TL;DR

A belt tracking to one side is almost always a tension imbalance or a crown alignment issue on the end rollers. Adjust the tracking roller in small increments and allow the belt several belt lengths to respond before adjusting again.

What you might see

belt running to one side of the lehr
glass containers tipping or falling off belt edge
belt edge contacting the lehr sidewall
belt wear concentrated on one edge

Likely causes

Tap to mark as ruled out

End roller not parallel to the lehr frame allowing the belt to walk to one side
Belt tension higher on one side from uneven tracking adjustment
Belt splice joint not square causing periodic tracking deviation
Product loading asymmetric on the belt shifting the belt center of gravity

Required tools

Precision level
Wrench for tracking adjustment
LOTO kit

Safety first

Lock out the lehr conveyor drive before any roller or belt adjustment. Running belt contact in a hot lehr causes severe burns and entanglement.
Lehr interior temperatures are high. Use heat-resistant gloves for any work near the lehr opening.

Procedure

6 steps · ~30 min

1
Observe the belt tracking direction. Identify which end of the lehr the deviation is occurring from.[1]
2
Stop the lehr and lock out the drive before touching any roller adjustment.
Warning: Lock out the conveyor drive before touching any roller adjustment. The lehr belt moves continuously and entanglement with a running belt in a hot lehr is extremely dangerous.
3
Adjust the discharge end tracking roller in the direction that moves the belt toward center. Make one small adjustment at a time (0.5 mm turns of the adjustment bolt).[1]
4
Restart and allow the belt to run for at least 5 belt lengths before re-evaluating.
5
Check the belt splice for squareness. A non-square splice causes a repeating tracking deviation every belt revolution.
6
Verify the end rollers are parallel to the lehr frame using a precision level. Adjust if necessary.

Sources

Pennekamp Pennekamp Profile / Mosaik Annealing Lehr general technical documentation, Pennekamp
General glass lehr conveyor belt tracking and alignment maintenance procedures (general)

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