Keyless Locking Assemblies for Your Specific Application

Keyless Locking Assemblies: Internal & External

Locking Assemblies are friction-locked shaft-hub-connections. These keyless, frictional devices provide an easily adjustable and releasable mechanical shrink fit while eliminating problems associated with backlash, including fretting, corroding, and wallowing.

Keyless locking devices are separated into two types: internal (resides between the shaft and the hub to create internal and external connections) and external ( resides outside the hub, compressing it down onto the shaft) locking assemblies (Shrink Discs). They are classified according to:

 

Locking Assemblies With Low Surface Pressures

Low Surface Pressure Locking Assemblies minimize the tension in the components joined by the set. These are mainly used for highly thin-walled hubs and low-yield strength hubs or those made of grey cast iron or aluminum. Aluminum timing belt pulleys and thin-walled levers are typical areas of use.

 

Locking Assemblies Without Axial Displacement

Without Axial Displacement, locking assemblies are used when the following displacement is possible to affect the function of the connection negatively. This clamp set is suitable for various applications, including machine tools, spiral wheels, rotary table devices, pumps, and brake disc mountings.

 

Locking Assemblies Self-Centering

Self-Centering Locking Assemblies enable extremely precise concentricity in the clamped components. The maximum concentricity error for the clamping sets machined in a clamping process is an extremely low 0.04 mm. The main areas for these clamping usage are gear wheel mounting, rotary pumps, and machine tools (the ones that require the highest level of precision).

 

How Keyless Locking Devices Work

The devices create a 360-degree clamping force on the shaft to position components. They allow the axial or torque loads to be transmitted by radial clamping pressures and friction between the functional surfaces of the shaft hub and locking assembly.

 

Product Benefits 

  • The majority of units are self-centering
  • Endlessly reusable
  • High capacity for both dynamic and static load-bearing
  • Axial and angular adjustments can be carried out on the spot
  • Minimal loss in torque due to the presence of a keyway in the shaft
  • Overload capacity and eventual sliding will not endanger the integrity of the shaft
  • Easy assembly and disassembly: doesn’t require any prior hub or shaft preparation
  • Corrosion-resistant: active surfaces are protected, and no space between connections
  • Can handle various loads, including torque, bending moment, and axial and radial thrusts.

 

Device Failure Causes and How to Avoid Them

 

  • Weak Locking Assemblies Fail Any flexion in drum or pulley shafts will generate bending moments that create high stresses within the locking assembly. These stresses are not equally distributed through the assembly, which leads to two distinct failure modes:

  1. One side of the locking device will experience very high stresses, sometimes to the point that they exceed the yield strength of the materials used for the locking device.
  2.  The other side of the locking device will see lower forces from the bending moment. But the low force side tends to lift away from the shaft. This lift is almost invisible, but it’s enough to allow small sliding movements between the locking device and shaft. The result is fretting wear that can ultimately destroy the locking assembly and shaft.

 

  • Robust Locking Assemblies Survive - To avoid the previous failures, you need to specify a locking assembly explicitly designed to tolerate bending moments. Here are three differences in the design:

  1. Design provided for these bending moment applications, for example, uses materials with yield strengths up to 40% higher than a standard locking assembly. 
  2. Designs for high-bending moments tend to be wider because broader assemblies inherently have a higher resistance to the moment forces.
  3. Lastly, we reduce the working stresses the assembly can tolerate by optimizing the number and location of bolt holes. As a result, we can substantially improve the locking assembly’s ability to resist moment loads.

 

  • Added Benefits - These design enhancements that help with bending moments also have an added benefit related to component sizing and cost. The locking assembly’s bending moment capability determines the shaft size. Thus if you upsize the locking assembly based on moment loads, you’ll have to upsize the shaft and bearings. And that type of engineering can be costly.



Product Application

 

 

 

 

Check our article Installation and Removal Procedure of Ringfeder Smart-Lock.

Feel free to Contact Us if you have any questions, need more information, or are interested in purchasing keyless lock assemblies.

HVH Industrial Solutions is an authorized distributor of Ringfeder, Ringspann, and Rota Free / Compomac.

We work closely with the companies' engineering teams mentioned above to provide superior customer service and support.

 

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Vladimir Harutyunyan

Vladimir Harutyunyan is the founder of HVH Industrial. He has masters degree in mechanical engineering and over 10 years of experience in mechanical power transmission field. 

Feel free to connect with Vlad on Linkedin: https://www.linkedin.com/in/vladharut



image

Vladimir Harutyunyan

Vladimir Harutyunyan is the founder of HVH Industrial ...

Feel free to connect with Vlad on Linkedin: https://www.linkedin.com/in/vladharut