Malfunctions happen. And when they do, damage and repair costs follow. Safety couplings are the mechanical connecting elements designed to protect other machine components surrounding a drive system. When a malfunction occurs, safety couplings help keep the damage to a minimum.
Safety couplings include torque limiters to handle mechanical overload. In disconnect types, torque limiters decouple when a drive system reaches overload. In torque limiting types, the limiter allows the coupling to slip. This slippage allows the driving shaft to rotate faster than the driven shaft. The excess energy is dissipated as heat.
For many applications, vibration reduction is as important to the drive system as torque limiting capabilities. Dynamic equipment that is often subjected to impacts, reversals, or vibration are usually equipped with vibration-damping safety couplings.
Elastomer inserts of thermoplastic polyurethane (TPU) are the vibration damping element in this type of coupling. The insert lies between the two coupling hubs. The spring-like properties of the insert not only reduce vibration but also help compensate for axial misalignment and act as electrical insulation. For applications with minor oscillations and slight impact stresses, inserts with high torsional stiffness and low damping properties are appropriate. High damping capability and low torsional stiffness inserts are used for applications with strong impact stresses and strong vibrations. The degree of hardness for the elastomer insert is rated by the Shore hardness for all elastic materials.
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