Conveyor Belt Safety
Conveyor belt maintenance not only includes proper care of the belt itself but also includes care and maintenance of the frame and accessories.
The first step in the process is to design an inspection form to encompass all aspects of each conveyor. This brochure is designed to assist in the actual design of the inspection report and the steps needed to correct any problems that you see when making this inspection.
- Belt Shut Down and Empty
The first step is to inspect the conveyor belt when the system is shut down and empty. This allows the opportunity to check for any damage to the belt or splice. The conveyor should be locked out while making this inspection.
Rubber belt damage should be repaired using the hot vulcanised repair method or the cold repair method. Belt fabrics that are exposed to the weather or to product contamination should be properly cleaned, dried, then covered with new rubber. These repairs are critical to prevent moisture from penetrating the belt and breaking down the cover adhesions, and to prevent product contamination from abrading the carcass and also breaking down the adhesions.
Very few, if any repairs can be made to lightweight belts.
The splice can also be inspected and if damage in the splice is visible it is suggested that the splice be repaired or replaced.
- Belt Running Empty
The conveyor should be turned on and run empty. The purpose of this is to walk the conveyor, while running empty, to check for any tracking problems. Before any adjustments are made to correct a tracking problem, the system will need to be inspected under running conditions when loaded, because empty belts and loaded belts do not necessarily track the same way.
A conveyor system with carry back on the return side is the single biggest reason that conveyor belts are replaced, return idlers and pulleys are replaced and structure is worn through. Material build up on the belt and hardware causes tracking problems, that will lead to edge damage, that leads to new belt and new idlers.
We urge you to use scrapers on the head pulley and plows in front of the tail pulley as prevention for damage in your maintenance planning. Some sticky materials present a real challenge when it comes to preventing carryback. We would like to offer a few additional suggestions as to handling these products.
Cleated belts may be reversed to allow better release at the discharge point. A dual scraper system on the head pulley is the most common way to eliminate product carryback.
A water spray on the belt cover along with wiper blades will effectively remove most products from sticking to the cover.
A series of out of round (cam shaped) return idlers will also assist in cleaning. These idlers are spiral wound from the edges towards the center of the idler and work on the premise of a turning beater bar arrangement.
A compressed air blast has been successfully used on material like coal and fine wet sand.
A power driven revolving brush will help remove product from the belt. This method is rarely used because the bristles tend to clog up with material and wear out quickly. A brush may be the only solution for cleated belts.
Product build up on return side pulleys is a major concern. If your belt is not effectively clean on the return run, then any bend pulleys or head snub pulley that come in contact with the carry side of the belt will accumulate product.
Hints on pulley and idler cleaning
All return side pulleys that come in contact with the carry cover can be lagged with a soft rubber vulcanized to the pulley.
The constant flexing action of the soft lagging will cause material to fall off and reduce material accumulation.
A lever weighted urethane scraper pressed against the pulley face, is an excellent way to remove build up. This system causes additional wear on the pulley face so it is suggested to use heavier walled return bend pulleys when using a scraper. If a scraper is applied to a head snub or bend pulleys at the take-up area then deflector plates will have to be installed to deflect he build up away from the belt.
Return idlers can be rubber covered and will help prevent product from sticking to the return idlers.
Return idlers can be purchased that are nothing more than discs mounted on a shaft. These discs can be made of soft rubber, urethane, or ceramics. This type of return idler can be very effective to prevent build up. The major problem when using this style of return roller is that the manufacturers do not put enough discs on the shaft to effectively support the belt in the middle, and support the edges of the belt if any mis-tracking occurs.
Another effective measure is called a turnover system. By the use of a series of rollers the belt is flipped over at the head and tail on the return side. This allows the belt to run the return side with the carry (dirty side) side up and the pulley (clean side) side down in contact with the return rollers. Any spillage from the product carryback will be limited to the two twist areas..
