Get your conveyor belts on track

Says PPI’s Jeff Poe: “You can have a conveyor track perfectly in the center for years, and then all of a sudden it will want to track to the left or the right.” Photo: P&Q Staff

Conveyor component manufacturers largely agree: effectively tracking a conveyor belt is the top challenge aggregate producers face related to their belts.

Producers, of course, can follow a number of best practices to avoid belt misalignments. Plus, there are “Band-Aid” product solutions out there to ensure belts run as they should.

Still, a conveyor belt may go off track at one point or another. This operational issue unfortunately isn’t going away anytime soon.

“It’s going to be an ongoing challenge,” says Steve Cook, general manager of Martin Sprocket & Gear’s Idler & Pulley Division. “As maintenance practices change, the general housekeeping of a plant plays a big role in belt tracking. Keeping belts clean is a big thing. Properly installing, adjusting and maintaining belt-cleaning systems plays a pretty big role in belt tracking, as well.”

Belt installations

Fasoli

The proper installation of conveyor belts goes a long way to mitigate belt tracking issues, too. As Luff Industries’ Matthew Fasoli describes, tracking issues can emerge long before belts even turn.

Making sure troughing idlers are spaced evenly from one another is essential, he says.

“Guys will bolt on their first trough set and then run a tape measurer to the second, and then to the third,” says Fasoli, CEO of Luff Industries. “By the time you get 100 units down the conveyor, you can be canted off 4 or 5 degrees.”

During installation, Luff’s field technicians take a special approach to avoid issues created by spacing each successive idler incorrectly.

“They’ll take a 100-ft. tape [measurer], vice grip it to the conveyor pulley and clamp it to one end of the conveyor – either the tail end or the head end,” Fasoli says. “That way, you can ensure you’re staying square to the structure.

“The biggest thing is setting up the initial install to make sure the trough idlers are square/perpendicular,” he adds. “You can use a drywall square to check it. The belt edges are usually plum and square. You can put it against your trough idler and know within 30 seconds if you’re off.”

Jeff Poe, field engineering managing at PPI (Precision Pulley & Idler), agrees that establishing alignment upon installation is a must.

“All conveyors have to be aligned,” he says. “If any one of them is out of alignment, cocked, tilted or slanted in some way – if the belt is going to roll around it – it could cause tracking issues.”

Common issues

Poe

Even if a conveyor belt is installed properly, producers are still bound to face tracking issues throughout the life of a conveyor. Off-center loading is a common source of misalignments, and it can lead to more serious operational problems.

“Think about transfer points where you’re loading material onto a conveyor,” Poe says. “If, for whatever reason, the material is being loaded toward one side versus being loaded into the center of the conveyor belt, the off-center loading of the conveyor will cause tracking issues.”

Once the entire belt is loaded off center, the weight of the material on the belt will cause the belt to roll.

“When it rolls, it’s going to track off to one side,” Poe says. “That’s very common in the industry.”

Another common source of a belt misalignment is crooked belt splicing, Poe says.

“The people who do the planned belt splice generally do a very good job,” he says. “But, generally, if a customer has a belt break or some type of issue where they have to make a splice during production and they’re rushed, a lot of times they’ll splice the belt back together and the two edges don’t match up.”

Substantial tracking issues can result, according to Poe.

“Normally, you have to make yourself a list of checks,” he says. “Observe the conveyor, watch how it’s performing and check how it’s loaded onto the belt. Then, you can dial in on the root cause of the tracking.”

Other considerations

Cook

Cook agrees that simply walking the belt can go a long way to solve a tracking problem.

“After they’ve tried the basics, we would have people walk the conveyor with the maintenance people, discuss and work systematically through a list of items to determine the root cause,” Cook says. “They’re likely to start at the tail pulley and work their way up the conveyor, looking at the way things are mounted. Look at the environmental conditions, as well.”

For example, a conveyor out in the open with a lot of wind – especially with a gravity take-up – may get pushed around, according to Cook.

“Look at the physical conditions and the environment,” he says.

Conveyor spillage, with a pile accumulating on the ground to the point where it’s contacting the belt, can undoubtedly happen, too. Once that belt runs over the spillage or buildup, Poe says the belt will track in the direction that it’s being pushed.

“Housekeeping is critical to keep your conveyor tracking,” Poe says. “It’s one of the biggest issues with tracking. It’s a big issue because anywhere you have a transfer point – whether loading material onto a belt from a hopper or a conveyor to a conveyor – material is moving at a velocity.”

Once that material comes in contact with a moving belt, it can create dust and spillage, which maintenance personnel must manage.

“You can have a conveyor track perfectly in the center for years, and then all of a sudden it will want to track to the left or the right,” Poe says. “Generally, what can happen there is the lagging wears on the pulleys.”

Most pulleys have a rubber coating over their steel shells, Poe adds. If that rubber wears over time, pulleys can wind up developing a smaller diameter in the center and a larger diameter toward the ends.

“When you have that happen, it’s kind of like a reverse crown, and the belt’s always going to want to track to the large-diameter side,” Poe says. “It’s not going to track in the center. The reason for that is because of the crown in the pulleys. The lagging has worn down in the center such that the center is slightly less than the ends.”