Conveying
Conveying
Conveying
Objectives _____________________________________________________________________________________________4
Objective 7
Definition of conveying: 7
Objective 11
Accumulation _________________________________________________________________________________________13
Objective 13
Dynamic accumulation 14
Objective 17
Line Rating 17
V-profile 19
Objective 20
Major Components 20
Can Conveyor 21
Conveyor Chain 22
Widths of Conveyors. 24
Objective 25
Nesting Pattern. 27
Objective 29
Page 1 of 90
Transfers 29
Dead Plate 29
Dividers 31
Combiners 32
Objective 36
Conveyor drives 36
Conveyor controls 39
Conveyor lubrication 41
Objective 43
Combiners 43
Parallel transfers 43
Objective 46
Objective 50
Crate Accumulation 50
Crate transfers 51
Crate turners 53
Objective 55
Objective 57
Conveyor controls 58
Objective 59
Types of pallet 61
Page 2 of 90
Objective 62
Types 62
Pallet magazines_______________________________________________________________________________________64
Objective 64
Objective 66
Conveyor controls 67
Safety ________________________________________________________________________________________________69
Objective 69
Nip-points 71
Safety Features 72
Questions ____________________________________________________________________________________________78
Answers 90
Page 3 of 90
Objectives
Having completed this course the student should have achieved the following objectives:
Types and construction of bottle and Cover the types and construction of bottle and
can conveyors can conveyors.
Guide rails and nesting patterns Identify the types & operation of guide rails &
the concept of nesting patterns.
Transfers, dividing and combining Cover the concept of conveyor transfer, flow
dividers and flow combiners.
Drive systems, control systems and Identify the common drive systems, control
lubrication systems and lubrication maintenance of
conveyors.
Types and construction of crate and Identify types and construction of crate and
case conveyors case conveyors.
Page 5 of 90
Types of conveying systems
Objective
There are many different types of conveyors in use in industry. In the brewing industry,
conveyors are used to transfer brewing materials such as malt and adjuncts; and
packaging materials such as pallets, crates, bottles, cans, kegs, cartons, trays and crown
corks. Transportation can be by gravity, mechanical, fluid, air driven or by vibration.
Definition of conveying:
The systems and mechanisms used to move materials or product from one location
to another.
Page 7 of 90
Vibrating Conveyors: Simonazzi label
extraction systems use a vibrating plate to
convey labels from within the label
extraction drum. The plate shakes
backward and forward, but is angled so
that the labels gradually slide to the catch
tray. This has the advantage of allowing
liquid detergent to return to the tank
through holes in the plate.
Page 8 of 90
Trough Belt Conveyor : This uses a
flexible belt which forms a trough shape
due to the angle of the support rollers and
the weight of the material being moved.
Frequently used for moving ore, coal etc..
Page 9 of 90
Conveyors found in the bottling hall
Although there is an almost unlimited variety of different conveyor types found in industry,
we can categorise the conveyors we find in the bottling hall into 4 groups:
Pallet Conveyors
Bottle/can conveyors
Crate/Tray conveyors
Pallet conveyors
Auxiliary conveyors
Page 10 of 90
Conveyor manufacturers
Objective
There are many different conveyor manufacturers, partly because the manufacture of
conveyors requires much less in the way of specialised engineering equipment than
does the manufacture of, for example, a bottle filler. There are thus numerous
companies who build conveyor sections and conveying systems.
We have here included only the manufacturers of complete conveying systems who also
produce packaging machinery.
Manufacturer
Page 11 of 90
Simmonazzi (Italy)
Page 12 of 90
Accumulation
Objective
Accumulation is the storage of production units that are not yet required by the next
production stage. For example, the bottle washer may produce more washed bottles
than the filler requires for filling. These bottles are stored on a conveyor, and can be fed
to the filler later on, for instance when there is a problem that causes the bottle washer
to stop production.
Accumulation thus allows short line stoppages to be accommodated (for example a jam
at the washer infeed) by supplying product to the next machine (for example the filler)
until the first machine is running again.
The accumulation table is controlled by sensors mounted on the conveyor either side of
the table. When the conveyor is full of bottles, the table matt moves inwards/backwards
so that it is filled up with the excess bottles. However, this accumulation table is not
FIFO (first in - First out) concept.
When the conveyor sensors indicate that the conveyors are empty then the table matt
moves towards the conveyors feeding the bottles back onto the conveyors.
Page 13 of 90
Dynamic accumulation
Mass bottle conveyors (conveyors more than one chain wide) are designed to have more
space on them than is needed to convey the bottles from one machine to the next.
A typical bottle conveyor arrangement is shown above. Each conveyor is six slat-
chains wide, the red lines indicate the conveyor guide rails.
Page 14 of 90
When the two machines at either end of the conveyor are running normally, the
conveyor will be loaded approximately half full as shown below.
The UPSTREAM machine is the machine supplying the conveyor, the downstream
machine is the machine that is supplied BY the conveyor. To remember this, think of the
conveyor as a flowing river.
If the upstream and downstream machines are at the same speed, then the same
number of bottles are fed onto the conveyor by the upstream as are removed by the
downstream machine. The amount of conveyor available for use by the bottles is known
as its transit capacity.
If the downstream machine is now stopped, the conveyor fills up until the upstream
machine is forced to stop because there is no more space on the conveyor.
Page 15 of 90
The amount of bottles that can be added to the conveyor in excess of the transit
capacity is the conveyors dynamic accumulation.
Dynamic accumulation can only be measured after the conveyor has been loaded to its
transit capacity. The total number of bottles on a conveyor is not its accumulation
capacity!! (The total number of bottles on the conveyor is called the static
accumulation).
The dynamic accumulation is usually expressed in time, so that at rated line capacity, if
the conveyor is loaded to its transit capacity and the downstream machine stops, the
time for which the upstream machine can continue running at rated speed is the
dynamic accumulation time.
Depending on machine reliability, line design may provide for between 2 and 5 minutes
of dynamic accumulation between each major packaging machine.
Page 16 of 90
The V profile
Objective
Line Rating
If the upstream and downstream machines connected by the bottle conveyors shown
below could operate perfectly, then no accumulation would be necessary.
We should thus be able to see that accumulation and machine running speeds are
closely related. In beverage packaging lines we usually have a line rating, the speed at
which the line should run continuously. This rating is usually the maximum capacity of
the filler. It is this rated speed that is used to calculate the efficiency of the line. The idea
is to keep the filler running continuously.
Page 17 of 90
Machine speeds upstream of the filler
The machines that supply bottles to the filler each run progressively faster than the filler.
The bottle washer may be 15% faster than the filler, and the unpacker 20% faster.
The bottle washer is thus continuously trying to fill up the conveyor feeding the filler. If
the bottle washer stops, the filler utilises the bottles on the conveyer. Once the washer
is running again, it runs at a faster speed to fill up the spaces on the conveyor.
The machines that take bottles away from the filler each run progressively faster than
the filler. The labeller may run 15% faster than the filler and the packer 20% faster.
The labeller is thus continuously trying to empty the conveyor between the filler and the
labeller. If the labeller has to stop, the space on the conveyor allows the filler to keep
running until the conveyor is full. Hopefully the labeller will start running again before the
filler has to stop. The labeller must then run at a higher speed to empty out the
conveyor and provide spaces before another labeller stoppage occurs.
UPSTREAM of the filler we try to keep the filler supplied with bottles, DOWNSTREAM
of the filler we try to keep the filler supplied with space on the conveyors so that it does
not have to stop.
One of the common habits observed with labeller operators is the setting of the labeller
speed to be equal to the filler speed. By doing this you effectively remove the
accumulation between the filler and labeller. As soon as the labeller stops the filler also
has to stop because the conveyor is never emptied. With the labeller running at the
correct speed the filler stop could have been avoided provided the labeller stopped for
only 2-3 minutes (about 15% of filler capacity).
Page 18 of 90
V-profile
When the upstream and downstream speeds of the various machines on a packaging
line are drawn on a graph, they should form a V shape as shown below.
This gives the lines V-profile, the set of machine running speeds that will make the
best use of the available accumulation and ensure the most efficient operation possible.
130
125
Percentage of 120
Filler Rated 115
Capacity 110
105
100
Depalletiser
Filler/Crowner
Empty Bottle
Unpacker
Pasteuriser
Palletiser
Washer
Labeller
Packer
Bottle
Inspector
Machines
The speeds shown here would apply to a typical returnable bottling line.
If, in this case, the filler is rated at 45000 bottles per hour, then the depalletiser, at 125%
(see graph above) of this, would run at a speed of:
Page 19 of 90
Types and construction of bottle and can conveyors
Objective
Major Components
Modern bottle and can conveyors are manufactured from a frame of stainless steel, on
which the slat chains are driven by a motor and gearbox.
Page 20 of 90
Can Conveyor
Can conveyors use either a plastic slat chain or a plastic roller chain, as a stainless steel
slat chain would cause damage to the cans.
Page 21 of 90
Conveyor Chain
Page 22 of 90
Straight or Curved Conveyors.
The chains on the conveyor are supported by plastic strips called SLATS. The slats are
in fact a wear strip made of plastic (usually ultra-high molecular weight poly-ethylene or
certain grades of Nylon). The wear strip supports the conveyor chain, and provides a
guide for the chain, as the chain links and pins fit inside of the gap between the wear
strips (or slats).
Page 23 of 90
Widths of Conveyors.
Page 24 of 90
Guide rails and nesting patterns
Objective
Identify the types & operation of guide rails & the concept of nesting patterns.
Page 25 of 90
Purpose of Guide Rails.
The purpose of the guide rails is to prevent bottles from falling and to deflect the bottles
along the desired path. This must be achieved without metal to glass contact at any point,
as this will scratch and scuff the bottles, and without contacting the labels after the
labeller.
The positioning of the guide rail is important in directing the bottle flow, without causing
excess pressure that leads to jams and bottle locking.
Here the guide rail follows a parabolic curve, which gradually diverts the bottles onto the
second conveyor.
Secondly the distance between the guide rails on either side of the conveyor determines
whether the correct nesting pattern is achieved.
Page 26 of 90
Nesting Pattern.
Below a good nesting pattern is shown, all of the bottles are arranged in neat rows with no
holes in-between.
Page 27 of 90
Correct guide rail settings
The correct guide rail setting for a bulk bottle conveyor is given by the formula:
W = D + ((N-1) x D Cos 30 )
Where W = the distance between the conveyors, D = the bottle diameter and N = the
number of bottles nested across the conveyor at the degree angle.
In the diagram above, if the bottle diameter = 100mm (D), N = 6 and Cos 30 = 0,866
W = D + ((N-1) x D Cos 30 )
W = 100mm + (5 x 86,6 )
W = 100mm + 433mm
W= 533mm
For a single lane conveyor, the correct guide rail setting is merely 3mm more than the
bottle diameter:
Page 28 of 90
Transfers, dividing and combining
Objective
To cover the concept of conveyor transfer, flow dividers and flow combiners.
Transfers
In general, bottle conveyor transfers can be either of the parallel type or of the type
shown below which is a 90 degree transfer using a deadplate.
Dead Plate
A dead plate is an un-driven joining plate between two conveyor chains. It is a point at
which containers may fall, and a point where containers may be left standing when the line
is run empty.
Page 29 of 90
Some of the different conveyor transfers used on bulk accumulation conveyors are:
In all cases the deadplate must be exactly level with the conveyors, and must be smoothly
polished. Fixing screws must be countersunk:
With aluminium cans, which are very light and prone to falling, the slightest misalignment
of the deadplate can cause fallen containers.
Page 30 of 90
Dividers
Dividers are used to divide a single stream of bottles into two or more separate streams.
They are commonly found before twin machines, and also before tunnel pasteurisers when
the pasteuriser has two separate decks.
If properly designed, bottle dividers should not give too many problems. Difficulties occur
when, as below, the divider is immediately followed by a combiner that is merging the
bottles into a single lane:
Page 31 of 90
Combiners
Possibly the most problematic area of container conveying is the combining of a mass of
bottles into fewer rows or a single lane.
Combiners are either conventional pressure types (with guide rails on both sides of the
bottles) or pressure-free combiners (PFC) where on one side no guide rail is needed.
Page 32 of 90
Pressure type combiners use various devices to prevent the bottles from locking as they
are channelled into a single lane. Here the guide rail consists of a set of rollers:
Here the bottles are combined in an S-curve or snaking pattern. The movement across the
conveyor caused by the S-curve helps break up any bottle locking or bridging across the
guide rails.
Page 33 of 90
Here a vibrator is fitted to the guide rails. It shakes at a high speed and helps to prevent
bottle jams.
Page 34 of 90
Pressure free combiners
Page 35 of 90
Drive systems, control systems and lubrication
Objective
Identify the common drive systems, control systems and lubrication maintenance of
conveyors.
Conveyor drives
Page 36 of 90
An alternative method of controlling the
conveyor speed is to use a variable speed
gearbox, as shown here. An encoder is
used to measure the speed of the drive
and provided feedback to the VSD.
Turning the handle on the side of the gearbox moves the motor as shown by the arrow.
This changes the gear ratio and thus the speed of the conveyor.
Modern conveyors have the drive motor bolted directly to the conveyor frame.
A frequency converter changes the frequency of the current supplied to the motor. At a
frequency of 60Hz the motor will run very fast, at 20Hz it will run very slowly.
Page 37 of 90
The frequency converter in this panel is
the red box. The converter can be
programmed to give a range of
different speeds for different operating
conditions, and to allow for a gradual
speed increase and decrease of the
motor, which reduces power
consumption and provides a smoother
conveying operation.
Page 38 of 90
Conveyor controls
Conveyor controls use capacitive or inductive proximity switches to detect the amount of
bottles on a conveyor and then stop/start or speed up/slowdown the conveyor accordingly.
For slow speed lines (up to 400 containers per minute) it is sufficient to have a few build-
back sensors that are linked to a control system that stops the appropriate conveyor drive
when the sensor is activated (which means the conveyor is full).
For high-speed lines a more sophisticated system is required. Each conveyor may have
more than one sensor, so that different operating speeds can be used. If the conveyor is
empty then it may run at 150% of normal speed (catch-up speed), and depending how full
it is it may run at 100%, 50% and then stop once it is completely full. This is called
Modulated Speed Control, and gives maximum use of accumulation as well as gentle
bottle handling .
Page 39 of 90
Overhead sensors do not require the
cleaning and adjustment that photocells
need. They are available as capacitive (for
uncrowned bottles) or inductive (for crowned
bottles). They can however give false
signals if the nesting pattern is not
maintained. If a void in the nesting pattern
falls under the sensor, the sensor may
indicate that the conveyor is empty when in
fact it is full.
Page 40 of 90
Conveyor lubrication
Bottle conveyors require a lubricant on the surface of the conveyor chain to reduce the
friction between the bottle and the steel chain. This lubricant is usually applied in the form
of a liquid soap, diluted to 1% or 2%, and sprayed onto the chain as a liquid.
Here conveyor lubricant is delivered in a bulk container which is connected to the pump
(mounted on the wall) and then distributed to the bottle conveyors by the pump.
Distribution systems utilise either plastic or stainless steel piping. The piping supplies a
manifold at the beginning of each conveyor, with spray nozzles fitted to the manifold.
The spray nozzles direct a precise amount of diluted lubricant onto the conveyor chains.
Insufficient lubrication will lead to bottle jams, fallen bottles and cause the conveyor drive
motors to overload. A frequent cause of several motors tripping due to overload is often
insufficient chain lubricant.
Excess chain lubricant tends to form foam which builds up on the sides of the bottles. In
front of the Empty Bottle Inspector (EBI) this can cause bottles to be rejected as the EBI
sees the foam as if the bottle is dirty. After the Labeller excess foam can mark and stain
the bottle labels.
Generally chain lubricant is not needed on can conveyors, as the cans are coated with a
varnish that has a low coefficient of friction. However, with aluminium cans frequent
Page 41 of 90
conveyor cleaning is essential, as the aluminium that rubs off of the base of the cans
builds up to form a sticky and abrasive compound.
This bearing has been installed without a grease nipple being fitted. It will have an
operating life of about 5000 hours, after which it will fail.
For a single shift operation this may be adequate, but for a multiple shift operation the
bearing must be fitted with a grease nipple and lubricated weekly.
Page 42 of 90
Design parameters
Objective
To cover some design parameters of conveyors and the effect of design on performance
efficiency.
Here we explain a few of the more important concepts, but this is not an exhaustive
compilation of conveyer design specifications.
Combiners
The deflection angle on the guide rails should be as small as possible, ideally less than 10
degrees:
Parallel transfers
Parallel transfer units should have a length of at least 1,8m where one or two 81.25 mm
chains are used, increasing to 2,8m when eight to ten 81.25 mm chains are used.
Page 43 of 90
Incline or decline angle: the angle of incline
or decline of any conveyor should be equal
to or less than 3 degrees from the horizontal
to prevent bottles from falling. Picture shows
an incline conveyor under the subject of
incline conveyor angle.
Page 44 of 90
The chain drive and idler sprockets are
available as one-piece or split sprockets.
The split sprockets are not as durable, but
are easier to replace.
Dead plates should be as short as possible, must be exactly level, must have countersunk
screws and must allow the smooth transfer of containers.
Page 45 of 90
Types and construction of crate and case conveyors
Objective
Crate conveyors convey plastic crates, case conveyors convey cardboard cases or
boxes, and tray conveyors convey cardboard trays. All three types will be considered in
this section.
Modern crate and case conveyors often have a frame of stainless steel, though mild steel
is also used, particularly in dry areas.
Page 46 of 90
Types of case Conveyors
Note: Wherever a guide rail is used it must be plastic and there must not be metal parts
touching the crates. Metallic guide rails can cause scratching and scuffing of the crates,
which must be avoided as they are expensive and designed to last for several years.
Page 47 of 90
Different types of crate conveyor slat chain are available:
Page 48 of 90
Different types of crate conveyor roller are available:
Page 49 of 90
Accumulation, dividing and combining
Objective
Crate Accumulation
Unlike bottle conveyors, crate and case conveyors are almost always single lane
conveyors. There are no bulk conveyors to provide dynamic accumulation, thus
transfers are relatively simple. The reasons that single lane conveyors provide sufficient
accumulation are:
The crate or case conveyor will provide significant dynamic accumulation if it is of the
roller or slat-chain type.
Each crate accumulated will itself accumulate between 10 and 25 bottles, depending
on the crate used.
Crate accumulation is only really needed between depalletiser and unpacker, and
between packer and palletiser. This is achieved with relatively long single lane crate
conveyors.
Page 50 of 90
When the downstream machine stops, a total of 12 crates will be fitted onto the
conveyor (11 are shown). The dynamic accumulation is thus 12 crates for this short
section.
Crate transfers
Crate transfers from one conveyor to the next are relatively simple because the
conveyors are normally single lane.
At the point of transfer, idle rollers may be fitted to bridge the gap between the two
conveyors. This prevents the crates from rocking or falling as they cross the gap.
The idle roller is not driven, it merely supports the crates and is the equivalent of a
deadplate on a bottle conveyor.
One area where crate transfers are more complex is on the depalletiser unloading table.
Here the crates have been unloaded onto the table and need to be separated into a single
lane.
Page 51 of 90
Image courtesy KHS
To do this the accelerating roller pushes each row from the table and onto the discharge
conveyor. As soon as a row moves onto the roller, the table conveyor must stop so that
the rows are separated.
Page 52 of 90
Crate turners
In our example of the depalletiser table, the crates have been divided into a single lane
conveyor.
However the orientation is still random. The orientation of a crate can be LONG edge
leading or SHORT edge leading.
When the crates are discharged from the depalletiser, some will be long edge leading and
some will be short edge leading. The first task is to ensure that they are all in the same
orientation, which is achieved with a crate turner.
Page 53 of 90
Crate dividers / combiners
Page 54 of 90
Crate magazines
Objective
If the line is empty and being started up, as the bottles are fed into the washer, through the
filler, pasteuriser, labeller and up to the packer, more and more empty crates are being
discharged from the unpacker, but are not being used by the packer as no bottles have
arrived at the packer.
Static accumulation is thus required whilst the line is being loaded with bottles. The
simplest method of doing this is to remove the empty crates at the unpacker discharge and
stack them on the floor.
More sophisticated methods include the robotic crate magazine shown below, which
automatically stacks or destacks crates as required by line conditions.
The crate magazine is also essential during normal line operation, to accommodate
variations between the packer and unpacker. If, for example a problem occurs at the crate
washer, then the crate magazine can be used to supply empty crates to the packer whilst
the problem is being rectified.
Page 55 of 90
It is essential that in normal operation the crate magazine is not allowed to be
completely full. It should normally (with packer and unpacker both running) be about 75%
full. This is important, otherwise a small stoppage at the packer will immediately stop the
unpacker (As the empty crates from the unpacker cannot be loaded into the full
magazine), and then the whole line is quickly stopped unnecessarily.
You may ask why should it be that the crate magazine would fill up; it should be designed
to be of the correct size. The answer is that the crate magazine gradually gets fuller and
fuller because of glass breakage. For every bottle broken on the line, if a crate holds 12
bottles, then 1/12th of a crate is added extra to the line. For every 12 bottles broken, an
additional crate is added to the magazine.
On a typical production line running 45000bph, with glass breakage of 1%, about 600
crates extra are added to the magazine each 24 hours.
The magazine will thus quickly fill up, and if the crates are not removed every day the
lines performance will soon suffer.
Page 56 of 90
Crate conveyor drive controls systems and lubrication
Objective
Identify types and construction of crate conveyor drives, their lubrication and their control
systems.
Page 57 of 90
Conveyor controls
The control systems on crate and case conveyors tend to be simpler than those of bottle
conveyors. Crate conveyors are usually of fixed speed, so complex speed control is
avoided.
Generally, photocells are used to detect when the conveyors are full, the control system
then stops the drive motor to prevent undue pressure on the crates. Note that the
photocells shown here are protected from damage and fixed to a strong steel plate so that
they will not vibrate out of position.
Steel slat chains do not need continuous lubrication for conveying plastic crates. A small
amount of chain lube should however be applied to reduce wear. The drive chains for
roller conveyors require periodic cartridge lubrication, as do each of the many bearings
found on all types of crate and case conveyor.
Page 58 of 90
Types and construction of pallet conveyors
Objective
The pallet conveyor frame is almost always made from mild steel, because the conveyor is
used in a dry area, and the high strength needed for heavy loaded pallets would be
prohibitively expensive if made from stainless steel.
A typical conveyor consists of a set of rollers mounted inside the frame that are driven by a
motor.
Page 59 of 90
There are two major types of pallet conveyors:
Note: Pallet conveyors are usually constructed in units that accommodate a single pallet,
as shown above. Each individual section is then independently driven and controlled.
Unlike crates or bottles, the pallets are not allowed to press up against each other and
provide accumulation. There is thus no dynamic accumulation, merely the static
accumulation provided by the conveyor holding a single pallet. This is sufficient as a single
pallet may hold 1000 bottles.
Page 60 of 90
Types of pallet
Unfortunately not all pallets are the same. They vary in height, width and length, as well as
in the number of fork lift entry points.
Page 61 of 90
Pallet transfers
Objective
Types
Page 62 of 90
Pallet shuttle. Used to transfer from
several pallet conveyors to a single
conveyor. Often seen when several
palletisers supply pallets to one pallet
pick-up point. The shuttle car travels on
rails and moves to each conveyor as
needed.
Page 63 of 90
Pallet magazines
Objective
If the line is empty and being started up, as the bottles are fed to the unpacker, into the
washer, through the filler, pasteuriser, labeller and up to the packer, more and more
empty pallets are being discharged from the depalletiser, but are not being used by the
palletiser as no crates have arrived at the palletiser.
Pallet accumulation (storage) is thus required whilst the line is being loaded with
bottles. The pallets are stacked in a magazine, usually in stacks of 15 pallets. Typically
each stack of 15 pallets is discharged from the pallet stacker and removed by a fork
lift.
Pallet magazines, or pallet stackers, are often installed as dual purpose stackers and
destackers. They can thus feed pallets into the line when required, or stack pallets
from the line when required.
This pallet magazine accepts pallets from a chain conveyor. The pallet stack is lifted
by a hydraulic lift conveyor section, after which forks are inserted to support the
pallets.
Page 64 of 90
Page 65 of 90
Pallet conveyors drive control systems, and lubrication
Objective
Drive systems
The most common variation required in drive systems is the use of SOFT-START motors.
For empty pallets, or full pallets that are very stable, a normal motor is acceptable. The
normal drive conveyor motors give a jerk when started, as the conveyor is suddenly
changed from stationary to running at normal speed.
Where the pallet load is unstable, a soft-start motor should be installed. These motors are
designed to gradually change from stationary to normal speed over a period of 1-2
seconds. Soft start drive motors thus prevent crates falling from unstable pallets, and are
much cheaper than installing an expensive frequency converter.
Pallet conveyor motors always drive a chain mechanism, connected to the rollers in the
case of a roller conveyor, or connected by sprockets to other chains in the case of a chain
conveyor.
Page 66 of 90
Conveyor controls
Like crate and case conveyors, the control systems on pallet conveyors also tend to be
simpler than those of bottle conveyors.
Pallet conveyors are almost always of fixed speed, so complex speed control is avoided.
Often reflective photocells or pressure bar with limit switches are used to detect when the
conveyors are full, the control system then stops the drive motor to prevent collisions
between the pallets.
Some pallet conveyor control systems use pressure bars with installed limited switches
built in between the rollers of the conveyor to control the start and stop of the conveyor.
The pressure bar is activated by the weight of the pallet.
Conveyor lubrication
No lubrication system is needed for the conveyor surface, as the pallets are moved
positively by the rollers or chains and do not slide on them to take up dynamic
accumulation.
The drive chains require periodic lubrication, as do each of the bearings found on the drive
shafts. Most rollers are fitted with sealed bearings so that the individual rollers do not need
to be lubricated.
Page 67 of 90
Page 68 of 90
Safety
Objective
Your Safety
The two areas of concern regarding conveyors and safety are the risk of injury from
the moving parts of the conveyor systems (sprockets, chains etc), and the risk of injury
from flying glass on bottle conveyors (and sometimes crate conveyors) which occurs
when bottles break under pressure.
Injuries caused by flying glass are primarily defended against by wearing protective
glasses, safety gloves and overalls. However, this does not address the root cause of
these injuries, they are often the result of excess line pressure, fallen bottles or faulty
control systems. It should be compulsory to wear eye protection in this area.
Page 69 of 90
This man is feeding test bottles into a
Filtec machine, on a line running at
1000bpm. He is wearing safety goggles
however he is not wearing safety gloves
with a consequent risk to his hands.
However he should NOT be inserting
bottles like this. Filled glass bottles can
burst any time.
Page 70 of 90
Injury from moving parts.
Nip-points
Page 71 of 90
Nip points exist on crate and case
conveyors at almost every transfer,
particularly between belts and rollers.
Safety Features
It is important to have safety switches on bottle conveyors, crate conveyors and pallet
conveyors. The minimum standard should be to have a lockable isolator next to each
conveyor motor.
It is preferable to also have rope stops fitted to the full length of crate conveyors. These
are wire ropes running the length of the conveyor. Should your hand become trapped
between the rollers, you can immediately pull on the rope switch to stop the conveyor.
An emergency stop switch is of little use to you if your hand is trapped in a conveyor
and you cannot reach it !
Secondly use should be made of friction drive rollers wherever possible, as these
rollers will not injure your hand if trapped, as the friction drive slips and the roller stops
turning.
Page 72 of 90
On this pallet conveyor plates have been
fitted between the chains so that
operators may cross safely.
Index of terms
90 degree corner Type of transfer that utilises two straight conveyors where
Page 73 of 90
transfer transfer takes place at a 90 degree corner using a dead
plate.
Dead Plate A fixed plate used to bridge between two conveyors over
which the conveyors move by being pushed from behind.
Flex-Top Type of slat chain that can flex to travel around corners.
Friction drive Type of clutch fitted to rollers so that the rollers stop
turning under extreme load.
Page 74 of 90
Garvens divider Type of divider using sliding slats on a set of conveying
rods.
Guide rail Plastic wear strip on either side of the conveyor that directs
the flow of containers.
Incline Slope up
Inductive Sensor Sensor that detects the movement of metallic items, such as
the crowns on bottles.
Mass bottle Bottle conveyor more than one slat chain wide.
conveyor
Parabolic curve The shape of curve followed by a ball thrown from a height
and falling to the ground.
Parallel Transfer Conveyor section of double width that allows for the smooth
Unit transfer from one conveyor to the other without the use of a
dead plate.
Photocell Sensor that emits a light beam and detects if the beam is
reflected back into the sensor.
Page 75 of 90
Combiner into a single lane, and thus needs no guide rail on one side.
Screw Conveyor Conveyor that uses a rotating screw to move solid particles
or granules
Trough Belt Conveyor that utilises a rubber belt, formed into a trough
Conveyor shape, to move ore or minerals. An endless belt.
Two way entry / Type of pallet defined by the number of directions forks can
four way entry enter the pallet
pallet
UHMWPE Ultra high molecular weight poly ethylene. A dense and hard
wearing plastic.
Page 76 of 90
Page 77 of 90