RDC Heavy-Duty Steel Disc Coupling – up to 9,000 Nm
The RDC is the heavy end of the MISHKIN disc coupling range: one laminated stainless steel disc pack bolted between two machined steel hubs, rated from 15 to 9,000 Nm. Hubs are C45E or 42CrMo4 to EN ISO 683; the disc pack is EN 1.4310 (AISI 301) spring steel; the joint is made with ISO 4017 / ISO 4762 class 10.9 bolts. There is no elastomer, no bush and no lubricant anywhere in the coupling.
That is the point of an all-steel disc coupling on industrial drives. A pump, a fan or a compressor runs hot, runs continuously and is expected to run for years without attention. An elastomer coupling in that position hardens, creeps and eventually fails, and nobody notices until the vibration starts. A steel disc pack has nothing to age: it works from -30 °C to +270 °C and its torque capacity does not drift with time.
The single-disc type A is deliberately short axially – short enough to sit between a motor and a pump without a spacer – while still compensating angular misalignment up to 1.3° and axial displacement up to ±1.6 mm with high radial support stiffness. Bores are ISO 286-2 H7 with keyways to DIN 6885-1 JS9; sizes run from 20 to 115.
Product features
- Single laminated disc pack in EN 1.4310 stainless, bolted between steel hubs
- Hubs in C45E / 42CrMo4 to EN ISO 683, keyway to DIN 6885-1 JS9
- Rated 15 to 9,000 Nm across sizes 20 to 115
- Bolts ISO 4017 / ISO 4762, class 10.9
- Angular misalignment up to 1.3°, axial up to ±1.6 mm
- High radial support stiffness – the disc pack does not sag under shaft load
- Maintenance-free, no lubrication, no wear parts
- Operating range -30 °C to +270 °C (all-metal design)
- ATEX 2014/34/EU (EN ISO 80079-36) execution available, Ex h IIC T6..T4
Design & materials
Disc pack. A single pack of laminated EN 1.4310 stainless discs, clamped between the two hubs by the fastening bolts. The pack carries the torque in shear and provides angular and axial compliance.
Hubs. Forged or machined C45E / 42CrMo4 steel. Bore ISO 286-2 H7, keyway DIN 6885-1 JS9. Hub outside diameter and overall length per size as in the datasheet dimension table.
Fasteners. ISO 4017 / ISO 4762 class 10.9. Tightening torque per size; the joint relies on bolt pre-load, so bolts must be replaced if the coupling has been overloaded.
Environment. All-metal construction gives -30 °C to +270 °C operation and an ATEX-capable design for dust and solvent-laden plants.
Heavy duty disc coupling: technical data
Sizes are nominal torque in Nm. Where a size lists several values, they correspond to the standard overall lengths offered for that size, in the same order.
Scroll the table sideways to see the larger sizes →
| Parameter | RDC type A single-disc |
|---|---|
| Rated torque range TKN | 15 – 9,000 Nm |
| Design | single laminated disc pack between two steel hubs |
| Hub material | C45E / 42CrMo4 (EN ISO 683) |
| Disc pack material | EN 1.4310 (AISI 301) stainless |
| Bolts | ISO 4017 / ISO 4762, class 10.9 |
| Bore tolerance / keyway | ISO 286-2 H7 / DIN 6885-1 JS9 |
| Angular misalignment ΔKw | up to 1.3° |
| Axial misalignment ΔKa | up to ±1.6 mm |
| Sizes | 20 – 115 |
Made to your drawing
- Bores outside the standard range and non-standard keyways
- Hub geometry matched to a customer flange or brake drum
- Spacer (double-disc) executions for longer shaft spans
- Stainless hubs for corrosive duty
- Balanced assemblies for high-speed fans and compressors
- Material and dimensional certification for project work
Typical applications
Pumps
Close-coupled and long-coupled pump drives.
Fans and blowers
Continuous duty at temperature.
Compressors
High torque with reversing or pulsating load.
Mill and kiln drives
Heavy duty with high radial shaft loads.
Conveyors and crushers
Shock loads where elastomer couplings fail.
Steel and cement plant
High ambient temperature and dirty atmosphere.
Frequently asked questions
Why choose a disc coupling over an elastomer coupling?
Temperature and life. An elastomer element is limited to roughly 80-100 °C, stiffens with age and eventually fails without warning. A steel disc pack runs to +270 °C and its characteristics do not change over the service life – which is why the RDC is specified on pumps, fans and compressors.
How much misalignment can the RDC take?
Up to 1.3° angular and ±1.6 mm axial on the single-disc type A. Radial stiffness is deliberately high so the coupling supports the shaft rather than sagging under it. Permissible radial values per size are in the datasheet.
Is the RDC available for ATEX zones?
Yes. The all-metal design is available to ATEX 2014/34/EU (EN ISO 80079-36) as Ex h IIC T6..T4. Tell us the zone and the temperature class when you enquire.
What is the difference between RDC and REC?
RDC is the all-steel heavy-duty series with bolted steel hubs, 15 to 9,000 Nm. REC uses conical clamping rings for a backlash-free friction joint on large servo and gearbox shafts. Both use the same laminated stainless disc technology.
Replacing a coupling on an existing drive?
Send the shaft diameters, the centre distance and the motor rating; we will match the RDC size and confirm the bore and keyway.