Ruland’s new shock-absorbing jaw couplings protect power trains from the shock loads caused by rapid acceleration and deceleration. Shock loads can result in excessive vibration and increased settling time, reducing machine efficiency; in extreme cases, they can lead to premature component failure. These zero-backlash jaw couplings now include more compliant spider elements for applications where a greater degree of shock absorption is desired.
The three-piece components comprise two hubs with curved jaws and an elastic element. The shock-absorbing polyurethane spider elements come in three different hardness levels, each represented by a different colour: blue for a durometer of 85 shore, yellow for 92 shore, and red for 98 shore. These elements ensure that couplings are easily customised to meet special requirements for torsional stiffness and shock absorption - ‘soft’ for highest shock absorption and ‘hard’ for highest torsional rigidity.
All spiders are press fit on the curved jaw profile, with generous chamfers on both the spiders and jawed hubs facilitating easy assembly. It is the press fit that provides the zero backlash performance. In standard jaw couplings, the jaws have a straight profile, and a press fit would distort the elastic element as the forces extrude the spider’s limbs. With a curved jaw profile, the forces on the spider are concentrated at the centre, improving the effectiveness of the elastomer material. Standoffs, located on the spider limbs, improve tolerance of angular misalignment, as well as introducing electrical isolation.
The coupling’s three-piece design eases blind assembly and allows for an easy mixing of inch and metric bore sizes. Jaw couplings are considered fail safe, so should the spider element ever fail, the jaws on the hubs provide a direct power transmission, allowing the application to shut down safely, after which the spider can easily be replaced.