Shaftloc® Keyless Shaft Mounting System – Fast, Secure, and Vibration-Resistant
Shaftloc® by SDP/SI is a patented, precision-engineered fastening system designed to securely mount rotating components onto a shaft—without the need for keyways, set screws, or adhesives. This innovative two-piece assembly uses a unique asymmetric thread profile that generates a powerful radial clamping force when the nut is tightened. The result is a compact, self-locking shaft collar that is easy to install, reusable, and ideal for high-speed or high-precision applications. Shaftloc® is vibration-resistant, dynamically balanced, and perfectly suited for mounting hubless gears, sprockets, pulleys, cams, and thin-walled components onto small-diameter shafts.
Available in multiple styles—including single-ended, double-ended, M-type, and A-type—Shaftloc® fasteners offer flexible solutions for a wide range of motion control and mechanical power transmission systems. SDP/SI also manufactures a variety of molded pulleys specifically designed for Shaftloc®, including HTD® (3 mm and 5 mm pitch), L (3/8" pitch), and XL (1/5" pitch) series with single or double flanges. With simplified assembly, outstanding holding power, and reliable performance, Shaftloc® delivers cost-effective, maintenance-friendly shaft locking for engineers and OEMs alike.
Download Shaftloc® White Paper
Want to learn how to eliminate keyways, reduce assembly time, and improve shaft-to-component connections? Download our free Shaftloc® White Paper to explore the engineering behind this patented, two-piece keyless fastening system. This detailed guide explains how Shaftloc® works, its unique advantages over traditional methods, and how to apply it effectively in your designs. Whether you're working with gears, pulleys, or cams, this white paper is an essential resource for engineers seeking efficient, high-performance solutions.
Shaftloc® Pulleys
Available In:
Materials: Nylon with Steel InsertPitch: 1/5", 3/8", 3mm, 5mm
Profile: XL, L, HTD®
Shaftloc® Pulleys are specially designed for use with SDP/SI’s patented Shaftloc® keyless fastening system, offering a reliable, compact solution for mounting pulleys without the need for keyways or set screws. Molded from high-strength, fiberglass-reinforced black nylon and overmolded with a precision steel insert, these pulleys provide excellent durability and dimensional stability for high-speed applications. Available in both single and double flange configurations, Shaftloc® pulleys are offered in a range of popular timing belt pitches: XL (1/5", for 3/8" belts), L (3/8", for 1/2" belts), HTD® 3 mm (for 9 mm belts), and HTD® 5 mm (for 15 mm belts). Pulleys with 19 to 24 grooves are designed without webs for optimized weight and clearance.
Whether you're working with robotics, motion systems, or automation equipment, Shaftloc® Pulleys deliver easy installation, secure shaft mounting, and outstanding performance. When paired with the Shaftloc® fastening system, they eliminate the need for keyways and reduce assembly time. To learn more about how Shaftloc® can improve your designs, Download the Shaftloc® White Paper and explore the full range of Shaftloc® solutions.
Double-Ended Shaftloc® Sleeves
Available In:
Materials: Stainless SteelBore Size: 0.375 in and 0.500 in
Max. Torque Capacity: 15 - 250 lbf. in.
SDP/SI’s Double-Ended Shaftloc® Sleeves offer a reliable, keyless method for mounting components to shafts using a patented two-piece design. As the inner and outer sleeves are threaded together, the outer sleeve expands while the inner sleeve contracts—securely clamping the component to the shaft with high radial holding force. Made from durable 416 stainless steel and available in 3/8" and 1/2" bore sizes, these sleeves are ideal for high-speed, high-precision applications. Designed for use with precision ground shafting (Catalog Number A 7X 1-...), Double-Ended Shaftloc® Sleeves simplify assembly, eliminate the need for keyways, and provide a compact, efficient fastening solution. For details on Shaftloc® installation and performance, refer to the technical notes.
Single-Ended Shaftloc® Sleeves
Available In:
Materials: Stainless SteelBore Size: 0.125 in (3mm) - 0.500 in (18mm)
Outer Diameter: 0.25 in (6mm) - 0.75 in (27mm)
SDP/SI’s Single-Ended Shaftloc® Sleeves provide an efficient, keyless fastening solution for securely mounting components to shafts with ease. This patented system works by threading the inner and outer sleeves together, causing the outer sleeve to expand and the inner sleeve to contract, firmly clamping the component to the shaft without marring. Made from durable 416 stainless steel, these sleeves are designed for easy assembly, making them perfect for high-precision applications where a clean, secure fit is crucial. With a maximum torque capacity optimized by degreasing the mating components, the Single-Ended Shaftloc® Sleeves offer high reliability, especially when used with precision ground shafting (Catalog Number A 7X 1-...). For best performance, ensure that the clearance between the shaft, Shaftloc®, and housing does not exceed .001". For full installation details and performance guidelines, refer to the technical notes.
A-Type Shaftloc® Fasteners
Available In:
Materials: Stainless SteelBolt Diameter: 0.25 in (6.5mm) - 0.50 in (13mm)
SDP/SI’s A-Type Shaftloc® Fasteners offer a simple yet highly effective solution for securing parts with a self-locking, vibration-resistant design. This patented two-piece fastener system consists of a bolt and nut, with the nut turning freely until it contacts the components being clamped. As additional turns are applied, the wedging action between the nut and bolt locks the parts in place, creating a secure, vibration-resistant connection. Made from 416 stainless steel and passivated for corrosion resistance, A-Type Shaftloc® Fasteners are reusable and can be easily installed with standard tools. With asymmetric threads that ensure reliable self-locking, these fasteners are ideal for applications where maintaining a tight connection is crucial. Special sizes are available upon request, and A-Type Shaftloc® Fasteners are sold in pairs for convenience.
M-Type Shaftloc® Fasteners
Available In:
Materials: Stainless SteelBore: 0.25 in (6mm) - 0.50 in (12mm)
SDP/SI’s M-Type Shaftloc® Fasteners provide a highly effective, keyless solution for rigidly mounting mechanical components onto a shaft. This patented two-piece system consists of a slotted bolt and a nut. As the nut is tightened, it causes the slotted sleeve to contract, gripping the shaft while simultaneously clamping the part to the sleeve, creating a secure and vibration-resistant connection. Made from 416 passivated stainless steel, these fasteners are non-marring, reusable, and can be easily installed with standard tools, eliminating the need for keyways and screws. The asymmetric thread geometry generates a large radial clamping force, making them ideal for high-speed applications. M-Type Shaftloc® Fasteners are precision-engineered for quick, cost-effective assembly and are suitable for use on shafts with or without existing keyways. Special sizes are available upon request, and they are sold in pairs for convenience.