Locking assemblies

Clamping sets

Locking assemblies are used in mechanical engineering to create a friction-locked shaft-hub connection. The clamping set connects the hub of a gearwheel, for example, to a shaft by means of a frictional connection. This backlash-free connection between shaft and hub allows torques and axial forces to be transmitted reliably. Depending on the design of the clamping set, high bending moments can also be transmitted with this type of connection.

Functional principle of clamping sets

Clamping sets (also known as ‘conical clamping elements’ or ‘internal clamping elements’) consist of one or two conical thrust rings and a conical clamping sleeve, depending on the design. By tightening the clamping screws to the specified tightening torque, the conical thrust rings are pulled onto the conical surface of the clamping sleeve. This process generates a radial force both inwards and outwards. While the outer diameter increases, the diameter inside the clamping set is reduced. This creates a frictional connection between the clamping set (cone clamping element) and the shaft and hub.

In contrast to a keyway in conventional parallel key connections, the stresses in the shaft are distributed evenly over the entire contact surface when using a clamping set. The even distribution of tension creates a reliable, freely positionable and, above all, wear-free connection. The shaft can also often be made smaller, which can lead to a reduction in the weight of the design.

Types of clamping sets

Clamping sets are available in a wide variety of designs and types. In addition to the torsional or bending moments to be transmitted, the available installation spaces and loads also play a key role in selecting the right product. Whether self-centring, low surface pressure, high speeds or stainless versions for the food and chemical industries – the product portfolio of TAS Schäfer GmbH offers a suitable solution for all areas.

Clamping sets are divided into two groups: The more compliant cone clamping elements and the rigid cone clamping elements.

Compliant cone clamping elements

The flexible cone clamping elements have a total of four conical functional surfaces and several individual components. Due to the design and the resulting larger cone angle, the more flexible clamping sets are not self-locking. This means that it is not necessary to press off the thrust rings during disassembly. As the thrust rings are not moved axially on the shaft during assembly, there is no axial displacement between the shaft and hub.

Rigid cone clamping elements

Rigid cone clamping elements only have one or two conical functional surfaces. This results in different technical properties than the more flexible cone clamping elements. Due to their design, rigid Cone Clamping Elements can transmit higher bending moments. In addition, this design has the property of better self-centring and self-locking. A further characteristic is that the clamping screws are not subjected to any further loads from forces during operation after installation. This increases the safety and service life of the rigid cone clamping elements.

Examples of rigid cone clamping elements are series 3012 and 3006

In general, the various clamping sets can be categorised according to the type of application and the available installation space. Short clamping sets are usually able to absorb low to medium torsional and bending moments. Wide clamping sets, on the other hand, are used for high to very high torsional and bending moments. The properties of individual clamping sets, the transmittable torsional and bending moments and their installation length can be found in the product overview below. Further properties, such as self-locking, self-centring or the possible bending moment component of the clamping set, can be found on the respective product pages in the catalogue.

Advantages of clamping sets

The performance of individual components, cost benefits, reduced assembly times or increased service life play an important role for industry when fastening components on rotating shafts.

A conventional method in the past was the connection via a keyway. With this type of connection, a keyway is milled into the shaft. This is also done in the hub. However, milling these grooves is costly and time-consuming. Another disadvantage is the reduction in the transmittable torque due to the weakening of the shaft. A grooved connection often results in movement and ultimately play, which can affect the accuracy of a machine system and create the risk of failure.

This risk can be avoided with a friction-locked shaft-hub connection with a clamping set, as there is no play. The use of a clamping set therefore ensures precision and safety. In addition, costly manufacturing processes, such as milling or shaping the grooves, can be avoided.

Another advantage of using a TAS Schäfer clamping set is the positioning on the shaft. Unlike with a keyway, the clamping set can be moved freely on the shaft.

TAS Schäfer clamping sets can also be used for existing shafts with a groove, enabling existing systems to be optimised.

Series such as the TAS 3015 DK clamping set prevent direct movement on the shaft during assembly. This avoids costly damage to the shaft during assembly.

Assembly of clamping sets

Assembly is carried out by inserting the clamping set between the components and then tightening the clamping screws. The screws must be tightened in a specified sequence and to an identical tightening torque. The use of conical surfaces increases the outer diameter and reduces the inner diameter of the clamping set. Radial pressure is built up.

The clamping forces are provided by the screws (force-controlled). This enables direct compensation of the play between the shaft and hub. The clamping sets from TAS Schäfer GmbH are delivered ready for installation. To ensure proper functioning and to achieve a sufficient and uniform coefficient of friction, the contact surfaces of the shaft and hub must be clean and coated with a film of oil.

The relevant installation instructions for the clamping sets are available on the TAS Schäfer GmbH online platform: TAS Schäfer installation instructions

Typical examples of clamping set applications

Clamping sets have a wide range of uses and are employed in many different industrial sectors. These include classic mechanical engineering, conveyor and drive technology, and the packaging and food industries, to name just a few examples. Ultimately, the clamping set enables precise fastening of hub bodies to shafts or axles, such as when fixing gear wheels and sprockets. In addition, our clamping sets are used in conveyor belt drums and crushers. In the food and petrochemical industries, stainless steel versions of the clamping sets are often used in filling or stirring systems. Clamping sets are used in the packaging industry to fasten pulleys and to transport objects within the machine.