Belt Conveyors

[sh71382]

Very little material makes it back into the tunnel once its on the belt, 95% of what is in the tunnel on the floors, or at the base of the loop belt is spillage off the belt during travel. There are at least a dozen locations on the boom belt, loop belt, and tunnel belt combined that have these home made and rigid scrapers. There is some residue that sticks to the tunnel belt and that us usually taken care of by a scraper at the head or tail roller. But a very large portion of the spillage, or residue in the tunnel is from over loading the belt and it spilling off the sides as it moves, it bouncing off during travel, or it spilling out from the loop belt when it is pinched together. However there is the occasional exception to that. On rare occasion the vessel will take on a cargo of extremely fine materials like sand, or the load of coal, ore or stone is Very dirty and leaves a thick layer or dirt on the belt, and it is scraped off for the most part. Most ships I sailed on also have a water spraying system that not only keeps the dust down but also in a few places sprays the belt and keeps it plyable so it can be scraped off.

[Alakshak]

The reason I bring this up is because I am employed at a company in Michigan that makes conveyor belt maintenance and cleaning equipment and I also have a personal interest in great lakes shipping and history. I've come to realize that these self-unloaders may be doing a lot of laborous activities with conveyor men cleaning material that's carrying back in the tunnel when there's engineered equipment to address the issue. I'm not trying to be salesy but just making an observation.

[Randy S]

A rigid style of scraper could be used if the belt splice were vulcanized. However, it would most likely have to be replaced if the belt had to be repaired with mechanical fasteners. I have had no experience with loop belts, but on all of the boats I worked on, the scrapers were usually just an old piece of belting that was attched to or within a rigid frame. They would have a lot more "give" when the splices came around. Shoveling - I don't think that we will ever see the day when deckhands won't be using that laborious tool.

[Alakshak]

I was referring carry-back as material that sticks to the belt after its transfer point. Aside from rubber belt scraps and other rigged things, there is actual belt cleaners that mount to head pulleys and secondary cleaners that clean just back from the head pulley. Usually these are polyurethane blades or carbide tips, based on a vulcanized splice or fastened splice.

[syd bc]

Like Randy S said don't know what carryback means But there are rubber scapers at the end of the boom.Not much sticks to the belts.In the tunnel the is some spillage around the transfer belts and loop belt.If it builds up it can cause a shut down and has to be shovled out.Otherwise its just hosed out and run off as spillage

[Randy S]

I'm not sure what you are referring to when you say "carryback", but if you mean a device to scrape the belts clean, they employ a variety of methods from mounted brushes to scraps of old belting.

[Alakshak]

Do all self-unloaders run primary cleaners and secondary cleaners on belts under the tunnel as well as on the boom to prevent carry back? If so, Martin, Flexco, Argonics, etc? I'm assuming carry-back is a huge concern on these ships due to the best method for clean up being a shovel.