Energy Efficient Hydraulic Rotary Drive: Analysis and Comparison of Two Different Displacement Controlled Solutions

This paper discusses, analyzes, and compares two different displacement controlled solutions for a rotary drive of a mobile machine. In particular, the first solution is a hydrostatic transmission based on a closed circuit structure while the second solution employs secondary controlled hydraulic drives. In detail, these alternatives are evaluated in the context of a machine with a huge mass that performs repetitive working cycles with frequent stops and goes that require a precise positioning. Consequently, the ability to recover energy via regenerative breaking becomes a key aspect in order to improve the global efficiency of the machine. Therefore, the paper will present a dynamic system model that was used to compare the two alternatives.