Ruland is offering shock-absorbing jaw couplings for high acceleration/deceleration applications. These applications create shock loads to system components. If not absorbed, the shock can result in excessive vibration and increased settling time, with a resulting loss in machine efficiency. In some more extreme cases, undampened shock can lead to premature component failure and machine downtime. Ruland has expanded its line of zero-backlash jaw couplings to include more compliant spider elements for applications where greater shock absorption is desired.
Zero-backlash jaw couplings are three-piece couplings comprised of two hubs with curved jaws and an elastic element. The spider, made of an advanced polyurethane material, provides dampening of impulse type loads, minimising shock to the motor and other sensitive equipment. With this addition, spider elements of three different hardness levels are offered - each represented by a different colour. The new blue spiders have a durometer of 85 shore, yellow spiders are 92 shore, and red spiders 98 shore. The availability of spiders with three hardness levels allows the end user to customise the jaw couplings performance given applications parameters, including torsional stiffness and the amount of shock absorption required. Selecting the new soft spider element will give the jaw coupling the greatest dampening characteristic, while a harder spider element will provide the greatest in torsional rigidity.
All spiders are press fit onto a curved jaw profile; generous chamfers on the spiders and jawed hubs make this assembly easy. Because of this press fit, Ruland jaw couplings operate with zero backlash. This would not be possible without the special design of the curved jaw profile. In standard jaw couplings, the jaws have a straight profile, and a pressed fit would result in distortion of the elastic element as forces push the spider's "limb" out. With a curved jaw profile, forces on the spider's "limb" are concentrated to the centre, improving the effectiveness of the elastomer material. Standoffs, located on the spider "limbs", assist in angular misalignment capabilities, as well as electrical isolation.