Truco Belting Care

7/28/2019 Truco Belting Care

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Care of Belting

Rubber compounds are subject to attack by ozone (0), ultra violet light, heat, oils and

solvents. The conveyor belting is continually subjected to varying degrees of human abuse.

What are the effects of these on the life of the rubber conveyor belts?

Ozone and Ultra Violet Light

The presence of ozone is predominant in the atmosphere where electrical storms occur.

South Africa ranks high in the world for this climatic condition. A high concentration of

ozone together with ultra violet light causes oxidisation of the rubber. Degradation of the

rubber compound from oxidisation manifests itself as surface cracking or perishing as it iscommonly termed. Such attack is most severe when the rubber is static and under

stress. Thus the rubber covers of a rolled up conveyor belt in storage can degrade. Also a

belt left static on the structure for long periods would suffer from rubber degradation. In

order to minimise the problem Truco Belting incorporate antioxidants and anti-ozonants

into the rubber compound which act as a barricade against attack. The user can also assist

by storing the belting in a position well sheltered from direct sunlight and sources of ozone

such as operating electric motors and arc welding equipment.

Heat

Rubber compounds are degraded by heat. Some polymers withstand the effects of heatbetter than others but all are degraded. Additives can be added to the cover rubber of

conveyor belts to enable them to perform under conditions of prolonged high temperature.

These are termed 'heat resistant' conveyor belts. Conveyor belting should not be stored in a

hot environment as it will seriously effect the life expectancy. Ideal storage temperature for

conveyor belting is between 10C and 25C.

Oil and Solvents

As is the case for heat resistant belting, specially formulated oil resistant compounds are

available. These oil resisting compounds are based on synthetic polymers. Standard Grade N

and M rubber covers (which have a very high Natural rubber content) are readily attackedby oils causing swelling and reduction of physical properties.

Abuse

One of the most common enemies of the conveyor belt is abuse of one kind or another.

Abuse arises either through ignorance or the desire for ever increasing achievement. The

consequences of abuse are vast. Between 80% and 90% of all belts are replaced due to

physical damage before they have worn out.


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Handling of Conveyor Belt Rolls

The correct way to lift rolls of belting is with a bar passed through the centre core, then

depending on the width and weight, the roll may be lifted by a fork lift truck or crane. If

chains or slings are used on the bar at each side of the roll, a spreader bar should be used to

prevent damage to the edges of the belt. If a spreader bar is not available use off-cuts of

belting between the sling and the belt edge to help prevent damage.

Correct Storage Procedures

The belt should be stored upright in its original packaging. If storage is likely to be for a long

period it is preferable that the roll be suspended on a bar passed through the centre. This

facilitates regular turning of the roll to relieve pressure concentration points. The belt roll

should be rotated through 45 every 3 to 4 months. Always store belting out of direct

sunlight. Never store belting in the vicinity of operating electric motors. Always keep beltingclear of arc welding or other sources of high voltage. Ideal storage temperature is between

10 and 25C.

Store belting on firm ground away from any possibility of oil contamination. A waxy film

appearing on the surface of the conveyor belting is normal, It should not be removed as this

provides protection against ozone.

Protection of Conveyor Belting

The conveyor structure should be assembled so that the belt runs true on both the carry

and return strands. The loading of the material onto the belt should not affect the true

running. Clearances between the belt and structure should be sufficient to prevent foulingat all points. International standards for straight running of belting allow a movement of

5% of the belt width or 75mm whichever is the smaller, a larger clearance is required in

the conveyor structure. Conveyor structure should have sufficient clearance to

accommodate belt movement.

Movement of the structure will require that regular inspection and adjustment is carried out

to ensure that the belt always runs true and free. Long conveyors with high installed power

are prone to extensive damage when foreign objects become jammed between belt and

structure. Many belts have been ripped from end to end in such circumstances. Long

conveyors should therefore be provided maximum protection.


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Means of protection can take the form of

1. Overhead magnets to remove foreign magnetic material.

2. Magnetised head pulley for removal of small magnetic objects.

3. Regular checks for loose liner plates.

4. During inspections checks must also be made for jammed, seized and missing idler rolls.

5. Belt run out limit switches should be installed at loading and discharge points.

6. Blocked chute detection must be installed and checked regularly for correct operation.

7. Scrapers or types of belt cleaning devices should be installed maintained to limit material

carry back.

8. Vee ploughs installed on return strand to prevent material passing between pulleys and

the belt.

9. Rip detection devices installed ahead of load point and immediately after discharge point.

10. If iron is a hazard the belt may be protected by feeder belt incorporating a magnet to

remove the iron.

Conveyor Belt Training

The important factor for continuous central belt training is stable alignment

Alignment

1. The conveyor structure must be true.

2. All pulleys and idlers must be centred on the centre line

3. Pulleys must be perpendicular to the centre line.

4. Idler bases must be perpendicular to the centre line.

5. All idler bases or brackets must be horizontal.

6. Gravity take-ups and trippers must move centrally on the centre line and the movingpulleys must remain parallel to the other pulleys on the system.

7. All idler rolls and non-driven pulleys must rotate freely.

8. There must be no build up of material on idler rolls or pulleys.

9. The belt joins must all be true.

10. The belt must not be so stiff as to prevent troughing when empty.

11. The load must be placed centrally on the belt. If the

basic alignment factors are thoroughly checked

there should be no difficulty training the belt.

Aids for checking alignment of idlers and structuresOptical idler alignment instrument

Theodolite

Spirit level

Plumb bob

Fish line

Measuring tape

Idler profiling jig


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How to establish if a belt splice is true

1. Remove the idlers for 6 -10 metres on either side of the belt splice.

2. Lay the belt flat on boards supported on the conveyor stringers. There must be no wavy

edge as this indicates that the belt is not lying straight on the flat surface. (It is normal for

the belt edges to curl up from a flat surface but

pressing the edge down should cause the belt edge to lay flat without any waviness.)

3. Construct belt centre lines on either side of the splice from a splice extremity to about 5

metres distance from thesplice.

4. Stretch a fish line from the furthest points of these centre lines, across the splice. The

splice is true if the fish line runs on the two centre lines along the entire length of the centre

lines.

1. Check structural steel alignment. Even in the case of old conveyor structures, the

alignment must be periodically checked and should always be checked when the belt is

replaced.

2. Using the procedure described above, check that all splices are true.

3. Make sure that there are no obstructions to the belt along the entire conveyor length and

that no foreign materials have been left on the belt.

4. Position the belt centrally in the structure and check that it clears the conveyor structure

at all points along the length.

Procedure for tracking a newly installed belt

1. Check structural steel alignment. Even in the case of old conveyor structures, the

alignment must be periodically checked and should always be checked when the belt is

replaced.

2. Using the procedure described above, check that all splices are true.

3. Make sure that there are no obstructions to the belt along the entire conveyor length and

that no foreign materials have been left on the belt.

4. Position the belt centrally in the structure and check that it clears the conveyor structure

along the length.

5. Check that the belt has been correctly reaved.

6. Make sure that belt alignment switches are active.

7. Position observers at critical points such as the pulleys, loading chutes and any other

points of least clearance.

8. It will prove convenient to mark the belt on both surfaces at each of the belt splices. Each

splice should be uniquely marked.

9. Start the belt and while running empty observe the tracking.


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9.1. Allow two to three complete revolutions before making any initial adjustments. During

this time determine the general tracking characteristics to ascertain that all points along the

belt length have a similar tracking position at a particular point of the conveyor. The general

tracking characteristics are best observed at the lowest tension pulley.

9.2. Start immediately behind the drive pulley and check alignment along the return run of

the conveyor, working toward the tail pulley.

9.3. Do not adjust any of the pulleys which must always be perpendicular to the belt centre

line, central and horizontal.

9.4. If the belt runs out at any position.

9.4.1. Double check the horizontal alignment of the idlers in the vicinity of the belt run out

and adjust if necessary. The belt will move toward the high side of idlers that are not

horizontal.

9.4.2. Adjust the idlers preceding the point of run out to steer the belt back to the centre.

Make small adjustments to a few idlers and wait for a few minutes or a complete belt

revolution before making further adjustment.

10. Do the same to the carry side of the conveyor, commencing at the tail pulley and

working toward the head pulley.

11. When the empty belt runs true a load can be applied. Commence with a small

percentage of the design capacity and check that the belt alignment does not alter. Thenincrease the load in gradual increments checking for true belt alignment after each

increment. If the belt runs out of true when material is loaded then adjustments to the load

chutes are necessary to ensure that the load is placed centrally on the belt.

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Truco Belting Care