Investigation and justification of the layout and parameters of the hydraulic drive of the lifting mechanism of the forest manipulator

The paper describes ways of reducing the dynamic loads on a forest manipulator construction according to the layout of the hydraulic cylinders of the boom lifting mechanism. A mathematical model of the manipulator boom lifting process has been generated. The parameters of the boom lifting hydraulic drive have been optimized. It is established that the optimization of the hydraulic cylinders layout for lifting the forest manipulator boom by taking into account the inertia forces and the hydraulic drive flexibility will reduce working fluid pressure surge during transient modes of forest freight lifting. A new design and technological scheme of the boom lifting mechanism of the manipulator has been developed to provide automatic optimal positioning of the hydraulic boom lifting cylinder and working fluid vibration damping. It is found that with a decrease in the nominal feed the angular velocity tends to stabilize and peak pressures increase from 16 MPa to 40 MPa. It has been verified that with twofold increases of the flexibility coefficient of elastic hydraulic drive elements and of the leakage factor the pressure of the working fluid increases and decreases by 2 times respectively. The optimal value of the parameter b1, that is the point of the hydraulic cylinder attachment to the boom should be equal to 0.6 m. Dynamic loads are reduced by 41 % due to optimizing the layout of the hydraulic boom lifting cylinder and increasing the flexibility coefficient of the elastic elements of the hydraulic drive. However, the time of damped pressure fluctuations during transients is increased by 32 %. Therefore, the manipulator repair downtime due to hydraulic equipment breakdowns will be reduced to compensate for a slight increase in the time of transient modes.