Polyurethane elastomer element for a torsionally flexible jaw coupling. It sits between the two hubs, transmits torque through its cams in compression, and accommodates shaft misalignment while damping torsional shock.
Prices on request. Contact us for availability and quotations.
A jaw coupling is made of two hubs whose cams interleave, with an elastomer spider between them. Torque passes from one hub through the spider cams to the other, so the elastomer teeth are loaded in compression only rather than in bending. That is what gives the design its load capacity and its tolerance of parallel, angular and axial misalignment.
Polyurethane is the usual spider material where torque density matters, because it carries a higher load than nitrile at the same size and resists abrasion well. KTR, which originated the ROTEX jaw coupling, publishes three polyurethane hardness grades for its spiders: 92 Shore A, 98 Shore A and 64 Shore D. Harder elements give higher torsional stiffness and less damping; softer elements damp more and are more forgiving of misalignment.
Colour is not a reliable indication of hardness on unbranded product. KTR marks its own T-PUR elastomer orange for 92 Shore A, purple for 98 Shore A and light green for 64 Shore D, but that is KTR's convention and generic makers use their own. The spiders in the product photograph are yellow, red and green, which is not KTR's scheme. Confirm the hardness against the part or the supplier rather than by colour.
The name carried in the older catalogue, 'Spider Jaw Coupling Washer', is misleading: the part is a coupling element, not a washer. When ordering, state the coupling size, the number of cams on the spider, the hardness, and whether the open star or the closed outer-ring form is required, since these must match the hubs already fitted.
| Material | Polyurethane (AU/EU) |
|---|---|
| Hardness Grades | 92 Shore A, 98 Shore A and 64 Shore D - the three polyurethane spider grades KTR publishes for ROTEX jaw couplings |
| Loading | Elastomer cams are stressed in compression only, not in bending |
| Effect of Hardness | Higher hardness raises torsional stiffness and lowers damping; lower hardness damps more and tolerates more misalignment |
| Colour Identification | KTR T-PUR: orange 92 Sh A, purple 98 Sh A, light green 64 Sh D. That is KTR's own convention; colour conventions differ between makers, so colour is not a reliable hardness code on unbranded product. |
| Polyurethane Service Limits | Approximately -40 to +82 °C as a polymer property; water service only to +50 °C. A specific spider compound may be narrower. |
