A HYDRAULIC SYSTEM FOR A WORKING MACHINE AND A METHOD FOR CONTROLLING A HYDRAULIC SYSTEM

摘要

The present invention relates to a hydraulic system comprising: a first and a second rotating hydraulic machine, the first and second hydraulic machine being arranged to provide a torque via a common output shaft; a first valve means for providing a differential hydraulic pressure level over the first hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels; a second valve means for providing a differential hydraulic pressure level over the second hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels; and a control unit configured to control the first valve means and the second valve means such that different discrete levels of torque are provided via the output shaft of the hydraulic system. The invention also relates to a hydraulic system for providing different discrete levels of torque using one hydraulic machine and a plurality of differential pressure levels, and to a method for controlling a hydraulic system.