isn't better than the other. They just fit different mounting styles. We'll cover that in detail shortly.

Block vs. linear bearing: What's the difference?

The difference is in the motion—cue the names.

Block bearings support rotating shafts, while linear bearings guide straight-line motion along a shaft or rail.

Different designs. Different jobs.

Also read: Linear Bearings Explained: What Type Should You Get?

Pillow block bearings: The basics

A pillow block bearing is a mounted unit with a flat base that bolts directly to a surface. It supports a rotating shaft and keeps it aligned. And because it comes fully assembled, installation and maintenance are straightforward.

Design

Most pillow blocks follow the UCP series design, which includes two main components:

• A 2-bolt mounting base
• A bearing insert seated in a split housing

The housing allows for slight shaft misalignment while keeping it stable and supported. The insert itself is replaceable, making long-term maintenance simple and more cost-effective.

Locking styles

There are several ways to secure the bearing insert to the shaft. The most common options include:

• Set screws
• Eccentric locking collars
• Adapter sleeves

Each locking style varies in holding strength, ease of installation, and use case.

Locking style	Holding power	Ease of installation	Best for
Set Screws	Moderate	Easy	General-purpose applications
Eccentric Locking Collar	High	Moderate	Applications with vibration or shock
Adapter Sleeve	Very High	More complex	Heavy-duty or high-speed applications

Common uses

Pillow block bearings are known for their durability, ease of use, and wide availability in standard shaft sizes. They're commonly found on horizontal shafts in:

• Conveyors
• Agricultural equipment
• Food processing lines
• HVAC systems

Pro tip: For wet, corrosive, or high-humidity environments, choose stainless steel pillow block bearings. They resist rust and extend service life.

Cartridge bearings: the compact alternative

Cartridge bearings are cylindrical bearing housings that hold a bearing insert and fit into a machine frame or bracket. Unlike pillow blocks, cartridge bearings are designed for internal or recessed mounting. They are ideal when external bolt holes or flanges aren't feasible.

How they work

Cartridge bearings lack a flat mounting base. Instead, they slide into a pre-machined bore or cartridge seat and are typically secured using:

• Snap rings
• Clamps
• Set screws

This design keeps the shaft and bearing assembly compact and aligned within the equipment frame. In turn, there is no obstruction in tight spaces.

When to use cartridge bearings

Cartridge bearings are perfect for tight or enclosed spaces where traditional mounted units like pillow blocks would be too bulky. Their low-profile design makes them ideal for:

• Conveyor systems
• Screw conveyors
• Bulk material handling equipment

Also, the enclosed fit offers protection against dust, debris, and abrasive particles. Hence, they are most useful in agriculture, food processing, and mining.

Key advantages

• Space-saving: Mounts flush within the equipment
• Clean design: Minimal exposure to contaminants
• Modular: Replace just the insert without removing the housing
• Versatile: Supports both horizontal and vertical shaft orientations

Pro tip: While compact and efficient, cartridge bearings need precise installation. This is due to their press-fit tolerances, locking mechanisms, and heat expansion.

Pillow blocks vs. cartridges: Key differences

Pillow block bearings and cartridge bearings serve different needs, depending on the machinery and available space.

TL;DR: Side-by-side breakdown across five key areas:

Feature	Pillow block bearings	Cartridge bearings	Winner
Mounting style	Bolted to a flat surface using a 2-bolt or 4-bolt base	Press-fit or inserted into a pre-machined round bore	Cartridge bearings
Space requirements	External mount, requires clearance for bolts and tools	Compact and recessed inside equipment	Cartridge bearings
Ease of replacement	Easy to access, unbolt, and replace	Often requires the disassembly of machine parts to reach	Pillow blocks
Versatility	Compatible with a wide range of shaft sizes and general equipment	Specialised for tight, enclosed machine designs	Pillow blocks
Visibility	Visible and accessible, ideal for inspection	Hidden within the machine, offers protection and a cleaner design	Depends on application

Mounting style

Pillow blocks are mounted on flat surfaces using bolts through the base. In contrast, cartridge bearings are inserted into a round bore or machined seat within the equipment frame, which makes them less visible and more integrated into the machine design.

Winner: Cartridge bearings!

Space requirements

When space is limited, cartridge bearings offer a better solution. Their cylindrical design allows them to be recessed inside the machine, unlike pillow blocks that sit externally and require clearance for bolts and tools during maintenance.

Winner: Cartridge bearings!

Ease of replacement

Pillow blocks are easier to access, unbolt, and replace. Cartridge bearings, while modular, often require partial disassembly of the surrounding structure, making them less convenient for quick maintenance in some setups.

Winner: Pillow blocks!

Versatile

Pillow blocks are versatile and compatible with different shaft sizes and equipment. Cartridge bearings are more specialised and are mainly used in compact or enclosed machinery where external mounting isn't feasible.

Winner: Pillow blocks!

Is one mounted bearing better than the other?

In the case of pillow blocks and cartridges? Not really; it depends on your application.

Use this quick guide:

• Choose pillow blocks for visible, easy-access setups like HVAC blowers, conveyor belts, or farming equipment.
• Go with cartridge bearings when working with compact, enclosed machinery like screw conveyors or dust-prone systems in agriculture and mining.

Both offer reliable shaft support. It all comes down to how your machine is designed and how much room you have to work with.

Below is a more detailed guide to choosing between the two mounted bearings.

How to choose the fitting mounted bearing

Choosing between a pillow block and a cartridge bearing depends on the specific demands of your application. Factors like load, speed, space constraints, mounting style, and operating environment can guide.

Here's how to evaluate each factor:

Load & speed

• Pillow blocks are typically better suited for higher radial loads and continuous operation. Their solid base and large-size options give them more load-bearing capacity. As a result, they are ideal for conveyors, motors, or industrial fans.
• Cartridge bearings handle moderate loads well but are more compact. This may limit their capacity under high-stress or high-speed conditions.

Always check the bearing's load and speed ratings against your machine specs to avoid overheating or premature wear.

Space constraints

• Cartridge bearings are designed for compact setups. Their cylindrical shape fits neatly into pre-machined bores. Hence, they are perfect for tight frames or internal mounts.
• Pillow blocks, by contrast, sit on top of surfaces and need space for bolts and tools. That bulk gives you easier access but takes up more room.

Do you need compact integration, or will external mounting make maintenance easier?

Mounting style

• Pillow blocks are plug-and-play: bolt them to a surface, align the shaft, and they're ready for use. They're available in 2-bolt and 4-bolt configurations.
• Cartridge bearings need more planning. They must fit precisely into a machined bore and need snap rings or clamps to stay in place.

Retrofit complexity could be a dealbreaker if your equipment doesn't support cartridge mounting.

Operating environment

• Use stainless steel pillow blocks in wet, corrosive, or dusty conditions. They offer robust protection and are easier to clean and grease.
• Cartridge bearings stay better shielded by design, sitting inside equipment frames. But they can still benefit from additional seals.

Choose materials and seals based on your exposure level. That decision directly impacts bearing lifespan and service intervals.

Verdict:

There's no one-size-fits-all. Here's a simple rule of thumb:

• Choose pillow blocks when you need heavy-duty support, straightforward installation, and easy maintenance access.
• Choose cartridge bearings when space is tight, integration is key, or you're building enclosed systems that need minimal exposure.

Installation & maintenance tips

• Align shafts properly – Use a straightedge or laser alignment tool to ensure the shaft is centred. Misalignment causes uneven wear and shortens bearing life.
• Don't overtighten bolts – Bearings need a bit of float to adjust during operation. Follow torque guidelines to avoid distorting the housing.
• Grease correctly – Use the recommended lubricant type and follow a regular schedule. Over-greasing can cause heat buildup and seal damage.
• Check for vibration regularly – Periodically inspect for abnormal noise or shaking. It's often an early warning sign of misalignment or bearing failure.

Final thoughts

Pillow blocks and cartridge bearings support rotating shafts but differ in how and where they're mounted. Choosing the right type comes down to load, speed, space, and operating environment.

Whichever you choose, get it from a trusted source like Uber Bearings. We have a wide range of durable, high-performance mounted bearings built to last.

Browse our collection today!