Diagnosis and elimination of belt routing problems in belt conveyor systems

1. Problem description and scope

Belt routing problems (mistracking) lead to uneven wear, edge damage, material shedding and, in critical cases, total failure of the conveyor system due to belt damage or structural damage to the conveyor frame. This document supports maintenance technicians in systematically identifying causes.

• Critical Level: Belt is running against the conveyor frame or structure. Immediate shutdown required.
• Main problem: Belt does not run in the middle, causes edge wear, but does not yet touch the framework.
• Subsidiary problem: Periodic swaying of the belt running.

2. Safety instructions

DANGER: Before starting any inspection or adjustment, the system must be switched off in accordance with the LOTO protocol (Lockout/Tagout) and secured against being switched on again. Work on running systems is only permitted if a risk assessment expressly permits this and appropriate protective distances are maintained. PPE: safety shoes, hearing protection, tight-fitting work clothing, protective gloves.

3. Diagnostic tools

4. Initial assessment (checklist)

5. Systematic diagnosis

The diagnosis is made using a decision tree:

1. Symptom: Belt only runs out of the center at a certain point.
   • Check: Is there a local deformation of the belt frame?
     • If yes: straighten the frame.
     • If no: Are the support rollers stiff or tight at this point? (Check by turning by hand at LOTO).
       • Result: Replace rollers.
2. Symptom: Belt runs crooked over the entire circuit.
   • Check: Drum alignment. Are the drive and deflection drums exactly parallel to each other and perpendicular to the longitudinal axis of the conveyor?
     • Measurement: Check with laser alignment tool. If not: readjust the drum bearing.
   • Test: belt tension. Is the tension even?
     • Measurement: Check belt stretch. If not: readjust the clamping station (take-up).

6. Error-cause matrix

7. Root cause analysis

7.1 Asymmetric loading

When material hits the belt off-center, the gravity of the material creates a force component toward the unloaded side that pushes the belt off center. Confirmation by observation at operating load. Required action: Install centering device in the transfer chute.

7.2 Drum alignment

Deflection pulleys must be at right angles to the longitudinal axis of the belt. A misalignment of just a few millimeters across the belt width is enough to cause the belt to move. Confirmation by laser escape tool. Consequences: edge wear, belt stretching on one side.

7.3 crooked splice

A splice seam that is not made at right angles leads to periodic belt running behavior (the belt moves with each revolution). Test: Measurement of the squareness of the belt ends during assembly or standstill. A splice that is not square is not repairable; the belt needs to be re-spliced.

8. Repair procedures

1. Adjustment of drum alignment:
   • Secured by LOTO.
   • Loosen the drum bearing blocks.
   • Adjust to 0.1mm/m parallelism with laser alignment tool.
   • Tighten screws with a defined torque.
2. Exchange of support rollers:
   • Securing by LOTO.
   • Pry the defective roller out of the holder.
   • Insert new role.
   • Check freedom of movement (roller must rotate without resistance).

9. Prevention

10. Spare parts and components

Detailed specifications can be found in our E-Catalog.

11. References

• DIN 22101: Continuous conveyor - belt conveyor for bulk goods
• VDI 2341: Design of belt conveyor systems
• OEM drive unit service manuals