The "D" in Dover could stand for diversity. Dover manages 35 companies that make equipment ranging from car wash systems to aerospace components. Dover operates in four segments: engineered systems (products for printing and identification, transportation, waste handling, and industrial markets) energy (extraction and handling of oil and gas); fluids (fluid handling products for retail fueling, oil and gas, chemical, and hygienic markets); and refrigeration and food equipment (systems and products serving the commercial refrigeration and food service industries). Dover traces its historical roots back to 1955.