A brief ABC of Couplings
The main function of a shaft coupling is the connection of two shafts and the transmission of torques and rotational movements.
Furthermore, shaft couplings are also required to fulfil a number of additional functions such as compensating shaft misalignment, dampening torque impulses and vibrations, protecting machines and drives against damages through overload et cetera.
That is why many designs have emerged that can be differentiated in accordance with VDI 2240.
One distinguishes primarily between shiftable (manual, speed-controlled, direction of rotation-controlled, torque-controlled) and non-shiftable shaft couplings.
Since it is often not possible to cover all requirements with one design, you will often also find combinations of shiftable and non-shiftable couplings in industrial applications.
The non-shiftable couplings are differentiated between:
Rigid couplings
The shafts are connected together rigidly by the coupling. Torques and rotational movements are directly transferred without a rotational angle offset. The couplings cannot, however, compensate any axial, radial or angular misalignment of the shafts.
Accordingly, significant reaction forces can arise during operation for example due to inadequate alignment or thermal deformations that additionally stress the bearings of the drive train.
Torsionally stiff couplings
They act in the peripheral direction torsionally stiff, i.e. torques and rotational movements are transferred almost without rotational angle offset. Depending on the design, however, these couplings can compensate axial, radial or angular shaft misalignment.
Elastic couplings
These couplings are equipped with an elastic element that transfers the torque from the drive side of the coupling onto the output side. Elastic elements are commonly made of plastic or rubber. In special cases, elastic elements made of steel are also used.
The elastic intermediate element leads to a torque-dependent rotational angle offset between the input and output side of the couplings. Furthermore, intermediate elements made of plastic dampen torque impulses and influence the resonance frequency of the drive train.
Elastic couplings can also compensate axial, radial and angular shaft misalignment via the deformation of the intermediate elements.
Highly elastic couplings
These couplings are characterised by a high degree of torsional elasticity and large spring travel. This enables them to have a high damping capacity and can thus reduce rotational vibration and load impacts.
By selecting a suitable elastomer, you can also influence the natural frequencies of the drive train in such a manner that they lie outside the operating speed range of the unit. This prevents resonance vibrations and limits torque peaks.
Our offerings in couplings – a key component for more flexibility in the drive train
RINGSPANN has been massively expanding its portfolio of non-shiftable shaft couplings. It began the process a few years ago with a large-scale product offensive in the field of shaft couplings.
The introduction of five completely new coupling types and the supplementation of numerous existing models resulted in a massive expansion of the overall range.
The full-range supplier is thus providing engineers and product developers in industrial drive technology with even more options for the realisation of safe, powerful and installation space-optimised connections between shafts, motors, gearboxes and machines.
RINGSPANN was able to announce the implementation of the next stage of its development towards becoming a one-stop supplier for high-grade drive technology components.
The company’s brakes and coupling division announced the massive expansion of its range of non-shiftable shaft couplings.
It is important to realise that RINGSPANN has been devoted to the development and production of safety and starting clutches shiftable under load for more than 60 years.
“However, this latest expansion of the product range is as yet unrivalled in the history of the company”, stresses RINGSPANN Germany head of the brakes and couplings division Franz Eisele.
While the focus of RINGSPANN’s portfolio in this field had been previously placed primarily on flange, flexible and cone clamping couplings, the overall selection is now being expanded thanks to the current product range with five completely new models.
What that means is with immediate effect, you can now also find gear couplings, grid couplings, disc couplings and pin-and-bush couplings and jaw couplings ready to deliver.
“This range now allows us to offer a total of eight models that cover almost all technically relevant types of rigid, torsionally stiff and elastic shaft couplings that are currently needed in industrial drive technology”, says Eisele.
Eight models up to 1,299,500 Nm
Across all eight models, the now available RINGSPANN spectrum of shaft couplings covers an astonishing range of nominal torques from 2.0 to 1,299,500 Nm.
This also means that purchasers and engineers from every conceivable industrial sector and branch now have a comprehensive range of non-shiftable shaft couplings for applications in almost every area of drive technology available to them.
Eisele explains: “The beneficiaries of our comprehensive coupling range will not only be our current core target groups in conveyor technology, crane construction und gear manufacturing, but also many other plant manufacturers and mechanical engineers – for example those in fluid and process engineering, raw materials industry and steel production.”
A complete overview of RINGSPANN’s new portfolio of shaft couplings can be found in the freshly issued product catalogue, which is available for free download on the company’s website (www.ringspann.de).
Here you find all coupling types and variants sorted according to design and area of application and described and depicted: cone clamping couplings and tru-line flange-couplings for rigid connections; gear, disc and flexible couplings for torsionally stiff connections; grid couplings for initially elastic and later torsionally stiff connections; and pin-and-bush and jaw couplings for elastic shaft connections.
“We offer suitable couplings for applications in which the torque is transferred torsionally stiffly without phase shift but where the shaft displacements need to be compensated, just like applications in which a defined torsional stiffness must be ensured through elastomers. The coupling connoisseurs amongst us may miss the highly elastic elastomer coupling model; but we will soon be putting that right”, says Eisele.
What customers have come to expect from RINGSPANN freewheels, brakes, shaft-hub-connections, overload clutches, clamping fixtures and push/pull cable systems, also applies to our shaft couplings: customer-specific modifications can always be realised beyond the standard version shown in the catalogue to adapt series clutches to unusual and special applications.
While on the subject of coupling, it would be remiss not to mention RINGSPANN’s offerings of three-part shrink discs for high torques.
In the area of shaft-hub-connections connected via friction lining, shrink discs rank among the most important drive elements for mechanical engineers and plant manufacturers.
As one of the leading manufacturers of these components worldwide, RINGSPANN is therefore responding to the current demands of design engineers and developers with regular expansions of its range.
Three-part shrink discs were introduced to the successful standard series RLK 603 S. Those who stand to profit are, for example, manufacturers of drive systems for conveyor systems, stirrers, mixing plants, construction machinery and wind turbines.
In 2019, RINGSPANN integrated a number of new shaft-hub-connections into its overall range and upgraded many series in performance on the basis of a new, improved method for frictional locking calculation.
Since then, the range of shrink discs, cone clamping elements and star discs has been subject to constant further optimisation, supplementation and refinement.
The next gap in RINGSPANN’s range of shaft-hub-connections connected via frictional lining was closed with the expansion of the globally successful shrink disc series RLK 603 S.
“To be able to more comprehensively meet the increasing demands of our customers for compact and cost-efficient three-part shrink discs with high power densities, we have expanded our RLK 603 S series with additional versions in new sizes and intermediate sizes. The complete series now spans shaft diameters ranging from 14 to 190 mm, which means the current demands of the market are almost fully covered”, explains Marvin Raquet, product manager for RINGSPANN’s shaft-hub-connections.
Like all shrink discs in the RLK 603 S series, the new designs are also already available with descriptions, data sheets and CAD models in the company’s online shop for selection and are quickly available from stock.
Key feature: Extremely high torque capacity
The RLK 603 S series shrink discs are powerful externally clamping connections for the play-free connection of hollow shafts or hubs on shafts.
Among the significant advantages of these frictional connections are their very high torque capacity across a range from 18 Nm to 156,700 Nm, as well as their compatibility with key industry and supplier standards in drive technology.
Installation and setup are carried out very easily via the clamping screws of the shrink discs.
Design engineers and developers of drive units for use in bulk goods conveyor systems, stirrers, mixing plants and crushers, plants for energy generation, and construction, forestry and agricultural machinery particularly stand to profit from the expansion of the RLK 603 S series.
RINGSPANN’s engineering department also implements customer-specific and project-specific versions beyond the standard RLK 603 S series shrink discs at short notice for many OEMs in these sectors.
Across all 30 series, RINGSPANN offers shaft-hub-connections connected via friction lining for torques ranging from 0.16 Nm to 4,225,000 Nm.
At the same time, the current catalogue range spans all technically relevant designs of shaft-hub-connections.
In addition to the externally clamping shrink discs, you can also find internally clamping cone clamping elements, internally clamping star discs and individual star spring washers for ball bearing compensation, as well as clamping systems for fixing torque motors onto machine shafts connected via friction lining.
The highlights include – besides the cost-efficient three-part shrink discs in the RLK 603 S series – the double-slotted premium elements RLK TC (true centring), which are proven to have very high centering accuracies.
Measured by its technical bandwidth, the current RINGSPANN range of shaft-hub-connections ranks amongst the best offers worldwide.
“It exemplifies the development of the company into an international one-stop supplier for industrial drive elements”, emphasises Raquet.
On RINGSPANN’s website, design engineers and developers can also find the new online calculation tool for the shaft-hub-connections, which is based on the improved frictional locking calculation method. It not only takes into account all the important parameters (hub dimensions, surface pressure, torque, tightening torque et cetera), but can also calculate the transmissible torque, even factoring in axial forces and additional bending moments.
We hope you enjoyed reading this story. We will bring you more in the future so watch this space for more from us at RINGSPANN Australia.
Today, the RINGSPANN Group has nine manufacturing plants located in four continents. The success of our products are a testimony of company’s market leadership on a global scale. We offer a one-stop solution for high-quality components in industrial drive engineering.
Customers can contact us in Australia on info@ringspann.com.au or (03) 90690566.