Doosan Construction Equipment has brought out two new heavy-duty excavators in the 50-tonne class, both of which meet the Stage IIIB emissions standard: the DX490LC-3 model, with an operating weight of 49 tonne, and the DX530LC-3, with 52 tonnes. According to this Korean manufacturer, the ratio of productivity (excavated cu m/h) to fuel consumption (l/h) in standard operating mode was increased by nine percent in both these models as compared to the previous models. The secret to the lower overall fuel consumption, says Doosan, lies in improved cooling, a display to inform the driver about fuel consumption and optimized main control valves, which reduce energy losses and deliver higher efficiency. In addition, extra sensors are fitted which ensure better electronic control of the pumps, the engine and the main control valve. As a result, throughput, pressure and torque can all be precisely adjusted to suit the individual operating requirements.