gravity conveyor

8/3/2019 Gravity Conveyor

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The Two Different Types Of Gravity Conveyor, And HowTo Choose Between Them

Gravity conveyors have a justified reputation of being the most economical and cost effective

solution for moving items from one place to another. Although they will not always be the

best solution to the problem due to other factors, there are a great many cases where they are.They can be set up with greater ease than competing systems, because they need no external

power source to be effective, and they will always be the most cost effective system in terms

of energy because they simply don't use any.

There are two fundamentally different ways in which a gravity conveyor can operate. The first

and most obvious way is by the use of what its name suggests, gravity. By making one end of

the conveyor belt higher than the other, items will naturally slide from the high end to the lowend. This can have significant advantages, in that it is a fast way to distribute goods, but there

are a couple of problems. It really needs a workshop to be designed specifically with this typeof conveyor in mind, and if you don't have a suitable structure you could be facing an

expensive refit.

The other disadvantage is that the steep incline needed to ensure the speedy movement of the

goods can compromise the safety of any fragile items which need to be sent. This can be

overcome somewhat by having the incline smooth out to a straight board, rather than using a

vertical board to stop the item sharply. This will be more effective in stopping heavy items

than light ones.

The other way in which gravity conveyors can operate is by manual movement. The conveyor

will be set up with little or no incline, and the movement will be facilitated by manualoperation of the conveyor. In a way, this defeats the purpose of the automated conveyor,

because the whole idea of automation is to take away the need for human intervention so thatthe worker time can be spent more productively. It does, however, still ensure that the

operation remains power free, and for many organizations the saving in electricity willcompensate for the need for employees to manually operate the system.

There is no clear definitive answer as to which of the gravity conveyors is better. It is entirely

up to you to make your own choice. If you only have a short distance between the two points,

and have no further need to move the item beyond that point, then a genuine gravity conveyor

may well be your best choice. It will free up the time of your employees to the optimum

degree without any requirement for fuel consumption. If you have a need for the item to be

moved a longer distance, you will probably be better off with a manual operation than a

genuine gravity conveyor.

FROM: http://www.etconveyors.com/ar/gravity-conveyor.php


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Several types of conveyor are available for many different applications. Below are some sample

images and cutaways of the many different types of conveyor. If you have any questions about the

best conveyor solution for your operation, please visit www.sjf.com contact one of our conveyor

experts that can assist you in choosing the right kind of conveyor for your application.

Gravity ConveyorsGravity Conveyors are non-powered, free flowing conveyors used in a push or level application to

facilitate product movement. They can also be set up with declining stand heights to allow product to

flow from a high to a lower elevation. Gravity conveyors are available in roller or skatewheel

configuration. Both types can be used with a variety of powered conveyors to form a complete

conveyor system.

Roller Conveyor

Gravity Roller Conveyors can be used when conveying flat, smooth bottomed surfaces like cartons,packages or pallets as well as most other items with an uneven bottom surface such as drums, cans,

molds, etc.

While available in many custom lengths, gravity roller conveyor is typically sold in 10 foot sections

while overall widths of 12, 18, 24, & 30 inches are considered industry standard. Several different

roller sizes & types are also available.

Skatewheel Conveyor


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While gravity is a good all-purpose gravity conveyor, skatewheel is best when conveying flat, smooth

bottomed surfaces such as cartons, tote boxes, trays and plywood or masonite skids.

Gravity skatewheel conveyor is a lighter-weight and more economical alternative to gravity roller

conveyor. Skatewheel conveyor is typically used in situations where its lighter weight makes it easily

moved or reconfigured to make space for storage of larger products. It can be found everywhere

from shipping areas to pick and pack stations. Both aluminum and steel frame models for lighter or

heavier duty applications are typically available.

Power Conveyor

Many Different Power Conveyor types can be used in a conveyor system. Each has a different, but

important function. Here are several of the more common varieties.

Accumulation Conveyor

Accumulation conveyor is typically used in conjunction with other conveyor types in acomplete conveyor system. Accumulation conveyor consists of pop-up sensor rollers located

in zones which use a pressurized air system to hold your product in a queue until it receives

a signal to release it to the next stage of operations. This can include moving products one at

a time onto a weigh station, case sealer, sort system, palletizer, or any other work station.

There are several types of common accumulation conveyor, however two are more common

than the others. Zero pressure accumulation conveyor will eliminate package collisions on

the conveyor line by leaving gaps between each individual box, while minimum pressure

accumulation conveyor will place the individual boxes next to each other with little back

pressure.

Accumulation conveyor can be the most vital link in any large conveyor system. Without it,

your sortation system, packaging machine, or other machines will quickly become

overloaded and will not function properly.


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Belt Driven Live Roller Conveyor

Belt driven live roller conveyor consists of load rollers, a drive belt, return rollers and an external

motor. The load rollers make up the surface on which product is transported. The rollers move using

a belt that is located underneath the load rollers which provides friction directly on the rollers and

creates forward movement. The return rollers are used to kep the belt in place under the conveyor

as well as to maintain tension on the belt at all times.

Belt driven live roller conveyor can be used in accumulation, induction, and merge systems where

product sizes and weights tend to vary. It provides limited capabilities for inclined movement or

packages of differing shapes.

Belt Over Roller Conveyor (aka: Belt On Roller)

With belt over roller conveyor, the belt can be either sliderbed supported or supported by

return rollers located underneath the load rollers. Belt on roller conveyor is a fairly common

type of powered conveyor and is what many people think of when they envision powered

conveyor. Belt on roller conveyor is very useful for transporting light and medium weight

loads between locations.

In addition to being a good general purpose powered conveyor, belt over roller is also a

desired solution for inclines or declines. Powered belt over roller conveyor provides much

control over the orientation and placement of loads, which can be good for bulky, irregularly

shaped products. Because product orientation is easily controlled with belt over roller, it also

makes a good conveyor to use in induction and sortation conveyor systems.


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Lineshaft Conveyor

Lineshaft conveyors can be used used for both transporting and accumulating products.

Lineshaft makes use of a drive shaft which runs the length of the underside of the conveyor,

and drives the load rollers individually using belts. Since the rollers are individually powered,

lineshaft conveyor can easily be used for accumulation operations where there is a minimum

amount of backpressure on the product being transported.

The driveshaft is powered by a motor. Some configurations of lineshaft conveyor allow the

conveyor to run both forwards or backwards depending on the situation desired. Because

there are fewer moving parts, todays lineshaft conveyor is typically quieter than traditional

live roller conveyors. The belts also assist in reducing noise by holding the rollers firmly in

place inside the frames which results in less rattling.

Chain Driven Conveyor

Chain driven live roller conveyor (sometimes referred to as pallet conveyor) is typically used

to transport heavier loads at controlled speeds. Chains drive sprockets on the load rollers

which in turn drives a chain and the sprocket on the next roller, etc. These systems transmitthe same amount of power to each roller thus insuring a smooth, even ride.

Chain Driven conveyor offers several advantages that other types typically do not or cannot.

For instance, because there is no belt(s) chain driven conveyor can transport both hot and

cold loads that could damage other conveyor types. Chain driven conveyor can also resist

contamination by grease and other particulate matter better than other conveyor types. Chain

driven live roller conveyor is also better able to tolerate uneven pallet bottoms or drums.


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Trash Conveyor

Trash conveyor and regular sliderbed conveyor are two very similar products with one

important difference. Trash conveyor has guard rails attached to the sides of its frame to

prevent materials from falling off the conveyor belt into the work area. Return rollers keep

tension on the conveyor belt keeping it taut.

Trash conveyor is used mainly to transport empty boxes, paper trash and other light-weightrefuse to a disposal area, compactor or incinerator while keeping it out of the way of

production areas. It can help to create a better organized work area that will allow your

employees to perform their work efficiently and without hinderance. Since trash conveyor

utilizes a sliderbed design, there are few moving parts to create noise. The sliderbed design

of trash conveyor also makes it great for transporting materials on inclines and declines.

Sliderbed Conveyor

Sliderbed conveyor and trash conveyor are very similar products, but regular sliderbed

conveyor does not usually have guard rails. Many capacities of sliderbed are available, but

lighter weights are more common. Sliderbed conveyor uses return rollers to run a conveyorbelt along a smooth bed, thus allowing for the smooth transportation of many different load

types.

Sliderbed can easily carry loose components and other materials that roller conveyors have

a harder time transporting. Since sliderbed conveyor has few moving parts, it does not create

much noise. The sliderbed conveyor design also makes it useful for transporting loads on

inclines and declines. Typical sliderbed applications include inspection, transportation and


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Tilt Slat Sortation

The conveying surface is made up of slats that can be tilted to the right or left. Packages

travel in close proximity and only the slats under them will be activated to tilt.

Pop-Up Belt/Chain Sortation

These sort boxes or containers to either side of a main conveyor line. They work by pulling

heavy packages onto angled spurs at high speeds. The belt or chain used is matched to the

package being handled.

Sliding Shoe Sortation

One of the fastest continuous sorters, a row of sliding shoes travels across the sorter path

smoothly, easing containers onto takeaway spurs. Typically, this is used in conjunction with

photo eyes that either puch the package onto an alternate lane or allow the package to

continue down the main conveyor line to the correct lane.


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Pusher/Diverter

Pusher diverters have spur or sort points located very close together and handle heavy

products. P/Ds are slow to medium speed because the diverter mechanism must return

across the belt before intercepting the next package.

Pop-Up Roller Sortation

The pop-up roller is driven by its own motor at a higher speed than the main-line conveyor. In

sorting, the roller grabs the leading edge of the container and leads it off onto a spur.

Swivel Wheel/Roller SortationThis diverter can work with belt or roller conveyors to drive packages off to the right or left

using a roller that will swivel in place to either allow the package to pass or be diverted.

Divert points can be as close as three-foot center. Main-line belt conveyors are typically less

noisy than most roller types.

FROM: http://knol.google.com/k/conveyor-types-and-uses#


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Gravity Roller

Gravity Roller Conveyor

The gravity roller conveyor design is by far the most popular conveyor design in use today.

They are used extensively in distribution, packaging, and manufacturing applications. Onlevel conveyors, items are placed on the conveyor and manually pushed along to the nextstation or operation. Gravity roller conveyors can also be used in declines, where the items are

placed on the conveyor and gravity takes over to convey the product forward.

BIPCO, Inc. offers gravity roller conveyors for very light and narrow loads up to extremely

heavy and oversized loads, even up to 10,000 lbs. The following considerations must be takeninto account in the design of gravity roller systems:

y Product size, weight, and type of bottom surfaces

y How the product is loaded and unloaded from the conveyor

y Roller spacing, capacity, and bearing requirements

y Grades for declinesy Environment the conveyor is used in (foundry, warehouse, outdoors, etc.)

Gravity Roller Conveyor

Standard widths are offered from 8" up to 76" and rollers from 1.38" diameter up to 6.5" in

diameter with over 40 different bearing options to ensure the right solution for your

application. Gravity conveyors are offered in straight and curved sections. Curved sections are

also available with tapered rollers to help items being conveyed track correctly throughout the

curve.


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.

Flexible Gravity Conveyors

The flexible, extendible conveyor design is used primarily in truck loading and unloading

operations, but also provides great flexibility for other applications. These conveyors typicallycollapse down into a small package when not in use, saving floor space, and are easily

extended when needed. Since they are flexible, they can be set at angles and the product willconvey following the pattern of the conveyor, which allows for moving product between lines

or lanes to different truck docks, accumulation conveyor or other operations. These conveyorsare offered in wheel or roller configurations as well as powered roller systems.

Flexible Roller Conveyor

http://www.bipcoinc.com/products/conveyor/gravity.htm


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Hytrol's ABC Conveyor

Book

WHAT IS A CONVEYOR?

A conveyor moves material.

A conveyor moves cardboard boxes, wood boxes, metal boxes and plastic boxes.

A conveyor can move material

BY GRAVITY

This is called a GRAVITY CONVEYOR.

A conveyor can do more. It can move boxes UP against gravity . . . DOWN . . . or HORIZONTALon a moving belt.

The belt is moved by electric power.

This is called a BELT CONVEYOR.


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WHAT IS A BELT CONVEYOR?

It is a machine with a moving BELT.The machine is made with these parts:

A BED

This is a conveyor bed.It comes in many sizes-many lengths-many widths.

A PULLEY

A pulley is like an IRON pipe.

Pulleys are put on each end of the bed.

The pulleys are as wide as the "bed".Each pulley has a steel shaft through it.

The shaft turns on a bearing . . . and the pulley

turns with the shaft.

WHAT IS A BEARING?

When two pieces of steel touch each other; they cannot

turn easily without bearings.

Bearings use little steel balls to keep the pulley shaft and theconveyor bed from rubbing together.

Now the shaft can turn easily.


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Pulley "A" is the drive

pulley.

Pulley "B" is the tail

pulley.

The drive pulley is

usually larger because

it does the work.

HOW THE DRIVE PULLEY DOES THE WORK

The drive pulley is turned (driven) by a motor. A sprocket is put on the drive pulley shaft.

A sprocket is put on the motor.

WHAT IS A SPROCKET?

A sprocket is a metal "wheel" with "teeth" on the outside.


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HOW THE DRIVE PULLEY IS "DRIVEN"

A chain is put around the Drive Pulley Sprocket and the motor sprocket.

The chain moves when the motor is started.The chain turns the drive pulley.

BUT ! . . .

Because a motor turns very fast (1750 times per minute). . .A SPEED REDUCER must also be used.The SPEED REDUCER is put between the motor and the drive pulley.

. . . The motor is connected to the reducer with a V-Belt (like the fan belt in your car) or a "C" Face

Coupling.

The reducer is connected to the drive pulley with a chain . . . Now the Drive Pulley turns slower.

All those parts (the motor, the speed reducer, and the drive pulley) are called:


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THE CONVEYOR DRIVE

They must be put

together to take up as

little space as

possible - so

The motor and reducer areput under and within theconveyor BED.

But what about the

TAIL PULLEY?

The tail pulley is located at the tail end of the conveyor and it turns freely.

Now a "belt" can be put around the pulleys.

The Drive Pulley turns and moves the belt around . . . and around . . . and around.

BUT . . .

. . . it is dangerous to have the belt hang down under the conveyor bed - So small rollers are put


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into the Conveyor Bed to hold up the belt.

These turn freely -- and just idle.They are called "Return Idlers".

SOME TYPES OF BELTSSTRETCH MORE THAN OTHERS

What to do?

1.Move the tail pulley! It can be moved to "take-up" the belt stretch.

There are "take-up" screws on both sides of the conveyor.Move these screws out slowly.Move them the same amount on both sides!

This keeps the belt tight.

2. What do you do when the take-up screws are still all the way out - and the belt still stretches?

LONGER CONVEYORS ARE PROVIDED WITH ONE OR MORE SHORT PIECES OF BELT ADDED.

REMOVE THE SHORT PIECE(S) OF BELT.

Now you can start the "take-up" procedure all over again.


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NOTE: If a "Dutchman" was not provided, you may need to add an UNDERSIDE TAKE-UP toyour conveyor.

HOW TO GET MORE BELT TAKE-UP

There is more belt stretch on a long, long conveyor than the regular take-up and dutchman willgive. So an "Underside Take-Up" should also be used.

WHEN TO USE UNDERSIDE TAKE-UP?

ON CONVEYORS 60 FT. LONG (OR MORE)

NOTE: AN UNDERSIDE TAKE-UP is often used when the overall length of conveyor cannot bechanged and the TAIL PULLEY "take-up" cannot be used.

HOW CONVEYORS ARE MADE TO DO A BETTER JOB

1. BELT MOVES AT SPEED OF 65 FEET PER MINUTE (FPM)This is best speed to move objects from one place to another.

A person can walk about 4 miles per hour. If they were carrying a box they would walk muchslower. Conveyors move boxes at about the same speed as a person carrying them. This is about

65 feet per minute (or about 3/4 of a mile per hour).

2. DRIVE PULLEY IS CROWNED AND LAGGED.

A. The drive pulley is larger in the center than the

ends. This helps keep the belt in the center. This

is called a "Crown".

B.The drive pulley is completely covered with vulcanizedrubber. It is called "lagging". This keeps the pulley from

slipping under the belt.

3. THE CONVEYOR DRIVE IS NORMALLY LOCATED AT THE END TO WHICH THE BELT

MOVES.


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SO A DRIVE PULLEY "PULLS" THE BELT.

NOTE: If the belt movement were reversed, the pulley would be pushing the belt. When the

conveyor was fully loaded or when the belt stretched, the pulley could turn and not move

the belt.

4. THE SNUB IDLER

The Snub Idler is closer to the drive pulley.

It makes the belt hug more of the drive pulley surface.

The Snub Idler is ADJUSTABLE.

It is ADJUSTABLE ON BOTH SIDES of the conveyor. (Each side of snub idler can be

adjusted independently).

Reason - The Snub Idler is used to steer the belt.

5. HOW TO "STEER" THE BELT

y When belt runs forward and if i t moves toward side "A" - move return idler nearest tailpulley on side "Y" toward "B". If belt moves toward side "B" - move return idler on side "X"toward "A".

y When belt runs in reverse and if it moves toward side "A" - move snub idler on side "X"toward "A". If belt moves toward side "B" - move snub idler on side "Y" toward "B".

IMPORTANT: Move snub idler or return idler only 1/16 in. at a time. Then wait a few minutes to

see if belt moves back to center. Only small adjustments are usually necessary.


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6. POWER FEEDER (Used with incline Belt Conveyors)

A.When boxes move from gravity conveyor to inclined belt conveyor, the box usually stops or

"hangs up". The box will not transfer.

B.With a Power Feeder, transfer of the box is positive.

The Power Feeder is driven from main conveyor by a short chain connection.

7. CENTER DRIVE(Used with Horizontal Belt Conveyors)

A.When belt movement is REVERSIBLE (on conveyors 40 ft. long or more)

B.When overall length of conveyor cannot change (belt take up by tail pulley increases conveyor

length)

CENTER DRIVE SHOULD BE USED

Because:

A.Drive pulley now "pulls" belt in either direction

B.Take-up pulley can now be used to take-up belt.


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8. ROLLER BED CONVEYORS

When heavy total loads must be moved, it is best to use a conveyor bed with rollers (instead

of regular conveyor bed).

This is a RollerBed belt conveyor

Heavy total loads can be moved without using large motors when a ROLLER BED belt conveyoris used.

BELT CONVEYORS are often used with GRAVITY CONVEYORS.

You should know about GRAVITY CONVEYORS TOO!

WHAT IS A GRAVITY CONVEYOR?

A gravity conveyor moves objects without motor power.

To help objects move "easier" . . . and with as little slant or slope as possible -

WHEELSOR . . .

ROLLERS ...


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ARE USED

The WHEELS or ROLLERS are put

into channel frames held

together with "bed spacers."

Different widths can be made. Framescan be either STEEL or ALUMINUM.

WHEEL CONVEYORS

Wheels are put on axles.

Aluminum spacer tubes are

put on the axle between the

wheels. This keeps wheels

from moving from side to

side on the axle.

In the drawing above, the axles are on 3 in. centers (also available in 1-1/2 in. centers). The

number of wheels on each axle can vary. This determines the number of wheels per foot on theconveyor.

BUT ..

There should always be a minimum of 10 wheels under a box.


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This helps you decide the number of wheels per foot to order.

ROLLER CONVEYORS

Rollers have their own axles. Most axles

are SPRING-LOADED. This means. . .

...The axle can be moved to one side.

Rollers can be easily removed or replaced

in ConveyorChannel frame. The spring

also keeps the roller in place.

The rollers are put in the frame as close together -


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Tote boxes will not move easilyUse as many wheels aspossible for best results.

MOVE THESE ON ROLLER CONVEYORS

Any Items with an uneven or open bottom, or with a rim on the bottom. These items should never

be bigger around than the rollers are long.


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HOW GRAVITY CONVEYORS ARE SET UP

1. ALL SECTIONS HAVE COUPLINGS

PORTABLE TYPE

PERMANENT TYPE

Sections can then be used together by coupling them to each other.

2. PORTABLE SET-UP USS TRIPOD STANDS

Always use one more stand than the number of conveyor sections (3 sections use 4 stands.)

3. PERMANENT SET-UP USES STATIONARY SUPPORTS

Always use one more support than the number of conveyor sections (3 sections use 4 supports.)

POWERED AND GRAVITY CONVEYORS CAN BE USED TOGETHER!


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This is called a "Flow System".

FROM: http://www.hytrol.com/brandinfo/hcctraining/abc.html

WhatAre Gravity Conveyors and How Do They Work?

ByJeremy P Stanfords

Gravity conveyors are used to transport a variety of products and items. They facilitate orders

from the manufacturer to the distributor to the retailer. They can be seen in warehouses, onloading docks and in storage rooms. Depending on where the product needs to go and whattype of environment it is in, a gravity conveyor can be set up to make handling more efficient

and cost-effective. There are two basic types of these conveyor systems; wheel-based androller-based. To work effectively, they both require items with a solid, flat bottom for

handling. As a result, products or packages that are loose, bumpy and round, such as bottles or

loose foodstuffs cannot be processed effectively unless they are in a flat-bottomed container

of durable quality so that it can ride across rollers and wheels. The top of the box or package

does not need to be closed, however.

ConstructionMost systems of this type are made from aluminum or steel construction. Aluminum material

is lighter and associated more with portability. Steel systems are used more for durability andstability for long-standing wear and heavy duty capacities. Different widths and lengths of the

tracks are usually available to order from the manufacturer in increments by the inch. Curved

pieces constructed at 45 or 90 degree angles can be used to change the direction of transport

from Point A to Point B, depending on the type of package being moved and the construction

of the rest of the system. End pieces can be attached to ensure that loads stop at the end of the

line.


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Rollers

Gravity roller conveyor systems can work with a variety of set-ups. Made from medium- orlight-duty construction, they are made of metal tubes with bearings inside each end. The

rollers are mounted on spring-loaded axles. When it is time to replace or remove a roller, itcan be simply pushed to the side and pulled out of its seating. A new spring-loaded roller can

be inserted in its place. Items with level, relatively solid bottoms can be transported using a

roller conveyor.

Wheels

Wheel systems consist of a series of wheels in vertical and horizontal rows that move productfrom Point A to Point B. They can be mounted at a sloping angle or be activated by a human

or automated force moving the product across a level push line. Packages that are lightweight

and have a smooth, solid bottom surface can be transported on a gravity-based wheelconveyor system.

FROM: http://ezinearticles.com/?What-Are-Gravity-Conveyors-and-How-Do-They-

Work?&id=5770245

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