maintenance of crane
Selection and maintenance of crane
According to statistics, the fault about the hydraulic system of engineering machinery is approximately 70%,due to improper selection of hydraulic oil, careless use, replacement is not timely caused. So the hydraulic oil correctly, and maintain a reasonable choice of performance and economic performance is an important condition to extend the service life of the host, and components of the hydraulic system.
1 Construction machinery on the hydraulic oil performance requirements
(1) an appropriate viscosity. The viscosity is the magnitude of the intermolecular frictional resistance when the fluid flows. Viscosity is too large will increase the transmission resistance in the pipeline, the process of energy loss increases, the host no-load loss increases, temperature rise and high operating temperature, the main pump suction side may appear “hole” phenomenon; Hour can not guarantee good lubrication conditions of construction machinery, exacerbate the wear parts and system leakage increases, causing the pump volume efficiency decline. Depending on the specific use of hydraulic system work pressure, operating temperature and the speed of the implementation of components may be. High-pressure, high temperature should choose high viscosity, high-speed exercise should choose low viscosity.
(2) good viscosity temperature. Viscosity temperature refers to the viscosity of oil viscosity rise and fall with temperature and the degree of change, usually with the viscosity index. Viscosity index, the greater the hydraulic system work with oil viscosity decreases with decreasing temperature, so that the hydraulic system of internal leakage will not be too large. Engineering machinery operating conditions are generally more adverse, the process of operating temperature of the hydraulic oil load and ambient temperature changes, the viscosity index generally not less than 90.
(3) good abrasion resistance and lubricity. The purpose is to reduce mechanical friction, to ensure the service life of construction machinery.
(4) good anti-oxidation stability. Antioxidant stability refers to the resistance of the oil against oxygenates to a chemical reaction at elevated oil temperatures. Practice shows that the oil temperature increased by 10 ℃, the chemical reaction rate increased by about doubled. Good oxidation stability of hydraulic oil for a long time is not easy to oxidative deterioration, can guarantee the normal circulation of hydraulic oil.
(5) anti-emulsifying and anti-foam good. Emulsifying resistance refers to the ability of oil to be mixed with water and, after agitation, to be an emulsion from which water is separated. Anti-foam refers to the oil mixed with air and stir to generate emulsion, bubble separation from the oil. Mixed with water or air to reduce the oil after the volume modulus, compressibility increases, the hydraulic components slow, and easy to produce shock and vibration.
(6) anti-shear stability. To improve the viscosity index of oil, oil is often added to the polymethyl acrylate, polyisobutylene and other polymers, the molecular chain of these substances is longer, the oil flow through the hydraulic components of the slit by the great shear Role, often make molecular chain breaking, oil viscosity-temperature characteristics of decline. Engineering machinery opera