Log Unloading at Logging Enterprise Berths

In the development of market economy in Russia, the main trend in the log processing industry is the implementation of the cutting edge technology and effective innovation in order to boost the labor productivity and reduce the production cost on the basis of environmentally friendly and rational use of timber resources. Taking into account the important role of water log transport used for timber rafting, the problem of efficiency of loading and unloading of flat rafts at log unloading berths is quite urgent. The current research considers the ways of increasing unloading efficiency of multi-row flat rafts at logging enterprise berths. The aim of this research is to present the results of the experiments of unloading multi-row flat rafts at logging enterprise berth. In these experiments, a load lifting crane equipped with special load grippers was used for unloading multi-row flat rafts at log unloading berth. During the experiments, the duration of unloading sequence from water to the unloading berth was defined and applied to multi-row flat rafts calculated by Northern (Arctic) Federal University named after M.V. Lomonosov and Volga State University of Technology based on the results of the laboratory experiments and statistical processing of the obtained data. We also carried out a strength test of the crane load gripper used for transposition of lengthy flat rafts in timber onshore yards and log unloading berths. The research was carried out on lifting force fluctuation amplitude and oscillation period of the load gripper during the process of flat raft unloading from water on log unloading berth. The fluctuation amplitude of the lifting force of the load-gripper from the ground is higher by 11–33% than from the water, facilitated by the water damping capacity. Based on the laboratory research, the durability of load grippers, patented in the Russian Federation under No. 2476366 and No. 2526767, was experimentally tested. The hypothesis of theoretical calculations of the special load gripper based on the equitability of gross load distribution on the gripper applicable to general purpose lifting apparatus for four choker grapples was experimentally confirmed. The certainty assumption amounted to 97.6%.