Page 40 - HUB-4 Magazine Issue 90

Quarrying
Find your centre:
Keeping conveyor belts on track
By Andrew Timmerman / Global Engineering Manager / Martin Engineering
The moment a conveyor belt begins to wander, the safety and
productivity of the system quickly degrade, and the cost of
operation rises. Even a slight belt misalignment can lead to a
variety of issues, from small annoyances to full-blown
catastrophes involving a conveyor system.
A misaligned belt can also come in contact with the stringer,
causing fraying, shredding or splice damage. If this condition
isn’t noticed right away, great lengths of valuable belting can
be destroyed, and the structural steel itself can be damaged.
In fact, a high-speed belt edge rubbing on the support
structure can cut through steel mounts with surprising speed,
leaving a razor-sharp edge that poses a safety risk. [Fig. 1]
rubbing on the conveyor frame at some point, degrading
the edge, reducing the usable width and increasing the
chance of a fire.
• Excessive spillage – Could mean that one side of the belt
has drifted higher on the trough angle, allowing cargo to
discharge along the belt path.
• Idler fouling – An off-center load and uneven belt plane can
foul idlers. Bearing abrasion can then cause the idler to
seize, and the ensuing friction against the running belt can
erode its coating and increase the risk of fire.
• Off-center at head or tail pulley – This type of drift can lead
to a fast-moving belt coming in contact with the conveyor
stringer structure. There is also a chance of splice failure,
which puts the entire system in jeopardy of the fast moving
belt detaching and causing a serious injury to workers in
close proximity.
• Lack of tail pulley protection - On many systems, the belt
collects lumps of spilled material on the non-carrying side.
If these objects are not removed, they can become trapped
between the tail pulley and the belt, causing mistracking
and often doing significant damage to both.
• Uneven discharge - As the belt drifts to either side of the
head pulley, the belt cleaners do not properly clean the
entire surface, causing excessive carryback. Material
collects on the pulleys and structure, fouling the return side
of the belt, resulting in slippage, lost product and other
negative effects.
• Uneven loading - If the belt path leading from the tail
pulley into the loading zone is uneven, the cargo can be
loaded off-center and cause excessive spillage. This may
also be caused by inadequate transfer point design. [Fig. 2]
Figure 1 – Contact with the support structure can cause serious belt damage.
Copyright © Martin Engineering 2025
Further, a compromised bracket or support can cause a
catastrophic idler failure, which could damage other
components of the system. All of these consequences of
mistracking result in added expenses, higher maintenance and
reduced efficiency.
Senior Product Specialist for Martin Engineering, Dave Mueller,
points out that beyond the many causes for mistracking, the
belt training system that came with the conveyor may in some
cases actually worsen the problem. “We’re seeing increased
belt speeds and greater cargo loads across most industries,”
explained Mueller. “But some systems are equipped with belt
tracking devices that aren’t able to handle those higher
thresholds. We often see OEM trainers tied off with rope or
chain in an attempt to drive a belt back into line.”
In the vast majority of cases, mistracking is a problem that can
be corrected. Belt behavior is based on a set of principles,
which serve as the guidelines for “belt training.” Training a
belt is the process of adjusting the conveyor structure, rolling
components and load conditions to correctly center the belt.
Wandering is prevented by first understanding the basic
patterns of belt behavior and then following established
procedures to carefully align the structure and components to
correct any fluctuations in the belt’s path.
Mistracking Indicators
Belt drift can begin in any part of the conveyor system, and
identifying mistracking is the first step toward correction. All
of the traits listed below could be indicators of mistracking.
• Edge Fraying – Probably an indication that the belt is
Figure 2 - When the belt is not center-loaded, the cargo weight
pushes the belt toward the more lightly-loaded side.
Copyright © Martin Engineering 2025
Identification Begins at The Head Pulley
Starting at the head pulley, the belt should also be inspected
for cupping, bow/camber (a long curvature) or crooked
splicing. When observing the empty belt running over the
head pulley, a cambered belt will drift to one side in the
middle of the camber and then slowly return to center as the
belt travels through the head pulley. If a splice is crooked, the
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www.hub-4.com Jan/Feb - Issue 90