Pysartsov O. Crane Ropes Durability Increase by means of Substantiation of Rational Parameters of Rope Sheaves

The calculations provided in the thesis evidence that when determining the diameter of the sheaves according to the regulations of the State Committee on Labour Safety of Ukraine the durability of the rope is reduced by approximately 3 times compared with the calculation based on the service life. In this case, the diameter of the sheave increases by only 30%. To ensure the absence of wear of the rope and the sheave, at the point of the rope coming off the sheave, a mathematical relationship has been obtained for the maximum allowable deflection angle of a rope coming off the sheave. The maximum allowable rotation angle of the rope at the point of its detachment from the surface of the sheave has been determined based on the contact of the rope with the sheave rim and prevention of the rope fracture along the edge of the groove rim. The application of the proposed machine with a linkage mechanism for fatigue tests will make it possible to expand empirical data on the rope wear at various angles, which in turn will increase the durability of the use of ropes in hoisting machines. The following parameters were measured during the experimental research: the rope force, deflection angle of a rope, the number of rope load cycles until breakage. The durability of the rope was determined in accordance with the change of the angle of the rope coming off the sheave. For this purpose, the 3º, 5º, 7º angles were applied. In addition, the effect of the diameter of the sheave and the diameter of the rope on the durability of the rope was also considered. All data received were processed using the theory of statistics and enabled to assess the impact of these factors on the durability of the rope. On the basis of the conducted research, the method of calculating the rope in terms of the service life which was developed by Kovalskyi B.S. was improved.