Experimental investigation of direct drive hydraulic units implemented in a mining loader

The average mining loader is a diesel-hydraulic off- road mobile machine that is expected to routinely operate in enclosed areas. While traditional valve-controlled setups are common, there are other possible hydraulic systems that might grant benefits to such machines in addition to conventional hybridization. One avenue of improvement lies in electrification, which in itself is advantageous to underground mining machinery that would otherwise require extensive ventilation of their ICE exhaust. Electric power allows the application of direct pump control instead of conventional valve control, eliminating throttling losses. This is one possible method to achieve higher efficiencies when compared to conventional systems. This paper investigates the efficiency of a direct-driven hydraulic system for a mining loader, and compares it to a conventional load-sensing system that was previously installed in the same machine. The efficiency of the direct-driven system was determined to be superior in all tested cases, increasing from 21% to 53% at high velocity and from 2% to 22% at low velocity. In addition, the DDH system is capable of energy regeneration, recouping a portion of energy used for lifting thus allowing longer runtimes with a given battery capacity.