5-2 Lower Mechanism: Travel Drive Unit [2] Types of hydraulic oil and selecting appropriate one There are various types of hydraulic oil. They can be systematically categorized as follows: (1) Mineral-based hydraulic oil This oil is generally used and can be easily obtained. Thus, most hydraulic equipment uses this type of hydraulic oil. (2) Synthetic hydraulic oil This oil been developed for aircraft-related uses that have special requirements, and has excellent temperature characteristics and low temperature fluidity. However, this type of hydraulic oil is expensive. Phosphoric acid ester-based hydraulic oil, which is used as flame-resistant hydraulic oil, also belongs to this category. (3) Aqueous hydraulic oil This oil is used as flame-resistant hydraulic oil for those pieces of hydraulic equipment that are in extreme danger of fire that can be caused by oil leaking or other factors. Die casting machines, mills, and heating furnaces, for example, use this type of oil. (4) Biodegradable hydraulic oil This oil has been developed for the purpose of environmental conservation. This type of oil is decomposed by bacteria so that soil and rivers will not be contaminated by oil leaks. Table 5 shows the compatibility of each type of oil with the motor. Select hydraulic oil by following this table. Table 5. Compatibility of Hydraulic Oil with the Motor Hydraulic Oil Mineral-based hydraulic oil Synthetic hydraulic oil Aqueous hydraulic oil Biodegradable hydraulic oil
Compatibility with the Motor {
× × U
{ : This type of oil has no problem to be used. U : Please contact us if this type of oil needs to be used. × : Do not use these types of oil as they can cause a problem.
[3] Selecting hydraulic oil appropriate for the operating temperature The viscosity of hydraulic oil varies depending on the operating temperature. Since the viscosity of hydraulic oil significantly affects lubrication and drive force transmission of the motor, changing to hydraulic oil appropriate for the operating temperature is necessary. Check the operating temperature of the mother machine and the management temperature of the hydraulic oil in the hydraulic equipment, and then select hydraulic oil to use based on Table 6.
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