Mobile machines, particularly excavators, consume significant fuel during their operational lifetimes, leading to economic and environmental concerns. Hydraulic systems are often cited as major contributors to fuel losses, prompting extensive research into more efficient hydraulic architectures aimed at reducing throttling losses from hydraulic valves. While these new systems improve hydraulic efficiency, they are also more costly, raising doubts about their effectiveness in reducing fuel consumption alongside diesel engines. This work adopts a broader design perspective, revealing that focusing solely on hydraulic efficiency can be misleading. Surprisingly, a less efficient hydraulic circuit may actually reduce overall consumption. By emphasizing absolute losses and fuel consumption, the design process can uncover simpler methods to enhance current machines. Analyzing real test data from a machine indicates that a hybrid architecture, featuring an additional energy storage device, could be a promising alternative. Rather than pursuing an electric hybrid model, this research introduces a hydraulic hybrid system known as STEAM. The thesis explores the advantages of this new system through theoretical analysis and measurements conducted on an 18-ton prototype excavator.
