United Tractors Mining Services. Mining service company, United Tractors Tbk (UNTR) seeks to maintain the performance of its mining services business. Amid the downward trend in global coal prices. Just for the record, UNTR runs a mining service business through its subsidiary Pamapersada Nusantara. As of May 2020, Pamapersada overburden removal volumes fell 11.08% YoY to 349.9 million bcm.