Belt conveyors are the most versatile and widely used type of conveyor. They can handle a wide range of materials and capacities over long distances. Belt conveyors are composed of the belt, idlers, pulleys, drive equipment, take-ups, and supporting structure. Conveyor belting typically uses rubber and cord materials. Belt conveyors use electric motors, speed reducers, and various drive arrangements. They also employ take-up systems and a variety of pulley and shaft component designs. Belt conveyors are used in many typical arrangements and applications.

1. CHAPTER THREE

2. BELT CONVEYORS
 Belt conveyors are the most versatile and widely used of all conveyors.
 They are suitable for handling a wide variety of materials.
 They can handle a wide range of capacities over longer distance than possible with other
types of conveyor systems.
 They are adaptable for performing numerous other functions such as weighing, blending
(combination) sampling and stock piling.

3.  The belt conveyor is composed of the belt, the idlers, the pulleys, the drive equipment,
the take-up and the supporting structure.

4. CONVEYOR BELTING
 The belt cover is made of special wear-and impact- resisting rubber compound with cord
breaker strips imbedded in tough rubber
Typical Cross-section of the Conveyor Belt

5. 1. Cotton-Fabric Ply-Constructed Belting: is the most widely used kind of rubber
covered conveyor belt, in which the fiber is made up of a number of layers or plies
of woven cotton fabrics of various weight.
2. Cord Belts are made up of longitudinal fibers or steel cords imbedded in rubber
provide greater strength, more flexibility and somewhat greater impact resistance.
3. Heat Service Belts are available for jobs where hot materials up to 1200C must be
handled.
Belt Idlers
 Idlers must be selected to properly protect and support the belt and load to be carried.

6. Types of Idlers

7. DRIVES
 Practically all belt conveyors are driven by an electric motor directly connected to a speed
reducer unit through a flexible coupling.
 A high-speed motor, which costs less and occupies less space, is preferred to a slow speed
motor.

8. Belt Conveyer Drive Arrangements

9. TAKE-UPS
 Allow for stretch and shrinkage of the belt due to variation of temperature and atmospheric
pressure.
 Insure that the maximum tension in the belt is sufficient to prevent undue sag between
idlers
 Insure that the tension in the belt in the back of the drive pulley is sufficient to permit such
pulley to transmit the load
Types of Take-ups for Belt Conveyors

10. PULLEYS, SHAFTS AND BEARINGS
 Pulleys for belt conveyors are usually welded steel, drum types, for maximum strength,
minimum weight, and for resistance to shock during handling and operation.
 The factors involved in pulley diameter selection include the amount of wrap, belt tension at
the pulley, space available, characteristics of the materials handled, belt life expectancy,
shaft and bearing size and size and ratio of reducer.
 The shaft and the pulley are treated as a single structure. • The resultant force on the bearing
(shaft) is the vector sum of belt tensions, pulley weight, and weight of the shaft.
 Note that the force on the shaft is opposite to the direction of the resultant force R.

11. TYPICAL ARRANGEMENTS
Typical Belt Conveyor Paths

12. DISCHARGING MATERIALS FROM THE BELT
Material Discharge Arrangements

13. MAGNETIC SEPARATION
Magnetic Separation

14. TYPICAL CROSS-SECTIONS
Typical Cross-sections

15. BELT CONVEYOR DESIGN CALCULATION
Basic Data Requirements
1. The material to be handled
2. Capacity peak or surge rate expressed in ton/hr
3. Path of travel
4. Feeding and discharge conditions
5. Operating conditions
6. Required life of installation
Preliminary Check
 Is the belt conveyor is suitable for the material?
 Is the angle of inclination is within safe limits? etc.

16. CAPACITY OF A BELT CONVEYOR
a. If the material to be conveyed is a unit load the capacity Q [tons/h] is calculated using
the following formula
where q = distributed load [kg/m2]
B = width of the belt [m]
v = velocity of the belt [m/s]
b. If the material to be conveyed is in bulk, then the capacity Q [tons/h] is calculated using
equation
where = the density of the mat [kg/m3]
A = the cross-sectional area of the material being conveyed [m2]
v = Velocity of the belt [m/s]
qBv
Q 6
.
3

Av
Q 
6
.
3


17. 
pQ
Q 

110
B
4)
+
(B
=
A
2
f A
2
=
A f
c

18. RESISTANCE FORCES

l
fq
r s

1
l
fq
l
fq
r
r
r s
s
'
'
'
'
'
1
'
1
1 




19. 
m
ml
fq
r 
2
H
q
r m

3

20. d. Discharging force
Fixed discharger:
Mobile discharger:
where a and b are discharge coefficients (Table 7.3).
e. Fixed resistance:
It takes into consideration frictional forces at the conveyor terminal bearing, at the conveyor
loading skirts and other minor power absorbing terms
m
aq
r 
4
b
r 
5
l
lo 2
.
0
60

)
(
1 o
s l
l
fq
r 

)
(
2 o
m
m l
l
fq
r 


21. The total resistance to motion, R, : is the sum of the resistances.
(fixed discharge)
(mobile discharge)
Belt Tension
 The belt tensions, in addition to their effect on power requirements they also influence the
design and selection of all component parts.
Loads on Drive Pulleys
4
3
2
1 r
r
r
r
R 



5
3
2
1 r
r
r
r 




22. We know that R =T-t. The relationship between T and t may be expressed
and can be expressed in terms of the number of cords and the width of the belt.
where  = coefficient of friction
= wrap angle
n = number of cords of the belt
B = the width of the belt in meters.

e
t
T

nB
t 50
min 

23. 
Belt Tension on a Horizontal Belt Conveyor
Belt Tension on an Inclined Belt Conveyor

24. 
)
(
2
2
'
1 n
o P
r
t
T 



25. NUMBER OF FIBERS
 After calculating the tension, T, it is possible to calculate the number of fibers in the nucleus
of the belt
where: n = number of fibers
K = resistance of one fiber per unit width (5 to 7 kg/cm) and
B = width of the belt
Power Requirement
 In order to determine the required motor power [kW], we use the total resistance R and
calculate the power N.
where: v = speed of the belt in m/s.
= efficiency of the electromotor
KB
T
n 

102
Rv
=
N

26. OSCILLATING CONVEYORS


27. Oscillating Conveyor with Variable Pressure on Deck
Vibrating conveyors operating frequencies
normally range from 200 to 3600 vibrations per
minute with an amplitude or stroke range from
0.08 to 3.75cm total movement.

28.  The velocity of the deck changes roughly as a sine wave whereas the deck displacement
rectilinearly.
 Its acceleration can be resolved into two components, a horizontal and a vertical
 In the forward stroke a particle of material with a mass m is subject to a vertical component
of inertia force press the load against the deck, a horizontal component of inertia force
tending to displace the load along the deck, and a friction force acting along the deck in the
direction of the stroke.

29. Basic Designs Basic elements
1. A trough supporting system.
2. The source of the controlled vibrating.
Reviewing of the elements:
1. The trough is the only portion of the vibrating conveyor that comes in contact with the
material being conveyed.
2. The base is primarily a means of mounting the conveyor and is usually of a simple design
incorporating structural steel members.
3. The trough supporting system's primary function is to control and direct the motion of the
trough
4. The drive is the prime element in a vibrating conveyor because it is the source of the
controlled vibration.
5. The reactor spring system can assume many forms including steel coil springs, flexible steel
or glass slats, rubber blocks, circular rubber toroids, and torsion bars.

30. TYPES OF OSCILLATING CONVEYORS
a. Flexmount Oscillating Conveyors are used for light duty applications. They have
simple construction, remarkably rugged, compact and require minimum maintenance
and attention.
b. Coilmount Oscillating Conveyor are rugged, well reinforced and require minimum
maintenance. The coil springs operate in the natural frequency rang. They are used
for medium duty service. The trough is supported by separate legs that are rubber
bushed at articulated points and do not require lubrication.
c. Torqmount Oscillating Conveyor are rugged, dependable and easy to adjust and
maintain. They are used for heavy and extra duty applications. Torsion bars fixed at
one end and steel backed rubber bushed at the other end, absorb the energy of the
trough movement at the end of the stroke at all points of support along the trough
length.

31. SELECTION OF OSCILLATING CONVEYORS
The selection of oscillating conveyors boils down to:
i. Determining the trough width for the required capacity
ii. Selecting the drive for the required capacity

32. CHARTS FOR SELECTION OSCILLATING CONVEYOR
Charts for Selection of Flexmount Oscillating Conveyor

33. Charts for Selection of Coilmount Oscillating Conveyor

34. Charts for Selection of Torqmount Oscillating conveyors

35. Charts for Selection of Torqmount Oscillating conveyors

36. CHAIN CONVEYORS AND BUCKET ELEVATORS
Chain conveyors employ single or double strands of continuous chains wrapped around head
and tail end sprockets.
The units are generally operated by motor drives attached to the head/drive shaft.
Material can be carried directly on aprons or pans or pushed in a trough by flights attached to
the chain(s).
The chain conveyor derives its name from the type of attachment, that is, apron, pan, or
flight.

37. APRON CONVEYORS
 Apron conveyors consist of a series of jointed overlapping or interlocking apron pans on
which the material is carried.
 They can handle abrasive materials that cannot be scraped along a trough, and as the
loading is readily controlled, it may be used as a feeder.
 As an alternative to a rubber belt, it can handle materials at a temperature higher than
1500C that cannot be handled with rubber.
Types of Conveyor

38. DESIGN CONSIDERATIONS OF APRON CONVEYORS

m
m
g l
q
f
f 
1

39. 
s
s
g l
q
f
f 
2
H
q
f m


3

40. 5. After calculating the maximum force required, maximum tension, T can be used
to find the stress on the shaft. The traction force R is equal to the maximum tension
T.
where p = the stress on the shaft[kg/mm2]
d = diameter [mm]
b = width [mm]
6. The power absorbed [kW]
where T = the maximum fraction force [kg]
v = velocity [m/s]
=efficiency (0.7 - 0.8)
db
T
p
2
 3
2
1 f
f
f
R
T 




102
Tv
N 

41. FLIGHT AND WIDE CHAIN DRAG CONVEYORS
 A flight conveyor consists of one or more endless propelling mediums, such as chain or
other linkage, to which properly spaced scrapers or flights for moving material along the
length of a stationary trough.

42. Wide chain drag conveyors
 do not have flights as the open links serve to move the material. These conveyors operate
at slow speeds generally 0.1 m/s or less.
 They are used for conveying abrasive materials like ashes, coal or sand. In addition one
typical application can be quenching hot materials

43. Bucket Elevator
 The typical bucket elevator consists of an endless chain or belt to which are attached
buckets for elevating pulverized, granular, or lumpy materials along a vertical or a steeply
inclined path.
 The driving traction element is a chain or a belt.
 Unit loads are conveyed with the aid of arms or candles attached to the traction element.

44. Bucket Elevator Components
The principal elements of a bucket elevator are:
1. Head shaft with pulley for belting or sprockets for chain
2. The drive, gear reducer, and motor drives,
3. Foot shaft with pulley or sprockets
4. Elevator buckets mounted on belting or chain
5. The elevator enclosure houses the bucket and belting or chain assembly and
generally provides mounting and enclosure for the rotating machinery Platforms,
ladders, and hoist beams arc frequently mounted on elevator housings for maintenance
access.

45. Types of Bucket Elevators
1. Centrifugal Discharge
The materials are discharged by centrifugal action as the buckets pass over the head wheel.
2. Perfect Discharge
The buckets are carried between two strands of chain snubbed under the head wheels to bring
them into an inverted position above the discharge chute. This is a slow speed machine for
fragile, sticky or slow flowing materials.
3. Continuous Bucket
The buckets are mounted continuously along the chain. At the head, the discharge from each
bucket is over the front of the preceding bucket, which forms a chute or guide to the fixed
discharge.
4. Gravity Discharge
Material is loaded as in type 1, but discharge is through gates in a trough is in flight
conveyors.

47. Design Considerations
 Buckets exist in a number of types used depending on application.
 The tendency of material to pack in the elevator boot is one of the factors deciding bucket
choice.
 Free-flowing non-packing material as, for example, grain is handled by high front round-
bottom buckets

49.  Chain can be selected knowing tight- (ascending) side tension only; however, for belt
selection, tight and slack-(descending) side tension must be known. In either case, in
calculating tensions for component selection may be taken.
Tight-side tension T must have an additional factor added to compensate for digging in the
boot. In tall and continuous elevators, digging forces are of less concern than in short or
spaced elevators. This is due to the compensating effect of materials design safety factors;
therefore,

50.  The power required to drive bucket elevators can be estimated, in most cases, from the
following equations:
 For spaced-bucket elevators with digging boot
N = 0.0194Hm' kW
 For continuous-bucket elevator with loading leg
N =0.0176Hm' kW
Where m’= material flow rate [kg/s]
H = vertical lift [m]

51. SCREW CONVEYORS
 The screw conveyor, one of the oldest and simplest methods used for the movement of bulk materials.
 The movement of the materials is forced through the trough by a rotating screw, which is formed by a
helical blade attached to the drive shaft 8, which is coupled to a drive 1and supported by end bearings
2,6 and by inner bearings 4.
 The trough 7 of the round-bottom shape is topped by a cover plate 3 with an opening 5 for loading the
conveyor.
 A similar unloading opening 9 is provided in the bottom of the trough. The loading and unloading points
can be located anywhere along the trough

52. CONVEYOR COMPONENTS
a. The Conveyor Screw consists of spiral flying mounted on a pipe and is made either right
or left hand to suit the screw rotation and the desired direction of material travel.

53. b. The Drive Shaft, End Shaft and Coupling
 The drive shaft supports the conveyor screw section and keeps it in alignment.
 The end shaft is located at the end opposite the drive shaft.
 Couplings are used to connect successive conveyors screw section when more than one
section is necessary to make up the total length of conveyor.

54. c. The End Seals
 The plate seal is an economical, effective sealing device, designed for exterior mounting
between the end bearing and the trough end. Split gland seals are designed for interior or
exterior mounting.
 The universal type of seal is arranged for use with waste packing or with cartridge type
lip or felt seals. Packing gland seals are effective means for sealing the conveyor both
internally and externally.
 Air purge shaft seals are arranged for attaching to standard or special trough
ends. A constant air pressure is maintained to prevent material from escaping from the
trough along the shaft.
d. The Conveyor Complete with the Trough and the Drive
 The trough is the enclosure in which the material is confined and guided in its movement.
A shaft mounted speed reducer makes a simple and compact drive combination.

55. Typical Drive Arrangements
 With specialized design, the unit may operate at a slope or in the vertical
position. There could be many drive arrangements to meet the practical
limitation like space, type of drive, etc.

56. TYPICAL APPLICATIONS
Screw conveyors serve a wide variety of purpose in many industries.
1. When the materials are extremely hot, cast screws and troughs may be used or the screws
and troughs may be made of high temperature alloy metals.
2. If the materials are sticky or viscous, ribbon flight screws may be the choice.
Furthermore, special coatings applied to the screw and troughs may also aid
the flow of the material.
3. When extremely abrasive materials are to be conveyed they may require screws and
troughs made of abrasion resistant metals or the screws may be provided with hard surface
flights.
4. When the materials are corrosive it may be desirable to make the conveyor screws and
troughs of stainless steel, Monel metal, nickel, aluminum, etc.

57. 5. When the materials are to be mixed or aerated, a conveyor screw of ribbon flights or cut
flights or one of these combined with paddles may be used to obtain the desired results.
6. If materials are to be heated or cooled, which conveying they may require jacketed troughs
arranged for circulating heating or cooling media.
7. When contaminable materials are handled they may require self lubricated bearings, screw
and trough construction which will eliminate pockets, creels, etc.

58. DESIGN CONSIDERATIONS
 The trough is commonly fabricated from flat sheet from 2 to 8mm thick.
 The screw pitch t = (0.5 to 1.0) D. The screw diameter D is at least twelve
times that for loads of uniform lump size and at least four times the maximum
lump size in case of un sized bulk materials.
 Conveyors handling heavy materials operate at around 50rpm and those designed to
convey light loads, at up to 150rpm.
 The cross-sectional loading of a screw conveyor is given by

59. Material 
Heavy-weight abrasive loads 0.125
Heavy-weight mildly abrasive 0.250
Light-weight mildly abrasive 0.320
Light-weight non abrasive 0.400
Values Capacity Factor
 The hourly capacity can be calculated by
 (degrees) 0 5 10 15 20
k 1.0 0.9 0.8 0.7 0.75
Values of k corresponding the Inclination 

60.  The speed of the conveyor
 The capacity formula can be rewritten,
where ,
t = pitch of the screw (lead) [m]
n = rpm of the screw
From practical experience,

61. Where:
𝑁ℎ= power requirement for horizontal conveyor
𝐶𝑜= friction factor
L = conveyor length [m]
And for sloping installation
Where : 𝑁𝑠= power requirement for inclined conveyor s
H = level difference
Load per meter [kg/m]

62.  Axial force, P [kg]
The friction factor is adopted based on experimental data.
Material
Flour, cereal, saw dust 1.2
Peat, Soda ash, pulverised coal, finely ground chalk 1.6
Coal (lump anthracite and bituminous, air dry brown), rock salt 2.5
Gypsum, dry clay, sand, cement, ash, lime, moulding sand 4.0

63. PNEUMATIC CONVEYORS
•Pneumatic conveying is a method of transporting bulk materials in the form of
powder, short fiber and granules over a pipeline as a mixture with air or due to
pressure of air. There are three basic system used.
a) Suction or Vacuum System utilizes a vacuum created in the pipeline to
draw the material with the surrounding air.
 These systems are particularly suited to moving material from multiple
pickup points to a single location, the reason being that the bulk of the
system's expense is in the terminal end where the receiver, rotary valves, and
vacuum source are located.

64. Pneumatic Conveyor - Vacuum System

65. b) Pressure-type System is ideally suited for conveying from one pickup Location to many
discharge locations.
• Generally, this type of system is more economical when going from one point to several.
A pressure system of this type generally conveys with a product-to-air ratio of about 20kg of
material per kg of air, or approximately 24kg of material/m3 of air (or 20 m3 of air/m3 of
product).
Pneumatic Conveyor -Pressure System

66. C)COMBINATION SYSTEM (PUSH-PULL SYSTEM)
 This is a system in which a sanction (permit) system is used to convey
material from a number of loading points and pressure system is employed
to deliver it to a number of unloading points.
Such installations are utilized when conveying over a long distance is required.

67. Applications and Limitations:
Pneumatic conveyors have many advantages:
 delivery of materials over a path capable of changing its direction in any
plane,
 processing of the material simultaneously with its conveying,
 an almost limitless number of loading and unloading points served by a single
system,
 air and gas tightness eliminating dust nuisance (pains) and dust hazards
 an almost totally automated conveying with considerable reduction of losses of
material,
 improved labor conditions and minimum of human attendance.

68. THE LIMITATIONS OF THE SYSTEM ARE
 high power requirements (15kWh/t, 10 to 15 times higher than mechanically
conveyors),
 rapid wear of equipment, the problem of dust recovery from the exhaust air
 inability to convey wet, caking (block) and sticky loads.

69. PNEUMATIC CONVEYOR COMPONENTS
Intake Units
One of the most delicate problems in pneumatic conveyors is the
introduction of material to the flow of air at a regulated rate
a. Nozzle Injector
Nozzle Injector

70. B. ROTATING VALVE
Rotating Valve
Stationary Screw Feeder

71. CONT’D
Suction Nozzle
Conveying Pipe and Changeover Valves

72. CONT’D
Separator

73. DESIGN CONSIDERATIONS
In pneumatic conveyor calculations given are properties of the material,
required capacity Q tons per hour and the configuration of the conveying pipe.
Required are:
1. Calculated (reduced) conveying length, Lred [m]

74. 2. CONVEYING AIR STREAM VELOCITY, = [M/S]
air 1
v    BL2
red
Values of Factor for the Size of Load Particles

Material
Particle Size

Powdered 1-1000(micron) 10-16
Granular Homogenous 1-10mm 17-20
Small Lumped Homogenous 10-20mm 17-22
Medium Lumped Homogenous 40-80mm 22-25
Where,  = factor for the size of load particles
γ1 = specific weight of the load particles[tons/m3 ]
B = factor assumed as equal to (2 to 5) 10-5 , the lower values being taken for dry powder materials.

75. 3. WEIGHT CONCENTRATION OF THE MIXTURE, :

Graph Showing the Dependence of the Weight Concentration of the Mixture  on the Reduced Conveying Length Lred
Note:Graph (1):
1. for dry free flowing materials of high specific weight (γ1 =
2.5 to 3.2 t/m3),
2. for materials of a lower specific weight (γ1= 1.8 to 2.5 t/ m3) but higher moisture content and
high abrasivity. Graph (2): for grain.
.

76. 4. Air consumption, 𝑉𝑜𝑙= [𝑚3
/s]
where Q = capacity of installation [tons/hour]
5. Conveying pipe inner diameter dp [m]
6.The required air pressure in the pipe, [kg/cm2]
Where: air= specific weight of the air (average for a given vertical section).

77. FOR PRESSURE CONVEYING SYSTEM;
Where,
= a factor; for pressure conveying systems,
 depends on the value of
 = 1.510 7
and for suction and for suction conveying system:
And for suction conveying system

78. • The plus sign before in equation is taken for upward, the minus sign for downward movement.
Graph Showing the Dependence of Factor  on the Value of s

79. 7. THE REQUIRED AIR PRESSURE OF THE COMPRESSOR OR AIR BLOWER, [KG/CM2]
Pb Pw  Ploss

80. 8. The required capacity of the compressor or blower, [m3/min]
Where: ='factor for losses due to leaks = 1.1.
9. The required motor power, [kW]
Where: Lb = theoretical work of the blower reduced to 1 m3 drawn in during isothermal
compression [kgm/m3].
 = total efficiency of compressors =0.55 to 0.75

81. THANK YOU