Conveyor Troubleshooting: Causes & Fixes

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Problems on this page:

Belt slipping Belt mistracking (wandering)Unusual noise or vibration Conveyor won't start Material carryback / spillage Belt damage or rips Product jams at transfers and merges Drive motor or gearbox overheating Chain or modular belt wear and elongation

Belt slipping

Hits OEE: Performance

Symptoms: Belt slows or stalls under load, squeal at the drive pulley, product backing up.

Low belt tension

Re-tension to spec at the take-up; check for permanent stretch.

Worn or glazed pulley lagging

Inspect and replace lagging; clean a contaminated drive pulley.

Overload or jam

Clear the blockage; confirm load is within rated capacity.

Wet/contaminated belt

Fit scrapers/wipers; fix spillage upstream.

Prevention: Scheduled tension checks, pulley-lagging inspection, keep belt and pulleys clean.

Belt mistracking (wandering)

Hits OEE: Quality

Symptoms: Belt drifts to one side, edge wear, rubbing on the frame, spillage.

Frame/pulleys out of square

Check level and squareness; align idlers and pulleys.

Uneven or off-centre loading

Centre the load at the feed point; add load chutes/skirting.

Material build-up on a pulley

Clean pulleys; add a belt cleaner.

Worn idlers

Replace seized or worn idlers; add training idlers if needed.

Prevention: Routine alignment checks, belt cleaners, centred loading.

Unusual noise or vibration

Hits OEE: Availability

Symptoms: Grinding, knocking or squealing; vibration felt at the frame.

Failing roller/idler bearings

Locate by touch/listening; replace the faulty roller.

Debris in the mechanism

Lock out and clear debris from rollers and return path.

Drive chain/coupling wear

Inspect chain tension and coupling; replace worn parts.

Prevention: Vibration/bearing checks, guarding to keep debris out, lubrication schedule.

Conveyor won't start

Hits OEE: Availability

Symptoms: Motor hums or is dead, no movement on start command.

Tripped overload or blown fuse

Check the starter overload and fuses; reset and find the cause of the trip.

E-stop or interlock open

Verify all E-stops, guards and pull-cords are reset/closed.

Jam/mechanical seizure

Lock out; turn by hand to find the seizure; clear it.

Control/sensor fault

Check start signal at the PLC and the run permissive.

Prevention: Periodic interlock testing, overload sizing review, keep transfer points clear.

Material carryback / spillage

Hits OEE: Quality

Symptoms: Material drops along the return run, housekeeping and slip hazards.

Worn or missing belt cleaners

Fit/replace primary and secondary belt scrapers.

Mistracking spilling at edges

Correct tracking; add skirting at load points.

Carryback sticking to the belt

Address material moisture; add belt washing if needed.

Prevention: Belt-cleaner maintenance, tracking, load-point skirting.

Belt damage or rips

Hits OEE: Availability

Symptoms: Longitudinal rips, gouges, edge damage, frequent repairs.

Trapped or sharp material

Fix loading; add rip detection and chute design.

Seized idlers gouging the belt

Replace seized idlers; inspect the return run.

Tracking causing edge wear

Correct tracking; protect belt edges.

Prevention: Loading/chute design, idler maintenance, tracking control.

Product jams at transfers and merges

Hits OEE: Performance

Symptoms: Product tips, stops or bridges where two conveyors meet, at dead plates and at merges; photo-eye blocked faults and short stops.

Height or gap mismatch at the transfer

Set both conveyors level at the transfer, close the gap, and fit a transfer plate or rollers where product is small.

Speed mismatch between sections

Run the downstream section slightly faster to pull gaps, and tune the accumulation settings.

Worn or badly set guide rails

Realign and replace worn guide rails; set the width to the product with an even clearance on both sides.

Unstable product (light or tall packs)

Add side guides, soften starts and stops, and use low back-pressure accumulation.

Prevention: Check transfer heights, gaps and guide-rail settings at every changeover against a settings sheet per product.

Drive motor or gearbox overheating

Hits OEE: Availability

Symptoms: Motor trips on overload, gearbox hot to the touch, burning smell, oil weeping at the seals.

Dragging load: seized rollers or bearings

Spin the rollers by hand to find the ones that drag, replace seized bearings, and confirm the load is within rating.

Low or wrong gearbox oil

Check the oil level and grade against the gearbox maker's spec and replace degraded oil.

Blocked motor cooling

Clean the fan cowl and cooling fins; keep washdown covers and product off the motor.

Misaligned coupling or over-tight chain

Align the coupling and set chain tension to the OEM guidance; lubricate the drive chain.

Prevention: Thermal checks on motors and gearboxes, scheduled oil changes, clean cooling paths and roller spin checks.

Chain or modular belt wear and elongation

Hits OEE: Availability

Symptoms: The chain or plastic modular belt jumps sprocket teeth, surges, sags on the return side, or breaks pins and modules.

Elongated chain and worn sprockets

Measure elongation against the chain maker's limit; replace chain and sprockets together.

Wrong return-side catenary or take-up

Set the return-side sag and take-up to the belt maker's guidance.

Wrong lubrication or contamination

Use the lubricant the belt maker specifies, or none where it says dry running; clean out debris.

Worn wear strips

Replace worn wear strips and check the belt edges for rubbing.

Prevention: Measure chain elongation on a schedule, change chain and sprockets as a set, and keep wear strips and lubrication to spec.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Alarm codes: ABB ACS550 drive fault codes · Siemens MICROMASTER 440 fault codes

Stop the same fault coming back

Recurring conveyor stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover