Bellows couplings

The BK4 bellows coupling from R+W Couplings has high operational reliability and a very compact design. The hub with tapered sleeve is specially designed as an interface for Fanuc servomotors. By using friction clamp connection, this precision clutch possesses a high clamping capacity, resulting in an absolutely backlash-free clutch. Thanks to its forced bellows shape, the element can simultaneously accommodate lateral, axial and angular misalignments. As long as they do not fall outside the maximum area, no metal fatigue will occur in the bellows material and the clutch is completely free of wear. For specific questions about bellows couplings, contact VARIODRIVE.

Clamping ring and taper sleeve
Nom. Torque
15-150 Nm
up to 10,000 rpm
Temperature range
-30 to +100 oC
Bellows material
Hub material
Peak load
Up to 1.5x nom. Torque
No service
ATEX, clean room version

  • Bestelcode instructies
  • ATEX instructies
  • Datasheet BK4
  • Manual BK/MK koppelingen
BK4 drawing
BK4 Series153060150
Rated torque (Nm)TKN153060150
Overall length (mm)A247 | 5468 | 7672 | 8282 | 94
Fit length (mm)c19222732
Inside diameter range H7 (mm)D10-2212-2312-2915-37
Outside diameter (mm)B49556681
Moment of inertia | (10-3 kgm2)Jges.0,10 | 0,120,22 | 0,270,58 | 0,611,1 | 1,4
Approximate weight (kg)0,250,40,81,35
Torsional stiffness (103 Nm/rad)CT20 | 1539 | 2876 | 55175 | 110
Axial (mm))max.1 | 21 | 21,5 | 22 | 3
Lateral ± (mm)max.0,15 | 0,20,2 | 0,250,2 | 0,250,2 | 0,25
Angular ± (degree)max.1 | 1,51 | 1,51 | 1,51 | 1,5
Axial spring stiffness (N/mm)ca25 | 1550 | 3072 | 4882 | 52
Lateral spring stiffness (N/mm)cr475 | 137900 | 2701200 | 4201500 | 435
Fastening screw (ISO 4017)E6xM46xM56xM56xM6
Tightening torque of the fastening screw (Nm)E46812
Jack screw ISO 4017F3xM43xM43xM53xM5
Outside diameter of hub (mm)G20273030
Hub length (mm)H8,5221820
Cone Ø (Fanuc-Motor)(mm)11161616
Key width (mm)K4555
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Frequently Asked Questions

You can place an order with VARIODRIVE by sending your request to orders@variodrive.nl. Your request will then be processed directly by our internal sales team.

By choosing VARIODRIVE’s complete solution, you won’t need to worry about integrating different drive components into the machine’s drive chain. We stand behind our complete solution and can guarantee its functionality.

Due to our in-depth knowledge of our products and their integration into applications, we can provide a system warranty. At that point, we guarantee that the application will function using our motion control and traction solutions.

For most products on our website, you can download the 3D files. If the desired 3D file is not available, please contact sales@variodrive.nl, and we will send you the 3D file as soon as possible.

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