Locking Assemblys are the cornerstone of modern power transmission systems, providing a superior, maintenance-free alternative to traditional keyed, splined, or shrink-fit connections. At Raydafon Group, we have engineered our locking assemblies to deliver unparalleled precision, reliability, and ease of installation for a vast range of industrial applications. Unlike mechanical fasteners that can loosen under stress, our assemblies utilize a unique, radially-applied clamping force to create a friction-locked connection between hubs and shafts (or similar components) that is free of backlash and completely immune to fretting corrosion.
The principle is both elegant and robust. The assembly consists of two concentric rings with tapered surfaces and a set of high-strength clamping screws. When these screws are tightened, the inner ring is compressed onto the shaft while the outer ring expands against the bore of the hub. This simultaneous radial action generates immense frictional force, creating a single, solid unit capable of transmitting high torque, axial force, and bending moments. The connection is fully reversible, allowing for easy adjustment, repositioning, or disassembly without damaging the connected parts—a significant advantage for maintenance and design flexibility.
**Key Advantages of Raydafon Group Locking Assemblies:**
* **Zero Backlash:** Provides precise, rigid connections critical for positioning accuracy in drives and motion control systems.
* **High Torque Transmission:** Capable of handling very high torsional loads without slippage.
* **Compensation for Tolerances:** Forgives minor deviations in shaft and hub dimensions (e.g., diameter tolerances), simplifying machining requirements.
* **No Keyways Needed:** Eliminates stress concentrations, fatigue points, and wear associated with keyways, resulting in stronger shafts and longer component life.
* **Easy Assembly & Dismounting:** Standard tools are sufficient for installation and removal, drastically reducing downtime.
* **Corrosion Resistance:** The uniform clamping pressure prevents micro-movement, effectively stopping fretting corrosion at the contact surfaces.
* **Space and Weight Saving:** Offers a compact design compared to bulky flange or spline connections.
### **Raydafon Group Locking Assembly: Technical Parameters & Selection Guide**
Selecting the correct locking assembly requires careful consideration of your application's mechanical demands. The primary parameters are the transmitted torque (M
T), the axial force (F
A), and the bending moment (M
B). The following tables outline the standard specifications and performance data for our core product series. All assemblies are manufactured from high-grade, heat-treated alloy steel with zinc-flake coating for superior corrosion protection unless otherwise specified for custom orders.
**Series RDF-LA100 (Standard Duty)**
Ideal for general machinery, conveyors, pumps, and fans.
| Model |
Shaft Diameter (mm) |
Bore Diameter (mm) |
Max. Torque MT (Nm) |
Max. Axial Force FA (kN) |
Clamping Screws (Qty. & Class) |
| RDF-LA110 |
20 - 30 |
30 - 45 |
850 |
45 |
6 x 12.9 |
| RDF-LA120 |
30 - 40 |
45 - 60 |
1,800 |
80 |
8 x 12.9 |
| RDF-LA130 |
40 - 55 |
60 - 80 |
3,500 |
130 |
10 x 12.9 |
| RDF-LA140 |
55 - 70 |
80 - 100 |
6,200 |
200 |
12 x 12.9 |
**Series RDF-LA200 (Heavy Duty)**
Designed for high-power drives, marine propulsion, heavy processing equipment, and wind turbine yaw systems.
| Model |
Shaft Diameter (mm) |
Bore Diameter (mm) |
Max. Torque MT (Nm) |
Max. Axial Force FA (kN) |
Clamping Screws (Qty. & Class) |
| RDF-LA210 |
70 - 90 |
100 - 130 |
11,000 |
320 |
16 x 12.9 |
| RDF-LA220 |
90 - 120 |
130 - 170 |
24,000 |
600 |
20 x 12.9 |
| RDF-LA230 |
120 - 160 |
170 - 220 |
48,000 |
1,100 |
24 x 12.9 |
| RDF-LA240 |
160 - 220 |
220 - 300 |
85,000 |
1,800 |
32 x 12.9 |
**Series RDF-LA300 (Precision / High-Speed)**
Featuring balanced components and special tolerances for applications requiring high concentricity and minimal vibration, such as spindle drives, printing machinery, and precision test stands.
| Model |
Shaft Diameter (mm) |
Max. Operating Speed (rpm) |
Runout Tolerance (mm) |
Special Features |
| RDF-LA310 |
15 - 40 |
12,000 |
< 0.01 |
Lightweight alloy option, ground surfaces |
| RDF-LA320 |
40 - 80 |
8,000 |
< 0.015 |
Dynamically balanced to G2.5 grade |
| RDF-LA330 |
80 - 130 |
5,000 |
< 0.02 |
Integrated sealing groove option |
### **Installation Guidelines for Optimal Performance**
Proper installation is critical to achieving the rated performance of any locking assembly. Follow these essential steps for a Raydafon Group assembly:
1. **Preparation:** Ensure the contact surfaces on the shaft and in the hub bore are clean, dry, and free of burrs, oil, or paint. A slight chamfer on the edges of the hub bore is recommended.
2. **Lubrication:** Lightly lubricate the threads and under the heads of the clamping screws with a standard mineral-based oil. **Do not lubricate the tapered contact surfaces or the shaft/hub interfaces.**
3. **Positioning:** Slide the locking assembly onto the shaft and into the hub to the desired axial position.
4. **Initial Tightening:** Hand-tighten all clamping screws in a diagonal pattern to ensure the assembly seats evenly.
5. **Final Torquing:** Using a calibrated torque wrench, tighten the screws in a crosswise pattern to the specified torque value provided in the assembly's technical datasheet. **Never exceed the maximum recommended torque.**
6. **Re-tightening:** For applications subject to significant cyclic loads or temperature variations, a re-tightening check after the first 24-48 hours of operation is advisable.
### **Locking Assembly FAQ: Your Questions Answered by Raydafon Group Experts**
**What is the main difference between a locking assembly and a traditional keyed connection?**
A keyed connection relies on a positive mechanical interlock (the key) to transmit torque, which creates stress concentrations and wear points in both the shaft and hub. A locking assembly transmits all forces through uniform radial friction, distributing stress evenly, eliminating backlash, and preventing fretting corrosion, resulting in a stronger, more durable, and maintenance-free connection.
**How do I calculate if a specific locking assembly is suitable for my application?**
You must determine the three main load types: the maximum torsional torque (M
T), the maximum axial force (F
A), and the maximum bending moment (M
B). Compare these calculated values to the permissible load capacities for the selected assembly size, which are provided in our detailed engineering catalogs. Raydafon Group offers comprehensive online selection software and direct engineering support to assist with this calculation.
**Can a locking assembly be used on stainless steel or hollow shafts?**
Yes, but with important considerations. For stainless steel shafts (softer than hardened steel), the permissible surface pressure is lower. A larger locking assembly or a special series with a wider contact area may be required. For hollow shafts, the wall thickness must be sufficient to withstand the radial expansion pressure without deformation. Our technical team can provide specific guidance and solutions for both scenarios.
**What happens if the clamping screws come loose?**
Properly installed with the correct torque, Raydafon Group assemblies are designed to remain secure. However, in extreme conditions with severe vibration, screw loosening is a risk. We recommend using thread-locking adhesives on the screws for such applications or specifying our pre-applied locking patch screw option. Regular maintenance checks are also prudent in harsh environments.
**Is it possible to re-use a locking assembly after dismounting?**
Absolutely. One of the hallmark benefits of Raydafon Group locking assemblies is their reusability. As they do not create permanent deformation on the shaft or hub, they can be dismounted, repositioned, and re-tightened multiple times without loss of performance, provided all components are in good condition and the recommended installation procedure is followed.
**How do I handle applications with extremely high temperatures or aggressive chemicals?**
Standard assemblies are rated for temperatures up to 120°C (248°F). For high-temperature applications, we offer special versions with heat-resistant screws and coatings. For corrosive environments, we provide assemblies made from stainless steel or with specialized protective coatings such as Dacromet or Geomet. Please consult with our application engineers for the best material specification.
**What surface finish and hardness are required for the shaft?**
For optimal performance, the shaft surface should have a roughness (Ra) between 1.6 and 4.0 µm. A smoother finish can reduce the coefficient of friction, while a rougher one may cause scoring. The shaft hardness should generally be a minimum of 120 HB. For high-load applications, a hardened shaft (e.g., 55 HRC) is beneficial. Our datasheets provide precise recommendations for each series.
**Does Raydafon Group offer custom locking assembly designs?**
Yes. While our standard ranges cover most industrial needs, Raydafon Group has extensive expertise in designing and manufacturing custom locking assemblies for unique applications. This includes non-standard dimensions, special materials, integrated components (like gears or pulleys), and solutions for exceptional load cases.
Raydafon