IMMT 211

MODULE 4

LUBRICATION PRACTICES

__________________________________________________________________________________________________
Yanbu Technical Institute 66
 Module 4 Lubrication Practices

MODULE 4

INTRODUCTION:

The force of friction always opposes relative motion between two bodies Whenever the
surfaces of two bodies are in contact, the force of friction will resist relative motion between
them. The operation of almost all industrial equipment relies on the relative motion of
separate machine elements and lubrication is necessary to overcome the effects of the
friction forces. Friction causes energy to be wasted in the form of heat and causes the
rubbing surfaces to wear.

The basic purposes of lubrication are to:

 Reduce friction
 Reduce wear
 Dampen shock
 Cool moving elements
 Prevent corrosion
 Seal out dirt

Figure 4.1 Friction Force

LEARNING OBJECTIVES OF THIS MODULE:

Instruction in this lesson should result in students achieving the following objectives:
 Identify the basic function lubricants and describe the selection of lubricants.

 Identify the methods of application of lubricants.

 Identify the properties and characteristics of lubricants.

 Describe the handling, storing and disposing of lubricants.

 Describe the maintenance and servicing of lubrication systems.

KEYWORDS:

Friction, Lubrication, Oil, Grease, Wear, Contamination, Rust, Corrosion, Additives

__________________________________________________________________________________________________
Yanbu Technical Institute 67
 Module 4 Lubrication Practices

4.1 BASIC FUNCTIONS OF LUBRICATION

The basic functions of lubrications are to reduce friction, reduce wear, control temperature
rise, absorb shock, minimize corrosion, and seal out/flush out contaminants.

A. Reduce Friction
Lubrication reduces friction by separating moving surfaces under a load. The two
types of friction reduced by proper lubrication are sliding friction and rolling friction.

B. Reduce Wear
Lubrication reduces wear of both moving and stationary parts by reducing actual
surface area contact between two moving parts or one stationary part and one moving
part.

C. Helps Dampen or Absorb Shock

Lubricant trapped between the teeth of two meshing gears is pressurized as the teeth
come together, and the pressure is gradually released as they roll apart. Proper lubrication
thus prevents the teeth from chattering or banging as they turn.

D. Reduce Temperature Rise

Lubrication reduces heat buildup by reducing friction and carrying the heat to other
cooler areas of the machine.

E. Minimize Corrosion
Lubrication minimizes corrosion by forming a protective film over the lubricated
surfaces; corrosion of the moving and/or stationary parts is reduced.

F. Seal Out Contaminants

Lubrication prevents contamination by occupying the space between contact
surfaces and by maintaining a positive fluid pressure in the bearing areas.

G. Flush Out Contaminants

Flow of grease through labyrinth seals will flush contaminants from the bearing. Flow
of thin film/dry-film lubricant will flush contaminants from mating surfaces.

The golden rule of lubrication is said to be: ‘Good lubrication depends on the right lubricant
being available in the right quantity at the right time’. For this to be achieved the technician
must be aware of a number of basic principles governing the application of lubricants.

__________________________________________________________________________________________________
Yanbu Technical Institute 68
 Module 4 Lubrication Practices

 Cleanliness is vital. Lubricating equipment must be kept free of dirt and other
contaminants.
 Lubricants are not necessarily interchangeable and as a general rule should not be
mixed. Before changing lubricant, the equipment should be cleaned out.

 An excess of lubricant, especially grease, will cause excessive heat to build up and
eventual breakdown of the lubricant.

 Lubricant filters or strainers should always be changed at the recommended time.

 The selection of lubricant for a particular application should be left to qualified

personnel if possible.
 Inadequate lubrication can often be identified by the operating condition of a
bearing, especially its temperature. As a general rule, if a bearing is too hot to hold a
hand on it, then lubrication may be inadequate and should be investigated.

 Lubricants are potentially hazardous materials and should be stored with regard to
safety and environmental procedures.

Figure 4.2 Purpose of Lubrication

__________________________________________________________________________________________________
Yanbu Technical Institute 69
 Module 4 Lubrication Practices

4.2 METHODS OF APPLICATION

There are four basic methods by which lubricants can be applied and these are selected
according to design criteria and the particular demands of the equipment.

A. Manual Application
Whether the lubricant is liquid, semi-solid, or solid, the simplest method of application is
by hand. An oil can may be used for liquid lubricant, a grease gun for grease and a brush
or spray gun for solid lubricant.

Figure 4.3 Equipment for manual application of lubricant

Lubrication Lubrication Lubrication

system Basics Basics

__________________________________________________________________________________________________
Yanbu Technical Institute 70
 Module 4 Lubrication Practices

Gravity
This method is only suitable for liquid lubricants and is sometimes referred to as drip-feed

oiling. There are various types of drip-feed oilers and they usually include some method of
feed regulation.

Figure 4.4 Drip-feed oiler

B. Splash and Bath Lubrication

Splash lubrication relies on the components requiring lubrication being partially immersed
in an oil sump so that they pick up oil as they rotate. The oil picked up in the process may
also be deposited on the shaft bearings and other components. A variation on this method
is the ring- type oiler, which uses a steel or brass ring, which rotates with the shaft and picks
up oil which it deposits on the upper surface of the shaft. Examples of these methods are
shown in (Fig4.5).

__________________________________________________________________________________________________
Yanbu Technical Institute 71
 Module 4 Lubrication Practices

Figure 4.5 Splash and bath lubrication methods

C. Pressure Lubrication (circulating)

Many industrial applications, especially where loads are heavy and operating speeds are
high, require a pressurized system to ensure that an adequate supply of lubricant can be
determined. This usually takes the form of a circulating system.

Figure 4.6 Circulating system of lubrication

D. Automatic Lubrication
The simplest automatic lubricators are the single-point, small-reservoir units that mount on
the bearing in place of the grease fitting and dispense the correct amount of grease to
bearings as needed.

There are three types of these units available.

1. One is spring-activated, with orifice flow plugs selected for each application.
2. The second is a chemically generated gas-activated unit with fixed flow rates.

__________________________________________________________________________________________________
Yanbu Technical Institute 72
 Module 4 Lubrication Practices

3. The third unit is an electrochemical gas-activated unit. The grease feed rate is
controlled by setting dipswitches in the battery-powered lubricator.

Types of Automatic Lubrication Systems

Types of lubrication systems have changed dramatically in the last decade. With the advent
of programmable microprocessor controllers, proximity switches, and temperature
monitoring devices, it is now possible to precisely control and monitor lubrication systems.

Automatic lubrication systems generally fall into the following simply defined categories:

 Oil mist system

 Orifice-control system
 Injector system
 Series-progressive system
 Twin-line system
 Duo-line system
 Pump-to-point system
 Zone-control system
 Ejection system
 Injection system

Each of these lubrication systems has its place in industry. The range in applications from
machine tool, primary metals, automotive, agriculture, mining, textile, and food packaging
and processing to the military and aerospace industries. Each system, however, has its own
unique characteristics and specific requirements.

Figure 4.7 Example of an automatic lubrication system

__________________________________________________________________________________________________
Yanbu Technical Institute 73
 Module 4 Lubrication Practices

TYPES AND ADDITIVES OF LUBRICANTS

There are four basic types of lubricant:
 Liquid

 Semi-solid or plastic

 Solid

 Gaseous

And they can be classified according to their source:

 Animal

 Vegetable

 Mineral

Most lubricants are mineral based and are obtained from petroleum by refining processes
and further purification and blending. Petroleum and petroleum products belong to the
group of chemicals known as ‘hydrocarbons’ because they are compounds of the elements
hydrogen and carbon in varying combinations.

Animal fats come from common animals such as cattle, sheep and fish and are melted down
to remove impurities. Vegetable oils are produced by squeezing vegetables and seeds.

Lubricants are classified according to their properties and a number of standard tests are
applied to common types of lubricants, such as oils and greases, in order to determine their
properties.

Automatic
Lubrication System

__________________________________________________________________________________________________
Yanbu Technical Institute 74
 Module 4 Lubrication Practices

CRITERIA OF MEASURING OF OILS PROPERTIES

The properties of lubricating oils are measured by the following criteria:

A. Viscosity:

This is the single most important characteristic and refers to the ‘thickness’ of a fluid
and is also described as resistance to flow. Viscosity is affected by temperature.
There are various ways of measuring viscosity, all of which are based on the time
taken for a fixed volume of oil to pass through a standard orifice under standard
conditions. The SI unit is the centistoke (cSt).

B. Viscosity Index:

The rate of change of viscosity with temperature is known as the viscosity index. It
is normally desirable for the viscosity of a lubricant to remain the same over a wide
range of temperatures. A high viscosity index indicates such a property whereas a
low index indicates that the oil tends to thin out rapidly with increasing
temperature.

4.5 CRETERIA OF MEASURING GREASES PROPERTIES

The properties of greases, being semi-solid rather than liquid, are measured by a
separate set of criteria:

A. Hardness:

Because greases are semi-solid they can be considered as ranging from hard to soft.
These ratings are based on the results of a penetration test and the standard grading
used by the National Lubricating Grease Institute (US) are as follows:

 Dropping Point: This is the temperature at which the grease will change from
semi-solid to liquid i.e. the melting point.
 Pump-ability: This is a measure of the ease with which the grease will flow
through a system.
 Water Resistance: This determines whether or not a grease will dissolve in
water. This property is important where there is a likelihood of water coming
into contact with the lubricant.
 Stability: This property determines the ability of grease to retain its
characteristics with time. Some greases become soft and thin after being in use
for a while.

__________________________________________________________________________________________________
Yanbu Technical Institute 75
 Module 4 Lubrication Practices

SELECTION OF LUBRICANT
The selection of a lubricant is determined by the following factors:

A. Load:

The load on the bearing will determine the pressure that the lubricant will have to work
against.

B. Speed:

As operating speeds increase the lubricated surfaces will tend to wear faster.

C. Temperature:

The operating temperature may affect the properties of the lubricant.

D. Environment:

The lubricant may be required to cope with the presence of water or corrosive materials.
Lubricant selection should normally be left to those who are expert in the field. However, as
a general rule it is worth remembering that for plain journal bearings:

 For light loads and high speeds — use a lubricant of low viscosity.
 For high loads and low speeds — use a lubricant of high viscosity.
 The decision of whether to use oil or grease as the lubricant will depend on the operating
conditions.

The following comparative advantages should be taken into account:

 Oil: Provides cooling Feeds more easily and can be fed from a central supply Washes away
dirt and can also lubricate other elements such as gears Absorbs less torque
 Grease: Allows simpler bearing designs Provides better sealing against dirt, easier to contain
and seal also allows longer periods without attention.

____________________________________________________________________________________________________
Yanbu Technical Institute 76
 Module 4 Lubrication Practices

LUBRICANTS HANDLING AND DISPOSING

Lubrication supervisors, oilers, and operators have the greatest responsibilities involving
lubrication. Lubrication personnel have to be properly trained on storage, handling, application,
and use of lubricants.

A. Storage of lubricants:

A clean, well-lighted room or building is advisable, with provisions for heating in cold
weather. It should be specifically kept for lubricant storage and reserve lubricating
equipment. In most plants, one or two individuals are assigned the responsibility for
inventory and dispensing of lubricants.

These individuals should be trained on the importance of protecting lubricants

from contamination and commingling with other lubricants. Drums should be
labeled clearly to ensure application/use of the correct lubricant.

B. Bulk Storage:

Can be an investment that provides benefits in improved efficiency, reduced handling

costs, reduced risk of contamination, and simplified inventory. Each product requires its
own dedicated bulk storage system, including tank, pump, and receiving line. The tank
should be equipped with a water draw-off line, sampling line, and entry to permit periodic
tank cleaning. If tanks are equipped with electric heating coils or steam lines, precautions
must be taken to prevent overheating and thermal degradation of the lubricant.

Bulk shipments may be supplied in tank cars, tank trucks, or tote bins. Upon arrival
of bulk shipments, each product should be inspected visually for clarity and cleanliness
and checked for viscos, it with a handheld viscometer. Prior to unloading, each tank
should be gauged to ensure sufficient room. Tank lines and valves should be checked to
ensure that the product is being unloaded into the correct tank. If dedicated lines and
pumps are not being used, the system should be flushed with one to three times the
volume of the lines to prevent cross-contamination of products. Samples should be
obtained from the tank after unloading and labeled with product name, date, invoice
number, and batch
number. The samples should be stored for at least 6 months.

____________________________________________________________________________________________________
Yanbu Technical Institute 77
 Module 4 Lubrication Practices

A. Fire Protection:

The possibility of fire in a well-planned lubricant storage area is remote, assuming that no-
smoking rules are observed, that casual visits from other plant personnel are prohibited, that
oil drip is prevented or cleaned up promptly, that waste or wiping rags are stored in metal
containers and in minimum quantity, and that sparking or arcing tools are used only under
conditions of good ventilation.

Even so, insurance regulations will require installation of suitable fire-extinguishing

equipment and possibly a sprinkler system. The accepted foam-type device for smothering
is best. In a small storeroom, one or two hand units may suffice. In a larger area, a multiple-
gallon foam cart with adequate hose may be required.

B. Disposal of Lubricants:

is the last step that must be addressed in fluid management when the monitoring results
indicate that the oil is severely degraded and/or depleted of additives that cannot be
restored. Various options to consider include recycling, burning, land-filling, and re-refining.

The most appropriate method of disposal will depend on local regulations. These will clearly
be affected by the location, which makes the best method of disposal site-specific. Lubricant
disposal needs to be considered carefully on a case-by-case basis.

____________________________________________________________________________________________________
Yanbu Technical Institute 78
 Module 4 Lubrication Practices

Lubrication System and Maintenance work:

 When using a grease hand gun: always clean the end of the grease gun and the grease
fitting with a clean rag or towel.

 When using a grease hand gun: always know the amount of grease required and the
frequency. Ask a vendor’s lubrication engineer to assist in this area. Check and mark your
grease gun to ensure the amount of grease is known and can be visualized for each type
of grease gun one uses.

 Always take oil samples when changing oil in a gearbox.

 When installing a new gearbox, replace the oil 24 hours after installation to remove any
contamination that may have been washed from the gearbox cavity and gears.

 Always add hydraulic fluid into a reservoir using a filter cart.

 Never touch a hydraulic filter with your hand during installation. By touching the filter, you
will introduce contamination to the hydraulic system.

 Never accept leaks on any type of lubrication line or bearing. Identify the true problem and
make a permanent repair.

 ALWAYS read and follow lubrication instructions from an equipment manufacturer. If you
must change the instructions, contact the manufacturer first for comments.

In conclusion, lubrication can cause up to 80% of your equipment problems if not performed in
a disciplined manner.

____________________________________________________________________________________________________
Yanbu Technical Institute 79
 Module 4 Lubrication Practices

REVIEW QUESTIONS:

4.1 Define Frication?

4.2 What are the functions of lubrication?
4.3 What are the methods of applying lubricants?
4.4 What are the types of lubricants?
4.5 What are the “golden rules” of good lubrication?
4.6 What are the general rules of lubrications?
4.7 Mention with examples the different methods of lubrication?
4.8 What are the advantages of “Automatic Centralized Lubrication”?
4.9 What are the criteria for measuring the properties of oil?
4.10 What are the factors controlling “Lubricant Selection”?
4.11 What are the sources of lubricants?

____________________________________________________________________________________________________
Yanbu Technical Institute 80
IMMT 211

MODULE 5

BEARINGS
 Module- 5 Bearings

MODULE 5
INTRODUCTION:

Bearing is an equipment component. Its main function is to hold the shaft properly by
supporting it against the loads. Engineers take bearing design with extreme care, since it is
an important and critical component. Consequently, Bearings varies according to the design
needed (e.g. Loads, available space, cost, etc.). In this lesson, we will showcase the basics
of bearings

LEARNING OBJECTIVES OF THIS MODULE:

Instruction in this lesson should result in students achieving the following objectives:

 Identify bearing function

 Identify bearing classifications
 Compare plain and rolling bearing
 Identify the terminology of plain and antifriction bearing.
 Understand bearing housings and its types

KEYWORDS:
Bearing, friction, wear, replace, load, axial, radial, thrust, shaft, rolling, needle, tapered,
lubrication, split, Babbitt, rubber, race, cage, clearance, spherical, groove, mount, sleeve,
journal, bushing

_________________________________________________________________________________________________
Yanbu Technical Institute 82
Module- 5 Bearings

1.1 FUNCTION OF BEARINGS

Shafts, turning gears and wheels are held in place and protected from friction and wear by
bearings. Bearings perform the following jobs:

 Support the moving part.

 Reduce friction by reducing metal to metal contact.
 Reduce wear.
 Provide a replaceable wear surface.

Figure 3.0.1 Loads acting on bearings

_________________________________________________________________________________________________
Yanbu Technical Institute 83
Module- 5 Bearings

1.2 TYPES OF BEARINGS

There are two basic types of bearings:

 Plain bearings (also referred as bushings and journal bearings)

 Anti-friction bearings

Figure 3.2 Plain Bearings (Journal Bearings)

Plain bearings, provides a sliding contact between the mating surfaces. They are also
called “bushings” or “journal bearings”.

Figure 3.3 Anti-Friction Bearings (Rolling Bearings)

Anti-Friction Bearings (Figure 3.2) give a rolling contact between mating surfaces. They
do this by using rollers (Balls, needles, etc.)

_________________________________________________________________________________________________
Yanbu Technical Institute 84
Module- 5 Bearings

1.3 LOAD FORCES ON BEARINGS

Since one of the function of bearings is to hold and support the shaft, they are subjected
to two types of loads:

 Radial loads: loads which act perpendicularly to the shaft.

 Thrust Loads (axial loads): loads which act parallel to the shaft.
For this reason, bearings vary according to the design needed and the loads acting on the
shaft.

Figure 3.4 Different types of load acting on bearings

Bearings that used to withstand the radial loads are called redial bearings. On the other
hand, bearings that should support thrust loads are called thrust bearing. However, there
are some bearings that are designed to withstand both radial and thrust loads combined,
called tapered roller bearing.

_________________________________________________________________________________________________
Yanbu Technical Institute 85
Module- 5 Bearings

1.4 PLAIN BEARINGS

1.4.1 Plain Bearing Types:

A. Sleeve Bearings:
A sleeve bearing is a non-moving or rotating surface on which a moving part such as a shaft
slides or rolls. It usually depends on some type of lubrication to help reduce wear and
friction. Sleeve bearing there are two basic types of sleeve bearings now in common use
they are the single piece type and the split type

Figure 3.5 Split and single-piece bearing

Solid bearing or sleeve, usually made of copper, brass, bronze, or plastic. Split bearings,
are initially formed into a strip then rolled into final shape. Split bearings are usually made
of copper, bronze, or steel. This type, is normally constructed with a steel back lined with
bronze, or plastic. Both types support radial loads only.
Solid bearing has a fluted rubber structure supported by a rubber shell. The flutes in the
rubber form a series of passages that allow the lubricant, normally water, to flow through
the bearing. This bearing supports radial loads only.

Split bearing is normally used for engine crankshaft bearings. It is usually made with a steel
or bronze back with a softer Babbitt lining. However, there are linings such as copper-lead,
tin, or silver, which will be discussed later.

_________________________________________________________________________________________________
Yanbu Technical Institute 86