Energy dissipation of the hydraulic circuit of remote auxiliary utilities of an agricultural tractor

The aim of this work is to analyze the energy dissipation related to the hydraulic circuit which controls the remote auxiliary utilities of an agricultural tractor. This circuit is a typical hydraulic load sensing multi actuators system. This kind of system provides a good control strategy but it is characterized by quite high energy dissipation, especially when several actuators are working together under different variable loads. In this paper, the traditional load sensing system is modelled using a lumped parameter approach, and theenergy dissipations are evaluated with reference to an actual duty measured on an agricultural tractor. Then, an alternative and more energy saving circuit architecture is introduced, based on an independent metering concept: in this architecture the single spool auxiliary valve is substituted with two electronically controlled proportional valves. The system has been also equipped with an electronically controlled variable pump; twostrategies to control both the pump and the proportional valves are introduced. The energetic analysis is performed also for the alternative architecture using the same duty cycle, with the aim to identify the advantages, disadvantages and the critical features of this system with respect to the original one. Significant energy saving percentage characterizes the independent metering architecture, which seems to be a promising alternative to the standard hydraulic load sensing system.