HKDS / HKDSI 5 Safety Double-joint Couplings



Safety double joint couplings

  • For encoder attachments requiring functional safety (PL e)
  • Play-free, torsion resistant and failsafe
  • Extends service life of encoders
  • Options: Isolated version (HKDSI 5) or Ex certified version (HKDS 5 Ex)

Safety double joint couplings

Corrosion proof HKDS metal multiple disc couplings compensate a parallel misalignment up to ±0.5 mm and an axial misalignment up to ±1 mm as well as extending the service life of encoders in the process. They are safety components in accordance with DIN EN ISO 13849-2 (PL e) with CE declaration of conformity and designed in high safety factors relating to fatigue resistance and fault exclusion. In addition, it is possible to implement failsafe encoder attachment solutions in potentially explosive atmospheres. As a consequence, they are ideal for extreme operating conditions. Double joint couplings are available with different hub lengths and bore diameters in addition to isolated coupling versions for attachments where the risk of shaft currents is a concern.

Technical Data


Product usage
  • Compensate axial misalignment
  • Compensate parallel misalignment
  • Attachment points with functional safety requirement (SIL/PL)
  • Attachment points in potentially explosive atmospheres (ATEX / IECEx)
  • Isolate against existing bearing/shaft currents
Coupling specification
  • HKDS 5… / HKDS 5… Ex:  Stainless steel coupling
  • HKDSI 5…: Stainless steel coupling with plastic isolating bushing (electrically isolated)
Bore drive side Ø 22 mm with keyway
Bore encoder side
  • HKDS 5… / HKDS 5… Ex:  Max. Ø 22 mm with keyway
  • HKDSI 5…: Max. Ø 10-14 mm with keyway (plastic isolating bushing)
Outer diameter Ø 54 mm
Total length 68 – 120 mm
Mounting accuracy Radial misalignment: up to ±0.5 mm / axial misalignment: up to ±1.5 mm
Maximum rotation 6000 rpm
Temperature range
  • HKDS 5…: -50 °C to +120 °C
  • HKDSI 5…:  -25 °C to +85 °C
  • HKDS 5… Ex: -50 °C to +70 °C
Shock resistance 10 g (briefly 100 g)
Vibration resistance 3 g (briefly 20 g)
Insulated against currents
  • HKDS 5… / HKDS 5… Ex: No
  • HKDSI 5…:  Yes
Mechanical options
  • Isolation against bearing/shaft currents (type HKSI)
  • Attachment to larger shaft diameters possible with adapter shaft
Special features and certificates
  • Designed as safety component with fault exclusion to DIN EN ISO 13849-2 (up to PLe), with CE declaration of conformity
  • Additional safety claws ensure availability even if spring washers fracture due to overload
  • Spring washers made of high tensile steel with special corrosion protection
  • Certified for Ex zones 1 and 2 (gas) as well as 21 and 22 (dust); isolated version type HKSI 5… not available for Ex applications due to the risk of build-up of electrostatic charge (plastic).



HKS(I) … / HKDS(I) … (en)


HKS(I) … / HKDS(I) … (en)
Operating and assembly instructions


HKS … Ex / HKDS … Ex (en)
Operating and assembly instructions


HKS(I) … / HKDS(I) … (de/en)
EU declaration of conformity


HKS … Ex / HKDS … Ex ATEX (de/en)
EU declaration of conformity


ATEX (de/en)


IECEx (de/en)