We do everything possible to supply our customers the highest-quality drag chain conveyors, but even so, much can go wrong after startup. Oftentimes, what’s gone wrong stems from from operational error. Customers (and anyone owning a drag conveyor) can avoid these mistakes, however, thereby increasing the lifespan of their conveyors and preventing failures.
Altering the Material and Infeed Rates
One of the most devastating errors someone can make in regards to their conveyor is to alter the material and flow rates without consulting us (or whomever manufactured the conveyor). Industrial conveyors are designed to specific specs, so when you increase the infeed rate, increase the chain speed, or change the material specs, it’s likely you’ll encounter problems. This is why we highly recommend our customers contact us before making changes to the conveyor—and why such changes will invalidate the warranty. ALWAYS speak to us before making adjustments. We or whomever you purchased from will have a good idea of how adjustments will affect the conveyor’s performance and can tell you whether the changes you wish to make are even possible.
Customers have at times severely damaged our conveyors because they altered the infeed volumes or otherwise ran the conveyors to specs the conveyors weren’t designed to handle. Damage like bent paddles and frames, and chains that wear prematurely indicate a problem related to changes in the system, likely that the conveyor is running past its capacity or being contaminated with foreign materials.
Welding Conduit to the Frame
Another problem we’ve seen is that maintenance technicians commonly weld conduit to the side panels of our conveyors. While crews may get away with this on other paddle conveyors, welding to the sides of our conveyors will damage the plastic wear liners over which the chains run. Damaged wear liners will affect the chains, the paddles, and the overall efficiency of the system. The damage can also make it difficult to replace the liners.
This error occurs frequently enough that we offer bolt-on conduit mounts that allow crews to run conduit alongside our conveyors without damaging them.
Over tightening the chain
While customers change material specs and weld where they shouldn’t too often, the most common errors we see them perform relate to maintenance. Neglect is by far the most common mistake, but incorrect maintenance occurs frequently, too. In the latter case, maintenance crews will most often over tighten the chains. Really, chains in our SMART Conveyors™ only need the slack taken out of them—they don’t need to be tight, as they have little wiggle room in the channels they run through. Maintenance personnel need to avoid over tightening the chain because it will accelerate wear on the curves, chains, sprockets, and bearings and damage shafts.
Uneven Take-up in Chains
Uneven take-up is another common maintenance error. In dual-chain conveyors like ours, uneven take-up will cause paddles to run crooked and hasten the pace of wear on the paddles and chains. In single-chain conveyors, uneven take-up can cause the chain to run crooked through the trough and accelerate wear of the bottom panels. In either, it can pull the shafts out of alignment.
Always adjust the take-up when the drag conveyor is running, and make sure you adjust the take-ups evenly and gradually to keep the tail shaft perpendicular to the length of the conveyor. Check the take-up per the manufacturer’s suggested maintenance schedule (weekly for SMART Conveyors™).
Neglecting Preventative Maintenance
More than any other issue, neglecting preventative maintenance altogether is the most common mistake customers make. For SMART Conveyors™, we suggest the following maintenance schedule (see your conveyor’s manual for complete details):
- Daily clean chips and debris from machine working area, gear motors, and take-up systems. Ensure that no strings are wrapped around rotating components and that no shards are wedged between components. Watch for excessive play and listen for unusual noise that could indicate maintenance requirements. Immediately shut down any machine making unusual noise and address it accordingly.
- Weekly open covers and remove excess chips from tail areas of the conveyors. Inspect that all machine guards are installed and functioning properly, and test emergency stops. Ensure that keys are fully engaged with sprockets. Inspect that all paddles are straight on the conveyors. Inspect curve chain wear strips. Inspect chain for stretching.
- Monthly clean all electrical systems. Replace defective components with equivalently rated parts. Lubricate the take-up and head bearings. Check the oil levels in the gearboxes. Inspect the chains systems, bearings, and fasteners.
- Semi-annually conduct a thorough inspection of the machine, noting all items that should be ordered for shutdown replacement.
- Annually replace the oil in the gear motor and check with Biomass Engineering & Equipment for retrofits and upgrades.
Never Checking Chain Stretch
Among all preventative maintenance tasks, we find that maintenance crews most often neglect the chains, specifically. Chains tend to stretch more quickly the first few months of operation and should be adjusted regularly. By neglecting to check the chain, crews risk having the chain bunch around the sprockets and run unevenly through the conveyor. They also are unable to tell when a chain is approaching the end of its working life. When a chain stretches to 3 percent of its rated pitch, it is time to replace the chain. Running the chain past this point substantially increases the risk of catastrophic failure.
On a similar thread, maintenance crews will often neglect to check the sprockets. Worn sprockets are problematic in general in that they tend to cling to the chains. They can also indicate problems that can lead to damaged shafts. If you see wear on the side of the teeth, it indicates that the sprockets may not be aligned correctly or that the take-ups are not evenly adjusted. Misaligned sprockets can also pull shafts out of parallel, which creates a cycle of wear: misaligned shafts wear faster, and as shafts walk in the bearings or move around due to a loose set screw, the sprockets move, too.
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