Diaphragm vs. Jaw Couplings for Packaging Servo Drives

A selection guide for equipment OEMs and maintenance buyers. Compare stiffness, damping and shaft fit, then prepare the data needed for a coupling quote.

Which coupling should I compare first?

For a positioning axis, shortlist a precision steel diaphragm design when torsional stiffness and repeatable motion are priorities. Consider a precision elastomer jaw design when vibration damping is also needed. Check the exact configuration’s stiffness, backlash, torque, speed and allowable displacement against the drive requirements before selecting it.

What changes between the two designs?

A diaphragm coupling transmits torque through metal discs or laminas that flex to accommodate shaft displacement. The disc arrangement and hub geometry affect permitted axial, angular and radial movement. A jaw coupling transmits torque through an elastomer element between the hubs. The insert and hub configuration affect torsional stiffness, damping and fit.

KTR describes its steel-lamina RADEX-NC servo design as torsionally stiff and its preloaded ROTEX GS elastomer design as backlash-free with vibration damping. These are examples of different designs. Use the selected manufacturer’s drawing and ratings for the exact series and size.

What belongs in a quotation request?

Include the equipment and axis function, rated and peak torque, speed, start-stop or reversal duty, shaft diameters and tolerances, engagement lengths, hub attachment and installation envelope. Add expected misalignment, operating temperature and any exposure conditions.

For a replacement, send the existing part number, nameplate photos, and the drawing or revision if available. Add quantity and destination.

Can a jaw coupling be used on a precision servo axis?

A precision, preloaded jaw design can be suitable. Verify the specific size’s backlash, torsional stiffness, insert, torque and speed ratings against the axis requirements.

Can I match a replacement coupling by shaft diameter alone?

Also check bore tolerances, hub attachment, shaft gap, envelope, torque, speed and permitted shaft displacement. Send the existing part number and a drawing or photos for a fit review.

Compare Haozong diaphragm couplings

See PMC precision jaw couplings

This article is provided for general information only and does not constitute commercial, legal or tax advice. Import regulations change frequently — always confirm the current rules of your destination market before purchasing.