Keyless Locking Assembly vs Keyway – Which Shaft-Hub Connection Is Right for You?
Keyless Locking Assembly vs Keyway – Which Shaft-Hub Connection Is Right for You?
For decades, keyways have been the standard method for connecting shafts and hubs. But keyless locking assemblies (shrink discs / cone clamping elements) offer significant advantages in torque capacity, precision, and maintenance.
This guide compares the AL-S double taper keyless locking assembly with traditional keyway connections, helping you choose the right solution for your application.
1. Quick Comparison: Keyless Locking Assembly vs Keyway
| Feature | Keyless Locking Assembly (AL-S) | Traditional Keyway |
|---|---|---|
| Torque Capacity | Higher (friction-lock) | Limited by key shear strength |
| Backlash | ✅ Zero | ❌ Clearance → backlash |
| Stress Concentration | None – uniform pressure | High – at keyway corners |
| Shaft Strength | Full shaft diameter | Reduced by keyway |
| Axial Positioning | Precise – no axial movement during tightening | Dependent on key fit |
| Installation | Tighten screws – no special tools | Key fitting, may require filing |
| Removal | Easy – removal screw holes | May require pullers |
| Reusability | ✅ Yes – multiple times | ❌ Keyway wears over time |
| Design Flexibility | High – no keyway machining | Low – keyway must be specified early |
| Maintenance | Low | Moderate |
2. What Is a Keyless Locking Assembly?
A keyless locking assembly (also called a shrink disc or cone clamping element) is a mechanical device that creates a friction-lock connection between a shaft and a hub. It consists of:
Tapered rings (inner and outer)
Pressure rings
Clamping screws
When the screws are tightened, the tapered rings are forced together, creating radial pressure that locks the hub onto the shaft. No keys or keyways are required.
3. The AL-S Double Taper Advantage
The AL-S series features a double taper (double cone) design with four components:
| Component | Function |
|---|---|
| Split Double-Taper Inner Ring | Grips the shaft |
| Split Double-Taper Outer Ring | Grips the hub bore |
| Double-Taper Pressure Rings (×2) | Transmit clamping force |
| Hexagon Socket Screws | Provide tightening force |
✅ Key benefit: Compared to single-taper designs, the double taper delivers greater radial pressure and higher load capacity with the same clamping force.
4. No Axial Movement During Installation
One of the key advantages of the AL-S design is no axial movement of the hub during tightening. This means:
Precise axial positioning is maintained
No re-alignment required after installation
Ideal for applications where axial position is critical (e.g., CNC spindles, printing rolls)
5. Why Choose Keyless Over Keyway?
Choose keyless locking assembly if:
High torque transmission is required
Zero backlash is critical (reversing loads, precision positioning)
Shaft strength must be maximized (no keyway stress risers)
Frequent assembly/disassembly is required
Design changes may occur late in the project
Maintenance and downtime must be minimized
Choose keyway if:
Low initial cost is the primary concern
Torque is very low
Precision is not critical
Assembly/disassembly is infrequent
6. Removal Screw Holes – Easy Disassembly
The AL-S series features removal screw holes (2–4 per pressure ring). To remove the assembly:
Insert screws into the removal holes
Tighten evenly to push the pressure rings apart
The assembly releases – no pullers or heating required
💡 This feature significantly reduces downtime and simplifies maintenance.
7. Applications Where Keyless Locking Excels
| Industry | Application | Why Keyless? |
|---|---|---|
| Packaging Machinery | High-speed drives | Zero backlash, no maintenance |
| Printing Presses | Registration rolls | Precise axial positioning |
| Textile Machinery | Spindles, rollers | High torque, easy maintenance |
| Machine Tools | CNC spindles | No backlash, high precision |
| Wind Turbines | Main shaft connections | High torque, reliability |
| Mining Equipment | Crushers, conveyors | Heavy loads, durability |
8. Real‑World Example – Printing Press Upgrade
A printing press manufacturer was experiencing registration errors due to keyway backlash on drive rolls. The backlash caused misalignment between print stations, resulting in waste.
They switched to Apex Coupling AL-S keyless locking assemblies (double taper, S45C steel). Results:
Backlash eliminated – registration accuracy improved
Axial position maintained – no movement during installation
Downtime reduced – easy removal for maintenance
Waste reduced – consistent print quality
9. Installation & Maintenance Tips
Clean shaft and hub bore – Remove oil, grease, and debris
Check dimensions – Ensure shaft and bore are within tolerance
Pre-center the assembly – AL-S is not self-centering
Tighten screws evenly – Use a torque wrench in a star pattern
No lubrication on tapered surfaces – Dry for maximum friction
For removal – Use the dedicated removal screw holes
Inspect periodically – Check for wear or damage
10. Selection Checklist
Torque requirement – 250–20,000,000 N·m range
Shaft diameter – Must match assembly bore
Hub bore diameter – Must match assembly outer diameter
Axial space – Ensure sufficient length for assembly
Installation access – Ensure screw access
Environment – Temperature, corrosion, moisture
11. Conclusion
The AL-S double taper keyless locking assembly from Apex Coupling offers superior performance compared to traditional keyways and single-taper designs. With higher torque capacity, zero backlash, no axial movement during installation, and easy removal, it is the ideal choice for demanding industrial applications.
👉 Need a keyless locking assembly for your application? Contact us with your shaft size and torque requirements.
Inquiry now:
ella@apexcoupling.com
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