Page 288 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

268 Major Process Equipment Maintenance and Repair

Table 6-3
Important Gear Factors and the Lubricant Properties Related to Each*
Factor Related Lubricant Prow*
Load Viscosity
EP Additives
Speed Viscosity
EP Additives
Temperature Viscosity
(Operating and Ambient) Viscosity Index
Fluidity
Oxidation Stability
EP Additives
Contamination Demulsibility
Corrosion Protection
Oxidation Stability
Life Oxidation Stability
Additive Depletion
Compatibility Synthetic (Paint and Seals)
EP Additives
*Equivalent viscosities of different classification systems are included for reference only in
Table 6-4.

There are many brand name lubricants available on the market today,
but all fall into five basic types. The following discussion is a brief sum-
mary of the characteristics, advantages, and disadvantages of each of the
different categories.

Mineral Oils

Mineral oils are still the most commonly used type of gear lubricant.
Containing rust and oxidation inhibitors, these oils are less expensive
than the other types, readily available, and have very long life. When
gear units operate at high enough speeds or low enough load intensities, a
type of mineral oil is probably the best selection.

Extreme Pressure Addltlves
Extreme pressure (EP) additives of the lead-naphthenate or sulphur-
phosphorus type are recommended for gear drives when a higher load
capacity lubricant is required. As a general rule, this type of oil should be
used in low speed, highly loaded drives with medium operating tempera-
tures. EP oils have the disadvantage of being more expensive and they
must be replaced more often than straight mineral oils. Some of these EP
oils have a very short life above a temperature of 160°F.