EP6 Series Setscrew Oldham Coupling — aluminium alloy body, zero backlash, high torsional stiffness. Rated torque 0.7–80 N·m, max speed 9,000 rpm, radial misalignment up to 3.8 mm, angular tolerance 3°. 8 sizes (EP6-16 to EP6-70), metric and inch bores available. Stocked and shipped globally by EP.
MOQ: 50 pcs. Minimum order value USD 1,500; mixed orders and trial quantities welcome.
This page reorganizes the technical information for Setscrew Type Oldham Coupling around the decisions a buyer or engineer normally has to make: duty, shaft interface, alignment, installation envelope, inspection and model selection. All model values are retained in the reference blocks below.
An Oldham coupling normally consists of two hubs with perpendicular drive slots and a center disc that engages both hubs. As the shafts rotate, the center member slides in the mating grooves, allowing parallel offset to be accommodated while torque is transmitted between the two hubs.
The three-piece Oldham arrangement is commonly used to accommodate parallel shaft offset.
Two hubs and a center disc form a simple torque-transmission structure with easy visual inspection.
The compact architecture is useful in smaller motion and positioning systems.
The center disc can be inspected and replaced without replacing both metal hubs when the surrounding design permits.
The design is especially useful where parallel misalignment is more significant than with many other compact coupling types. The center disc is a wearing and sliding component, so operating speed, surface condition, material pair, lubrication practice where applicable and the magnitude of offset all affect service life and generated heat.
Confirm torque, speed, bore sizes, shaft fit, outside diameter, hub length and the parallel-offset requirement. The center-member material should suit the required wear resistance, damping and operating environment. Where setscrews or keys are used, verify that the shaft connection can transmit the required torque without slipping.
Use the tables below as the dimensional and model reference. Confirm bore, shaft fit, speed, torque and installation envelope before final selection.
| Model | Bore d1, d2 (mm) | OD (mm) | L (mm) | F (mm) | L1 (mm) | M (Setscrew) | Wrench Torque (N·m) |
|---|---|---|---|---|---|---|---|
| EP6-16 | 4, 5, 6 | 16 | 18 | 3.5 | 7 | M3 | 0.7 |
| EP6-20 | 6, 6.35, 8 | 20 | 23 | 4.5 | 9 | M4 | 1.7 |
| EP6-25 | 6.35, 8, 9.525, 10 | 25 | 28 | 5.5 | 11 | M5 | 4.0 |
| EP6-32 | 8, 9, 9.525, 10, 11, 12, 14 | 32 | 33 | 6.5 | 13 | M6 | 7.0 |
| EP6-40 | 12, 14, 15, 16 | 40 | 35 | 7.0 | 14 | M6 | 7.0 |
| EP6-50 | 14, 15, 16, 18, 19, 20 | 50 | 38 | 8.5 | 17 | M8 | 15 |
| EP6-63 | 16, 18, 19, 20, 24, 25 | 63 | 47 | 10.5 | 21 | M10 | 30 |
| EP6-70 | 24, 25, 28, 30, 32, 35 | 70 | 59 | 12.5 | 26 | M10 | 32 |
| Model | Rated Torque (N·m) | Max Torque (N·m) | Max Speed (rpm) | Moment of Inertia (kg·m²) | Static Torsional Stiffness (N·m/rad) | Radial Misalignment (mm) | Angular Misalignment (°) | Mass (g) |
|---|---|---|---|---|---|---|---|---|
| EP6-16 | 0.7 | 1.4 | 9,000 | 3.0 x 10⁻⁷ | 29 | 1.0 | 3.0 | 6 |
| EP6-20 | 1.6 | 3.2 | 7,400 | 9.0 x 10⁻⁷ | 58 | 1.4 | 3.0 | 14 |
| EP6-25 | 3.0 | 6 | 5,800 | 2.8 x 10⁻⁶ | 125 | 1.9 | 3.0 | 24 |
| EP6-32 | 5.5 | 11 | 4,700 | 8.9 x 10⁻⁵ | 260 | 2.4 | 3.0 | 46 |
| EP6-40 | 9.0 | 18 | 3,600 | 2.1 x 10⁻⁴ | 505 | 2.8 | 3.0 | 80 |
| EP6-50 | 19.0 | 38 | 3,000 | 6.0 x 10⁻⁵ | 780 | 3.3 | 3.0 | 144 |
| EP6-63 | 33 | 66 | 2,400 | 2.1 x 10⁻⁴ | 1,200 | 3.8 | 3.0 | 318 |
| EP6-70 | 80 | 160 | 2,300 | 1.7 x 10⁻⁴ | 1,600 | 3.8 | 3.0 | 456 |
| Parameter | EP6 Oldham (Setscrew) | Jaw Coupling | Bellows Coupling | Disc Coupling |
|---|---|---|---|---|
| Parallel Offset Compensation | Excellent (up to 3.8 mm) | Limited (0.1–0.5 mm) | Low (0.1–0.3 mm) | Very Low (<0.1 mm) |
| Angular Misalignment Tolerance | 3.0° (all sizes) | Moderate (1°–2°) | Good (1°–3°) | Low (0.5°–1°) |
| Backlash | Zero | Low–Moderate | Near Zero | Near Zero |
| Electrical Insulation | Yes (polymer disc) | Yes (spider) | No | No |
| Torsional Stiffness | High (29–1,600 N·m/rad) | Low–Moderate (spider material) | Very High | Very High |
| Max Speed | Up to 9,000 rpm | Up to 6,000 rpm | Up to 10,000+ rpm | Up to 10,000+ rpm |
| Installation | Simple — hex key setscrew | Simple — spider accessible | Moderate | More complex |
| Relative Cost | Low–Moderate | Low | High | High |
Where a standard or designation is shown below, treat it as a reference tied to the original product data and verify the applicable revision when placing an order.
Align the shafts within the model limits, set the correct hub spacing and make sure the center disc enters both hub slots freely without binding. The coupling should rotate smoothly by hand before start-up. Excessive preload on the center member is a sign that shaft position or spacing needs correction.
Measure the actual shaft diameters and keyways before machining or confirming a finished bore. A drawing should identify shaft tolerances, key dimensions, required hub position and any shoulder, locknut or axial-retention feature. Alignment readings should be taken after the machine is in its normal installed condition because base distortion, pipe strain, belt pull or thermal growth can move the shaft centers after an initial bench alignment.
After assembly, turn the drive through at least one full revolution by hand where practical. Check for interference with guards, brake hardware and adjacent structures, then verify fastener security. On equipment that changes temperature significantly between start-up and steady operation, compare cold and hot alignment expectations before setting final offsets.
Check the sliding faces and center member for wear, heat discoloration, deformation or debris. Increasing backlash or noise can indicate that the disc or grooves are worn. Replacement should restore the designed fit rather than compensating for wear by over-tightening hub fasteners.
A coupling should not be used as a permanent correction for poor machine alignment. If vibration, temperature or noise changes after commissioning, compare the current condition with the initial baseline. Check connected bearings and shafts at the same time, because many coupling symptoms originate from looseness, soft foot, imbalance or movement elsewhere in the drivetrain.
For planned maintenance, record the installed model, actual bore sizes, fastener details, lubricant or flexible-element grade where applicable, and the measured alignment at return to service. That information makes later inspection more useful and helps distinguish normal wear from a change in machine condition.
No. Motor power is only a starting point. The selection should use actual torque, service factor, peak load, speed and the driven-machine characteristics.
Confirm the shaft interface first, then the overall installation envelope. Bore, key or locking method, hub length, pilot or flange details and available removal clearance all affect whether a listed model will fit.
Use the model-specific limit as a maximum capability, not as the target installation condition. Better initial alignment usually reduces cyclic load, heat and wear in both the coupling and connected bearings.
Provide a dimensioned shaft drawing or at minimum the shaft diameter and tolerance, keyway, engagement length, shoulder or axial-retention details and required hub position.
Yes. A short follow-up inspection after the machine has run under real load can reveal fastener settlement, lubricant leakage, unexpected movement or alignment change before these develop into a larger problem.
Treat the listed values as the model reference. Select a candidate from torque and speed, then verify every geometric field that affects your installation before issuing the final order drawing.
Used in compact motion systems where parallel offset and installation space must be managed.
Applicable to controlled motion assemblies that require a simple coupling between aligned shaft ends.
Suitable for lighter rotating equipment when torque and speed remain within the chosen model rating.
Considered for compact machine modules where maintenance access and shaft positioning are important.
Oldham couplings are widely used in positioning mechanisms, machine tools, packaging equipment, instrumentation and other compact drives where controlled parallel offset must be accommodated.
The same coupling family can behave very differently in a smooth continuous drive and in a reversing, impact-loaded or frequently started drive. For that reason, application name alone is not enough for selection. Supply the operating torque, peak load, speed, shaft dimensions, expected movement, ambient conditions and required service access so the configuration can be checked against the complete duty.
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