Top 3 Types of Shaft Couplings and How to Install Them Like a Pro

Alt: A picture of Rigid Couplings

When it comes to industrial machinery, the smallest connection can make the biggest impact. Shaft couplings might not look like much, but they're responsible for transferring torque, compensating for misalignment, and reducing vibration between rotating components. From motor shaft couplings to drive shaft couplers, getting this component right is critical.

The wrong coupling—or one installed carelessly—can mean early pillow block bearing wear, shaft damage, or even total equipment failure. Whether you're a maintenance tech, a mechanical engineer, or a hands-on machine builder, understanding the main shaft couplings types—and how to install them right—can save you serious downtime.

In this guide, we'll break down the three most common types of shaft couplings, how each works, and how to install them like a pro.

Type 1: Rigid Shaft Couplings

Alt: A picture of Rigid Shaft Couplings

Rigid shaft couplings are exactly what they sound like: solid, inflexible connectors that join two shafts together in perfect alignment. These are often used in motor shaft coupling setups where absolute precision is essential.

Best for: Systems where shafts are perfectly aligned and any flexibility would compromise performance, like in stepper motor drives, CNC machines, or precision machining setups.

Because there's no allowance for even minor misalignment, installation must be precise. You'll typically see rigid couplings used with keyed shafts, dowel pins, and hex bolts to ensure a rock-solid connection. Any deviation—axial or angular—can result in immediate stress on bearings and drive components.

Rigid couplings are great when you need direct torque transfer without motion dampening. They're simple, affordable, and reliable—but completely unforgiving.

Common types include:

• Clamp-style rigid couplings: Easy to install and remove.
• Set screw couplings: Cost-effective but require perfect shaft fits.
• Rigid flange couplings: Used for high-load, stationary applications.

Need durable, rigid couplings for your project? Browse our premium rigid shaft couplers, complete with hex bolts and dowel pin options, available here.

Type 2: Flexible Shaft Couplings

Alt: A picture of Flexible Shaft Couplings

Need to handle a bit of misalignment without sacrificing torque? That's where flexible shaft couplings come in. These are built to absorb angular, parallel, or axial movement between shafts, without cracking under pressure.

Flexible shaft coupling options vary widely. For instance:

• Jaw couplings: Two hubs and a rubber "spider" insert. Great for damping vibration.
• Oldham couplings: Three-piece design ideal for slight misalignment.
• Beam couplings: One-piece spiral-cut, compact, and precise.

You'll often find these in motor shaft adapter applications, small pumps, fans, and conveyor systems. Anywhere a shaft coupling flexible enough to account for thermal expansion, mounting shifts, or load shocks is needed.

They're easier to install than rigid options and often come with pre-engineered tolerances. Still, selecting the right flex coupling is key. Too flexible, you'll lose torque efficiency; too stiff, and you will defeat the purpose.

Look for:

• Torsional stiffness: For positioning systems.
• Misalignment tolerance: For dynamic environments.
• Material durability: Especially in rubber coupling or polymer inserts.

Brands like JLCMC offer long-lasting, industry-proven products.

Shop industry-grade flexible shaft couplings that reduce vibration and align easily with existing shafts. See our full catalog right here.

Type 3: Universal Joints (U-Joints)

Alt: A picture of Universal Joint Shaft Coupling

Universal joint shaft coupling is the go-to when you need to transmit torque across non-linear angles. U-joints allow shafts to operate at an angle to each other, perfect for irregular or moving systems where standard motor shaft couplings would fail.

You'll often see these in off-road vehicles, agricultural equipment, or rotary applications with changing shaft positions. Their ability to accommodate large angular displacements sets them apart.

However, they're not maintenance-free. Without proper lubrication or retaining clips, shaft couplings' universal joint setups can wear rapidly. The phasing of the yokes must be precise; otherwise, you'll get pulsations in motion—bad news for any rotating machinery.

Pros:

• Handles large angles of rotation
• Works in misaligned or dynamic shaft systems
• Durable with proper care

Cons:

• Requires regular lubrication
• More moving parts equal more failure points
• Can cause velocity fluctuations without precise installation

For optimal performance, look into splined shaft couplings for enhanced torque transfer without slippage or spring coupling designs if moderate angular flexibility and damping are needed.

How to Install Shaft Coupling (Step-by-Step)

Rigid Shaft Coupling Installation

1. Check for perfect alignment. Even 0.1° off can cause stress. Use laser alignment tools or dial indicators.
2. Clean shaft ends and remove oil or burrs. Even minor grime affects seating.
3. Tighten bolts evenly. Use a torque wrench and follow the manufacturer's torque spec.
4. Verify fit with feeler gauges to ensure no offset before final tightening.

Pro Tip: If using dowel pins or hex bolts, torque them in a star pattern to avoid warping.

Flexible Shaft Coupling Installation

1. Inspect for worn elements like cracked spiders or fatigued metal hubs.
2. Do not overtighten clamps. Over-torquing leads to element deformation.
3. Check for end float—some designs require a gap for axial play.

Pro Tip: Spin the shaft by hand post-installation. Any resistance suggests misalignment or binding.

Universal Joint Installation

1. Align the fork yokes properly to avoid phase mismatch.
2. Lubricate with high-temp grease on all joints.
3. Secure with clips or snap rings to prevent axial movement.

Pro Tip: Monitor the coupling after initial run. Watch for wobble—it may indicate out-of-phase yokes or bearing wear.

How to Remove a Coupling from a Shaft (Safely)

When it's time for a replacement, removal matters as much as installation:

1. Loosen all hex bolts or clamping screws.
2. Use a gear puller for press-fitted couplings.
3. Tap lightly with a rubber mallet—never hammer metal directly.
4. Clean the shaft thoroughly before installing a new motor drive shaft coupling or flex coupler.

If the coupling is corroded or seized, apply penetrating oil and allow time for it to work. Heat may help, but only as a last resort.

Troubleshooting: Signs of a Bad Shaft Coupler

Even the best shaft couplers wear out. Here's how to spot trouble early:

• Excessive vibration or noise.
• Loose connection between the shaft and coupling.
• Shaft misalignment symptoms, like inconsistent rotation.
• Visible wear or cracking in flexible shaft couplers.
• Slippage under load in drive shaft coupling systems.

When in doubt, swap it out. A $30 part is cheaper than a seized motor shaft or ruined pillow block bearing.

Final Thoughts

Installing a shaft coupling isn't just about connecting two parts—it's about ensuring smooth, efficient, and reliable power transmission. Each type of coupling serves a different purpose, and knowing how to install them correctly makes all the difference.

From rigid coupling setups that demand micrometer-level alignment to flexible shaft couplings that handle real-world tolerance, choosing and installing the right shaft and coupling is what separates downtime from uptime.

Still not sure how to join two shafts together? Start by choosing the right shaft coupler for your system, and install it like a pro.

At JLCMC, we’re home to a wide variety of shaft couplers, including rigid shaft couplings, Universal Joints, and flexible shaft couplings that are just right for your needs.

Please feel free to contact us, and we shall be more than happy to help.

FAQ's

Which is the simplest type of coupling?

The simplest type of coupling is the rigid shaft coupling. It's a solid, one-piece design that directly connects two shafts without allowing for any misalignment. Because it lacks flexibility, it's best suited for setups where shafts are perfectly aligned, like in stepper motor shaft attachments or precision tools.

Rigid couplings are often used with a keyed shaft to ensure a secure, torque-transmitting connection. While simple, they require exact alignment to avoid damage to the shaft and coupling system.

Why are shafts used?

Shafts are essential for transmitting mechanical power from one part of a machine to another. Whether in motor drive shaft coupling systems or gear couplings, the shaft delivers torque efficiently and continuously.

In rotating machinery, motor shafts link components like pulleys, pillow block bearings, and flex couplers, ensuring that power flows smoothly. Without a shaft, there's no physical medium to transfer rotational energy between connected parts, making it critical in everything from industrial equipment to small engine shaft couplings.

What are the 3 parts of the shaft?

The three main parts of a shaft include:

• The shaft body: The extended cylindrical portion that carries the load and transmits torque.
• The shaft ends: These may be threaded or keyed to fit components like a motor shaft coupler or spline shaft coupling.
• The shoulders or steps: Help with component positioning and bearing support, which are commonly found in systems using shaft couplings with flexible or rigid flange coupling designs.

These elements work together to ensure strength, alignment, and compatibility with various shaft couplings types.

Which coupling is universal type?

The universal type of coupling is the universal joint or U-joint. A flexible mechanical joint transmits torque and rotary motion between misaligned shafts. Popular in drive shaft coupling applications, universal coupling allows for angular movement while maintaining rotational power.

You'll often find this in automotive, agricultural, and industrial machinery, where shafts are not in a straight line. It's one of the most versatile types of shaft couplings, especially when paired with a splined shaft coupler or motor shaft coupling.

Bibliography/References

• Captiveaire, "Flexible Couplings," Industry Leading Commercial Kitchen Ventilation Systems - CaptiveAire, accessed May 27, 2025, https://www.captiveaire.com/MANUALS/MAKEUPAIR/SUPPLYFANTRAININ
• REGAL REXNORD, "4 Common Coupling Issues and How to Prevent Them," Just a Moment.., accessed May 27, 2025, https://www.regalrexnord.com/products/couplings/common-coupling-issues?srsltid=AfmBOoo2vp9XNGH0NjWJInjVKTqqKNt2bz5jltDqfl7B4bbryXxjEy_
• Reliability Analytics Corporation, "Rigid Shaft Couplings," Reliability Engineering Consulting Services from Reliability Analytics Corporation, accessed May 27, 2025, https://reliabilityanalytics.com/reliability_engineering_library/Handbook_
• Renold, "Universal Joint," IIS Windows Server, accessed May 27, 2025, https://www.renold.com/media/162074/renold_ajax_universal_joint_20
• RS-ONLINE, "INSTALLING COUPLINGS,", accessed May 27, 2025, https://docs.rs-online.com/6c6b/A700000007015489.pdf.