Open Cast Mining Tractors were massive nuclear-powered mining vehicles used on Sisuphos, among other places. They were at least a hundred feet tall and hundreds of feet long; to get to the command center, an elevator had to be taken form ground level. Camp 3 had a blue-painted OCM Tractor, while Camp 4 had an orange one. Both were destroyed in a duel on Sisuphos, killing the Gruber brothers.