ERD MARINE COUPLINGS
  General
 

Pre-compressed rubber blocks form the basis of all ERD coupling designs. Natural rubber of 55-60Sh.A hardness is the standard material, but alternative mixes are available and neoprene blocks are used where additional damping is required.

 

The blocks accommodate movement in all directions, making ERD couplings exceptionally tolerant of relative propeller shaft displacements in combination with flexible mounted propulsion engine and providing controlled torsional vibration excitation.

  Advantages of a ERD Marine Coupling
 
  • Reduction of torque fluctuations
  • Damping of torsional vibrations
  • Reduction of resonance symptoms
  • Compensating of radial, axial and angular shaft displacement
  • Isolation of vibration and noise transmission
  Specification
 

The ERD couplings are standard manufactured in steel and seawater resisting aluminum.  Other materials e.g. non-magnetic stainless steel can be supplied if required. They can be supplied with (S) or without (G) propeller thrust capacity and will maintain drive in the event of damage occurring to the rubber elements.

All ERD Marine Couplings can be supplied with an Adaptor flange (F) or Adaptor shaft (A), to fit for instance reduction gear boxes such as: Hurth, Masson, Paragon, PRM, Reintjes, Velvet, Twin Disc, ZF etc. All types can be supplied in a “Single” unit and in a “Twin” unit. In addition to the standard range, heavy duty and special couplings can be made to meet particular requirements.

  TECHNICAL DATA
  Nominal Torque Tn
 

The nominal torque Tn is the mean torque occurring in continuous service and calculated as follows:

  • Pn-   Nominal output in kW
  • Nn - Nominal shaft speed in min-1
  • Tn - Nominal torque in kNm
  Maximum Torque Tm
  The maximum torque Tm is the highest torque occurring during any normal drive condition, e.g. during starting, shock load, passing through criticals. For all applications, a service factor must be taken into account. If a service factor greater than three is required, the initial selection should be made on the basis of the expected maximum torque.
  Service Factor for Combusion Engines
 
  Coupling Selection, Single or Twin Marine Coupling?
  When using a “Single” coupling, the free shaft end - the distance between the output flange of the reverse gear and the centre of the first propeller shaft bearing - must have a length between Lmim and Lmax:
 
 
 
 
  If the distance is less than the minimal required length a Twin (Cardanic) Coupling must be used, the first propellor shaft bearing should then be positioned directly behind the coupling. We advise you to contact our technical staff in doubtful cases. The technical data for the individual coupling sizes are listed in the catalogue.

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