Installation Guide - Installation & Removal of a MAV Keyless Locking Device for Shaft to Hub Connections.

ADMIN Darren Butterworth
11 February, 2016

Author - Steve Hittmann Power Transmission Product Manager

Installation Guide - MAV Keyless Locking Device
Author - Steve Hittmann Power Transmission Product Manager

Why use a Keyless Locking Device?

The MAV keyless locking device, also known as frictional locking assemblies, provide a keyless, zero backlash connection between a shaft and hub in applications like gears, conveyor pulleys, vee & synchronous pulleys, sprockets, cams, levers, rotors, and many others. This locking method eliminates the need for keyways and the associated problems with keyway mounted applications.

MAV units are well suited to transmit torque, thrust loads, bending moments, and radial loads both separately and simultaneously. When considering a selection, the catalogue ratings do not consider any safety/service factor, and additional information is available from your local CBC branch or representative.

This type of keyless locking device is known in the market via a wide variety of descriptions including shaft locking device, friction lock, keyless friction locking device, shaft locking assembly, locking device, and Ringfeder.

Description of Friction Locking Devices and their Design

The MAV Keyless Locking Devices meet or exceeds the advantages of the traditional interference fit, press fit or shrink fit, yet is simplified for ease of installation and removal. It is based on the wedge principal. The axial load on the screws generates a high radial load through the tapers to the hub and the shaft that locks the components by using friction.

It is important to note that new designs have been developed for today’s market that offers advantages over the classic or initial versions of this type of locking device. The classic, or first style, relies on the fasteners to hold the radial load, as they have steep tapers within their design. The later designs offer shallow tapers, which are self locking and only use the fasteners for the initial installation. Once the installation is complete, the fasteners do not carry any load.

Main Features of the MAV Keyless Locking Device

  • Mounting and positioning is easy via a slide in/on fit due to the generous tolerances when the unit is in its free state. Shaft and Hub tolerances are sufficient for easy mounting and correct positioning.
  • High manufacturing precision results in close geometrical tolerances, leading to a well balanced connection, even in high speed applications.
  • The high pressures produced by the MAV allow for high torques to be transmitted. This type of locking has the additional advantages of assisting with bending moments with alternative designs either improving rigidity, i.e. MAV 2005, or providing shaft flexibility, i.e. MAV 1061. Eliminating fretting corrosion is an additional benefit.
  • With the absence of notches, found in traditional shaft connections, like taper lock bushes, keyed shaft connections, and splines, this type of locking device enhances static and dynamic strength, leading to lighter and more cost effective designs.
  • The large variation of design types available within the standard catalogue coupled with the possibility of designing and manufacturing customised units with short lead times, allow CBC and our customers to find the best solution for a wide variety of applications. 

Installation

CBC supply MAV keyless locking devices ready for installation. Catalogue specifications are based on a friction coefficient of (u=0.12), for lightly oiled rings, screws, shaft, and hub bore. 

Please note: DO NOT USE molybdenum disulphide lubricants like; Molykote, NeverSeez, Anti-Seez or similar.

  1. Disengage the rings by loosening the screws or by tightening some screws into the push-off threads.
  2. Insert the locking assembly into the application to be mounted and relocate any screws used to separate the unit.
  3. Ensure you have checked that your shaft and housing bore conform to the catalogue specified tolerances. Check with your local CBC Office or Representative.
  4. Ensure the correct position of the shaft and hub, and then tighten the screws by hand.
  5. Using a torque wrench set it approximately 5% higher than the specified tightening torque. This will be found in the box the MAV was supplied in, or you can check with your local CBC Office or Representative. Ensure you tighten the screws in a cross pattern in several steps, e.g. 12:00, 6:00, 9:00, 3:00, etc.
  6. As a final check, reset the torque wrench to the specified tightening torque and make sure no screw can turn at the specified torque, otherwise repeat the procedure from step 5.  

Removal

Prior to initiating the removal procedure, check to ensure no load is acting on the keyless locking device, shaft, hub or any mounted component.

  1. Remove all screws. Transfer required number of screws into all push-off threads.
  2. Tighten the screws in a cross pattern in several steps (e.g. 12:00, 6:00, 9:00, 3:00, etc) until the rings disengage

NOTE: Detailed installation & removal instructions for each specific series is also available from your local CBC Office.


For a demonstration video on installation and removal of a keyless Locking Device Click Here.


CBC have supplied this locking method for original equipment applications as well as upgrading old designs when problem solving. Issues such as keyway wear, within indexing (forward-reverse) applications, or difficulty when removing or installing press fit hubs, such as couplings, sprockets, pulleys, gears, and levers can often be completely eliminated. This can result in an ongoing maintenance saving. The capacity of a standard press or interference fit can be substantially increased when implementing this locking method.

Manufacturers of this type of keyless locking device assemblies available from CBC include, MAV, TAS, Tollok, TLK, Trantorque, Ringfeder, Compomac, Conex, Euroconic, Bikon, Peter, Ringblock, Clampex, Power-Lock, Shrink Disc, ConLoc, SIT, HiPerDrive, Powertech, Stuwe, Fenlok, and Super-Lock.