Guide to Shaft Collars in Conveyor Systems: Key Features Explained

Shaft collars are an important and often overlooked component, but they play an outsized role in conveyor systems, robotic equipment, and countless other applications. The standard design clamps onto shafts to serve as mechanical stops, spacers, bearing locators, and attachment points for other parts. In conveyor systems, shaft collars secure gears, sprockets, and bearings on the shaft, preventing slippage and misalignment during operation. In the robotics industry, where precision and reliability are paramount, high-quality shaft collars ensure precise alignment, strong holding power, and even load distribution for moving parts.

This guide offers a technical examination of key shaft collar features and types, including one-piece, two-piece, double-wide, quick-clamping, and threaded collars, to assist procurement professionals in robotics and automation in making informed decisions.

Why Shaft Collars Matter in Conveyors and Robotics

Shaft collars serve critical functions in industrial conveyors and robotic motion systems. By clamping around a shaft, a collar can hold a component in place under load, maintain precise spacing between parts, and act as a hard stop to restrict motion. For example, in a conveyor, collars might locate wheels or position bearings on a roller so that the belt tracks properly without drifting. In robotic assemblies, collars secure arms and gears at exact positions, preserving calibration. The best collars offer high axial load capacity and do so without damaging the shaft surface. Ruland Manufacturing notes that their clamp-style collars are designed for “secure, non-damaging clamping”, with an even 360° distribution of forces around the shaft. This even clamping not only protects the shaft (no gouging as set screws can cause) but also maximizes holding strength. Additionally, precision machining ensures the collar’s face is perpendicular to the bore (within 0.002″ TIR) – a vital feature when the collar is used as a load-bearing shoulder or alignment reference. In short, quality shaft collars improve holding power, alignment accuracy, and load distribution, all of which are essential in high-performance conveyor and robotic systems.

One-Piece Clamp Shaft Collars

One-piece clamp-style collars are the workhorse of shaft collars. These collars wrap around the shaft in a single, solid ring, with a cut split and a clamping screw. Tightening the screw causes the collar to uniformly squeeze the shaft, creating a tight fit. The key advantage is even distribution of clamping forces, which means strong holding power without marring the shaft’s surface.

Unlike old-fashioned set screw collars that dig into the shaft, one-piece clamp collars grip smoothly and can be adjusted or removed easily. They are “adjustable, and work well on virtually any shaft,” as Ruland describes. One-piece collars are ideal for installations where you can slide the collar onto the shaft’s end. They excel as spacers, stops, and holders for light to medium loads. Ruland’s one-piece collars are precision machined to keep the clamping gap open, ensuring easy installation and precise fit. They come in a range of materials like zinc-plated steel, anodized aluminum, engineered plastic, and stainless steel to suit different environments. For example, a 303 stainless steel one-piece collar such as Ruland MCL-12-SS (12 mm bore) provides corrosion resistance for washdown environments while still offering robust hold and easy removal without shaft damage. One-piece collars are stamped with the bore size for quick identification and are available in bore sizes from as small as 1/8″ (3 mm) up to several inches, covering the needs of small robotic actuators to large conveyor drums.

Two-Piece Clamp Shaft Collars

Two-piece shaft collars offer the same performance benefits as one-piece designs with added versatility in installation. A two-piece collar splits into two halves, each half wrapping around the shaft from opposite sides.

This split design makes it easy to install or remove without needing access to the end of the shaft – a major advantage when retrofitting collars onto existing conveyor assemblies or robotic shafts where other components are already mounted. When the two halves are bolted together, they use the full seating torque of their screws to apply uniform clamping force around the shaft’s circumference. This results in even greater holding power – in fact, a two-piece clamp collar generally has superior holding strength compared to a one-piece collar of the same size. Another benefit is adaptability to slight shaft size variances: because each half can tighten independently, a two-piece collar can compensate for minor out-of-round or undersized shafts better than a solid ring. Ruland emphasizes that they mate the halves throughout manufacturing so that each two-piece collar’s halves perfectly align. The outcome is excellent fit and perpendicularity, just like one-piece collars. Two-piece collars are also available in the full array of materials (steel, stainless, aluminum, titanium, plastic) and sizes. For instance, an anodized aluminum two-piece collar like Ruland SP-16-A (with 1″ bore) provides a lightweight, non-magnetic option with high holding power – “the clamp style design does not mar the shaft” even as it securely locks components in place. Two-piece collars often employ opposing screw arrangements (screws on opposite sides of the collar) for better balance at high RPM, which is beneficial in fast conveyor rollers or robotic spindles. Whenever ease of installation or maximum holding force is needed, two-piece collars are a go-to solution in conveyor systems and robotics.

Double-Wide Shaft Collars

When a standard collar isn’t enough to handle the load, double-wide shaft collars come into play. As the name suggests, these collars have approximately double the width of a standard collar, which greatly increases their surface contact area on the shaft. The result is roughly 25% higher holding power than an equivalent-size standard collar.

In conveyor applications that carry heavy loads or experience shock forces (e.g., a conveyor moving heavy parts in a manufacturing cell), a double-wide collar can provide extra gripping strength and distribute the clamping force over a larger shaft area for reduced shaft deformation. Double-wide collars also serve as “short rigid couplings in space-restricted applications”. For example, if a section of a robotic conveyor needs two shafts joined end-to-end but there isn’t room for a full coupling, a double-wide collar can effectively hold the shafts together with minimal added length. These collars are available in one-piece or two-piece clamp styles, combining the benefits of those designs with a wider profile. Common materials are high-strength 1215 steel (often with proprietary black oxide for corrosion resistance), 303 stainless steel, and 2024 aluminum for weight-sensitive uses. By choosing a double-wide collar in the appropriate material, engineers can achieve greater load capacity and stiffness while still maintaining the easy adjustability of clamp collars. For instance, a one-piece double-wide collar in aluminum might be used on a high-speed pick-and-place robot arm to secure a pulley without adding excessive weight, whereas a steel double-wide could secure a large conveyor drum under heavy tension. In both cases, the increased width ensures the collar won’t slip under high forces.

Quick-Clamping (Quick-Release) Shaft Collars

Modern automated systems often require frequent adjustments – think of a conveyor rail that needs repositioning for different product sizes, or a robotic fixture that must be reconfigured between tasks. Quick-clamping shaft collars are designed for these scenarios, allowing tool-free and rapid changes. Ruland offers two main types: a quick-clamping collar with a cam lever integrated into the collar, and a shaft collar combined with a separate clamping lever (ratcheting handle).

The cam lever style has a built-in lever that lies flush with the collar’s outer diameter; flipping the lever open releases the collar, and flipping it closed clamps it – all in seconds. This style is ideal for light-duty or low-RPM applications where convenience is paramount (packaging machines, lab automation devices, etc.). The cam lever collars are typically made of anodized aluminum with stainless hardware, making them lightweight and corrosion resistant. They do not mar the shaft and can be adjusted indefinitely, just like standard clamp collars. The other variant, the shaft collar with clamping lever, combines a robust one-piece collar (often in steel or aluminum) with a detachable adjustable handle. This essentially creates a quick-release mechanism where the user can turn the lever to tighten or loosen the collar without a wrench. The clamping lever approach is useful for more substantial applications since you can apply higher torque by turning the handle, and many such levers have ratcheting action to achieve a specific torque. Both quick-clamp types shine in applications like test setups, changeovers in manufacturing, or any scenario where a collar needs to be repositioned often and downtime must be minimized. For example, a robot integrator might use cam-lever collars to quickly adjust sensor positions on a conveyor with minimal tools, speeding up the reconfiguration between product runs. By using quick-clamping collars, engineers can slash adjustment time while maintaining reliable holding when locked – a win-win for productivity and safety.

Threaded Shaft Collars

While standard (smooth bore) collars grip the outside of a shaft, threaded shaft collars take a different approach: they engage with threads on a threaded shaft or rod. These collars screw onto a threaded shaft like a nut, but once in position they lock in place via their clamp design.

The primary advantage of threaded collars is much higher axial holding power – the threads provide a mechanical resistance to axial motion that is inherently stronger than friction alone. This makes threaded collars especially useful as bearing locknuts or axial stops. For instance, in a conveyor drive or a ball screw in a robot, a threaded collar can secure a bearing or component against a shoulder and handle significant thrust load without slipping. Ruland’s threaded shaft collars share the same clamp-style benefits as their round-bore collars (easy to adjust, no shaft marring) while adding the thread engagement for axial load support. They are often used in place of traditional locknuts because they are easier to install and more precise. Unlike a solid ring locknut that might require painstaking adjustment or locking tabs, a clamp threaded collar can simply be threaded to position and then clamped tight, offering both fine positioning and solid locking. These collars come in various thread sizes (acme, metric, UN thread forms, including left-hand threads) to match lead screws or threaded rods. Each Ruland threaded collar is double-tapped to ensure precise, burr-free threads for smooth installation. A practical example in robotics would be using a threaded collar on a lead screw that drives a linear actuator: once the end bearing is in place, a threaded collar can be screwed on and clamped to retain the bearing with high axial force, acting as a combined jam nut and clamp. Threaded collars are typically made from steel (for strength) or stainless steel (for corrosion resistance). By incorporating threaded shaft collars, designers achieve secure axial restraint with the convenience of the clamp mechanism – an elegant solution for high-thrust conveyor and motion control systems.

Materials and Part Number Options

Shaft collars are available in a variety of materials to suit different operating conditions, and understanding these options is key for procurement. Common choices include: black oxide steel (sturdy and cost-effective, with moderate corrosion resistance), 316 or 303 stainless steel (for high corrosion resistance in food-grade conveyors or outdoor robots), 2024 aluminum (lightweight, non-magnetic, and still fairly strong – great for reducing inertia on fast-moving systems), and even engineered plastics (for light-duty and low friction needs). Each material has its advantages: stainless steel collars, for example, can be used in washdown environments or cleanrooms without rusting, while aluminum collars like Ruland’s anodized series provide weight savings and an oxide layer for corrosion protection. It’s also important to note hardware consistency – e.g. stainless steel collars come with stainless screws to prevent galvanic corrosion. Manufacturers like Ruland stamp their collars with the bore size and often a part code for identification. You’ll encounter part numbers such as CL-8-F (which might denote a 1/2″ one-piece clamp collar in steel) or SP-16-A (as mentioned earlier, a 1″ two-piece collar in aluminum). The part numbers typically encode the style (CL for one-piece Clamp collar, SP for two-Split piece, etc.), size, and material (A for aluminum, SS for stainless, F for steel with black oxide Finish). For example, a Ruland part MSCL-12-SS would indicate a Metric Stainless Clamp collar in 12 mm size, stainless steel material. Knowing these codes can help procurement engineers quickly find the exact configuration needed. If you require a 1″ collar that is non-magnetic and lightweight, the code SP-16-A indicates a Split two-piece, as 1.0 inch (16 in sixteenths) bore, Aluminum. Conversely, for a 12 mm metric shaft in a corrosive environment, MCL-12-SS (Metric one-piece Clamp, 12 mm, Stainless Steel) would be a suitable choice. By understanding the material and coding, you can ensure you’re getting collars with the right properties – be it holding strength, environmental resistance, or weight – for your conveyor or robot design.

Sourcing the Right Shaft Collars

PIB Sales is an authorized Ruland Distributor that stocks and sells Ruland products.  If you are specifying components for a conveyor upgrade, a new robotics project, then contact PIB for the replacement shaft collars from our stock. Our online webstore features a full range of Ruland one-piece and two-piece collars, double-wide styles, quick-clamp versions,  in all standard sizes and materials. Browse our catalog of Ruland shaft collars on the PIB Sales webstore to explore available options and part numbers – you can conveniently filter by bore size, material, and style to find the perfect match for your needs.

Beyond just the products, PIB Sales provides engineering support and procurement services to help you make the best choice. Our team understands the demands of the robotics industry and can guide you in selecting collars with adequate holding power and the right features (for example, advising when a double-wide collar is warranted for a heavy load, or suggesting a quick-clamping collar for an application requiring frequent adjustments). We also offer quick quotes and volume pricing programs if you need larger quantities for production.

Conclusion

In summary, shaft collars are indispensable in ensuring that conveyor systems, robotics, and numerous other mechanisms to operate reliably. By choosing the correct Ruland Shaft collar, whether a one-piece clamp, a high-strength two-piece design, an extra-wide collar for heavy loads, a quick-release style for agility, or a threaded collar for axial locking, you can enhance the performance and longevity of your equipment. Modern shaft collars like Ruland’s are engineered to maximize holding power, protect the shaft, and maintain alignment under all conditions. When procuring these components, pay attention to material and design features that best fit your application..

Ready to integrate high-quality shaft collars into your system? PIB Sales is here to assist [email protected]. With a broad inventory of Ruland shaft collars and couplings, we serve as a one-stop source for motion control hardware in the robotics and automation fields. Contact PIB Sales for personalized guidance or to request a quote – our sales staff will ensure you get the right shaft collars tailored to your conveyor or robotic application. Secure your machinery’s performance and reliability by equipping it with the best-in-class shaft collars, and let our team at PIB Sales support your success from specification to installation.