The Role of Pulley-Protection Plows in Preventing Material Spillage and Damage
Any damage to the belt or pulley in a conveyor system can negatively impact its performance, as stability is crucial for controlling fugitive material. By eliminating potential sources of damage, the entire system's efficiency improves, and the risks of dust and spillage are significantly reduced.
To prevent material from getting trapped between the belt and pulley, proper loading control is essential. Factors such as the correct trajectory and drop height for the material, along with the relationship between the speed of the loading material and the speed of the moving belt, help to settle the load, reduce agitation, and minimize spillage. Maintaining proper belt alignment is also necessary to prevent spillage that can cause material to drop onto the return side of the belt. Another method to prevent cargo from falling onto the return belt is to enclose or cover it with decking. While this can be expensive for long conveyors, decking is typically applied near the loading zone. Even with full-length decking, material can accumulate on top and eventually spill onto the return run, necessitating a pulley-protection device.
Despite ideal installations and other precautions, there is still a risk that components or conveyed material will spill onto the inside of the belt. Therefore, a system is needed to prevent these items from damaging the conveyor’s rolling components. Pulley-protection plows are commonly installed at the tail pulley but may also be used to protect the take-up or other pulleys, depending on the specific material and conveyor characteristics. These plows remove fugitive materials with low-pressure scraping, directing them off the belt like a snowplow clears a road. Their primary function is to block large lumps or stray conveyor components, such as idler rollers, belt-cleaner blades, or other tramp iron, from entering the tail pulley and damaging the belt.
A plow installed slightly above the belt can capture a lump of material against the belt, risking surface abrasion and potential belt damage. Pulley-protection plows are usually designed to float on the belt’s surface, using either their weight or a tensioning mechanism to apply slight pressure (13 to 20 kilopascals or 2 to 3 lbf/in²) against the belt. These plows are built to be heavy-duty and tall enough to prevent fast-moving materials from going over the top. If the belt carries significant quantities of fines or slime on its inside surface, an additional return belt cleaning system should be installed. Although it consumes extra conveyor drive power, this system effectively removes material, reducing the risk of belt slip and accumulation on the pulley.
A pulley-protection plow used for cleaning fines should be positioned, such as directly under the load point, to scrape spillage off the belt and discharge the material where it can be easily collected. Care should be taken when discharging fugitive materials near the tail pulley, as it can cause material buildup below the conveyor, leading to other problems. As with any belt cleaner, removed material that accumulates under the conveyor can cause premature wear of the belt top cover.