Machinery & Energetics

In the article the researches of calculations of dynamic loads in a haul cable of a derricking mechanism of a tower crane are stated. In order to study the dynamic loads, a dynamic model of the motion of reduced masses of the system has been developed. On the basis of the dynamic model with the help of the d'Alambert's principle, a multi-stage mathematical model of the movement derricking mechanism has been designed. It has been established that the value of the force in the haul cable force includes three components: static, dynamic which is caused by the pendulum oscillations of a payload and dynamic which is caused by the elastic vibrations of the trolley relative to the rope drum.In the course of further research it is proposed to consider dynamic loads separately from each other. This is due to the fact that the frequency of the corresponding pendulum oscillation of the payload and the trolley relative to the rope drum varies considerably. The maximum forces in the haul cable from the pendulum oscillations of the payload and the fluctuations of the trolley relative to the rope drum have been calculated. As a result of the obtained results analysis, the value of the dissipation factor of the cable-damping system has been determined. It value provides aperiodic oscillations of the trolley relative to rope drum. Determination of maximum forces in the haul cable has been carried out on example of four tower cranes: KB-674, 200 EC-H 10 Liebherr, MTD 128 Potain, 5 LC5010 5t LINDEN COMANSA. In order to establish the adequacy of the obtained analytical results they have been compared with data of numerical integration of the movement equations of the derricking mechanism of tower crane KB-674.

tower crane, derricking mechanism, payload, haul cable, partial frequencies, oscillations, dynamic loads, dissipation factor