Spider Rubber Coupling

A jaw coupling is a power transmission coupling that can also be used in motion control applications, for example, a motor. It connects two shafts while minimizing vibrations and compensating for any parallel, angular, and axial misalignment.

Jaw couplings are made up of three parts: two metal hubs sandwiched around an elastomer insert commonly called a “spider.” The three parts press-fit together, and a metal jaw from each hub meshes with the lobes of the spider. Torque is transmitted through the elastomer spider in compression.


Material for the spider is chosen to accommodate a variety of factors: its ability to control vibration, handle misalignment, and function within a certain temperature range. The speed of machinery and chemical conditions are also important considerations. There are four materials from which to choose, rubber is the most popular:Nitrile butadiene rubber (NBR), Urethane, Hytrel, Bronze.

Rubber spiders come in a variety of designs

Along with the type of materials, there are also four basic designs for the coupling spiders:

Solid-center spider
By far the most commonly used design especially when the distance between the ends of the driving and driven shafts is large enough to accommodate the spider thickness.

Open-center type (OCT) spider
These spiders work best when the shaft ends must be positioned closer together. Since by such a thin segment of material joins the spider’s legs, they have limited support and speeds are limited to 1,750 rpm for NBR spiders.

Snap-wrap spider
With this style the spider legs are connected around the perimeter of the coupling, making it possible to install them without disturbing the hub alignment. One downside: They cost twice as much as the first two.

Load cushions
Load cushions are held in place by a collar and are easy to remove and install. They are only available for specific collar models.