Scraper conveyors generally use a single or double strand of chain. Flights are either welded directly onto the chain, or bolted onto the chains attachments.
Scraper conveyors can be horizontal or inclined, with the scrapers moving the product (usually free flowing bulk materials) along the conveyor bed, preventing adhesion whilst still moving the product gently.
The chains used in scraper conveyors are generally a forged chain or a bush chain (i.e. a chain without rollers) as rollers lift the chain/scraper and often jam due to being covered by the conveyed product.
The form of the scrapers is often bespoke to the application. On twin strand chains, a cross bar is generally bolted to L attachments on the chain. Some scraper conveyors simply use the bar to move the product, while for deep trough conveyors a further attachment ‘paddle’ would be bolted onto the cross bar, which would then move the product within the trough. Deep trough conveyors are perhaps the only scraper systems where a roller chain could be used, as the chains run above the product being conveyed. Caution should be taken however to protect the chain from product at the inlet.
For single strand chain conveyors, the flights are either welded directly onto the chain both sides, or are bolted on to ‘L’ or ‘F’ type attachments. If a roller chain is used, a deflecting plate is generally installed to deflect bulk materials past the chain and into the feed trough.
Scraper chains have a wide range of uses such as moving feed, ash, cement, wood shavings, slags etc, or scraping settlement tanks (either above or below the water lines) Tank scrapers are often given other names, such as submerged scraper conveyors, submerged flight conveyors or bottom ash handling conveyors.
Caution should be taken when manufacturing and running scraper conveyors to ensure that the system is always tensioned correctly. If the chain starts to ‘sag’, then it is possible for the leading edges of the scraper flights to come into contact with the trough. The contact of the flights with the trough can greatly increase the overall friction of the system, damaging or snapping the chain and flights.
With over 40 years experience in the manufacture of both standard and bespoke chains, we are able to assist with new scraper system designs, or simply 'like for like' chain and scraper flight replacements.