As illustrated in Fig. 1, the conventional spider has a straight edge, which is in 100% contact between the driver jaw and the driven jaw, even at no load condition. Obviously, when torque is applied the resultant force extrudes the elastomeric material of the spider only in the outward direction as illustrated in fig. 2 &3. Depending upon the torque fluctuations and the misalignment forces, there is a continuous abraised movement of the spider arm against the entire surface of the jaws, which causes substantial heat build-up due to friction and results into fracture of the molecular links in the spider, which causes its failure.

As illustrated in fig.4 the new NENFLEX spider has a special profile, which allows only a partial contact of the spider arm with the driver and the driven jaws of the coupling at no load. When torque is applied, the entire surface of the spider arm comes into contact with the driver and the driven jaws as illustrated in fig. 5 &6. There is less abrasion and heat build up because of the easier deformation of the spider arm by virtue of the space available as marked by the small arrows. This enhances the service life of the spider and also allows a larger load carrying capacity.