Shaft-hub-connections are clamping elements which enable a non-positive and backlash-free connection between cylindrical, non-keyed shafts and hub bores. Depending on the type, the clamping elements are released by simply loosening the screws or by additionally pushing apart the individual clamping set elements.
In the case of shaft-hub connections, a distinction can essentially be made between three variants of power transmission: force-locking, form-locking and material-locking.
Force-locking: Force-locking connections are, for example, clamping sets and shrink discs in which clamping or centring forces act to connect a drive shaft with an output shaft. Couplings with clamping hubs are also a good option for the force-locking transmission of torques. However, they lag behind clamping sets and shrink discs in the performance spectrum.
Form-locking: Shaft-hub connections can be form-fit, e.g. via a keyway. Keyways are the best known and most common form of torque transmitting in drive technology. They connect a drive shaft with an output shaft or a sprocket. Alternative form-locking connections include splined shaft profiles and toothed profiles. So-called grub screws also find suitable applications at low speeds and low power transmission.
Material-locking: Materially bonded connections are all adhesive, soldered, welded and therefore strong connections, which, however, have disadvantages in case of repair.
The key is not in itself present in a shrink disk or clamping set, as these types of shaft-hub connection function quasi as an alternative to the keyway. Instead of positive power transmission, clamping sets or shrink discs are used, which do not require a keyway or similar.
It offers the advantage of having no wear or breaking points. The concentricity is also much higher, as everything is “form-fit”. In other words, the shrink disc is shrunk onto the shaft and fits 100%, whereas with a keyway there is always a little play, which can lead to stress and abrasion during starting and braking. Therefore, a shrink disc or tensioner set will last longer and work more accurately, but are usually a little more expensive.
The clamping elements offered here are divided into internal clamping sets, which are self-centring or not, and external clamping sets and shrink discs. Classic applications are, for example, sprockets that are mounted on driving shafts or clutch hubs that are to be clamped onto a shaft without a keyway.
Shrink discs are force-locking shaft-hub connections, the more efficient and very reliable alternative to conventional shrink fits, such as the wedge, key or polygon connections. The difference to classic internal clamping connections, such as clamping sets, is that by pressing from the outside onto the hollow shaft or hub, an absolutely backlash-free, friction-locked connection is created between the shaft and hub.
The shrink disc is therefore not in the power flow, but the torque is transmitted at the joint surface between shaft and hub without an intermediate element, completely friction-locked. In addition to being wear- and maintenance-free, the advantages are that it is easy to assemble and disassemble. The shrink disc can also be of great advantage due to its excellent fatigue strength and concentricity. Almost all sizes are available in stainless steel versions, e.g. for use in the food industry. Axial and radial loads can be transmitted, as well as torsional and bending moments.
Non-self-centring internal clamping sets are placed between shaft and hub. A frictional connection is created between shaft and clamping set as well as hub and clamping set. Centring between hub and shaft is required. The best-known products include “Ring spring clamping set RFN 7012”, “Ring spring clamping elements RFN 8006”, “KTR clamping set 150” and “Ring clamping RLK 300”.
During assembly, there is no axial displacement of the hub. Clamping set, shaft and hub remain in position. Examples of self-centring internal clamping sets without axial hub displacement are the “Ring spring ECOLOC clamping set 7110” or “Ring clamping RLK 133”.
Shaft-hub connections are produced by well-known manufacturers such as “Ringfeder”, “KBK”, “KTR” or “TAS Schäfer”. As a long-standing partner of these companies, it is best to request a&s vertriebs gmbH, through which you can buy the desired connections.
In urgent cases we can also fall back on all available suppliers on the market, thus optimising prices and delivery times so that you receive your products as soon as possible. Just give us a call or send us an e-mail. Our competent team will be happy to help you quickly.
