Common cooling methods include ONAN (oil natural air natural), ONAF (oil natural air forced), OFAF (oil forced air forced), and OFWF (oil forced water forced). Dry-type units use AN (air natural) or AF (air forced). Radiators, fans, oil pumps, and heat exchangers enhance heat removal and allow higher loading. Some large units use directed oil flow and internal ducts to manage winding hotspots. Cooling class is a key specification, directly influencing kVA rating and overload capacity.