No abstract

The present paper compares the efficiency and dynamic behavior of a log crane while using two alternative transmissions. Firstly, the conventional mobile hydraulic valves with a load-sensing pump is used, and secondly, a novel electric-hydraulic energy converter and a direct driven hydraulic actuator is used. By applying lumped parameter models and the theory of centralized pressure, the hydraulic system models are constructed in MATLAB & Simulink environment. MathWorks Simscape Multibody is used in modeling of the multi-body system of the crane. The results of the simulation models are compared with those measured in the laboratory. Based on the verification results, such modes of operation in which the agreement between simulated results is the closest are selected for further investigation. The effectiveness of the system equipped with an electro-hydraulic converter is compared with that of the conventional system with a load sensing pump. Detailed models for components are given in the paper, and the results are discussed based on what obtained through simulation and experiments. The electric-hydraulic converter used in direct driven circuit is a novel prototype developed at LUT University. It has good power stiffness, and it provides good torque properties in a wide RPM area. The prototype is used in operating the lift or tilt cylinder, which is altered by using fast switching valves. The actual test circuit does not have electric storage. The ability of the converter to recover potential energy from the lifting system inertia is approximated in the efficiency comparisons.

No abstract