Metal Bellows Couplings
A metal bellows coupling transmits torque through a thin-walled stainless steel bellows formed into a series of convolutions. The bellows is the only flexible element: it compensates axial, angular and lateral shaft misalignment by bending its own walls, with no sliding parts, no wear ring and no elastomer to compress. The result is a coupling that is torsionally rigid, absolutely backlash-free and unaffected by temperature or ageing.
That combination is why bellows couplings are the default choice on servo axes. A servo loop cannot tolerate lost motion – if the coupling has backlash, the encoder sees the motor move while the load has not, and the loop either overshoots or hunts. A welded bellows has no such gap: the torque path is metal to metal from hub to hub.
The JK series comes in twelve executions, differing mainly in how the coupling attaches to the shaft: flange connection, radial clamping hub, conical clamping ring, tapered shaft, expanding mandrel or standard robot flange. Nominal torque ranges from 2 Nm in the economy JKL to 10,000 Nm in the largest JK2 and JK3 sizes. Every execution can be supplied with customer-specific bores, keyways and hub geometry.
Why MISHKIN bellows couplings
Backlash-free by construction. Torque passes through metal only. There is no friction ring, no spider and no spline to develop play, so positioning accuracy does not drift over the life of the machine.
Stiff enough to close a servo loop. Torsional stiffness from 14 × 10³ Nm/rad up to 10,950 × 10³ Nm/rad depending on size and length, with the low inertia that a high-dynamic axis needs.
Short axial envelope. A bellows needs far less axial space than a disc or gear coupling for the same misalignment capacity, which matters when the motor is close-coupled to the gearbox.
Made to the drawing, not just a catalogue size. Bores, keyways (DIN 6885), hub diameters, flange bolt patterns and ISO 9409-1 interfaces are machined to the customer drawing. Material certificates and dimensional reports on request.
By shaft connection
JK1 – with flange connection15 – 10,000 Nmpage in batch 2
- Direct flange connection to customer-specific drive elements
- Customized flange geometries and bolt patterns on request
JK2 – with clamping hub15 – 10,000 Nmfull page →
- Radial clamping screw, quick and secure installation
- Several standard overall lengths per size
- Low moment of inertia for high-dynamic servo drives
JK3 – with conical clamping system15 – 10,000 Nmfull page →
- High frictional surface pressure for heavy-duty torque transmission
- Integrated jacking threads for effortless dismounting
- Maximum reliability under reversing loads
JK4 – for 1:10 tapered shafts15 – 150 Nmpage in batch 2
- Standard 1:10 tapered bore with keyway to DIN 6885
- Custom taper ratios and bore configurations on request
JK7 – with expanding mandrel shaft15 – 300 Nmpage in batch 2
- Designed for direct plug-in mounting into hollow shafts
- Space-saving, cost-effective axial installation
- Solves mismatched shaft and bore diameters
JK8 – with EN ISO 9409-1 flange50 – 2,600 Nmpage in batch 2
- Mechanical interface to EN ISO 9409-1 for flange-output gearboxes
- Allows continuous hollow-shaft passage on right-angle gearheads
- Ultra-compact axial design
High-speed and special executions
JP3 – high-speed, conical clamping ring15 – 10,000 Nmpage in batch 2
- Rotationally symmetrical design for superior intrinsic balance
- Exceptional concentricity and true-running accuracy
- For high-speed spindles and test benches
JKH – split clamping hub15 – 4,000 Nmpage in batch 2
- Radial assembly and disassembly without moving adjacent shafts
- Fits onto pre-aligned drive trains
- Low inertia, high torsional rigidity
JKS – all-stainless welded15 – 500 Nmpage in batch 2
- 100% stainless construction, plasma-welded bellows
- Operating temperatures up to +300 °C
- For vacuum and corrosive environments
Compact and economy
JKL – economy, clamping hub2 – 500 Nmpage in batch 2
- Single radial clamping screw for fast installation
- Optional Easy-Clamp bore-opening system
- Lightweight, low moment of inertia
JKC – short, compact15 – 500 Nmpage in batch 2
- Reduced overall length for space-restricted installations
- Low inertia for rapid servo positioning
- Optional Easy-Clamp bore-opening system
JKM – torsionally rigid20 – 1,000 Nmpage in batch 2
- Very high torque density and maximum torsional stiffness
- Ultra-compact axial envelope
- Lowest inertia of all clamping hub designs
• Short-term peak overloads of up to 1.5 × nominal torque (TKN) are permissible on the clamping and flange executions.
• Where a size is offered in several standard overall lengths, torsional stiffness, misalignment capacity, spring rates and inertia change accordingly – the values are listed in the same order in the data tables.
• Speed limits depend on size, overall length and balance quality. Send us the required speed and we will confirm the execution.
Need a bellows coupling for a specific shaft?
Send the drawing with bore, keyway, torque and speed, and we will select the execution and quote it.