When setting up or upgrading a screw conveyor system, one of the key design decisions is whether to configure the drive to push material or to pull it through the trough. That decision, while seemingly subtle, can influence the alignment, wear, and reliability of your system. At KC Supply Co., we often guide clients through this choice to maximize lifespan and minimize maintenance. Here’s what you should know.
What Do “Pushing” and “Pulling” Mean in Screw Conveyors?
In a screw conveyor, a rotating helical flight moves material through a trough or tube. The drive (motor + gearbox) can be placed at either end:
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Pushing means the drive is at the inlet (tail) end, so the screw “pushes” the material forward.
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Pulling means the drive is at the discharge (head) end, pulling the material toward its exit.
Although either arrangement can move material, they impose different mechanical stresses on the system, which affects performance and maintenance.
The Case for Pulling: Why Many Prefer It
Many experienced designers and suppliers recommend configuring the conveyor to pull material toward the discharge end. Here are some of the key advantages:
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Tension on the Screw Sections
Pulling puts the internal tube or shaft in tension. This tends to keep the screw sections aligned and straighter, reducing deflection or bending under load. In contrast, pushing adds compression stress, which can magnify bowing or misalignment over time. -
Reduced Risk of Kinks or Misalignment
Think about pushing a chain versus pulling it. If you push, it may buckle; if you pull, it stays taut. The same principle applies to screw conveyors. Pulling tends to maintain a straighter path, especially in longer multi-segment systems. -
Less Fatigue on Components
Because pulling tends to minimize bending loads, bearings, shaft couplings, and joints may experience lower fatigue. That can translate into fewer breakdowns and longer service life.
Because of these benefits, many conveyor designers place the drive at the discharge end when space and layout allow.
Why You Might Be Pushing Instead
It’s not always practical or possible to use a pull configuration. Sometimes the layout, height constraints, or equipment positioning force a push arrangement. In those cases, you must design and maintain carefully to mitigate the drawbacks:
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Make alignment checks a routine part of maintenance. A pushing configuration is more sensitive to misalignment, so frequent checking and adjustment help avoid early wear or failure.
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Use robust components—stronger shafts, stiffer bearings, and higher-quality couplings—to resist compression stresses.
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Keep the conveying distance shorter if possible. Pushing over long distances increases the risk of deflection and component fatigue.
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Monitor for bending or bowing of the screw. If you notice it creeping over time, you may need to redesign the layout or consider rerouting to a pulling configuration.
Design and Operational Tips Regardless of Configuration
Whether your system is pushing or pulling, good design practice helps you get the most out of your screw conveyor:
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Match the conveyor speed and diameter to the material’s properties (density, abrasiveness, flowability). Overloading worsens stresses.
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Limit trough loading percentages so the material operates below critical stress levels rather than packing or overburdening the flight.
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Use intermediate supports or bearings carefully—especially in longer conveyors, to prevent sagging or misalignment.
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Plan for maintenance access to allow inspection, cleaning, and correction of alignment.
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Ensure strong drive components—a stiff shaft, properly sized gearbox, and high-quality bearings help counter the stresses introduced by pushing or pulling.
Conclusion
The choice between pushing and pulling in screw conveyors isn’t just a matter of convention—it’s a practical tradeoff affecting alignment, stress, and reliability. While pulling (drive on the discharge end) often gives better long-term stability, you should weigh your facility’s layout and constraints carefully. If pushing is your only option, designing defensively and scheduling regular upkeep can help you avoid premature failures.
At KC Supply Co., we can help you specify, design, and maintain your screw conveyor system—whether pushing or pulling—to get reliable, efficient material handling performance. Let us know your application and requirements, and we’ll work with you to find the best setup.