What are shaft collars? Everything You Need to Know
Shaft collars turn up in almost every kind of equipment. They’re simple rings of metal, but the way they hold parts in place makes a difference to how a machine runs. When the fit, material, or balance is off, it shows fast. Getting them right keeps everything running smoothly. In this guide, we’ll take a closer look, covering:
What is a shaft collar?
What are shaft collars used for?
What are some design considerations for shaft collars?
Different types of shaft collars
What is a shaft collar?
A shaft collar is a round, ring-shaped mechanical component that fits snugly around a cylindrical shaft. It has a central hole (called a bore) that matches the diameter of the shaft, and its outer surface is usually smooth and slightly thicker than the shaft itself.
The collar can slide along the shaft when loose and stay fixed when tightened. Once secured, it forms a solid ring that grips the shaft surface evenly. This simple shape gives it the strength and stability needed to hold parts in place without distortion or unnecessary wear.
What are shaft collars used for?
Shaft collars are used for several purposes, mainly involving positioning, stopping, and securing components on a shaft. Here’s how they’re typically used:
1. Positioning components
A collar holds a part at a set point on a shaft or linear shaft so it stays where it should during operation. It’s used when movement needs to be controlled or stopped entirely.
You should also see the guide our experts have put together, How to Select the Ideal Linear Shaft for Your Application.
2. Mechanical stops
Set against a moving part, a collar works as a limit on a linear shaft. It defines how far that part can travel along the shaft and stops it cleanly when it reaches the end.
3. Bearing spacers or retainers
A collar can sit between two bearings to keep them apart. It keeps the spacing even so the shaft turns straight and the bearings don’t rub or load unevenly.
4. Mounting points
Some collars are drilled or threaded so they can carry sensors, levers, or other small fittings. This provides a simple way to add attachments without modifying the shaft itself.
5. Axial retention
In rotating machinery, they prevent components from sliding off the shaft due to vibration, thrust loads, or torque transmission.
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What are some design considerations for shaft collars?
When you’re choosing or specifying a shaft collar, look at how it fits the shaft, how it holds under load, and how it performs over time. The details below cover the main points that affect reliability and service life.
Shaft size and fit
Keep the bore within +0.025 mm to +0.05 mm to the actual shaft size. Too much clearance and the collar won’t hold. Too little and you’ll scar the shaft on assembly. Always check the finished shaft dimension.
Holding power and clamping method
The way it grips changes how it behaves. A set screw bites into the shaft and won’t slip unless the load reverses. A clamp type wraps around and spreads the load more evenly. The clamping force comes down to the screw size, the applied torque, and the collar material, all working together to decide how firmly it stays in place.
Material selection
Material choice affects both mechanical properties and environmental resistance. Use carbon steel when strength matters.
Fastener design
Use good quality screws. Threads that cut rough or heads that round out ruin the fit fast. Tighten them just enough to hold—too much crushes the bore, too little reduces clamping force and lets it walk.
Alignment and balance
Misalignment shows up as vibration and uneven wear. Two-piece shaft collars usually seat better when added to an existing shaft. Always check for runout before final tightening.
Maintenance and adjustability
If the collar comes off often, a split or hinged style saves time. It can be installed or removed without disturbing the rest of the setup.
Different types of shaft collars
Shaft collars come in several designs to suit different mechanical and assembly needs.
One-piece shaft collar, semi-split
The one-piece semi-split shaft collar is a simple steel ring made to hold a part in place on a shaft. A single DIN 912 grub screw draws the collar closed until it grips firmly. The split gives it just enough flex to install or remove without forcing it over the shaft. Steel.
One-piece shaft collar, solid
This one-piece shaft collar is a machined steel ring used where the position on the shaft doesn’t need to change. It uses two DIN 553 grub screws set 135 degrees apart to pull evenly against the surface. That spacing keeps the grip balanced and helps prevent the collar from slipping under load.
Provides long-lasting performance and is ideal for fixed applications where frequent repositioning is not required. Its simple yet effective design ensures consistent axial retention and alignment. Steel.
Two-piece shaft collars
Two-piece shaft collars, also known as shaft clamps or collar clamp, allow for easy installation and removal without disassembling other components, offering excellent convenience and reusability. They can also serve as a mechanical stop, locating element, or bearing face. Finished with a sleek black appearance, it provides exceptional holding power through the impingement of a set screw onto the shaft.
Available in three variations—Full Set Collar (DIN 553), Semi-Split Collar, and Split Collar (both using DIN 912 head screws)—this line combines strength, precision, and adaptability for diverse industrial uses. Steel.
Applications and industries for shaft collars
The tables below highlight the key industries and applications where shaft collars are most commonly used.
|
Industries |
Purpose |
|
Manufacturing & automation |
Used in conveyors, robotics, & assembly lines for accurate component placement |
|
Automotive |
Used in drivetrains and steering assemblies to hold components in set positions under vibration & load |
|
Aerospace |
Applied in control systems & lightweight mechanical linkages |
|
Medical & laboratory equipment |
Used for precise alignment & clean operation in sensitive environments |
|
Agriculture |
Used in machinery such as harvesters & irrigation systems for durable performance |
|
Food processing & packaging |
Employed in hygienic & corrosion-resistant systems for conveyor & sealing machines |
|
Applications |
Examples |
|
Positioning components |
Hold bearings, sprockets, pulleys, gears, & other components in place along a shaft |
|
Mechanical stops |
Set on a shaft or rod to mark the end of travel. Prevents parts from sliding too far in either direction |
|
Spacers & locators |
Used between components to hold clearances & keep alignment steady |
|
Mounting & attachment |
Some collars are drilled or tapped so they can take sensors, levers, or brackets without altering the shaft |
|
Axial retention |
Secure components against thrust loads & vibration in rotating machinery |
|
Power transmission |
Used in motors, gearboxes, & drive assemblies to stabilise rotating shafts |
Conclusion
Shaft collars are one of those components that rarely get attention until they fail. Their simplicity hides the precision they demand—fit, torque, and installation all determine whether they hold firm or drift under load. When specified correctly, they become quiet enablers of accuracy, reliability, and long service life across almost every kind of mechanical system.
Educational resources
Mechanical Analysis: Shafts & Keyways — City University London
Covers fundamentals of shaft elements, including collars and related features.
Shaft Design (IIT Bombay course notes)
Includes locating collars and set screws in shaft design contexts.
Technical information on shaft collars and clamps — BuiltForFun / Buggies
An enthusiast / hobby site, but includes practical commentary about collars and clamping styles.
Lecture: Shafts & Shaft Components
A university lecture PDF that treats collars as part of the broader topic of shaft components.
Download free CADs
Free CADs are available for most solutions, which you can download. If you’re not quite sure which levelling component will work best for your application, our experts are always happy to advise you. Whatever your requirements, you can depend on fast dispatch.
You might also find it helpful to read our experts’ guide, How to Select the Right Linear Bushings for Your Application.
Questions?
Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application at 0345 528 0474.