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The article validates the necessity of increasing the transportation efficiency of longcut timber (LCT) by hauling tractors with timber drugs during their operation in conditions of poorly equipped logging roads with the presence of irregularities, defects, barriers, as well as frequent turns, ascents and descents. An original scheme of a recuperative swivel bunk device (RSBD) for a hauling tractor (HT) with a timber drug (TD) is designed as a result of earlier research on development and evaluation of various recuperative coupling devices for logging trucks operating in difficult road conditions. A computer program has been developed in order to identify the dependences of change in time of such parameters of the bunk device efficiency as recoverable power and horizontal acceleration of an LCT bundle, as well as to determine the regularities of influence of the studied heights of the logging road bearing area, the driving speed of a logging truck and the inner diameter of longitudinal and transverse hydraulic cylinders of the recuperative device on these parameters. It has been found out that equipping a logging truck with the proposed RSBD is reasonable when LCT transporting, especially in conditions of poorly equipped logging roads. With an increase in speed of the logging truck when it moves in difficult road conditions from 10 to 60 km/h recoverable power increases significantly from 3 to 24 kW, as well as the horizontal acceleration of the LCT bundle relative to HT changes from 0.4 to 2.3 m/s2. It is found that the optimum diameters of transverse and longitudinal hydraulic cylinders of RSBD, providing the maximum recoverable power of 6.7 kW and the average horizontal acceleration of the LCT bundle of 1 m/s2, is 50 mm. The results obtained can be useful to research and design organizations engaged in further improvement of recuperative devices of similar type used for timber road transport.

In this study, the benefits of logging transportation under modern conditions by semitrailer hauling rig are examined, which consists of a truck tractor connected to a semitrailer. Furthermore, an analysis is made of the operational implications of using log road trains in insufficiently arranged road conditions. The article describes the potential scientific directions that can optimize the efficiency of semitrailer trucks. An improved construction of a regenerative fifth-wheel coupling device is proposed. It provides better reliability, reduces fuel consumption for log trucks, and gives better working conditions for drivers, along with reduced dynamic loads between the links of the units that occur during the movement in unsteady modes. The research methodology includes the application of the mathematical framework of multifactorial optimization. The specified analytical formulas are derived to determine the performance efficiency of the regenerative fifth-wheel coupling. It is revealed the connections between the hydraulic cylinder piston stroke values of the regenerative fifth-wheel coupling device, the weight of the loaded semitrailer, the vehicle acceleration during speeding up and braking, and the modifications of the performance indicators of the latching mechanism. The optimal value of the stroke of the pistons of the hydraulic cylinder is determined, which is 200 mm. It provides a power recovery of 6.5 kW and better longitudinal acceleration of the semitrailer at 0.72 m/s2. Moreover, it is found that the change in acceleration during the increase in velocity and braking from 1 to 3 m/s2 gives the change in recuperated power from 2.2 to 6.8 m/s2. At the same time, the average longitudinal acceleration of the semitrailer varies from 0.27 to 0.75 m/s2. Changing the load of the semitrailer from 5 to 25 tons allows increasing the recuperated power from 1.6 to 7.9 kW and reducing the longitudinal acceleration of the semitrailer from 2.8 to 0.53 m/s2. The influence graphs and optimization cartograms present the diameter and hydraulic cylinder piston stroke values of the regenerative fifth-wheel coupling device on the regenerated power and longitudinal acceleration of the semitrailer. According to the optimization cartograms, the average regenerative power is determined using a graph-analytical method. It is equal to 6.5 kW with the diameter of a regenerative hydraulic cylinder of 110 mm and a hydraulic cylinder piston stroke of 200 mm. For citation: Posmetyev V.I., Nikonov V.O., Manukovskii A.Yu., Posmetyev V.V., Avdyuhin A.V. Optimization of Structural Parameters by Improvement of Pneumohydraulic FifthWheel Coupling Device at Semitrailer Hauling Rig. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 126–139. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-126-139