5-2 Lower Mechanism: Travel Drive Unit [2] Types of reduction gear lubricating oil and selecting appropriate one Table 8 shows the API Service Categories for reduction gear lubricating oil. Table 8. API Service Categories for Reduction Gear Lubricating Oil Service Categories GL-1
GL-2
GL-3
Type of Service Spiral bevels or worm gears with small surface pressure and sliding velocity Slightly more demanding worm gears than above mentioned. Slightly more demanding spiral bevels and manual transmission
GL-4
Hypoid gears under highspeed and low-load or low-speed and high-load
GL-5
Much more demanding hypoid gear to which shock load is applied
Applications Used for manual transmission on rare occasions and rarely used today. Used for industrial worm reducers. Mainly used for manual transmission. Hypoid gear reducer under normal conditions. Also used for manual transmission. Passenger cars, racing cars, and the track rear axle of the hypoid unit that have high requisite.
Use reduction gear lubricating oil equivalent to "GL-4 or GL-5".
[3] Reduction gear lubricating oil appropriate for the operating temperature Table 9 shows JIS viscosity grades for reduction gear lubricating oil. Table 9. JIS viscosity Grades for Reduction Gear Lubricating Oil Type (Viscosity grade) SAE 75W SAE 80W SAE 85W SAE 90 SAE 140
Kinematic Viscosity cSt (100°C) 4.1 or higher 7.0 or higher 11.0 or higher 13.5 or higher and less than 24.0 24.0 or higher and less than 41.0
Higher viscosity provides more load bearing but may cause a problem with the starting performance if the viscosity is too high. Therefore, selecting reduction gear lubricating oil appropriate for the operating temperature is necessary.
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