Experimental evaluation of a novel electro-hydrostatic steering solution for off-road mobile machinery

Abstract

This study introduces and evaluates a novel hybrid steering system that combines an electro-hydrostatic system with a traditional orbital steering valve for off-road mobile machinery. A test rig has been developed for this proof-of-concept study, with the primary objective of assessing the energy efficiency of the new steering solution while maintaining the passive redundancy of the orbital steering valve. This redundancy is required by safety standards to ensure that the vehicle can still be steered in the event of a failure in the primary steering system. The orbital steering valve has been customized for this purpose to minimize throttling losses under normal operating conditions. This paper presents the design, implementation, and testing of the system, along with a comprehensive analysis of its energy performance and safety features. The energy efficiency of the novel steering solution is evaluated, with a focus on minimizing hydraulic throttling losses to enhance overall system efficiency. Experimental results show a substantial improvement in energy efficiency, with overall system efficiency reaching approximately 50 %—a significant advancement over conventional hydrostatic systems, which typically achieve around 20 %. Notably, hydraulic throttling losses were reduced to approximately 8 % in two of the three main test scenarios and remained below 15 % even in the worst case studied, representing a marked improvement over the traditional hydraulic systems. Moreover, the system maintained full compliance with safety standards, demonstrating that hybrid electro-hydrostatic steering solutions can significantly enhance energy efficiency while ensuring reliable operation.