Bellows couplings

The BK7 bellows coupling from R+W Couplings is compact and makes assembly and disassembly very easy. The mandrel provides high clamping force in hollow shafts and pulleys or gears. Additionally, the coupling has a low moment of inertia. Thanks to the use of a friction clamp connection, this precision coupling is entirely free from play. Thanks to the forcibly formed bellows, the element can simultaneously accommodate lateral, axial, and angular misalignments. As long as these misalignments do not exceed the maximum range, there will be no metal fatigue in the bellows material, and the coupling will remain completely free from wear. For specific inquiries about bellows couplings, please contact VARIODRIVE.

Mandrel and clamp hub
Nom. Torque
15-300 Nm
tot 10.000 rpm
Temperature range
-30 to +100 oC
Bellows material
Stainless steel
Hub material
Steel or aluminum
Peak load
Up to 1.5 times the nominal value. Torque
No service
ATEX, cleanroom version

  • Bestelcode instructies
  • ATEX instructies
  • Datasheet BK7
  • Manual BK/MK koppelingen
BK7 drawing
BK7 Series153060150300
Rated torque (Nm)TKN153060150300
Overall length (mm)A-245 | 15253 | 6162 | 7271 | 8384 | 98
Inside diameter possible from Ø to Ø H7 (mm) DI8-2810-3012-3519-4230-60
Outside diameter (mm) B49556681110
Moment of inertia (10-3 kgm2) Jges.0,07 | 0,080,14 | 0,150,23 | 0,262,2 | 2,46,5 | 8,9
Approximate weight (kg) 0,150,30,41,74
Torsional stiffness (10³ Nm/rad) CT20 | 1539 | 2876 | 55175 | 110450 | 350
Axial ± (mm)) max.1 | 21 | 21,5 | 22 | 32,5 | 3,5
Lateral ± (mm) max.0,15 | 0,20,2 | 0,250,2 | 0,250,2 | 0,250,25 | 0,3
Angular ± (degree) max.1 | 1,51 | 1,51 | 1,51 | 1,51 | 1,5
Axial spring stiffness (N/mm) ca20 | 1250 | 3072 | 4882 | 52105 | 71
Lateral spring stiffness (N/mm) cr315 | 108730 | 2301200 | 13801550 | 4353750 | 1050
Fastening screw (ISO 4762) E1/2M5M6M8M10M12
Tightening torque of the fastening screw (Nm) E1/28143865120
Distance between centerlines (mm) F1719232739
Distance (mm) G6,57,59,51113
Mounting length (mm) Cl2227313643
Fit length (mm)C22025273245
Shaft diameter from Ø to Ø h7 (mm)D213-2514-3023-3826-4238-60
Hub materialAluminiumAluminiumAluminiumSteelSteel
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