The pair of machines, which were commissioned last month as well as in November 2018, respectively, came from Liebherr-Australia's Mt Thornley branch. Crews spent 13,000 man-hours to build the excavators using a core team of 20 technicians from both BHP and Liebherr.
The 800t R 9800s are the first of their class owned by BHP on site. They join Mt Arthur's other Liebherr machines, including two R 996Bs, one R 994B and the mine's 44 T 282C off-highway trucks.
Liebherr confirmed the excavators were delivered ahead of schedule and using safe work practices.
"During the build, the team's focus also realised several opportunities for improvement, not only demonstrating Liebherr core values, but our commitment to continuous improvement of our processes," officials added.
Mt Arthur, considered by BHP to be the largest individual coal production site in the Australian state's Hunter Valley region, produces coal for domestic and international use.