Hitachi Construction Machinery-Americas recently launched two rigid-frame haul truck models designed for use in large-scale mining operations: the 200-ton EH3500AC-3 (target gross machine operating weight of 709,888 lb) and the 240-ton EH4000AC-3 (target gross machine operating weight of 846,575 lb).

The two rigid-frame haul truck models are equipped with an advanced AC-drive system that was developed with Hitachi Group technologies employed in conventional models. Improvements include various sensors that provide information on drive conditions. The result is the Hitachi Drive Control System that reduces tire slippage on acceleration and tire lockup during braking, and prevents chassis oscillation in a front-rear direction and tire skid while steering.

Hitachi said it coupled the AC drive system, which has a high load-responsive IGBT inverter, with drive control software that was jointly developed with other Hitachi Group companies, to achieve a system that excels in controlling travel motor speed and torque. Whether taking off from a standstill, ascending grades or performing steering maneuvers, the system delivers an optimal, individual amount of power to each of the travel motors for smooth, quick operation, according to the company.