Since this era, the focus of domestic demand gradually started shifting from bulldozers to hydraulic shovels. Additional considerations, such as ease of operation, also became an important aspect of design.
The most Dump trucks used for postwar rehabilitation were of the 15 ton class. As the scale of construction became more massive, the demand for larger Dump trucks increased. HD180 was being developed to cope with the demand, however, it was more of an upgrade of the HD150. HD320, on the other hand, it was developed with a concept that was fundamentally very different.
Load capacity: 32,000kg
In addition to researching oversea products that were used at construction sites and mines in the United States and Australia, Komatsu took unique conditions of Japan into consideration developing this model. For example, it had a lower and wider vessel that shortened the cycle time of operation. It also had a smaller turning radius to accommodate use in smaller mines in Japan. This model was utilized at construction of Omura Nagasaki Airport.
With exports to mines in South Africa in 1976, Komatsu sent Japanese engineers there who then made a plan for assembly ensuring local procurement to cope with South Africa's national policy (high tax on imported goods).
The history of the dump truck as a transporting vehicle is also the history of increasing the amount of loading to improve productivity at construction sites. At mines especially, new technology is being introduced consistently even today. Enlarging the size by mechanical and electrical formulas, and adding the GPS control system are some of the examples.