What to do


Idler(s) behind a trouble point are not at right angle

Belt running to one side at a given point

Buildup of material on idlers

Crooked conveyor structure

Blocked idler(s)

Advance the end(s) of the idler(s) in the direction of belt travel.

Clean, and improve maintenance

Make corrections

Lubricate or replace idler(s)

Belt not joined squarely

Particular section of belt running to one side at all points

Crooked steel cord belt,

because of

- wrong lay of steel cords,

- transverse thickness difference,

- tension difference of steel cords,

- height difference of steel cords.

Crooked textile belt

Refasten resp. replace splice

Measures to be discussed with belt manufacturer.

In most cases, a replacement is inevitable.


If the textile belt is new, it might straighten out after a couple of days under full load.

Idlers out of square

Belt runs to one side for a longer distance

Off-center material feeding

Align idlers

Adjust chute and loading conditions.

Misaligned pulley or belt camber

Belt runs off-center around the tail pulley and in the loading area

Dirt build-up on pulley

Align the pulley

Clean the pulley or ...

install training idlers

Scraper pressed too hard on belt

Premature wear or abrasion of belt top cover

High speed differential between belt and conveyed material

Material build-up on return idlers

Adjust the scraper

Reconsider chute/feeding layout.

The chute should deliver the conveyed material to the belt as closely as possible to its speed and direction.

Use cleaning device.

Install (some) disc type return idlers

Dirty, frozen or misaligned idlers

Premature wear or abrasion of belt bottom cover

Slippage on drive pulley

Transition length too short

Overload in horizontal or convex curves

Clean, improve maintenance

Check pulley for correct lagging. Consider to use ceramic

Check, and extend, if possible.


Insufficient traction between belt and pulley

Belt slips


Counterweight too light or blocked

Worn pulley lagging

Increase belt wrap (contact length between belt and pulleys); improve belt cleaning.


Add counterweight or increase screw take-up tension or eliminate blocking.

Replace lagging. Consider to use ceramic.

Tension too high

Excessive elongation of belt

Buildup of material on idlers

High-elongation carcass

Belt strength too low.

Reduce tonnage; reduce counterweight.

Clean idlers, improve scraper systems

Replace by lower elongation belt, for instance with polyester warp.

Replace by stronger belt

Skirt board seals are pressed against the belt

Grooving, gouging of top cover

Material trapped under seals

Material impact

Skirtboard seals too hard

Leave enough clearance b etween seal and belt.

Install cushion idlers to hold belt up towards skirts.

Improve chute design for smoother feeding; install impact idlers.

Use proper sealing material (no old conveyor belts...).

Frozen (or even broken?) idlers

Grooving, gouging of bottom cover

Worn pulley lagging


Material buildup

Free the idlers and lubricate them

Replace it

Usually causing longitudinal grooves.

Install or improve cleaning devices, avoid spillage, improve maintenance

Impact of material falling onto belt, or foreign body clamped between belt and pulley

Holes or breaks in belt

Reduce impact; use cushion idlers; use belt with impact protection system; repair the spots.

If you want to increase strength and thickness of the belt, check the pulley diameters and motor power first

Note: For larger holes check the repair procedure with the belt supplier, because the safety factor may have become critically low.

Excessive abrasion of pipe belt outer side

Impressions from aggressive ceramic lagging

Material spillage between belt and pulley

Correct position of tilted training idlers.

Replace lagging

Improve loading conditions. Install plows or scraper before the tail pulley.

External damage,

improper splice manufacturing

Splice failure

Splice failure is most critical and needs immediate professional care.

In case of damaged steel cords or even excessive movements of steel cord ends (see also "Excessive elongation of belt"), the splice has to be cut out and removed.

How to make a proper splice.

Note: For longer, important conveyors it is recommended to have state-of-the-art belt 24/7 scanning by an X-ray system.

Lack of adhesion or overloading

Cover-ply separatation

Check whether adhesion between cover and carcass of the belt is sufficient and whether pulley diameters are big enough.

Random cracks in the top cover rubber perpendicular to the direction of belt travel can also be an indication of too small pulley diameters.


Damage by external body or jammed conveyor part

Longitudinal rip

Usually a cold or hot repair is required. Temporarily, mechanical fasteners may be used.

In many cases, replacement of the belt is unavoidable.

Mistracking belt

Edge damage

Critical especially with steel cord conveyor belts. Adjust pulleys and idlers for straight tracking. Severe damage should be repaired by hot vulcanization.


See animations on top of this page.




Groove in cover
Opened splice ramp
Torn steel cord belt splice
Steel cord impact damage

Compound too hard

Hard and/or cracking cover

Lack of ozone protection

Exposure to heat, temperature of conveyed material is too high


Compound contains too many sulfur bridges. No repair possible.

Use high temperature resistant belt type.

Sulfur bridges replaced by oxygen bridges. No repair possible

No repair possible. Monitor the crack progression

Cracked cover
Broken idler
Impact cover damage
Impression of pulley lagging
Material build-up on idler
Edge damage

Splice starting to open

Dangerous. Check splices (X-ray).

Drive pulley
Transition length

"Other" problems

Transportation accident