VULKAN Flexible Coupling
Spare Parts Supplier
Highly flexible couplings from VULKAN of Herne sit between propulsion engines and gearboxes and between engines and generators. Their rubber elements age in service and are the part that comes back on the requisition, so each element is quoted against the coupling it belongs to.
VULKAN coupling families behind element requests
VULKAN, based in Herne, Germany, makes flexible couplings for ship propulsion and generator drives among other duties. In a highly flexible coupling the torque passes through rubber elements, and the stiffness and damping of those elements are chosen so that the torsional vibration of the whole drive stays where the drive calculation put it. That is why the family name and the size on the plate decide the element, and why a request starts there rather than from the engine.
RATO S · RATO S+
Highly flexible couplings on ship propulsion engines. Torque passes through elastic elements that wear in service, and the coupling is built of several segments, so an element change can be handled one segment at a time. RATO S+ is a further member of the same family; read the plus sign from the plate, as the element sets are not assumed to match.
RATO R · RATO R+
The RATO line for high-speed main and power take-off drives, with a diesel engine or an electric motor on the driving side. Element sets and bolting are read against the coupling type and size; the plate tells R from R+, and the drawing shows how the coupling is arranged between the machines.
VULASTIK L
A VULKAN coupling met behind marine engines, built for bell-housing and freestanding installation. Its elements are made in natural rubber and in silicone, so two elements of the same size need not be the same part: the compound and any marking on the element or the drawing go on the request line.
VULKARDAN E · F · G
Highly flexible couplings whose plates read VULKARDAN with a letter. VULKARDAN G was developed for generators and Z-drives, and its elastomer can be changed without moving the connected machines. Rubber elements and the bolting that holds them are the usual lines; the letter on the plate selects the element design.
Natural rubber · silicone
VULKAN elements are made in natural rubber and in silicone, and one is never swapped for the other on a request. The compound and any hardness marking on the old element are part of the part reference, not a detail to settle after the quote.
VULKAN, not Vulcan
Coupling plates and manuals read VULKAN, spelt with a K. A requisition line that reads Vulcan and asks for an element or a coupling is checked back to the plate before anything is quoted, because the Vulcan name on this site belongs to a mechanical seal maker.
What brings a VULKAN coupling element onto the requisition
Rubber ages even under good running conditions, and its stiffness and damping drift with age, heat and load. VULKAN publishes its own inspection and replacement criteria for the elements; this page does not repeat its limit values, but these are the findings that usually start a request.
Cracks in the rubber
Surface cracks on the element, or a crack where the rubber is bonded to the metal, are judged against the service documents for that coupling. Photograph the cracks with a scale next to them and note on which segments they appear.
Permanent set
An element that has taken a permanent set no longer returns to its original shape. Where the coupling's service documents give a limit for it, send the reading taken as they describe, together with the coupling size, rather than a general description.
Heat, oil and age
Heat from the engine room, oil mist on the element and years in service harden the rubber and change how the coupling damps the drive. If elements age much earlier than expected, note the ambient conditions near the coupling and any oil leak above it.
Misalignment and changed loads
Poor alignment between the connected machines, or loads the drive was not calculated for, shorten element life. Where the engine is resiliently mounted, an alignment record taken before the element change helps the yard and the crew judge whether new elements alone will solve it.
VULKAN coupling items that appear on RFQ lines
Grouped by assembly. Each line should name the coupling family, the size and the position of the coupling in the drive, since one ship may carry several VULKAN couplings of different families.
- Rubber elements and element sets for RATO S and RATO S+ couplings, by coupling size
- Element segments for segmented RATO couplings, with the number fitted and the number to be renewed
- RATO R and RATO R+ elements against the coupling type and size
- VULASTIK L elements in the compound marked on the element or given on the drawing
- VULKARDAN elastomer parts for the letter on the plate
- Bolting sets and connecting parts from the coupling parts list
- Hub and flange parts, against the drawing number
Reading a VULKAN coupling plate and element
A coupling element is quoted from what is written on the coupling, on the element and in the drawing. These items make the request quotable without anyone guessing an element:
- Coupling type exactly as on the nameplate or the coupling drawing, for example RATO S+, RATO R, VULASTIK L or VULKARDAN G
- Coupling size as stamped on the plate or shown on the drawing
- Element part number from the element itself or from the coupling parts list
- Shore hardness marking on the element, if present, read exactly as it is moulded; the elastomer code reader explains the marking
- Rubber compound if stated, natural rubber or silicone
- Serial, order or drawing number of the coupling
- Position in the drive: main propulsion, generator set or power take-off, with the engine and the gearbox or generator it connects
- Number of elements or segments in the coupling and how many are to be renewed
- Photographs of the nameplate, the element markings and the damaged element
How a VULKAN element request is worked
Each line is reviewed as a genuine part or a checked alternative, and the route is confirmed before the quote. For a rubber element that review starts from the coupling type and size, because the element is part of the drive's torsional vibration calculation and not a loose rubber part.
The element follows the coupling
Elements are quoted against the coupling family, the size and the element part number. No element from another coupling maker is put forward in place of a VULKAN element, and no element is chosen from a photograph or a measured outline alone.
Stiffness belongs to the drive
The stiffness and damping of the elements were chosen when the drive's torsional vibration was calculated and accepted. A different rubber grade changes that behaviour, so the grade and hardness marking on the old element are carried through to the quote unchanged.
Standard items on a checked path
Bolts, nuts and washers in the coupling parts list can be catalogue items. Where the owner accepts it, these go on a checked alternative path once grade, size and length are confirmed from the parts list; the elements stay on the coupling's own part numbers.
One coupling, one list
Element segments, bolting and any hub or flange parts for one coupling are read as one list, so the coupling is not reassembled one segment or one bolt short. Several couplings on the same ship are kept as separate groups on the same request.
VULKAN coupling parts — questions from chief engineers
Is VULKAN the same company as the Vulcan seals?
No. VULKAN, with a K, makes flexible shaft couplings in Herne, Germany. Vulcan, with a C, is a mechanical seal maker read on the Vulcan seal page. If a requisition line says Vulcan but asks for a coupling element, the coupling plate decides which page applies.
Can a rubber element be quoted from a photograph?
A photograph of the element helps, but it does not fix the part. Send the coupling type and size from the nameplate or the drawing, the element part number and the hardness marking if the element carries one. Without the type and size the element set is not fixed.
Will you offer an element from another coupling maker instead?
No. The elements are part of the drive's torsional vibration calculation, and an element of another design or stiffness changes it. The request is worked against the VULKAN element for that coupling; only standard items such as bolting can go on a checked alternative path.
Does the hardness marking on the element matter?
Yes. VULKAN elements are made in natural rubber and in silicone, and the coupling size alone does not show the compound or the hardness. Read the marking exactly as it is moulded and put it on the request line next to the element part number.
The coupling sits in front of a Reintjes or ZF gearbox. Where do the gearbox parts go?
On the same request, as a separate group. Gearbox lines are read against the gearbox plate on the Reintjes page or the ZF page; the coupling elements stay with the coupling type and size from the VULKAN plate.
Is Vessel Core connected to VULKAN?
No, and there is no agreement of any kind. Vessel Core holds no distribution, representation or partnership agreement with VULKAN, and quoting a component against one of its designations implies no approval by the maker and no claim of interchangeability.
Start with the coupling plate.
Send the coupling type and size as they read on the nameplate or the drawing, the element part number, the hardness marking if the element carries one, the position of the coupling in the drive and how many elements are to be renewed. Each line is tied to the coupling it belongs to before a part reference is fixed against it.
