Industrial gearbox oil grades are classified by viscosity and performance standards. Common types include ISO VG 68, 100, 150, 220, and 320. Higher grades like VG 460 or 680 are used in heavy-duty or high-temperature applications.
ISO VG
ISO VG stands for International Standards Organization Viscosity Grade. This system classifies industrial oils based on their kinematic viscosity at 40°C (104°F).
The most common ISO VG grades for industrial gearboxes are:
- ISO VG 32: Has a viscosity of 28.8-35.2 cSt at 40°C. Used in high-speed gearboxes or those operating in cold environments.
- ISO VG 46: Has a viscosity of 41.4-50.6 cSt at 40°C. Works well for small to medium-sized gearboxes in moderate temperatures.
- ISO VG 68: Has a viscosity of 61.2-74.8 cSt at 40°C. The most versatile grade for general industrial applications.
- ISO VG 100: Has a viscosity of 90-110 cSt at 40°C. Suitable for medium to large gearboxes under moderate loads.
- ISO VG 150: Has a viscosity of 135-165 cSt at 40°C. Used in heavily loaded gearboxes or warm operating conditions.
- ISO VG 220: Has a viscosity of 198-242 cSt at 40°C. Ideal for slow-speed, high-load applications.
- ISO VG 320: Has a viscosity of 288-352 cSt at 40°C. Reserved for extremely heavy-duty gearboxes.
- ISO VG 460: Has a viscosity of 414-506 cSt at 40°C. Used in severe-duty applications with very high loads.
AGMA
The American Gear Manufacturers Association (AGMA) created its own numbering system for gear oils. AGMA grades correspond closely with ISO VG grades but include additional performance specifications.
Common AGMA grades include:
- AGMA 1: Equivalent to ISO VG 46. Used for high-speed, lightly loaded gears.
- AGMA 2: Equivalent to ISO VG 68. Suitable for moderate speeds and loads.
- AGMA 3: Equivalent to ISO VG 100. Works well for industrial enclosed gears.
- AGMA 4: Equivalent to ISO VG 150. Used in moderate to heavily loaded gearboxes.
- AGMA 5: Equivalent to ISO VG 220. Ideal for heavy-duty industrial applications.
- AGMA 6: Equivalent to ISO VG 320. Reserved for severe-duty conditions.
- AGMA 7: Equivalent to ISO VG 460. Used in extreme pressure applications.
- AGMA 8: Equivalent to ISO VG 680. For the most demanding industrial gear drives.
AGMA also uses letter suffixes to indicate additive packages. For example, AGMA 5 EP contains extreme pressure additives for better protection under high loads.
SAE
The Society of Automotive Engineers (SAE) classification primarily focuses on automotive applications but some industrial gearboxes use SAE-rated oils. SAE grades measure viscosity at both cold and operating temperatures.
Common SAE grades for industrial gearboxes:
- SAE 75W: Has a maximum viscosity of 4,000 cP at -40°C. Flows well in cold conditions.
- SAE 80W: Has a maximum viscosity of 7,000 cP at -26°C. Balances cold flow with protection.
- SAE 85W: Has a maximum viscosity of 11,000 cP at -12°C. Provides thicker film strength.
- SAE 90: Has a viscosity range of 13.5-18.5 cSt at 100°C. Standard grade for many applications.
- SAE 140: Has a viscosity range of 24.0-32.5 cSt at 100°C. Used for heavy-duty service.
- SAE 250: Has a minimum viscosity of 41.0 cSt at 100°C. Reserved for extreme loads.
Multi-grade oils like SAE 75W-90 combine the cold-flow properties of a 75W with the high-temperature protection of a 90-weight oil. These perform well across wide temperature ranges.
DIN Standards
The German Institute for Standardization (DIN) created DIN 51517 to classify industrial gear oils. This standard divides gear oils into three parts based on their additive packages and performance characteristics.
DIN 51517 Part 1 (C)
Part 1 covers oils without additives, designated with the letter “C”. These straight mineral oils provide basic lubrication without enhanced protection.
C-grade oils work in lightly loaded gearboxes where contamination and extreme pressures aren’t concerns. They come in viscosity grades from ISO VG 32 to ISO VG 1000.
DIN 51517 Part 2 (CL)
Part 2 covers oils with anti-corrosion and anti-oxidation additives, designated “CL”. These oils resist rust formation and last longer than straight mineral oils.
CL-grade oils protect gearboxes from moisture and oxidation damage. They suit applications where water contamination poses a risk but extreme pressures don’t occur. Available viscosity grades range from ISO VG 68 to ISO VG 680.
DIN 51517 Part 3 (CLP)
Part 3 covers oils with anti-corrosion, anti-oxidation, and extreme pressure additives, designated “CLP”. These provide the highest level of protection for industrial gearboxes.
CLP-grade oils excel in heavily loaded gearboxes where metal-to-metal contact occurs. The extreme pressure additives form protective films on gear surfaces, preventing wear and scuffing. These oils come in viscosity grades from ISO VG 68 to ISO VG 680.
