ENGINEERING

A LUBRICATION AND SEALS

LUBRICATION
To help maintain a rolling bearing’s anti-friction characteristics, • Demulsifiers to promote oil and water separation.
lubrication is needed to: • Viscosity-index improvers to decrease viscosity
• Minimize rolling resistance due to deformation of the sensitivity to temperature change.
rolling elements and raceway under load by separating
the mating surfaces.
• Pour-point depressants to lower the pouring point
at low temperatures.
• Minimize sliding friction occurring between rolling
• Lubricity agents to modify friction.
elements, raceways and cage.
• Transfer heat (with oil lubrication). • Antiwear agents to retard wear.

• Protect from corrosion and, with grease lubrication, • Extreme pressure (EP) additives to prevent scoring
from contaminant ingress. under boundary-lubrication conditions.
• Detergents and dispersants to maintain cleanliness.
Modern lubricants do this very effectively, although in many • Antifoam agents to reduce foam.
applications the means by which they accomplish this are • Tackiness agents to improve adhesive properties.
extremely complex and not completely understood. Because
the principles involved with lubricating rolling element bearings Inorganic additives such as molybdenum disulphide, graphite,
are complex and do not have to be known to employ lubricants and zinc oxide are sometimes included in lubricants. In most
successfully, this discussion will stress the practical rather than tapered roller bearing applications, inorganic additives are of no
the theoretical aspects of lubrication. significant benefit; conversely, as long as the concentration is low
and the particle size small, they are not harmful.
Recently, the effects of lubricant chemistry on bearing life (as
LUBRICATION SELECTION opposed to the purely physical characteristics) have received much
The wide range of bearing types and operating conditions emphasis. Rust, oxidation, extreme pressure and anti-wear additive
precludes any simple, all-inclusive statement or guideline allowing packages are widely used in engine and gear oils. Fatigue testing
the selection of the proper lubricant. At the design level, the first has shown these additives may, depending on their chemical
consideration is whether oil or grease is best for the particular formulation, concentration and operating temperature, have a
operation. The advantages of oil and grease are outlined in the positive or negative impact on bearing life.
table below. When heat must be carried away from the bearing, Consult your Timken representative for more information
oil must be used. It is nearly always preferred for very high-speed regarding lubricant additives.
applications. For limiting speeds of grease and oil-lubricated
bearings, refer to the section entitled “Speed, Heat and Torque“ GUIDANCE FOR OIL/GREASE SELECTION
section.
Oil lubrication
ADVANTAGES OF OIL AND GREASE Oils used for bearing lubrication should be high-quality, non-
OIL GREASE oxidizing mineral oils or synthetic oils with similar properties.
Selection of the proper type of oils depends on bearing speed, load,
Carries heat away Simplifies seal design
operating temperature and method of lubrication.
from the bearings and acts as a sealant
Some features and advantages of oil lubrication, in addition to
Carries away moisture Permits prelubrication of sealed the above, are as follows:
and particulate matter or shielded bearings • Oil is a better lubricant for high speeds or high temperatures.
It can be cooled to help reduce bearing temperature.
Easily controlled lubrication Generally requires less
frequent lubrication
• With oil, it is easier to handle and control the amount of lubricant
reaching the bearing. It is harder to retain in the bearing.
Lubricant losses may be higher than with grease.
LUBRICANT ADDITIVES
Additives are materials, usually chemicals, that improve specific
• As a liquid, oil can be introduced to the bearing in many
ways, such as drip-feed, wick-feed, pressurized circulating
properties when added to lubricants. Additives, when properly systems, oil-bath or air-oil mist. Each is suited to certain
formulated into a lubricant, can increase lubricant life, provide types of applications.
greater resistance to corrosion, increase load-carrying capacity
and enhance other properties. Additives are very complex and
• Oil is easier to keep clean for recirculating systems.
Oil may be introduced to the bearing housing in many ways.
should not be added indiscriminately to lubricants as a cure-all
for all lubrication problems.
The more common lubricant additives include:
• Oxidation inhibitors for increasing lubricant service life.
• Rust or corrosion inhibitors to protect surfaces from
rust or corrosion.

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LUBRICATION AND SEALS - continued

The most common systems are: OIL LUBRICATION GUIDELINES
A
• Oil bath. The housing is designed to provide a sump through Oil lubrication
which the rolling elements of the bearing will pass. Generally, Lubricating oils are commercially available in many forms for
the oil level should be no higher than the center point of the automotive, industrial, aircraft and other uses. Oils are classified
lowest rolling element. If speed is high, lower oil levels should as either petroleum types (refined from crude oil) or synthetic types
be used to reduce churning. Gages or controlled elevation drains (produced by chemical synthesis).
are used to achieve and maintain the proper oil level.
Petroleum oils
• Circulating system. This system has the advantages of: Petroleum oils are used for nearly all oil-lubricated applications
• An adequate supply of oil for both cooling and lubrication. of Timken bearings. These oils have physical and chemical
• Metered control of the quantity of oil delivered to each properties that can help in the selection of the correct oil for any
bearing. bearing application.
• Removal of contaminants and moisture from the bearing
by flushing action. Synthetic oils
• Suitability for multiple bearing installations. Synthetic oils cover a broad range of categories, and include
polyalphaolefins, silicones, polyglycols, and various esters. In
• Large reservoir, which reduces deterioration. Increased
general, synthetic oils are less prone to oxidation and can operate
lubricant life provides economical efficiency.
at extreme hot or cold temperatures. Physical properties such as
• Incorporation of oil filtering devices. pressure-viscosity coefficients tend to vary between oil types and
• Positive control to deliver the lubricant where needed. caution should be used when making oil selections.
The polyalphaolefins (PAO) have a hydrocarbon chemistry,
A typical circulating oil system consists of an oil reservoir,
which parallel petroleum oil both in their chemical structures and
pump, piping and filter. A cooler may be required.
pressure-viscosity coefficients. Therefore, PAO oil is mostly used
• Oil-mist lubrication. Oil-mist lubrication systems are used in in the oil-lubricated applications of Timken bearings when severe
high-speed, continuous operation applications. This system temperature environments (hot and cold) are encountered or
permits close control of the amount of lubricant reaching the when extended lubricant life is required. The silicone, ester and
bearings. The oil may be metered, atomized by compressed air polyglycol oils have an oxygen based chemistry that is structurally
and mixed with air, or it may be picked up from a reservoir using quite different from petroleum oils and PAO oils. This difference
a venturi effect. In either case, the air is filtered and supplied has a profound effect on its physical properties where pressure-
under sufficient pressure to assure adequate lubrication viscosity coefficients can be lower compared to mineral and PAO
of the bearings. Control of this type of lubrication system is oils. This means that these types of synthetic oils may actually
accomplished by monitoring the operating temperatures of generate a smaller EHD film thickness than a mineral or PAO oil of
the bearings being lubricated. The continuous passage of equal viscosity at operating temperature. Reductions in bearing
the pressurized air and oil through the labyrinth seals used in fatigue life and increases in bearing wear could result from this
the system prevents the entrance of contaminants from the reduction of lubricant film thickness.
atmosphere to the system. The successful operation of this
type of system is based upon the following factors: proper SELECTION OF OILS
location of the lubricant entry ports in relation to the bearings The selection of oil viscosity for any bearing application requires
being lubricated, avoidance of excessive pressure drops consideration of several factors: load, speed, bearing setting,
across void spaces within the system, the proper air pressure type of oil, and environmental factors. Since viscosity varies
and oil quantity ratio to suit the particular application, and the inversely with temperature, a viscosity value must always be stated
adequate exhaust of the air-oil mist after lubrication has been with the temperature at which it was determined. High viscosity oil
accomplished. To ensure “wetting” of the bearings and to is used for low-speed or high-ambient temperature applications.
prevent possible damage to the rolling elements and races, it Low viscosity oil is used for high-speed or low-ambient temperature
is imperative that the oil mist system be turned on for several applications.
minutes before the equipment is started. The importance of
“wetting” the bearing before starting cannot be overstated and Approximate Temperature Limits
has particular significance for equipment that has been idled For Oils
for extended periods of time. Petroleum 149° C 300° F
Super Refined Petroleum 177° C 350° F
Synthetic Hydrocarbon 204° C 400° F

WARNING Synthetic Esters

Silicones
204° C
260° C
400° F
500° F
Polyphenylether 288° C 550° F
Proper maintenance and handling practices are critical. Perfluorinated 316° C 600° F
Failure to follow installation instructions and to maintain
proper lubrication can result in equipment failure, creating
a risk of serious bodily harm.

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A LUBRICATION AND SEALS - continued

CLASSIFICATION TYPICAL OIL LUBRICATION GUIDELINES
There are several classifications of oils based on viscosity In this section, the properties and characteristics of lubricants
grades. The most familiar are the Society of Automotive Engineers for typical tapered roller bearing applications are listed. These
(SAE) classifications for automotive engine and gear oils. The general characteristics have resulted from long successful
American Society for Testing and Materials (ASTM) and the performance in these applications.
International Organization for Standardization (ISO) have adopted
standard viscosity grades for industrial fluids. Fig. A-31 shows General purpose rust and oxidation lubricating oil
the viscosity comparisons of ISO/ASTM with SAE classification General purpose rust and oxidation (R&O) inhibited oils are
systems at 40° C. the most common type of industrial lubricant. They are used to
lubricate Timken bearings in all types of industrial applications
where conditions requiring special considerations do not exist.
2 000 10 000
1 500 1 500 7 500 SUGGESTED GENERAL PURPOSE
250 W min. 5 000
R&O LUBRICATING OIL PROPERTIES
1 000 1 000
800 4 000 Base stock Solvent refined, high
600 680 3 000 viscosity-index petroleum oil
140
Kinematic viscosity, mm2/s (Centistokes, cSt) at 40˚C

460
Additives Corrosion and oxidation inhibitors
Viscosity, Saybolt Universal Seconds (SUS) at 100˚F
2 000
400
320 1 500
300 Viscosity index 80 min.
220 90 1 000
200
50 Pour point -10° C max.
150 150 700
40 85 W min.
Viscosity grades ISO/ ASTM 32 through 220
100 500
100
80 30 400

60 68 80 W min.
300 Some low-speed and/or high-ambient temperature applications
40 46 20 200 require the higher viscosity grades, and high-speed and/or low-
30 32 70 W min.
150 temperature applications require the lower viscosity grades.
10 W min. 100
20 22
15 15
5 W min.
SAE Crankcase Oils
SAE Gear lOi
75 Industrial extreme pressure (EP) gear oil
10 60 Extreme pressure gear oils are used to lubricate Timken
8 50 bearings in all types of heavily loaded industrial equipment. They
7
6 should be capable of withstanding heavy loads including abnormal
5
4 40
shock loads common in heavy-duty equipment.
3 3 35
2
33 SUGGESTED INDUSTRIAL EP GEAR OIL PROPERTIES
2
ISO/ASTM Base stock Solvent refined, high viscosity index
petroleum oil
Additives Corrosion and oxidation inhibitors.
Fig. A-31
Viscosity classification comparison between ISO/ASTM grades (ISO 3448/ Extreme pressure (EP) additive*
ASTM D2442) and SAE grades (SAE J 300-80 for crankcase oils, SAE J 306-81 - 15.8 kg (35 lb) min.
for axle and manual transmission oils). “OK” Timken load rating
Viscosity index 80 min.
The figure below can be used to predict the oil's kinematic Pour point -10° C max.
viscosity versus temperature (use base oil for grease). Viscosity grades ISO/ ASTM 100, 150, 220, 320, 460
* ASTM D 2782
TEMPERATURE VS. KINEMATIC VISCOSITY
10000 Industrial EP gear oils should be composed of a highly refined
petroleum oil-based stock plus appropriate inhibitors and additives.
They should not contain materials that are corrosive or abrasive to
Kinematic Viscosity (cSt)

1000
bearings. The inhibitors should provide long-term protection from
oxidation and protect the bearing from corrosion in the presence
100 of moisture. The oils should resist foaming in service and have
good water separation properties. An EP additive protects against
ISO VG
10
680
460
scoring under boundary-lubrication conditions. The viscosity
320
220 grades suggested represent a wide range. High temperature and/or
150
100
68
slow-speed applications generally require the higher viscosity
1 46
32 grades. Low temperatures and/or high speeds require the use of
0 50 100 150 200
lower viscosity grades.
Temperature (degrees C)
Fig. A-31a

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LUBRICATING GREASES CHARACTERISTICS AND OPERATING ENVIRONMENTS
A
Definition Listed below are the general characteristics of prominent rolling
According to the ASTM definition, lubricating grease is a “solid bearing greases.
to semi-fluid product of the dispersion of a thickening agent in a
liquid lubricant; other ingredients imparting special properties may Typical Usable** Typical
Dropping PT Temperature Water
be included.” If this definition were applied in the manner a chemist Resistance
would use to illustrate a chemical reaction, the composition of a Thickener C F C F
grease could be described by the formula below.
Sodium Soap 260+ 500+ 121 250 Poor
Lithium Soap 193 380 104 220 Good
Fluids +Thickening +Special =Lubricating Polyurea 238 460 149 300 Excellent
Agents Ingredients Grease
Lithium Complex
Mineral Oils Soaps Oxidation Inhibitors Soap 260+ 500+ 163 325 Good
Esters Lithium, Sodium Rust Inhibitors
Organic Barium, Calcium VI Improver ** Continuous operation with no relubrication. Depending upon the formulation the
Esters Strontium Tackiness service limits may vary. The usable limit can be extended significantly with
Glycols Non-Soap (Inorganic) Perfumes relubrication.
Silicones Microgel (Clay) Dyes
Carbon Black Metal Deactivator
Silica-gel
Non-Soap (Organic) Polyurea as a thickener for lubricating fluids is one of the most
Urea compounds
significant lubrication developments in more than 30 years. Polyurea
Terepthlamate
Organic Dyes
grease performance in a wide range of bearing applications is
outstanding, and in a relatively short time it has gained acceptance
At this time, there is no known universal anti-friction bearing as a factory-packed lubricant for ball bearings.
grease. Each individual grease has certain limiting properties and
characteristics. Consistency
Synthetic lubricating fluids, such as esters, organic esters Greases may vary in consistency from semifluids hardly thicker
and silicones, are used with conventional thickeners or chemical than a viscous oil, to solid grades almost as hard as a soft wood.
additives to provide greases capable of performing over an Consistency is measured by a penetrometer, in which a standard
extremely wide range of temperatures, from as low as -73° C weighted cone is dropped into the grease. The distance the cone
(-100° F) to a high of 288° C (550° F). penetrates (measured in tenths of a millimeter in a specific time)
The successful use of lubricating grease in roller bearings is the penetration number.
depends on the physical and chemical properties of the lubricant The National Lubricating Grease Institute (N.L.G.I.) classification
pertaining to the bearing, its application, installation and general of grease consistency is shown below:
environmental factors. Because the choice of a lubricating grease
for a particular bearing under certain service conditions is often NLGI Grease Grades Penetration Number
difficult to make, your Timken representative should be consulted
for proper suggestions.
0 355-385
1 310-340
Grease lubrication 2 265-295
The simplest lubrication system for any bearing application is 3 220-250
grease. Conventionally, greases used in Timken bearing applications 4 175-205
are petroleum oils of some specific viscosity that are thickened to 5 130-160
the desired consistency by some form of metallic soap. Greases 6 85-115
are available in many soap types such as sodium, calcium, lithium,
calcium-complex and aluminium-complex. Organic and inorganic Grease consistency is not fixed; it normally becomes softer
type non-soap thickeners also are used in some products. when sheared or “worked.” In the laboratory this “working” is
accomplished by forcing a perforated plate up and down through
a closed container of grease. This “working” does not compare
Soap type with the violent shearing action that takes place in a ball bearing
Calcium greases have good water resistance. Sodium
and does not necessarily correlate with actual performance.
greases generally have good stability and will operate at higher
temperatures, but they absorb water and cannot be used where
moisture is present. Lithium, calcium-complex and aluminium-
complex greases generally combine the higher temperature
properties and stability of sodium grease with the water resistance
of calcium grease. These greases are often referred to as multi-
purpose greases since they combine the two most important
lubricant advantages into one product.

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A LUBRICATION AND SEALS - continued

Low Temperatures
Starting torque in a grease-lubricated ball bearing at low
temperatures can be critical. Some greases may function
adequately as long as the bearing is operating, but resistance to
initial movement is such that the starting torque is excessive. In
certain smaller machines, starting is an impossibility when very Approximate Temperature Limits
cold. Under such operating circumstances, the greases containing For Grease Thickeners
low-temperature characteristic oils are generally required.
If the operating temperature range is wide, synthetic fluid Soaps 121° C 250° F
greases offer definite advantages. Greases are available to provide Complexes 177° C 350° F
very low starting and running torque at temperatures as low as Polyureas 177° C 350° F
-73° C (-100° F). In certain instances, these greases perform better Non-soap >260° C >500° F
in this respect than oil.
An important point concerning lubricating greases is that the
starting torque is not necessarily a function of the consistency
or the channel properties of the grease. It appears to be more a Timken Multi-Use Lithium Grease
function of the individual properties of the particular grease and
is difficult to measure. Experience alone will indicate whether one Soap Type: Lithium
grease is superior to another. Consistency: NLGI No. 1 or No. 2
Additives: Corrosion and oxidation inhibitors
High Temperatures Base Oil: Petroleum/Mineral
The high temperature limit for modern grease is generally Base Oil Viscosity at 40° C: 145.6
a function of the thermal and oxidation stability of the fluid and Pour Point: -18˚ C max.
Color: Light Brown
the effectiveness of the oxidation inhibitors. The graph, to the
right, was prepared using military-specification greases to
illustrate the thermal limitations of mineral oil, ester, silicone,
and fluorinated ether greases. The limits as shown apply only to
prelubricated bearings or to applications where relubrication is not
possible. Where provisions have been made for relubrication, the LUBRICATION GREASE TEMPERATURE RANGES
temperature limits may be extended provided the interval between
cycles is reduced accordingly. Petroleum MIL-G-25537
A rule of thumb, developed from years of testing grease-
lubricated bearings, indicates that grease life is halved for every Ester MIL-G-23827
10° C (18° F) increase in temperature. For example, if a particular
grease is providing 2,000 hours of life at 90° C (194° F) by raising Ester - MoS2 MIL-G-21164
the temperature to 100° C (212° F) reduction in life to approximately
1,000 hours would result. On the other hand, 4,000 hours could be Synthetic Hydrocarbon MIL-G-81322
expected by lowering the temperature to 80° C (176° F).
Silicone MIL-G-25013
It becomes obvious that the reactions started by the normal
reaction of lubricant with oxygen increases rapidly at higher
Perfluoroalkylpolether MIL-G-27617
temperatures. The lubricants undergo a series of chemical
reactions, that ultimately result in the development of viscous or
hard residues that interfere with the operation of the bearing. -73° C 18° C 38° C 93° C 149° C 204° C 260° C
Thermal stability, oxidation resistance, and temperature -100° F -0° F 100° F 200° F 300° F 400° F 500° F
Temperature Range
limitations must be considered when selecting greases for high-
temperature applications. In non-relubricatable applications,
highly refined mineral oils or chemically stable synthetic fluids
are required as the oil component of greases for operation at
temperatures above 121° C (250° F).

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A
Grease Compatibility Chart

Clay Non-Soap
N = Best Choice

Ca 12 Hydroxy

Li 12 Hydroxy

Polyurea S S
Ca Sulfonate
Ba Complex

Ca Complex
Ca Stearate
Al Complex

Li Complex
Li Stearate
N = Compatible

Polyurea
N = Borderline
N = Incompatible

Aluminum Complex

Timken Food Safe

Barium Complex

Calcium Stearate

Calcium 12 Hydroxy

Calcium Complex

Calcium Sulfonate

Timken Premium Mill

Timken Heavy Duty Moly

Clay Non-Soap

Lithium Stearate

Lithium 12 Hydroxy

Lithium Complex

Polyurea Conventional

Polyurea Shear Stable

Timken Multi-Use
Timken All Purpose
Timken Premium Synthetic

Timken High Speed

Timken Pillow Block

WARNING
Mixing grease types can cause the lubricant to become
ineffective, which can result in equipment failure, creating
a risk of serious bodily harm.

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A LUBRICATION AND SEALS - continued

WET CONDITIONS Water
Water and moisture can be particularly conducive to bearing Either dissolved or suspended water in lubricating oils can
damage. Lubricating greases may provide a measure of protection exert a detrimental influence on bearing fatigue life. Water can
from this contamination. Certain greases, the calcium, lithium and cause bearing etching that also can reduce bearing fatigue life.
non-soap type, for example, are highly water-resistant. However, The exact mechanism by which water lowers fatigue life is not fully
these greases exhibit poor rust preventative characteristics unless understood. It has been suggested that water enters microcracks in
properly inhibited. the bearing races that are caused by repeated stress cycles. This
Sodium-soap greases emulsify with small amounts of moisture leads to corrosion and hydrogen embrittlement in the microcracks,
that may be present and prevent the moisture from coming in reducing the time required for these cracks to propagate to an
contact with the bearing surfaces. In certain applications, this unacceptable size spall.
characteristic may be advantageous; however, emulsions are Water-base fluids such as water glycol and invert emulsions
generally considered undesirable. also have shown a reduction in bearing fatigue life. Although water
Many bearing applications require lubricants with special from these sources is not the same as contamination, the results
properties or lubricants formulated specifically for certain support the previous discussion concerning water-contaminated
environments, such as: lubricants.
• Friction Oxidation (Fretting Corrosion). The following chart gives a good idea of the influence of
• Chemical and Solvent Resistance. water on bearing life. Based on Timken Technology tests, it was
• Food Handling. determined that water content of 0.01 percent (100 parts per million)
or less, had no effect on bearing life. Greater amounts of water in
• Quiet Running.
the oil will reduce bearing life significantly.
• Space and/or Vacuum.
• Electrical Conductivity. LIFE REDUCTION WITH WATER CONTAMINATION
For assistance with these or other areas requiring special Relative (factor) life
lubricants, consult your Timken representative.
3

CONTAMINATION 2

Abrasive particles
When tapered roller bearings operate in a clean environment, 1

the primary cause of damage is the eventual fatigue of the

surfaces where rolling contact occurs. However, when particle 0.5
contamination enters the bearing system, it is likely to cause
damage such as bruising, which can shorten bearing life. 0.3

When dirt from the environment or metallic wear debris from

some component in the application is allowed to contaminate the
lubricant, wear can become the predominant cause of bearing
damage. If, due to particle contamination of the lubricant, bearing 0.1
0.5
0.001 0.01 0.1
wear becomes significant, changes will occur to critical bearing percent
% water
water in in the lubricant
the lubricant
dimensions that could adversely affect machine operation.
Bearings operating in a contaminated lubricant exhibit a higher
initial rate of wear than those running in an uncontaminated
lubricant. But, with no further contaminant ingress, this wear rate
quickly diminishes as the contamination particles are reduced in
size as they pass through the bearing contact area during normal
operation.

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GREASES - APPLICATIONS AND LUBRICATING GREASE LUBRICATION FOR
A
METHODS BEARING ⁄ HOUSING ASSEMBLIES
Grease lubrication is generally applicable to the following Polyurea and lithium-based greases are normally preferred for
conditions, and features low-to-moderate speed applications general purpose bearing lubrication and are advantageous in high
within operating temperature limits of the grease: moisture applications. Both greases have good water-resistant
• Easily confined in the housing. This is important in the characteristics. For temperature ranges of standard greases, see
food, textile and chemical industries. chart below.
• Bearing enclosure and seal design simplified. The grease must be carefully selected with regard to its
consistency at operating temperature. It should not exhibit
• Improves the efficiency of external mechanical seals to
thickening, separation of oil, acid formation or hardening to any
give better protection to the bearing. marked degree. It should be smooth, non-fibrous and entirely free
• Successfully used for integrally-sealed, prelubricated from chemically active ingredients. Its melting point should be
ball bearings. considerably higher than the operating temperature.
Frictional torque is influenced by the quantity and the quality of
Advantages of prelubricated ball bearings lubricant present. Excessive quantities of grease cause churning.
Prelubricated shielded and sealed bearings are extensively This results in excessive temperatures, separation of the grease
used with much success in applications where: components, and breakdown in lubrication values. In normal speed
applications, the housings should be kept approximately one-third
• Grease might be injurious to other parts of the
to one-half full.
mechanism.
Only on low speed applications may the housing be entirely filled
• Cost and space limitations preclude the use of a grease
with grease. This method of lubrication is a safeguard against the
filled housing. entry of foreign matter, where sealing provisions are inadequate
• Housings cannot be kept free of dirt and grit, water or for exclusion of contaminants or moisture.
other contaminants. During periods of non-operation, it is often wise to completely
• Relubrication is impossible or would be a hazard fill the housings with grease to protect the bearing surfaces. Prior
to satisfactory use. to subsequent operation, the excess grease should be removed
Prelubricated Timken bearings are prepacked with greases that and the proper level restored.
have chemical and mechanical stability and have demonstrated Applications utilizing grease lubrication should have a grease
long life characteristics in rotating bearings. Greases are filtered fitting and a vent at opposite ends of the housing near the top. A
several times to remove all harmful material and accurately metered drain plug should be located near the bottom of the housing to
so that each bearing receives the proper amount of grease. allow purging of the old grease from the bearing.
Relubricate at regular intervals to prevent damage to the
bearing. Relubrication intervals are difficult to determine. If plant
practice or experience with other applications is not available,
consult your lubricant supplier.
STANDARD LUBRICATION - TIMKEN BALL BEARINGS

Bearing Type Grease Type Grease Temperature

Range
Radial Bearings
(Double shielded and Polyurea thickener
Single and Double Sealed) Petroleum oil -30° to +275° F

Wide Inner Ring Bearings Polyurea thickener

(Contact Seal Types) Petroleum oil -30° to +275° F

Wide Inner Ring Bearings Synthetic thickener

(Labyrinth Seal Types) Synthetic hydrocarbon fluid -65° to +325° F

Note: Open type bearings and single shielded types are NOT prelubricated. They have
a rust preventative coating only and must be lubricated by the customer or end-user
before operation.

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Multi-purpose industrial grease Synthetic grease fill
These are typical of greases that can be used to lubricate many The use of “low torque” greases (or synthetic greases) can be
Timken bearing applications in all types of standard equipment. considered for rib speeds over 2,560 fpm (13 m/s), up to maximum
Special consideration should be given to applications where speed, of 4,920 fpm (25 m/s). Experience has shown that stabilized
load, temperature or environmental conditions are extreme. temperatures, around 15° C to 20° C (60° F to 68° F) above ambient,
can be obtained at the maximum permissible speed.
The following procedures must be respected to achieve the
Timken Multi-Use Lithium Grease
above performance:
• Very small initial quantity of grease is applied to
Soap Type: Lithium prevent excessive churning.
Consistency:
Additives:
NLGI No. 1 or No. 2
Corrosion and oxidation inhibitors
• Initial run-in period to evacuate unnecessary
grease from the bearing.
Base Oil:
Base Oil Viscosity at 40° C:
Petroleum/Mineral
145.6 • Good spindle design to retain grease around
Pour Point: -18˚ C max. the bearings.
Color: Light Brown • Efficient sealing to protect against external
contamination.
General purpose industrial grease should be a smooth,
homogeneous and uniform, premium-quality product composed M
of petroleum oil, a thickener, and appropriate inhibitors. It should Vsg = fsg x V = fsg x [ x T x (D2 - d2) x 10-3 - 7.8 x 10-3] (cm3)
not contain materials that are corrosive or abrasive to tapered 4
roller bearings. The grease should have excellent mechanical and where:
chemical stability and should not readily emulsify with water. The fsg = factor depending on speed: 0.15 < fsg < 0.3
grease should contain inhibitors to provide long-term protection
against oxidation in high-performance applications and protect the
bearings from corrosion in the presence of moisture.
The suggested base oil viscosity covers a fairly wide range.
Lower viscosity products should be used in high-speed and/or
lightly loaded applications to minimize heat generation and torque.
Higher viscosity products should be used in moderate- to low-
speed applications and under heavy loads to maximize lubricant
film thickness.

Mineral grease
When conventional (mineral) greases are used, the rib speed
should be limited to 5 m/s. This limit can be increased under pure
radial loads up to 13 m/s provided that the bearings remain in
endplay under all operating conditions. Generally, No. 2 consistency
greases are used with medium- to low-viscosity base oils.
M
Vmg = fmg x V = fmg x [ x T x (D2 - d2) x 10-3 - ] (cm3)
4 7.8 x 10-3

where:
fmg = factor depending on speed: 0.3 < fmg < 0.5
V = free volume of the bearing (cm3)
T = overall bearing width (mm)
D = cup outer diameter (mm)
d = cone bore (mm)
M = bearing weight (kg)

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LUBRICATION AND SEALS - continued

RE-GREASING CYCLE
A
The two primary considerations that determine the re-greasing
cycle on any application are operating temperature and sealing
Filling a bearing with efficiency. Obviously, seal leakage will dictate frequent relubrication.
synthetic grease Every attempt should be made to maintain seals at peak efficiency.
It is generally stated that the higher the temperature, the more
rapidly the grease oxidizes. Grease life is reduced by approximately
half for every 10° C rise in temperature.
The higher the operating temperature, the more often the grease
must be replenished. In most cases, experience in the specific
When using synthetic greases, the limiting factor is the application will dictate the frequency of lubrication.
"lubrication for life” concept (without re-greasing).
A normal way to fill the bearing with grease is to do it by hand
before heating and fitting the components. For the cone, the free
volume corresponding to the first third of the rollers, starting
from their large end, is filled with grease; an additional quantity
is provided below the cage. For the cup, a thin film of grease is
spread all around the race.
Grease lubrication of spindle bearings is generally preferred
by machine tool builders over oil circulation lubrication due to its
simplicity and low heat generation. For high loads or high speeds,
circulating oil is probably the most widely used method because
of its capability to remove heat from the spindle.

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LUBRICATION AND SEALS - continued

A Timken application specific lubricants have been developed by anti-wear and water-resistant additives offer superior protection
leveraging our knowledge of tribology and anti-friction bearings in challenging environments. This chart is intended to provide an
and how these two elements affect overall system performance. overview of the Timken greases available for general applications.
Timken lubricants help bearings and related components operate Contact your local Timken representative for a more detailed
effectively in demanding industrial operations. High-temperature, publication on Timken lubrication solutions.

LUBRICATION SELECTION GUIDE

Environment Application

High Wear • Moderate Loads Timken Premium Agriculture • Bushings/Ball Joints

Moderate Speeds All Purpose Industrial Truck and Auto Wheel Bearings
Moderate Temperatures Grease Heavy Duty Industrial

High Speeds • Light Loads

Timken Ball Bearing Alternators • Generators
Moderate Temperatures
Electric Motor Grease Electric Motors • Fans/Pumps
Moderate Water

Agriculture/Mining • Cement Plants

Extreme Heat • Heavy Loads
Timken Construction/Off Road • Rock Quarry
High Sliding Wear
Construction and Off- Earth Moving Equipment
Dirty Environments
Highway Grease Fleet Equipment • Heavy Industry
Slow Speeds • Shock Loading
Pivot Pins/Splined Shafts

Wet and Corrosive Conditions Lightly Loaded Pillow Blocks

Quiet Environments • Light Loads Timken Ball Bearing Idler Pulleys • Oven Conveyors
Moderate to High Speeds Pillow Block Grease Chemical Manufacture
Moderate Temperatures Noise-Sensitive Applications

Corrosive Media • Extreme Heat Aluminum Mills • Paper Mills

Timken
Heavy Loads • Wet Conditions Steel Mills • Offshore Rigs
Mill Grease
Slow to Moderate Speeds Power Generation

Incidental Food Contact

Hot and Cold Temperatures Timken Food and Beverage Industries
Moderate to High Speeds Food Safe Grease Pharmaceuticals
Medium Loads

Wind Energy Main Bearing

Extreme Low and High Temperatures
Timken Pulp and Paper Machines
Severe Loads
Synthetic Industrial General Heavy Industry
Corrosive Media
Grease Marine Applications
Slow to Moderate Speeds
Centralized Grease Systems

Timken Machine Tools Associated with:

Ultra-High Speeds
Ultra-High Speed Grinding • Drilling • Turning
Extreme Low Temperatures
Spindle Grease Milling • Lathes

Moderate Speeds General Industrial Applications

Timken
Light to Moderate Loads Pins and Bushings • Track Rollers
Multi-Use
Moderate Temperatures Water Pumps
Lithium Grease
Moderate Water Plain and Antifriction Bearings

This selection guide is not intended to replace the specifications by the equipment builder.

A156
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LUBRICATION AND SEALS - continued

SEALS
A
SELECTING THE RIGHT SEAL NON-RUBBING SEALS
When selecting the proper seal design for any Timken bearing Metal stampings
application, it is necessary to consider the type of lubricant, the Metal stamping closures are effective in clean applications.
operation environment, the speed of the application and general Where environmental conditions are dirty, stampings are used in
operating conditions. combination with other closure elements to provide an effective
labyrinth against the entry of foreign matter into the bearing
Shaft finish chamber.
It is important to ensure that no spiral grooves result from The stamping shown in Fig. A-32 is effective for applications that
machining of shaft surfaces since these will tend to draw lubricant are grease-lubricated and operate in clean conditions. The design
out of, or contaminant into, the bearing cavity. Plunge grinding illustrated in Fig. A-33 uses stampings on both sides of the bearing
normally produces a satisfactory surface finish. to keep the grease in close proximity to the bearing. The flinger
mounted at the outer side of the bearing adds a labyrinth effect.
Grease lubrication - venting Stampings should be designed to provide a clearance of 0.5
Venting should be provided in the cavity between the two to 0.6 mm (0.020 to 0.025 in.) on diameters between rotating and
bearings when grease lubrication is used in conjunction with stationary parts. A minimum axial clearance of 3 mm (0.125 in.)
rubbing or non-rubbing seals. This will prevent an ingress of should be provided.
contamination past the seals, in the event of a pressure differential
between the bearing cavity and atmosphere.

Vertical shaft closures - oil lubrication

Lubricating vertical shaft bearings is a difficult problem.
Normally, grease, oil mist or oil-air lubrication is used because
of the simplicity. However, some high speed and/or heavy load
applications will use circulating oil. This requires a very good
sealing system and a suction pump to remove the oil from the
bottom bearing position.
Fig. A-32 Fig. A-33
Metal stamping. Metal stampings.

Machined flingers
Machined parts, along with other closure elements, can be used
in place of stampings where closer clearances are desired. This
results in a more efficient retention of lubricant and exclusion of
foreign matter from the bearing housing. Examples are shown in
Fig. A-34 and A-35.
An umbrella-shaped flinger is shown in Fig. A-35 combined with
an annular groove closure. At high shaft speeds this combination
effectively retains oil and keeps out dirt.

Fig. A-34 Fig. A-35

Machined flinger combined Machined umbrella flinger
with annular grooves. combined with annular grooves.

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A LUBRICATION AND SEALS - continued

Annular grooves RUBBING SEALS
Annular groove closures are often used with grease lubrication Radial lip seals
in place of radial lip seals where considerable grit and dust are Many types and styles of radial lip seals are commercially
encountered. The closure usually has several grooves machined available to satisfy different sealing requirements. In clean
in the bore or on the outside diameter depending on the design. environments, where the primary requirement is the retention of
They become filled with grease, which tends to harden and lubricant in the bearing housing, a single lip seal with the lip pointing
provide a tight closure. When used with oil, the grooves tend to inward is often used. Where the critical concern is exclusion of
interrupt the capillary action which would otherwise draw oil out contaminants, the lip is usually pointed outwards (Fig. A-38).
of the bearing cavity. Annular grooves with a machined labyrinth
effectively protect a grease-lubricated bearing when the unit is
required to operate in an extremely dirty environment (Fig. A-36).
This type of closure is most effective when applied with close-
running clearances and the maximum possible number of grooves.
Suggested dimensions are shown in Fig. A-37.

Fig. A-38
Radial lip seals.

Lip seals are available with or without a spring-loaded lip. The

spring maintains a constant pressure of the lip on the sealing
surface, thereby providing a more efficient seal for a longer
period of time. When environmental conditions require a seal to
Fig. A-36 prevent contaminants from entering the bearing chamber as well
Annular grooves combined
with machined labyrinth. as retaining the lubricant, a double or triple lip seal is often used.
Additional flingers or shrouds should be used as primary seals
where extremely dirty conditions are present so that the seal lip and
a c sealing surface are protected to avoid rapid wear and premature
seal damage (Fig. A-39).
Seal wear surfaces are normally required to have a surface
finish in the order of 0.25-0.40 µm (10-15 µin.) Ra. For applications
b exposed to severe contamination, the seal wear surface should in
70˚
Clearance general have a minimum surface hardness of Rockwell C-45. The
seal supplier should be consulted for more specific guidance.
dimension “a” 3.20 - 4.80
0.125 - 0.190

dimension “b” 4.00 - 4.80

0.160 - 0.190

dimension “c” 0.5a

diametral clearance 0.25 - 0.40 for diameters to
0.010 - 0.016 50 mm (2 in)
1.3 max. for diameters
0.05 max. over 50 mm (2 in)

Fig. A-39
Fig. A-37 Lip seal plus machined labyrinth.
Annular grooves. Suggested
dimensions (mm, in.).

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“DUO FACE®-PLUS” seals Mechanical face seals
A
The “DUO FACE®-PLUS” seal (Fig. A-40) has double lips that These are often used in extremely dirty environments where
seal in the housing bore and the ground surface of the outer race rotational speeds are low. Fig. A-42 shows one of the proprietary
front face. This eliminates the need to machine a special seal types of mechanical face seals available. This type of seal generally
surface. The “DUO FACE®-PLUS” seal has proven successful in needs to run in an oil bath. Designs are also available for high-speed
many different types of grease-lubricated applications. The range and other special applications.
of Timken bearings available with “DUO FACE®-PLUS” seals is
listed in this book. Also, a brochure showing application examples
is available on request.

Fig. A-40 Fig. A-42

DUO FACE® –PLUS seal. Mechanical face seal for low speeds
and contaminated environment.

Diaphragm seals V-ring seals

Diaphragm seals (Fig. A-41) are commercially available. The V-ring seals can be used in conjunction with grease or oil
metallic lip is designed to be spring-loaded against the narrow lubrication. As rotational speeds increase, the lip tends to pull away
face of the outer race. The type shown in Fig. A-41b has a second from the sealing surface and act like a flinger. This seal may be
lip which seals against the housing. used with either oil or grease lubrication (Fig A-43). Consult your
V-ring seal supplier for application restrictions.

Fig. A-41 Fig. A-41b Fig. A-43

Diaphragm seal. Diaphragm seal. V-ring seals.

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BALL BEARINGS WITH SHIELDS AND SEALS

Shields (D-Type)
Both K and W single-row radial types are available with one
shield, designated by suffix D, or two shields, suffix DD. A shield
on one side provides protection against the entrance of coarse dirt
or chips and makes it possible to relubricate the bearing from the
open side as shown (at right).
Double-shielded bearings are prelubricated with the correct
amount of Timken suggested ball bearing grease and are designed
for applications where relubrication is not required. Typical One Shield-Suffix D Two Shields-Suffix DD
mountings are shown.

Labyrinth or Mechani-Seals (L-Type)

Bearings with Mechani-Seals are made in the non-filling slot
type only and are available with a single seal, designated by suffix
L, one seal and one shield, suffix LD, and two seals, suffix LL. These
bearings have standard bores, outside diameters and outer ring
widths, but the inner ring is wider than standard unshielded and
shielded sizes. As illustrated, in the L and LD-Types, the inner rings
Suffix L Suffix LD
are offset slightly on the side opposite the seal in order to permit
clearance when the bearings are mounted in blind housings.
The Mechani-Seal was developed by Timken to provide a
frictionless seal for effective grease retention and exclusion of
foreign material. It consists of two “dished” steel plates. The
inner member is fixed securely in the outer ring of the bearing
and provides an ample grease chamber plus effective grease
retention. The outer member is pressed on the outside diameter of
the inner ring and rotates as a slinger to throw off contaminants.
Close running clearances between the inner and outer members
assure effective sealing under extremely severe conditions. This Two Mechani-Seals Suffix LL
seal configuration is very effective under high speed, because
it is virtually frictionless and utilizes slinger action. Mechani-
Seal bearings are very popular in high-speed pneumatic tools,
small electric motors, pumps, domestic appliances and similar
high-speed applications. A typical mounting arrangement for the
LL-Type is shown.
Wide-type radial bearings (W-LL-Type) with Mechani-Seals
are designated by the prefix W and suffix LL for two seals. They
are made in standard bores and outside diameters, but in widths
the same as those of corresponding size double-row bearings.
The extra width affords greater space for long-life factory-filtered
W-LL-Type Typical Mounting
grease and provides extra support on shafts and in housings so that
locknuts and lockwashers are not needed on applications such as
electric motors. A typical mounting is shown (at right).

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Felt Seals (T-Type)
A
The felt seal consists of two metal plates fixed in the outer ring
of the bearing that enclose a felt washer. This felt washer, which
is saturated with oil before assembly in the bearing, contacts the
ground outside diameter of the inner ring to provide sealing with
minimum friction drag.
Bearings with felt seals are made only in the non-filling slot type
and are available with one seal (designated by the suffix T), one
seal and one shield (identified by suffix TD), and two seals (suffix
Suffix T Suffix TD
TT). Bores and outside diameters of these bearings are the same
as standard unshielded and shielded types, but overall widths are
greater. As illustrated, in the T-and TD-types, the inner rings are
offset slightly on the opposite side of the seal to permit clearance
when the bearings are mounted in blind housings as illustrated.

Rubber Seals (P-Type)

Radial bearings with rubber seals having one or two seals
are designated by the suffixes P and PP, respectively. With
the exception of the extra-small sizes, they are dimensionally
interchangeable with open-type and shielded bearings.
The P-Type design is a positive contact seal using a molded
synthetic rubber. Firmly fixed to the outer ring, the seal flares
outward and rides on the inner ring. The flare-out of the seal
against the inner ring radius assures constant positive contact to Suffix PP P Type PP Type
provide an effective barrier against the entrance of contaminants Typical Mounting Arrangements
or loss of lubricants.
Because they interchange dimensionally with standard
single-row radial types, Timken® rubber seal bearings provide a
convenient compact design.
Wide-type radial rubber seal bearings (W-PP Type) designated
by prefix W and suffix PP for two seals are made with standard
bores and outside diameters, but with widths the same as those
as corresponding double-row bearings. This design also utilizes
a molded seal.
The extra width offers a larger contact area for the shaft and
housing and also provides additional space for displacement of
grease under agitation.
These wide type rubber seal bearings are particularly well-
suited for use by electric motor manufacturers where their Electric Motor Assembly W-PP Type Typical Mounting
advantages have helped simplify design. A typical example of with W-PP Type Bearing
motor design simplification is illustrated (right).

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Rubber Seals (R-Type)
One of the most advanced sealing designs introduced by Timken
is the R-Type rubber seal bearing. This is a positive contact seal of
three-piece construction, utilizing a synthetic rubber seal retained
by two steel caps. The seal flares outward and rides or wipes on
the ground land of the inner ring. In this design, the rubber sealing
element is completely protected by a closely fitting outer cap or
shroud, which nests tightly against the seal member following
its flared-out shape at the inner ring of the outside diameter.
The innermost member is crimped into a groove in the outer ring
and encapsulates the seal and outside shroud. Providing firm
seal contact, the back-up plate of the seal assembly has a close
clearance with the outside diameter of the inner ring, preventing
the seal from being pushed inward. Shroud Seal suffix RR Shroud Seal suffix RR
Laboratory tests have clearly established the superior
performance of the shroud-type R-Seal. With improved lubricant
retention and greater protection against contaminants, the shroud
design guards the rubber seal against abrasive damage by dirt
and fiber wrap, which may be prevalent in agriculture and textile
applications. This seal construction also is available in standard
and heavy series wide inner ring bearings.

Tri-Ply Seals
Tri-Ply Shroud Seal ball bearings are designed for bearing
applications involving exceptionally severe contamination or
abrasion environments. They are produced in many types and
sizes, both in the radial and wide inner ring designs.
Each Tri-Ply seal consists of a triple-lip nitrile seal molded to
a heavy metal shroud cap. All three seal lips have heavy flare-
out contact with the inner ring outside diameter and provide
exceptionally effective protection against the loss of lubricant
and the entrance of wet or abrasive contaminants. The shroud
cap, which nests closely with the outside seal lip, helps protect
the rubber seal members from wrap and abrasion.
A feature of these bearings is the balanced design, consisting of Tri-Ply Seals
deep raceways, large ball size, and extra-wide or heavy inner rings.
The use of Tri-Ply bearings simplifies housing designs, and their
extra inner ring width provides greater support on the shaft. These
bearings are widely used on conveyors and farm machinery such as
disc harrows, hillers, tomato harvesters, cotton harvesters, etc.

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