CouplingFluid coupling

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Fluid couplings for large machinery with high torque of inertia
VULKAN fluid couplings are based on the Föttinger principle of hydrodynamic couplings. In its simplest version, a fluid coupling comprises a drive wheel connected with the driveshaft (e.g. an electric motor or combustion engine) and a running wheel connected with the driven machine shaft.

Fluid coupling operational principle
The drive wheel and driven wheel are fitted with radial rotor blades and there is no mechanical connection between them. The coupling is filled with a specific amount of fluid (mineral oil or a mixture of mineral oil and water). The main torque generated by the drive machine is converted into operating fluid hydrokinetic energy through a fluid swirl which circulates between the rotor blades in the drive wheel and in the running wheel. This energy is then reconverted into a mechanical torque and conveyed to the driven machine shaft

Versions and accessories
VULKAN fluid couplings are available with both constant filling and fluid level controlled couplings to meet the highest requirements. A comprehensive accessory range is also available, including:

  • Melting plugs for different temperature settings
  • Safety overload fuses and current load switches
  • Temperature sensors
  • Brake discs and drums
  • Electric/pneumatic actuators for speed control
  • Heat exchangers
  • Oil circulation pumps

Fluid coupling benefits
  • No-load motor start up
  • Limited maximum torque transmission to the motor during start up and therefore overload protection
  • Maximum torque transmission at start can be set to between 80% and 270% of the actuation torque
  • Motor can be based on the operating torque rather than the start up torque
  • Gradual acceleration of driven machine


  • Conveyor systems, crushes, shredders, ball mills, mixing machines, pumps, fans, boiler feed pumps, industrial drives


  • Motor Starting with no load
  • Smooth acceleration of the load
  • Machine and Motor protection against overload, limited to the maximum torque transmitted
  • Motor Selection through the operating torque, avoiding an oversizing selections of the motor by the starting torque
  • Low motor power consumption
  • Excellent ROI (short pay back period)
  • High efficiency due to the low sliding
  • Maximum torque transmission capacity can be achieved in the range of 80 up to 270% of the operating torque
  • Several designs

Tailor-made Solutions

  • Fixed speed
  • Modular design allowing several customization possibilities
  • Radial removability without having to move the connected machinery
  • Possibility of integrating braking discs or pulleys in combination with the coupling
  • Fusible trip device
  • Temperature transmitter (4-20Ma)
  • Variable speed
  • Radial removability without having to move the connected machinery
  • Possibility of integrating braking discs or pulleys within the coupling
  • Temperature transmitter (4-20Ma)
  • Heat exchanger – Shell & tube type Water cooled or Radiator type Air cooled
  • Actuator – Electrical / Pneumatic / Hydraulic with Single & dual speed
  • Control panel