Abstract: A method for operating a hydraulic system. The method including providing a delivered volumetric flow of a hydraulic medium for moving at least one hydraulic cylinder by a hydraulic device having at least one hydraulic pump and which at a minimum rotational speed of the at least one hydraulic pump provides a minimum delivered volumetric flow of a hydraulic medium. When reaching a predetermined delivered volumetric flow greater than the minimum delivered volumetric flow of the hydraulic device, a further hydraulic pump is connected having a minimum rotational speed for increasing the delivered volumetric flow of the hydraulic medium when the rotational speed of the at least one hydraulic pump is equal or greater than the minimum rotational speed of the at least one hydraulic pump and the rotational speed of the further hydraulic pump is equal to or greater than the minimum rotational speed of the further hydraulic pump.

Abstract: An industrial truck including a hydraulic system and at least one hydraulically operated component. The hydraulic system includes a first hydraulic pump, a second hydraulic pump, and a hydraulic line system. The hydraulic line system is configured to selectively connect the hydraulically operated component either exclusively to the first hydraulic pump or exclusively to the second hydraulic pump or simultaneously to the first hydraulic pump and the second hydraulic pump. The first hydraulic pump has a first efficiency maximum at a first volume flow and a first operating pressure and the second hydraulic pump has a second efficiency maximum at a second volume flow and a second operating pressure, and one or more of the first operating pressure is greater than the second operating pressure and the first volume flow is smaller than the second volume flow.