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Unformatted text preview: EM 1110-2-1424
28 Feb 99 Chapter 13
Lubricant Specifications and Selection 13-1. Introduction
Proper selection of a lubricant depends on understanding the lubricating regime (i.e., film, mixed,
boundary), established conventions of classifications, and an ability to interpret and apply the producer’s
product data specifications to the equipment. Without this background, it is impossible to make an
informed selection or substitution.
13-2. Lubricant Classification
Professional societies and organizations have established classifications for oil and grease. The most
widely encountered systems are those of the following organizations:
! SAE (Society of Automotive Engineers) ! API (American Petroleum Institute) ! AGMA (American Gear Manufacturers Association), ! ISO (International Standards Organization) ! NLGI (National Lubricating Grease Institute). a. Oil classification. Oil is normally classified by viscosity grade, additives, use, or by the producer's
brand name. Some oils are classified as nonspecialized industrial oils.
(1) Classification by viscosity grade. Classification according to viscosity is the most prevalent
method of describing oils, and the most common classification systems are those of the SAE, AGMA, and
ISO. Each organization uses a different kinematic viscosity range numbering system.
(2) Classification by additives.
(a) Oil may be further classified according to the additives included in the oil to enhance its
performance properties as follows:
! Inhibited or RO (rust and oxidation inhibited) ! AW (antiwear) ! EP (extreme pressure) ! Compounded ! Residual. 13-1 EM 1110-2-1424
28 Feb 99 The first three classes are discussed throughout this manual and require no further explanation; they
contain the indicated additives. Compounded oil contains from 3 to 10 percent fatty or synthetic fatty oils.
It is also called steam cylinder oil. The added fat reduces the coefficient of friction in situations where an
extreme amount of sliding friction occurs. A very common application is in worm gear systems. Compounded oil may be composed of either a normal mineral oil or a residual oil, depending on the desired
(b) Residual compounds are heavy-grade straight mineral oils or EP oils. These compounds are
normally mixed with a diluent to increase ease of application. After application, the diluent evaporates,
leaving a heavy adhesive lubricant coating. Residuals are often used for open-gear applications where
tackiness is required to increase adhesion. This type of heavy oil should not be confused with grease.
Residual oil with lower viscosity is also used in many closed-gear systems. Compounded oil may contain
residual oil if the desired viscosity is high.
(3) Classification according to use. This system of classification arises because refining additives and
type of petroleum (paraffinic or naphthenic) may be varied to provide desirable qualities for a given
application. Some of the more common uses are:
! Compressor oils (air, refrigerant). ! Engine oils (automotive, aircraft, marine, commercial). ! Quench oils (used in metal working). ! Cutting oils (coolants for metal cutting). ! Turbine oils. ! Gear oils. ! Insulating oils (transformers and circuit breakers). ! Way oils. ! Wire rope lubricants. ! Chain lubricants. ! Hydraulic oils. (4) Nonspecialized industrial oil. This classification includes oils that are not formulated for a specific
application and are frequently referred to as “general purpose oil” in the manufacturer’s product literature.
These oils are generally divided into two categories: general purpose and EP gear oils.
(a) General purpose oils. General...
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- Spring '11