HYDRAULIC OIL MAINTENANCE METHOD FOR HYDRAULIC ELEVATOR

PROBLEM TO BE SOLVED: To recover anti-oxidation ability of hydraulic oil in a simple method, by using liquid antioxidant as antioxidant to be added to hydraulic oil in a hydraulic tank and agitating the hydraulic oil in the hydraulic tank after injection of the antioxidant. SOLUTION: In order to recover anti-oxidation ability at a predetermined time, liquid antioxidant (recovery oil) is added to hydraulic oil. As the recovery oil, antioxidant which is liquid at using temperature, or oil formed by mixing antioxidant with base oil of the hydraulic oil and adding concentrated oil in the range between a minimum addition amount where anti-oxidation ability is provided and a maximum addition amount where the antioxidant does not separate or deposit is used. By using such liquid antioxidant, after its injection, with a simple agitation that a hydraulic elevator is normally operated again without performing a special agitating process, anti-oxidation ability of the hydraulic oil is easily recovered.