The Role of Set Screws and Eccentric Locking Collars in Shaft Fixation

When it comes to securing bearings to shafts, two of the most widely used methods are set screws and eccentric locking collars. From agricultural machinery to conveyor systems, these two options dominate when it comes to shaft fixation. Whether you’re selecting a pillow block bearing insert, specifying a 1 insert bearing for a compact motor, or integrating a ball insert bearing into your assembly, understanding how locking mechanisms affect performance and maintenance is critical.

This article explores the differences between set screw and eccentric locking systems, where each is best used, and why your choice of locking method can make or break system reliability. Know More

What Is Shaft Fixation and Why It Matters

Shaft fixation refers to how a bearing is secured to a rotating shaft to prevent slippage or unwanted movement. If the bearing slips on the shaft, it can cause:

• Excessive wear
• Misalignment
• Increased vibration
• Complete system failure

Components like the pillow block bearing insert or 1 insert bearing come in various locking styles, and selecting the right one can extend the life of both the bearing and the shaft.

Shaft fixation also plays a role in machine safety. In high-speed applications, a loose bearing could dislodge and create severe hazards for operators and surrounding equipment. In high-precision equipment, even the slightest shift could affect tolerances and performance. That’s why fixation isn’t just a mechanical necessity—it’s an operational imperative.

Set Screw Locking: The Straightforward Standard

Set screws are simple: small threaded screws that press directly onto the shaft. They’re embedded in the inner ring of a ball insert bearing or similar insert-type unit.

Advantages:

• Easy to install with standard hex tools
• Affordable and widely available
• Effective in light to moderate load applications
• Minimal training required for installation

Best For:

• HVAC blowers
• Light-duty conveyors
• Fans and motors
• Agricultural attachments with minimal vibration

Limitations:

• Can damage shaft surface over time
• Less suitable for reversing loads or heavy vibration
• May loosen if not secured with threadlocker or proper torque
• Requires periodic re-tightening in high-speed equipment

In applications using a pillow block bearing insert with a set screw design, make sure to position the screws 90 degrees apart for maximum holding power. Also, avoid over-torquing, as this may distort the inner ring and lead to premature wear or noise during operation.

Eccentric Locking Collars: Secure and Reliable

An eccentric locking collar uses an off-center ring that, when rotated, tightens against the shaft and bearing inner ring simultaneously. It offers an efficient mechanical interface without gouging into the shaft surface.

How it works:

1. Place the collar over the shaft
2. Rotate the collar in the direction of shaft rotation
3. Tighten the set screw on the collar to lock the assembly

Advantages:

• Excellent holding power without damaging the shaft
• More resistant to vibration and shock
• Ideal for frequent stop/start or bidirectional motion
• Often lasts longer than set screw configurations

Best For:

• Agricultural machinery
• Outdoor power equipment
• High-vibration environments
• Rotating assemblies in dusty or corrosive environments

Downsides:

• Slightly more complex to install
• More expensive than basic set screw designs
• Improper alignment during installation can reduce effectiveness

If you’re using a 1 insert bearing in a system with significant movement or frequent load reversals, eccentric collars may be a better long-term choice.

Comparing Set Screws vs. Eccentric Collars

Both methods are found in ball insert bearing housings, but the best choice depends on your specific application conditions.

Installation Best Practices

For Set Screws:

• Clean shaft and bearing bore before installation
• Apply a small amount of threadlocker to the screws
• Use a torque wrench for consistent tightness
• Check tightness during scheduled maintenance
• Avoid reusing old or stripped screws

For Eccentric Locking Collars:

• Ensure correct orientation (direction of shaft rotation matters)
• Rotate collar until resistance increases, then tighten set screw
• Re-check tightness after initial run-in period
• Use collars with hardened surfaces in corrosive environments

Proper installation ensures that your pillow block bearing insert stays secure and aligned for long-term reliability.

When to Use Each Locking Method

Choose Set Screws When:

• Loads are predictable and unidirectional
• Budget constraints matter
• Equipment is static or lightly loaded
• Shaft replacement or modification is not a concern

Choose Eccentric Collars When:

• Machinery experiences frequent motion or vibration
• Shaft marking needs to be avoided
• Durability and uptime are a priority
• You’re working in dusty, wet, or outdoor environments

For instance, a ball insert bearing used in a grain auger or vibrating screen should always have an eccentric locking collar for the best retention.

Maintenance and Inspection Tips

• Periodically inspect both locking types for signs of loosening
• Check shaft for scoring or wear under set screws
• Replace damaged collars or worn-out screws promptly
• Lubricate set screw threads if disassembly is frequent
• Use anti-seize compounds on threads in corrosive areas
• Keep spare collars and screws in inventory for quick swaps

A well-maintained 1 insert bearing or pillow block bearing insert will provide years of reliable service, especially when locked properly.

Considerations for Shaft Material and Surface Finish

• Soft shafts (like aluminum) are more prone to damage from set screws
• Hardened steel shafts benefit from eccentric collars for long-term reliability
• Surface finishes that are too smooth may reduce grip strength, especially with set screws

If you’re sourcing shafts to go with a ball insert bearing, consult bearing and shaft suppliers to ensure compatibility with your locking method of choice.

Environmental Factors That Influence Locking Choice

• Moisture and Dust: Favor eccentric collars with seals to prevent ingress
• Temperature Fluctuation: Choose locking methods that minimize differential thermal expansion
• Corrosive Environments: Use stainless collars or coated screws with locking methods that allow easy replacement

Choosing the right locking method based on environmental stressors can prevent early bearing failure, especially when using a pillow block bearing insert in exposed or outdoor conditions.

Final Thoughts

The right shaft fixation method can save hours of downtime and hundreds in repair costs. Whether you’re working with a pillow block bearing insert, specifying a 1 insert bearing, or installing a ball insert bearing into an industrial or agricultural setting, understanding the pros and cons of set screws and eccentric locking collars is essential.

Choose wisely based on load type, environment, and maintenance capacity. In the world of bearing reliability, how you lock it in place is just as important as which bearing you choose. The right fixation system won’t just keep things running smoothly—it’ll also protect your investment in bearings, shafts, and supporting machinery.