How to Choose Excavator Hydraulic Oil and How to Ensure Good Hydraulic Oil Heat Radiation

How to Choose Excavator Hydraulic Oil

(1) Viscosity of hydraulic oil

The principle of determining the viscosity of hydraulic oil is to make the viscosity of hydraulic oil (for components such as hydraulic pumps and travel motors) in the optimal range (16-36x10-6m㎡/s) under the premise of considering the working temperature and efficiency of the hydraulic circuit; The viscosity of the short-term cold start corresponding to the lowest temperature is ≤1000X10-6m㎡/s; and the viscosity corresponding to the short-term allowable maximum leakage oil temperature of 90℃ is ≥10X10-6m㎡/s.

(2) Viscosity Index (VI)

This index directly reflects the change of oil viscosity with temperature, (ie, the viscosity-temperature characteristics of oil). The higher viscosity index of oil means that the viscosity of the oil changes less with temperature; On the contrary, larger. The viscosity index of anti-wear hydraulic oil of foreign well-known manufacturers (such as Mobil, Shell, etc.) is VI≥110, and the viscosity index of domestic advanced anti-wear hydraulic oil is about 95. However, the viscosity index of high viscosity index hydraulic oil (HV) and multi-grade engine oil produced abroad are VI>140. This point must be paid special attention to users who use domestic hydraulic oil (or use engine oil as hydraulic oil) when using large imported hydraulic excavators. The lowering of the viscosity index will reduce the ambient temperature range that the oil can adapt to. If it is not necessary to use it, the relevant information should be inquired from the oil manufacturer, and the range of use of the oil should be adjusted appropriately. If necessary, the relevant setting values ​​of the equipment should be changed ( such as extreme temperature, etc.).

(3) Other comprehensive performance

Due to the high working pressure of the hydraulic system of modern large hydraulic excavators (≥32MPa), the maximum working oil temperature of the allowable hydraulic oil is also high (about 90°C), so in order to ensure that the hydraulic system(hydraulic parts) can work normally during the normal oil change cycle. , it is required that the oil selected for the system has good quality in terms of lubricity, oxidation stability, anti-wear, anti-rust and anti-corrosion, anti-emulsification, anti-foaming, shear stability and extreme pressure load.

2.How to Ensure Good Hydraulic Oil Heat Radiation

For the improvement of the hydraulic oil cooling system (more precisely, the hydraulic oil temperature control system) of large hydraulic excavators, although the specific methods adopted by various manufacturers are different, the basic idea is the same, which can make the hydraulic oil temperature In continuous operation, the balance is within an ideal range, and the hydraulic system can quickly heat up when it is put into work in a cold state (reaching the normal working temperature range of the oil). On the premise of using qualified hydraulic oil, when the hydraulic oil is overheated, the inspection steps for the hydraulic oil cooling and temperature control system are as follows:

(1) Whether the hydraulic oil radiator is blocked by dirt, which leads to a decrease in heat dissipation efficiency. Clean the radiator if necessary.

(2) Detect the actual working pressure of the system of the fan speed under extreme conditions to determine whether the hydraulic parts of the circuit are faulty, and whether the oil temperature sensor or control circuit is working normally. At this time, both the fan speed and the system working pressure should be at the maximum value; otherwise, the corresponding parameters of the system should be adjusted or the damaged components should be replaced.

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