Longitudinal Coupled Vibration of Parallel Hoisting System with Tension Balance Devices

In long travel lifting systems, multiple parallel ropes are connected to conveyance through a set of termination devices to achieve the lifting process. Due to external excitations coming from different wear levels and manufacturing error of rope grooves on the friction pulley, or rope slipping, each rope length is different and accordingly results in different rope tension. Therefore, a tension balance device is applied as the termination device to reduce the tension differences. In order to describe the dynamic behavior, rope sockets of the tension balance device are simplified into a lumped mass at the end of each rope, and a longitudinal vibration model of a parallel hoisting system with tension balance device is built. Both the normal and unsteady working conditions of the tension balance device are considered. To deal with the complex constraints between ropes and hoisting conveyance, Lagrange multipliers are used, and the equations are numerically solved. The characteristics of longitudinal vibration frequency are depicted and the dynamic behaviors are revealed, which are essential for optimizing the parallel hoisting system with the tension balance device. That will minimize the effects of external excitations and improve the security of the system.