Using mechanical lifting hydraulic oil requirements:
1, appropriate viscosity
Viscosity is one of the main factors in lifting machinery hydraulic system needs to be considered. Viscosity is oil flow performance indicators, showing fluid flow between the frictional resistance of the molecule size, the viscosity is too Assembly to increase the pipeline transportation of local pictures resistance, increased energy loss during operation, the host load losses increase, the temperature rise high, may appear in the main pump suction side "hole" phenomenon; viscosity is too small it can not guarantee the mechanical part good lubrication conditions, increased wear and tear of parts, and the system leakage increased, causing the pump volumetric efficiency decreases.
2, good viscosity-temperature characteristics
Viscosity-temperature refers to the degree the lift oil viscosity with temperature changes, usually expressed as viscosity-temperature index. The greater the viscosity-temperature index, work oil viscosity with increasing temperature drop is smaller, so the system will not leak too large. Construction machinery working condition is generally more severe, during the operation, the oil system with the load and ambient temperature changes, so the viscosity-temperature index of not less than 90.
3, good oxidation resistance and hydrolytic stability
General hydraulic oil temperature is preferably between 30 ℃ ~ 80 ℃, since the hydraulic oil temperature is closely related to life and work. When the oil temperature exceeds 60 ℃ or more, each additional 8 ℃, oil life will be halved. That is to say, at 90 ℃, oil life is the life of 60 ℃, about 10%, the reason is oxidized. At atmospheric pressure, per liter of oil contains slightly less than 0.1 liters of air. In fact, oxygen is always present, it reacted hydrocarbon oil, the oil slowly oxidized, black color of the oil, its viscosity increases. Finally oxide dissolved in the oil longer, but in a brown mucus layer is deposited in the system somewhere. This will cause friction valve bonding, ball valve body and piston pump, etc. is increased, while the oxidation of acid corrosion damage to hydraulic components. Slowly began to carry out the oxidation process, after a certain stage, a sudden rise in the rate of oxidation, viscosity suddenly increased. Which resulted in increased oil temperature, the oxidation process faster, when the oxidation precipitation, high viscosity as well as the accumulated acid accumulated to a certain limit, would cause fatal damage to the entire system. So that the whole form of fatal is injury.
4, anti-flammable and shear stability
In order to improve the viscosity index of the oil, the oil is often added polymethacrylate, and other polymers, the longer the molecular chain of these substances, when passing through the slit of hydraulic components, by the great shearing effect, tend to make the molecular chain scission, so the oil viscosity-temperature characteristics decline. When the crane operation, frequent reversing valve, throttling element of the hydraulic oil and so requires has a strong shear capacity.
5, and the sealing material, environmental compatibility
The sealing member makes contact with the hydraulic oil swollen, softening, hardening, the loss of the sealing material sealing function. Hydraulic system due to leaks, seal failure and other reasons, resulting in hydraulic oil outflow, if the hydraulic oil and the environment are incompatible, it will pollute the environment.
6, good abrasion resistance and lubricity
The purpose is to reduce mechanical friction, ensure the life of the host.
7, anti-flammable good
Hydraulic oil should have a higher flash point, ignition point and the ignition point.
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