Conveyor Belt Troubles (Bulk Material Handling)

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International Journal of Emerging Engineering Research and Technology
Volume 2, Issue 3, June 2014, PP 21-30
ISSN 2349-4395 (Print) & ISSN 2349-4409 (Online)
©IJEERT www.ijeert.org 21
Conveyor Belt Troubles
(Bulk Material Handling)
G.Velmurugan1, Dr.E.Palaniswamy2,M.Sambathkumar3,
R.Vijayakumar4,T.M.Sakthimuruga5
1,3,4,5Assistant Professor, Mechanical Engineering,
Excel College of Engineering & Technology, Tamil Nadu,
2Principal, Excel College of Engineering and Technology, Tamil nadu
1gvelmurugan06@yahoo.co.in,2prof.eps@gmail.com, 3sambathkumarkm@gmail.com
4rvijayakumar0305@gmail.com, 5sakthirames@gmail.com,
Abstract: There are two main industrial classes of belt conveyors; those in general material handling such as
those moving boxes along inside a factory and bulk material handling such as those used to transport large
volume of resource and agricultural materials. Conveyor belt maintenance not only includes proper care of the
belt itself but also includes care and maintenance of the frame and accessories. The same way life of a conveyor
belt not only depends on good design and manufactures but also on the care and attention it receives in storage
and service.
The main damages are occurring in bulk material handling system due to the sticking of the material which is
transporting and the damages due to the chemical reaction and also there causes failure due to carry back of
product. The problems and failures need a permanent maintenance. The removal of sticking materials can be
done by two methods, by using a wire brush which is placing under the conveyor belt; it will remove the sticking
materials when the conveyor rotates. There is one more solution for this is problem to use a water spray under
the belt conveyor belt for the sticky materials
1. INTRODUCTION
1.1. Belt Conveyors
Conveyor belt came into vogue around 1868 when lyster an English engineer described to British
engineering socketing bulk materials by endless belts made of rubber faced canvas. A belt conveyor
has the advantage of simplicity of construction, high efficiency and low power requirements and
economic in upkeep. It may be horizontal or inclined or a combination of both can be arranged to
convey material either up or down and inclined.
These are mainly two type of conveyor belt :- flat and troughed. A flat belt is generally used for bag;
bottle, box and other packaged materials although under certain conditions loose material in bulk,
such soap may also be satisfactorily handled. A troughed unable the loading capacity to be increased
over 60% without danger of spillage and suitable for almost any bulk material in a dry, damn or
spillage and is suitable for any bulk material in dry, damn or semi wet condition. The life of a
conveyor belt not only depends only on good design and manufacture but also on the care and
attention it receives in storage and service.
Belt life is often shortening by one or a combination of following factors which can all we avoided:
Neglecting to obtain the manufactures advice before buying a belt for difficult or unusual
conditions.
Buying a poor grade of belt because it is cheap in first cause, though not suited to be work
expected of it.
Injury to the cover or edges by carelessness during installation of the conveyor.
Joint not square with the belt, thereby causing the belt to run crooked and the edges to wear.

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International Journal of Emerging Engineering Research and Technology 22
Neglecting to use that heat resisting belts for carrying hot materials.
Inadequate loading chutes, causing jams and jammed materials prematurely wearing belt covers.
Not providing rubber impacts idlers at the loading section where the materials carries is large and
lumpy.
Neglecting to repair immediately any damages to cover or fabric.
Inadequate lubrication of idlers, causing belt cover deterioration due to contamination.
1.2. Different Components of Belt Conveyors
The different components of the belt conveyor system are
a) The conveyor belt:
Belt is main part of the belt conveyor system. In belt conveyor system materials are transported from
one station to another through these belts. Belts are generally classified according to British standard
specification No.490 into three groups A, B and C. Grade A is used in severe abrasion or cutting
action. Grade B is used in moderate conditions of abrasion or cutting. The different types of conveyor
belt are the following;
a. Untreated cotton canvas belts.
b. The impregnated cotton and canvas belts.
c. Coated belts.
d. Covered belts.
e. Reinforced belts.
f. Integral cleat belt.
g. White finishes belts.
The belt conveyor system (BCS) consists of:
 Drive unit (electric motor, coupling multistage gearbox)
 Pulleys (drive pulley and other)
 Belts (textile or with steel cords) with their joints
 Idlers
 Other (belt cleaning systems, control system, etc)
Belt conveyor may be viewed as a part of bucket wheel excavator or dumping machine.
b) Drive Unit:
The drive unit consist of electric motor, damping coupling, two or three stage gearbox and coupling
that connect output shaft with pulley. A crucial object in this subsystem is gearbox. According to the
industry even 14% of gearboxes may be replaced each year due to unexpected failures.
Fig 1.1. Drive Unit
c) Pulleys:
Pulleys are generally made of steel fabricated construction. The pulley shell is connected to the two
hubs one at each ends with the help of two diaphragms. Rubber lagged pulleys are supplied to
increase the friction in between the belt and the pulley. The lagging is either plain or herring plain
bone grooves.

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International Journal of Emerging Engineering Research and Technology 23
The mining pulley consists of two bearings, shaft, shell and coating (special material in order to
improve belt-pulley contact).
d) The idlers:
The idlers consist if seamless steel tube rolls enclosed by pulley heads at each end and fitted with
stationary shaft, anti-friction bearing and seals. The generally used idlers are:
Toughing idler
Toughing trainer
Return idler
Return trainer
Impact idler.
The failure analysis of idlers and belts are a bit different issue. Idlers are used for supporting belts
with transported materials. In some sense idlers are similar to pulleys and consist of bearings and
shells. One may expect similar types of failures. The support system for belt consists of three idlers.
Because of different load for each idler usually side idlers are more subjected to damage. It needs to
be added that in CM context of idlers change of condition is not the only one. Worn bearings in idlers
will significantly increase external load for drive units so power consumption will increase. Damaged
idlers and pulleys may be the reason of damage for belts.
Figure 1.2. Types of Idlers
e) Take-ups:
Belt conveyors are provided with take ups which perform the following functions:
Maintain necessary slack side tension for the drive to operate the belt.
Keep sag of the belt between the idlers at appoint when required horse power will be at a
minimum and load will move with least disturbance over idlers.
Permit length variation due to belt elongation or shrinkage.
The following types of takes-ups have been used.
 Screw take ups: In this take ups the tail pulley bearings are mounted on guides. The bearing
mounting are moved manually by single screws by which the tension on the belt can be varied
suitably.
 Vertical gravity take-ups: This is the common type of automatic take-ups.the take up pulley
bearings are usually mounted on a yoke which moves vertically along two posts guides. Extra
weights can be added to the take-ups as requirements to maintain the belt tension.

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f) Skirt boards:
Skirt boards are used in conjunction with delivery chutes at tail end of the conveyor, to guide the
material while loading. It essentially consists of a fabricated frame firmly supported on the conveyor
structure. A skirt rubber is attached at the bottom keeping uniform pressure on the belting.
g) Scraper:
Scrapers are provided at the discharge pulley to clean the carrying side of the belt and to avoid the
wear of return idlers to build up of material. A scraper is provided at the tail end pulley to clean the
inner surface of the belt and to avoid any material going inside the gap between tail pulley and belt.
Generally steel blade or rubber / fabric scrapers are used.
h) Safety devices:
The following safety devices are normally incorporated in the belt conveyor systems.
Anti-roll back devices.
Limit switches.
Zero speed switches.
Sequence protection switches.
1.3. Basic Structure
A conveyor belt (or belt conveyor) consists of two or more pulleys, with a continuous loop of material
- the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving the belt
and the material on the belt forward. The powered pulley is called the drive pulley while the
unpowered pulley is called the idler.
There are two main industrial classes of belt conveyors; those in general material handling such as
those moving boxes along inside factory and bulk material handling such as those used to transport
industrial and agricultural materials, such as grain, coal, ores, etc. generally in outdoor locations.
Generally companies providing general material handling type belt conveyors do not provide the
conveyors for bulk material handling. In addition there are number of commercial applications of belt
conveyors such as those in grocery stores .The belt consists of one or more layers of material. They
can be made out of rubber. Many belts in general material handling have two layers. An under layer
of material to provide linear strength and shape called carcass and an over layer called the cover. The
carcass is often cotton or plastic web or mesh. The cover is often various rubber or plastic compounds
specified by use of the belt.
1.4. Conveyor Technology
A conveyor belt (or belt conveyor) consists of two or more pulleys, with a continuous loop of material
- the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving the belt
and the material on the belt forward. The powered pulley is called the drive pulley while the
unpowered pulley is called the idler. There are two main industrial classes of belt conveyors; those in
general material handling such as those moving boxes along inside a factory and bulk material
handling such as those used to transport industrial and agricultural materials, such as grain, coal, ores,
etc. generally in outdoor locations. Generally companies providing general material handling type belt
conveyors do not provide the conveyors for bulk material handling. In addition there are a number of
commercial applications of belt conveyors such as those in grocery stores. The belt consists of one or
more layers of material. They can be made out of rubber. Many belts in general material handling
have two layers. An under layer of material to provide linear strength and shape called a carcass and
an over layer called the cover. The carcass is often a cotton or plastic web or mesh. The cover is often
various rubber or plastic compounds specified by use of the belt. Covers can be made from more
exotic materials for unusual applications such as silicone for heat or gum rubber when traction is
essential.
Material flowing over the belt may be weighed in transit using a beltweigher. Belts with regularly
spaced partitions, known as elevator belts, are used for transporting loose materials up steep inclines.
Belt Conveyors are used in self-unloading bulk freighters and in live bottom trucks. Conveyor
technology is also used in conveyor transport such as moving sidewalks or escalators, as well as on

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International Journal of Emerging Engineering Research and Technology 25
many manufacturing assembly lines. Stores often have conveyor belts at the check-out counter to
move shopping items. Ski areas also use conveyor belts to transport skiers up the hill. A wide variety
of related conveying machines are available, different as regards principle of operation, means and
direction of conveyance, including screw conveyors , vibrating conveyors, pneumatic conveyors, the
moving floor system, which uses reciprocating slats to move cargo, and roller conveyor system, which
uses a series of powered rollers to convey boxes or pallets.
Fig 1.3. Conveyor Technology
2. PROBLEM IDENTIFICATION
 Some sticky materials present a real challenge when it comes to preventing carry back.
 The belts may be reversed to allow better release at the discharge point.
 A dual scraper system on the head pulley is the most common way to eliminate product carry
back.
 A water spray on the belt cover along with wiper blades will effectively remove most products
from sticking to the cover.
 The most frequent failures for pulleys are: bearings and shells. For gearboxes number of failures
related to geared wheels is 50%.
 Other critical failure is the damage of input shafts (probably because of overloading). It may be
surprising that bearing faults are not so frequent in gearboxes.
Fig 1.4. Driving Unit
2.1 Failure of Conveyor Belt
The failure of the conveyor system is not only due to the damage of the belt but also due to the errors
occur in related parts, such as pulleys, motor, shaft, bearings, etc.

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Figure 2.1. Corrosions affected drum
For gearboxes number of failures related to geared wheels is 50%. Other critical failure is the damage
of input shafts. Most of the failures caused to related parts of conveyor belt will be due to some
reasons like overloading, rough loading, and due to some input problems. The action of the chemical
is also causes the failure in the related parts of the conveyor belt. The constant maintenance is very
important to avoid these failures which causes very huge loss to the company.
3. MAINTENANCE
Definition
It is defined as the set of activities on all plants and machineries, to maintain the same at prime
condition in economic ways, for smooth running of plants for the achievement of organizational
objectives. Prime condition refers to that the plant and machinery shall be in good condition for
efficient and effective utilization of the same for the functions for which it is designated and installed
for.
Objective
To ensure the maximum availability and reliability of their plant and machinery at an optimum cost
for uninterrupted operation of all units for the achievement of organizational goals with respect to
targets and to meet standards of environment, safety and ISO’s standards and conditions.
3.1 Types of Maintenance
Maintenance is classified mainly on the basis of nature of activities performed.
a) Preventive Maintenance
It is the set of activities performed on equipment periodically by improving the operational
atmospheres, to prevent any possible failures. The activities performed are checking of all fasteners
and bolts, checking of lube oil conditions, checking of other ancillary facilities like cooling water, seal
cooling system, seal quenching system, operating parameters like suction pressures, temperature,
discharge pressure, any abnormal noise, condition of seals or packing’s etc. The abnormalities are
corrected without disturbing the functioning of the plant. Preventive maintenance check depends upon
the criticality of the equipment.
 Critical equipment-
These are the running equipment having standby but whose failure will affect the production of
the plant directly. For these equipment Predictive maintenance is done once in 15 days.
 Semi-critical equipment
These are having standby and are used in production line. Predictive maintenance check is done
once in 30 days.
 Non critical equipment
These are not in production line and are used as standby. They are checked once in 3 months.
b) Predictive Maintenance or condition monitoring
The main step is to monitor the condition of the equipment under operation. This includes observation
and data collection on equipment’s, which are on line. The collected data will be analyzed and
possible abnormalities are derived and corrective measures are prescribed. All machines vibrate in

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International Journal of Emerging Engineering Research and Technology 27
operation. If any problem occurs there will be an increase in vibration. The unique characteristic of
increased vibrations can be analyzed and the problem developed in the equipment can be determined
by the nature of the vibration. To cover all equipment of plant under condition monitoring each
equipment is grouped based on its criticality/plant and a schedule is drawn to cover all equipment and
condition monitoring is performed on these equipment’s as per schedule. The set of activities carried
out are:
Physical observation of the machine in operation, the engineering parameters like RPM, bearings, no.
of blades or vanes, belt, coupling type, lubrication type, process fluid, mounting conditions are
checked and noted down. For gear boxes, no. of teeth and rpm and for electric motors, KW rating,
Volt and current, rpm are noted. The history of machine also is studied. After this the vibration data
collection is done on the machines and the following four stages of the condition monitoring is done
on the machines.
Detection
Analysis
Correction
Verification
c) Corrective Maintenance
It is the overhauling of equipment, checking alignment etc. Overhauling of equipment is done by
removal of equipment, dismantling/disassembling, inspection of parts, replacement of parts as found
necessary, reassembling and reinstallation. After reinstallation of equipment alignment of the driver
and driven equipment is carried out and then coupled.
Corrective maintenance is of two types - Planned and unplanned
i) Planned corrective maintenance:-
Planned corrective maintenance is adopted when trend (vibration, performance etc.) shows
deterioration in health of equipment. During annual turnaround the critical equipment like centrifugal
compressor, turbine, critical centrifugal pumps, reciprocating compressor, slide valve etc. are
inspected and necessary corrective actions are taken.

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Periodic condition monitoring indicates health. If trend indicates that there is constant increase in
vibration level, noise level etc or the flow has gradually reduced, the problem is analyzed. Analysis
reveals a problem increase in misalignment or increase in deterioration of bearing etc. The loss of
flow may be due to suction strainer blockage, increase in internal clearance etc. Appropriate
corrective actions are adopted. If needed a total overhaul is carried out.
ii) Unplanned corrective Maintenance:-
Unplanned corrective maintenance is adopted when failure of equipment occurs. Overhauling is
carried out depending on nature of failure. Overhauling refers to dismantling of parts, inspection, and
replacement of worn out parts and reassembling of parts. During reassembling the important points
are taken care of is the replacement of worn out parts, restoration of internal clearances and centering
of the rotating element with respect to stationary element both in radial and axial direction.
d) Mechanical Maintenance
a. Cleanliness
Both exterior and interior of every machine should be kept free from dust oil and moisture. Dust can
have a harmful effect if it is allowed to settle on the windings, to enter the bearing or to collect in the
ventilating passages. Motor should be blown out periodically depending on the atmospheric
conditions at site.
b. Lubrication
The original grease should not be removed unless the grease has become dirty or has deteriorated. The
hands must be perfectly clean and smeared with good quality material oil before any bearing is
handled.
A small quantity of old grease will unavoidably be left in the bearing and if this is clean and in good
condition it should be left rather than washed out with petrol to which a small quantity of lubricating
oil has been added. Before a bearing is packed with grease, a few drops of clean lubricating oil should
be introduced into the bearing. Lithium based multipurpose grease conforming to Grade 3 of ISO
1002-1956 amended up to date , is recommended for all machines fitted with antifriction bearings.
The approved grease is Castrol Ball Bearing Grease AP3.This safe operating temperature range for
the above grease is -25 to 120 degree Celsius (approx. value).
c. Bearing replacement:
Before replacing the bearings it is recommended to heat the new bearings in medium oil say ‘shell
Tellus-33’ at a temperature not exceeding 90 degree Celsius for about one hour to enable easy
mounting by push fit and avoid hammering of bearing which may result in premature failure of the
same. When bearings are removed from the motors or uncovered due to partial dismantling, wrap
them in a clean journal immediately to keep them free from dirt.
4. METHODOLGY
4.1 Dual scrapper system
Figure 4.1. Dual Scrapper System
A conveyor system with carry back on the return side is the single biggest reason that conveyor belts
are replaced, return idlers and pulleys are replaced and structure is worn through. Material build up on
the belt and hardware causes tracking problems that will lead to edge damage that leads to new belt
and new idlers. We urge you to use scrapers on the head pulley and plows in front of the tail pulley as

Belt Coveyor Troubles (Bulk Material Handling)
International Journal of Emerging Engineering Research and Technology 29
prevention for damage in your maintenance planning. Some sticky materials present a real challenge
when it comes to preventing carry back.
We would like to offer a few additional suggestions as to handling these products. Cleated belts may
be reversed to allow better release at the discharge point.
4.2 Brush System
A water spray on the belt cover along with wiper blades will effectively remove most products from
sticking to the cover. A series of out of round (cam shaped) return idlers will also assist in cleaning.
These idlers are spiral wound from the edges towards the center of the idler and work on the premise
of a turning beater bar arrangement. A compressed air blast has been successfully used on material
like coal and fine wet sand. A power driven revolving brush will help remove product from the belt.
This method is rarely used because the bristles tend to clog up with material and wear out quickly. A
brush may be the only solution for cleated belts. Product build up on return side pulleys is a major
concern.
Fig 4.2. Brush System
If your belt is not effectively clean on the return run, then any bend pulleys or head snub pulley that
come in contact with the carry side of the belt will accumulate product. We would like to offer a few
hints on pulley and idler cleaning. All return side pulleys that come in contact with the carry cover can
be lagged with a soft rubber vulcanized to the pulley. The constant flexing action of the soft lagging
will cause material to fall off and reduce material accumulation. A lever weighted urethane scraper
pressed against the pulley face, is an excellent way to remove build up. This system causes additional
wear on the pulley face so it is suggested to use heavier walled return bend pulleys when using a
scraper. If a scraper is applied to a head snub or bend pulleys at the take-up area then deflector plates
will have to be installed.
4.3 Rubber Scraper
Figure 4.3. Rubber scraper
Keeping the return rolls and snubs clean requires that the belt be clean when it enters the return run.
Scraping is the most common method of doing this rubber scrapers can be made by clamping rubber
slabs ½" to 1" thick between two metal or wooden bars. Extend the rubber about twice its thickness
beyond the bars and suspend the mechanism with a counter-weight to provide the pressure against the
belt. Replace the rubber when it wears down near the bars. Two or three such scrapers can be used in
succession.

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International Journal of Emerging Engineering Research and Technology 30
The most common steel scraper is a series of diagonally set blades mounted on the end of a leaf spring
to maintain pressure against the belt. These will scrape sticky materials which rubber scrapers may
ride over. It is preferable to clean just after the head pulley and before the snub. An exception to this
is that sticky material often requires scraping on the head pulley. This is because a large part of the
fine material sticks to the belt and must be scraped into the chute. Washing the belt with a water spray
before wiping with a rubber scraper will do a good cleaning job on almost any material.
5. CONCLUSION
The problems were found in different conveyer system was improper alignment of idlers, belt running
off at tail pulley, excessive wear on bottom of belt and corrosion in the frame.
We implement the strategy of preventive maintenance as the first step of our project, by this
maintenance future maintenance cost is saved. Regular maintenance and proper lubrication can keep
maintain alignment of idlers. Adjust loading material to properly center the load helps in reducing belt
running off at tail pulley. Greasing and painting can reduce corrosion in frames and drum. Use of dual
scrap system, brush system and rubber scrapper helps in effective running of the conveyor belt. By
following these methods the tendency to breakdown maintenance reduces and gradually the yearly
maintenance cost suppresses thereby profiting the companies.
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