New Bellows Couplings & Overload Clutches Agency combines with New website & e-mail address launch

Exponential Sales growth in Germany (& Overseas), in less than 3 years of producing metal Bellows, Flexible Spider and Overload/safety drive Couplings, has encouraged the owners of the manufacturing & marketing company KBK Antriebstechnik GmbH (experienced Production & Design Engineers from the industry), to seek expansion into the UK & Eire markets. Their searches culminated in an agreement in January, 2006, for their exclusive Representation in those two markets, with FRANCIS and FRANCIS Ltd., Kenley, Surrey for their supply of all three product ranges there.

The addition of these KBK products will both widen and complement the Francis and Francis current mechanical PT palate, which includes their SCHMIDT-KUPPLUNG GmbH, Offset, Semiflex, Controlflex & Omniflex drive couplings, as well as their POGGI Trasmissioni Meccaniche Spa, Bevel gearboxes, Gear couplings & other PT products.

The UK & Eire promotion of these new KBK products coincides with the launch of a new FRANCIS AND FRANCIS Ltd, multi-page, ‘powertransmissions’ ‘catalogue’ Website, which includes full details on every product, together with the launch of new E-Mail Addresses at that site.

...MORE on Bellows Couplings


KBK metal Bellows couplings - because of their extremely high torsional stiffness and both angular and axial flexibility - are installed wherever powers, up to the highest levels, have to be transmitted between shafts, highly efficiently and absolutely backlash-free. This means that they effectively compensate for manufacturing variations in drive or support shaft bearings, both for angular and axial misalignment, with only very low restoring forces; thereby extending bearing life considerably.

In today's ever increasing drive systems demands, KBK metal Bellows couplings prove an indispensable connection component. Their wide range of different shaft fixing versions; whether

  • by bore & keyway, with two locking set-screws, 1 over the key, the other at 120° onto the shaft, or
  • by 'key-less' bore only, with part axial-split & radial-cut hubs 'all-round clamping' via single socket-head screw
  • mounted in drilled, tapped & counter bored hole along a chord line across the split in the hub, or
  • via protruding expanding mandrel into hollow shafts, or
  • by the 'key-less' bore only, 'clamping' compression imposed, from tightening multiple-screws axially, across conical
  • mating ring/tapered surface hubs, or
  • by simple flange bolting connection,
  • the installation options are enormous.

On the one hand, there are large, extremely robust designs, withstanding the harshest environmental conditions and loads (=KB4-7; caters for shafts from 10 to 100mm, with torque capacities from18 to 5,000Nm); on the other hand, there are space-saving, very short installed length metal Bellows couplings for small diameter shafts - the MINI-Couplings - (=KB1-3; for shafts from 1 to 24mm & torques from 0.1 to 10Nm) in the range.

The coupling principle offers the advantage of very simple & easy handling and operation.

In most variations it comprises of only a single component.

With the key-less, split-/clamping- hub designs, drive shafts suffer no damage, with the elimination of any possibility of rubbed 'flats' from abrasion appearing in any form, on dismantling or even during operation. The torque to be transmitted is more evenly distributed, around the whole shaft surface, as opposed to only one side of the keyway. There is no possibility of fretting corrosion. Life span is substantially improved and it is maintenance-free.

The bellows part of the coupling is made from stainless steel, whilst hubs made from aluminium alloy are 'Loctite' glued to each end. However, with the larger hub sizes (from KB4/60 upwards) material changes to steel and they are soldered, or welded to each end of the bellows.

Combining all these positive qualities makes the bellows coupling one of the most popular and proven shaft connectors found, particularly, in the industrial sectors of NC machines, Servo Drives, Packaging Machines, Linear Devices, Machine Tools, Pulse Generators (encoders, etc.) and Robot Control Drives and also in practically every other area of the dynamics, even under the most difficult environmental conditions.

Specific 'KBK' Feature:

A particular feature of the KBK metal Bellows Couplings arises from their meticulous manufacturing process, where guaranteed high concentricity of assembled components is assured, because every single coupling is 'centred' at the jointing assembly, on a mandrel. The rotational concentricity is then measured (for high accuracy) again at the final inspection stage.

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...MORE on Overload/Safety Couplings


'KBK' Overload Protection Clutch- or, Safety- Coupling Combination Connection Units present a product, which is continually increasing in importance in today's era of advancing automation. Compared to alternative Overload Protection possibilities, such as an electronic 'cut-off' device, or the classic Friction-Clutch hub, these Combination Units offer a number of advantages. The distinguishing feature is their extremely short re-action times, within milli-seconds, which represents an almost immediate 'cut-off' of the torque transmission and, thus, protection for man and machine in a collision course situation.

Indeed, personal injury and extensive 'break-down' times, with their corresponding machine repair costs, can be avoided by installing these Combination Units.

Furthermore, these Units are unaffected by environmental influences, such as temperature changes, or being in contact with oils and greases, which have an especially negative effect on the function of friction-clutch hubs.

By means of definitive pre-tensioning across disc springs with digressive spring characteristics, every overload torque can be preset precisely, to a very high function-accuracy. Upon reaching this overload torque setting, the coupling disengages at the clutch and the torque transmission is interrupted, immediately. In addition, this disengaging clutch-plate movement process can be coupled to a mechanical or, electronic switch, which brings the drive to a halt.

After dropping below the overload torque setting, further rotation of the coupling Unit (at low speed) returns the sprung clutch multiple hardened & polished 'caged' steel balls into their corresponding V-groove detents to re-engage automatically and take up the torque transmission again. Rotation may be in either direction. 'Asymmetrically' arranged balls/cage bores & detents options only allow re-engagement after a full 360 ° rotation, whereas the 'symmetric' arrangement options offer multiple re-engagement positions. There are two overload torque setting ranges offered for each clutch-coupling size, ranging from 1 to a maximum 1,600Nm

To the overload protection function benefit arising from these clutch-coupling types, each according to requirement and execution, the positive characteristic features of a conventional metal bellows- or, flexible 'spider'- coupling is added, namely shaft misalignment compensation, as well as enormously high torsional rigidity, minimal reaction forces and backlash-free torque transmission.

With the flexible 'spider' variation, accommodation of shocks and vibrations, as well as electrical isolation, is achieved, in addition.

Alternatively, a single or, double support bearing design for direct Pulley, Gear or Flange mounting is also offered in the range.

The simple construction, with only few and single-part components - thereby ensuring minimal dimensions and moments of inertia - facilitates a problem-free integration into every drive line, as well as an uncomplicated installation and dismantling, without leaving any marks on the components to be connected.

Application areas for Overload Protection Safety Clutch-Couplings are found wherever there is a danger of a 'crash' or, of an overload generally; e.g., in high dynamic drives, Machine Tools, Textile- and CNC- controlled Machines, Servo Drives and many other areas in the dynamics.

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