Critical Considerations for Plow Placement and Functionality
Plows must be strategically positioned to ensure that material removed from the belt does not pose hazards where it falls or accumulates.
Similar to the necessity of having a roller above a secondary belt cleaner to apply downward pressure and prevent the cleaner from lifting the belt, it is equally important to install one or two pressure rollers below the pulley-protection plow. Here, the goal is to prevent the plow from altering the belt's alignment by pressing it downward, allowing material to pass beneath the blade. Depending on available space, this could involve a single idler roller directly under the plow or a pair of return idlers—one placed before the plow and one after.
Like any conveyor component that contacts the belt, installing a pulley-protection device increases friction against the moving belt, thereby increasing the conveyor's power requirements.
In its sixth edition of Belt Conveyors for Bulk Materials, the Conveyor Equipment Manufacturers Association (CEMA) recommends a normal force of 2 pounds-force per inch of belt width (equivalent to 0.35 newtons per millimeter of belt width) for plow-to-belt pressure. This force can be used to calculate power consumption using specific formulas.
Diagonal plows are installed across the belt at an angle of 45 degrees to the direction of travel
Selection Considerations for Pulley Protection
When specifying a pulley-protection device, several factors should be taken into account.
A plow should:
- Provide firm yet flexible pressure: This allows the device to effectively clean the belt surface, removing material efficiently while adapting to blade wear and variations in belt movement, speed, and path.
- Be securely mounted: Firm installation minimizes the risk of the plow breaking away and endangering conveyor components. A safety cable should be included to protect the conveyor system if the plow installation fails.
- Be designed for easy installation: The plow should be simple to install to minimize system downtime. It should fit within the conveyor structure without extensive modifications.
- Have a durable, easily replaceable blade: The blade material should withstand application conditions and allow for quick replacement when worn.
- Be easily accessible: Install the plow in an area where it can be monitored during operation and maintained without difficulty.