Power and signal transmission between encoders, motors and lead screws all rely on couplings. The two most common types are membrane (disc) and jaw couplings, and many buyers are torn between them. This article explains the difference once and for all.
1. Structural Difference
- Membrane (disc) couplings: transmit torque through metal membranes — backlash-free, high stiffness and high precision, compensating a certain amount of parallel, angular and axial misalignment.
- Jaw couplings: a star-shaped elastomer (polyurethane, etc.) in the middle transmits torque through elastic deformation, providing some damping/vibration absorption and allowing larger angular and radial misalignment.
2. Key Comparison
| Dimension | Membrane | Jaw |
|---|---|---|
| Transmission accuracy | High (zero backlash) | Medium (slight elastomer backlash) |
| Misalignment compensation | Medium | Large (elastic absorption) |
| Damping / vibration | Fair | Good |
| Stiffness | High | Medium |
| Cost | Higher | Economical |
| Typical use | Encoders, servo motors, high-precision drives | General motors, pumps, general machinery |
3. How to Choose?
- Encoder mounting: encoders are sensitive to coaxiality — choose membrane, zero backlash and stable signal transmission, avoiding reading jitter from shaft misalignment;
- Servo motor to lead screw: rigid transmission and precise positioning → membrane is better;
- Large misalignment, strong vibration, general drives: the jaw elastomer absorbs vibration and tolerates error — great value;
- Watch bore size and keyway: choose the bore to match both shaft diameters, and confirm the keyway/clamping matches the shaft ends.
4. KOSEND Couplings
KOSEND supplies membrane and jaw couplings in a full range with stock available, can be ordered together with encoders and electronic handwheels, and supports bore customization. For selection help, call 400-100-6802 or submit your requirements at www.kosend.com.