CAT Biggest Mining Trucks Production - Caterpillar dump truck factory (Decatur, Illinois) Decatur plant All 10 models of Caterpillar® off-highway trucks are produced at the Decatur, Ill., facility-one of Caterpillar’s largest plants. The facility covers nearly 350 acres and includes 25 buildings. The Caterpillar 797F mining truck is the world’s largest dump truck with a Gross Machine Operating Weight of 1.37 MILLION pounds. The behemoth of a machine measures 51 ft high, 50 ft long, and 32 feet wide and its largest area. It can also reach an impressive top speed of 42 miles per hour with a 1000 gallon fuel tank and can haul approximately 400 tons of material.