TL;DR

A belt rotation fault is most often idler misalignment or a blocked idler causing the pipe to open. Walk the belt and identify the first misaligned idler cluster, then realign.

What you might see

belt twist alarm triggered
idler roller contact on belt edge
material spillage at transition zone
belt speed sensor mismatch

Likely causes

Tap to mark as ruled out

Idler roller cluster misaligned causing the pipe to open or twist
Material buildup on an idler roller locking it and causing belt side loading
Belt edge damage or splice mismatch opening the pipe prematurely
Transition zone idlers set at wrong closing angle

Required tools

Angle gauge or protractor
Wrench set
Chalk or spray marker
LOTO kit

Safety first

Lock out the drive before walking alongside the conveyor for inspection. Unexpected belt restart is fatal.
Dust explosion risk in mineral ore environments. Avoid open flame or grinding sparks near the belt enclosure.
Falling material hazard at spillage points. Wear a hard hat and appropriate PPE.

Procedure

7 steps · ~60 min

1
Stop the conveyor and lock out the drive motor.
Warning: Confirm belt is fully stopped before walking alongside it. Belt restart without LOTO can cause entanglement.
2
Walk the full length of the conveyor and visually inspect each idler cluster for misalignment or a seized roller.
3
At any cluster where the belt edge contacts an idler, mark the location and check the cluster frame for displacement.[1]
4
Check each idler roller by hand for free rotation. Seized rollers leave a wear track on the belt edge.
5
Re-align any displaced cluster frame to the design angle and tighten the mounting hardware.[1]
6
Inspect the transition zone idlers where the belt changes from flat to pipe. Confirm the closing idler angles match the design drawing.
7
After realignment, jog the belt under no load and observe the rotation at the repaired clusters.

Sources

FLSmidth FLSmidth pipe conveyor Heavy-Duty Conveyor (Mining) general technical documentation, FLSmidth
FLSmidth pipe conveyor operation and maintenance documentation, idler alignment procedures (general)

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