2020-02-19

The classic is now online

RINGSPANN freewheels of the FXM series have been setting the global standard for almost 50 years

RINGSPANN’s FXM-series integrated freewheels have long since become a staple of drive trains in international machine and plant construction. Equipped with the now legendary sprag lift-off type X, they impress with maximum torques of up to 1,230,000 Nm, low lift-off speeds and wear-free continuous operation. The entire FXM series currently comprises more than 40 standard sizes and can now be ordered directly in the company’s online shop. In addition, the price structure has been optimised, which is of particular benefit to small series customers. The freewheel classic is currently arousing the interest of numerous e-mobility manufacturers and is part of the RINGSPANN product range at this year’s Hannover Messe.


Bad Homburg, February 2020. – The integrated freewheels from the FXM series are a central focus of this year’s RINGSPANN appearance at Hannover Messe (Hall 5, Stand D32/1). They are among the classics of freewheel technology and have been setting the international standard in terms of quality and performance since their market launch in 1971. RINGSPANN is now offering this bestseller in its wide range of freewheel products in its online shop. Furthermore, the price structure of the FXM series has been completely revised as part of its integration into the online order assortment. “This results in attractive economies of scale in pricing, which particularly benefits all those buyers and sourcing managers who often only want or need to order smaller quantities – for example to cover their spare parts requirements”, explains Thomas Heubach, head of the freewheels division at RINGSPANN. All sizes with standard bores are available at short notice and customer-specific special designs can be quickly implemented thanks to the modular design of the integrated freewheels. Design and development engineers can find technical data sheets and installation instructions for all FXMs in the company’s online shop – and above all: the respective 3D CAD models in various file formats and levels of detail for free download.


Deployable as a return stop and coupling


The integrated freewheels from RINGSPANN’s FXM series are universally usable machine elements that can be used as backstops and overrunning clutches and cover a very wide range of applications in machine and plant construction. They do not have their own bearing support, are prepared for front-sided screw assembly, and have race diameters from 31 to 750 mm. Depending on the variant, they generate torques ranging from 110 Nm to 1,230,000 Nm. These performance figures enable them to cover, for example, an enormously wide range of gear applications in light, medium and heavy machine construction. FXM freewheels are, for example, used as backstops between the shafts of spur gearboxes in conveyor belt drives or as overrunning clutches in the gearbox units of bucket elevators, where they automatically engage and disengage the main and creep drives. “The FXM series has been continuously developed over the years and adapted to new areas of application time and again. It’s one of the reasons why RINGSPANN engineering has a very high level of design competence for this incredibly versatile freewheel type. For example, our FXMs are currently under discussion for various e-mobility applications. This will be a topic of discussion at this year’s Hannover Messe”, says division manager Thomas Heubach.


Compact design and quality in detail


Among the most important design features of the FXM freewheels are their compact design, their guide elements for the cage rings and sprags that are milled with the highest precision, and the excellent functionality of the type-X sprags acting inside them – a pioneering development of RINGSPANN engineering. Thanks to the generally low lift-off speeds for the sprags, a well thought-out overall design and the high manufacturing quality of their components, these freewheels not only achieve the highest torques but also prove to be wear-free marathon runners. “As low-maintenance fire-and-forget solutions, our FXMs have been proven over many years in numerous long-term applications in mechanical and automotive engineering”, reports Thomas Heubach.


In addition, there are two other important factors that underline the universal character of these RINGSPANN integrated freewheels. Firstly, the exceptional X-geometry of their sprags allows the FXMs to be used with friction-reducing solid lubricants (e.g. molybdenum sulphide). And secondly, the FXMs do their job even with larger runout deviations! They are therefore very well suited for use in plain bearing applications, for example.


Today, the RINGSPANN Group manufactures in production plants on three continents. These integrated freewheels are thus not only a real example of the company’s market leadership on global freewheels markets, but also represent RINGSPANN’s development into an international one-stop supplier of high-quality components for industrial drive engineering.



Der Fliehkraft-Trick: Die Klemmstückabhebung X

Die Anbaufreiläufe FXM von RINGSPANN arbeiten mit der Klemmstückabhebung X. Sie wird bei Rücklaufsperren und Überholfreiläufen immer dann angewandt, wenn im Leerlaufbetrieb der Innenring mit hoher Drehzahl umläuft und in der Überholfunktion der Mitnahmebetrieb bei niedriger Drehzahl erfolgt. Im Leerlauf bewirkt die Fliehkraft, dass sich die in einer X-ähnlichen Form gefertigten Klemmstücke von der Laufbahn des Außenrings abheben. Der Freilauf arbeitet dann verschleißfrei und mit unbegrenzter Gebrauchsdauer. Dabei laufen die Klemmstücke – geführt in einem mit dem Innenring reibschlüssig verbundenen Käfig – mit dem Innenring um. Die Fliehkraft hat das Klemmstück im Gegenuhrzeigersinn gedreht und am Stützbord des Käfigs angelegt, wodurch ein Spalt zwischen dem Klemmstück und Laufbahn des Außenrings entsteht; der Freilauf arbeitet also berührungslos. Sinkt nun die Drehzahl des Innenrings soweit ab, dass die Wirkung der Fliehkraft auf das Klemmstück kleiner wird als die Anfederungskraft, legt sich das Klemmstück wieder an den Außenring an und „schaltet“ den Freilauf sperrbereit. Zu beachten: In der Anwendung als Überholfreilauf darf die Mitnahmedrehzahl 40 Prozent der Abhebedrehzahl nicht überschreiten. (Siehe dazu auch Bild 4.)

integrated freewheels of the FXM series from RINGSPANN
The freewheel classic at Hannover Messe (Hall 5, Stand D32/1): The integrated freewheels of the FXM series from RINGSPANN impress with maximum torques of up to 1,230,000 NM, low lift-off speeds and wear-free continuous operation.
RINGSPANN division manager Thomas Heubach
RINGSPANN division manager Thomas Heubach: “The new price structure for our FXM freewheels leads to attractive economies of scale, which particularly benefits those customers who only want or need to order smaller quantities – for example to cover their spare parts requirements.”
use of FXM integrated freewheel in a gear motor
FXM integrated freewheels from RINGSPANN are universal machine elements that can be used as backstops and overrunning clutches and cover a wide range of applications in mechanical engineering. The picture shows their use in a gear motor (blue/right; the green element on the left is a RINGSPANN shaft coupling).
RINGSPANN’s sprag lift-off X
RINGSPANN’s sprag lift-off X is always used in freewheeling operation when the inner ring rotates at high speed in freewheeling operation and when in overrunning operation driving operation takes place at low speed. In freewheeling operation, the centrifugal force causes the X-like sprags to lift off from the outer track.