Coupling Elements & Parts

Coupling Elements & Parts

Flexible shaft couplings transmit torque between two shafts while accommodating minor misalignment and damping vibration and shock loads. Over time, the flexible elements within these couplings — jaw spiders, disc packs, rubber inserts, and similar components — wear and must be replaced to maintain coupling performance. AIMS Industrial supplies replacement coupling elements and parts for jaw couplings and flexible couplings used in industrial drive systems.

Jaw Coupling Spiders

Jaw couplings use two identical hubs with interlocking jaws, with a flexible spider element between them that transmits torque and absorbs shock. The spider is the wear component — it compresses with each torque pulse and gradually loses its elastomeric properties. Spider materials are selected for the torque level, misalignment tolerance, and damping requirement:

• Standard polyurethane (98 Shore A): The most common spider material. Good torque capacity, moderate shock absorption, suitable for most general industrial drives.
• Hytrel (polyester elastomer): Higher torque capacity and temperature range than polyurethane. Used in demanding drives where the standard spider would be undersized or degrade prematurely.
• Rubber (80 Shore A): Greater compliance and shock absorption than polyurethane. Suited to drives with significant vibration or high-shock loading where damping is the priority over torque capacity.
• Bronze: Non-elastomeric, for applications where the coupling must survive in environments that degrade elastomers, or where high temperature precludes rubber or polyurethane elements.

Spider Replacement Intervals

Jaw coupling spiders should be inspected at every planned maintenance shutdown. Signs that replacement is due include visible compression set (the spider legs are permanently compressed and have lost their original cross-section), cracking or splitting, and increased backlash or noise in the drive. Waiting for a spider to fail completely risks damage to the coupling hubs and connected equipment. Spider replacement is a low-cost, short-duration task that prevents more expensive drive failures.

Identifying the Correct Spider

Coupling spiders are sized by coupling designation (e.g., L090, L100, L110 for Lovejoy jaw couplings) — a number that defines the hub and spider dimensions. The coupling size is usually stamped on the hub.

Stock of Critical Spares

Given the low cost of coupling spiders relative to the downtime caused by a coupling failure, holding one or two spare spiders for critical drives is straightforward insurance. A spider that is inspected and found approaching end-of-life can be scheduled for replacement at the next planned shutdown rather than as an emergency. For plants with multiple identical drive systems, holding a small quantity of the standard spider size avoids any procurement delay in an unplanned outage. If you need help identifying the correct spider for your coupling, contact our team with the coupling dimensions or hub marking and we'll identify the right replacement.