Patent ID: 7287374

Claim:
Method for controlling the viscosity of a hydraulic fluid, in which the hydraulic fluid is at least in part included in a hydraulic circuit comprising a pump, a first load, and a valve having a coupled position for coupling the first load to the pump and an uncoupled position for uncoupling the first load from the pump, the valve being arranged in series with the first load, the valve comprising, in the uncoupled position, a cavitation-preventing opening to the first load, the method comprising: increasing a temperature of the hydraulic fluid by: determining the temperature of the hydraulic fluid, determining a status of the valve, and increasing a pressure of the hydraulic circuit when the valve is in the uncoupled position and the temperature of the hydraulic fluid is lower than a predetermined temperature by controlling the pump such that a temperature-increasing pressure drop is created in the cavitation-preventing opening in the valve and so that the temperature of the hydraulic fluid is raised to the predetermined temperature primarily due to the temperature-increasing pressure drop.