Rock Products - The Leading Voice of the Aggregate Industries.

Peak Pulley Performance

By Carol Wasson

In today’s competitive environment, operations often face increasingly stringent productivity demands. Consequently, it is not uncommon for management teams to conduct periodic “audits” of their processes to ensure peak performance.

These audits are typically used to determine projected maintenance budgets and goals; and to identify any old or obsolete components which may compromise plant uptime and reliability. When auditing material handling systems, operations mayMHC-PEAK-1
wish to examine alternatives to the use of the conventional wing pulley.

While still a typical and traditional choice, the drawbacks of the standard wing pulley are significant especially when compared with the latest innovations in wing pulley designs. A recent development is the new V-shaped wing pulley, which extends pulley life and is engineered to deflect material and prevent belt damage, while minimizing noise and vibration during operation.

Prevent Material Buildup, Wing Bending

“When operating a traditional wing pulley, the impact of the material feed is directly perpendicular to the wing. Material is more easily entrapped between the wings, which over time can cause the wing to bend,” said Jarrod Felton, vice-president of sales, marketing and engineering for Superior Industries Inc.

Several years ago, Superior introduced its Chevron Wing Pulley, a V-shaped wing pulley design that according to Felton is fast replacing even the heaviest-duty traditional wing pulley. “On the V-shaped wing pulley, the rock does not hit at a direct impact but rather at a glancing blow. This deflects fugitive material out and away, and prevents rocks from being wedged between the wings and the belt, lessening the possibility of wing tipping and belt damage,” he said.

While the spiral wing pulley is also categorized as a self-cleaning pulley, Felton said that its corkscrew shape means that it requires many revolutions of the pulley to auger material from the middle out to the side, versus the material simply glancing or deflecting off the plow shape of the V-shaped wing pulley. “An important distinction is that the Chevron wing pulley is more affordable than the spiral wing pulley, yet also has an advantage in performance perks,” he stressed.

Protect the Belt

A standard wing pulley is “apexed” or is shaped as a many-sided polygon. As a result, the belt is always raising and lowering over one or two wings, which causes the belt to flap and results in more belt wear, and much more vibration and noise.

Canadian-based Stony Valley Contracting, located in Fort McMurray, Alberta, replaced all 20 of its conventional flat bar wing pulleys with new Chevron Wing Pulleys. Stony Valley Contracting supplies high-quality aggregate products to companies within the Athabasca Oil Sands region, one of the fastest growing industrial areas in Canada.

The Chevron Pulley has a round end view creating continuous belt contact, which significantly reduces any beating action. The smooth operation creates less vibration, less belt wear, less of an impact and load on the bearings and less noise.

Foreman Blake Krainyk said that his operation is always keen on efficiency. “We are getting a lot more life out of these new pulleys, with our oldest unit being more than four years old. Also, we chose mine-duty units as we found them to be really beefy. We’ve cut our downtime as we don’t have any material buildup. These pulleys stay clean, they’re quiet, and they last longer,” he said. “But most of all, we wanted to protect our belts. The flat bar wing pulleys have sharp edges on the corners, while the Chevron pulleys are round on the corners. They won’t puncture a belt or catch on a belt splice,” said Krainyk.

Felton adds that when a conveyor belt stretches around a traditional wing pulley, it stretches over each wing bar. “That leads to accelerated wear and tear on fasteners and splices, as well as an increased potential for mistracking,” he said.

Reduce Noise and Vibration

When material wedges or builds between a pulleys wings it can cause those wings to fold or bend. The resulting shape greatly reduces the pulleys effectiveness and can wreak havoc on other components.

From an engineering standpoint, Felton explains why the V-shaped wing pulley is able to able to operate more smoothly with less vibration and noise, less belt wear, and less of an impact and load on the bearings. He stressed that the Chevron wing pulley has a round end view, which allows continuous belt contact.

The belt is essentially rolling around a circle, which significantly reduces any beating action on the belt. This reduction in vibration is particularly important for tail pulley operation, as too much vibration will reduce the effectiveness of skirtboard seals.

On the other hand, the standard wing pulley is “apexed” or is shaped as a many-sided polygon. So the belt is always raising and lowering over one or two wings as the pulley is going around, which causes the belt to flap and results in more belt wear, and much more vibration and noise. As to the latter, Felton said that it’s similar to comparing a jet engine to a vacuum.

Tests have shown that the standard wing pulley operates at an average 20-noise-decibel level, while a Chevron wing pulley averages only 70 decibels. “Operations that make safety a top priority realize that reducing hazardous vibration and harmful noise levels is an absolute imperative,” added Felton.

Minimize Downtime

While traditional wing pulleys are prone to trap fugitive material, v-shaped Chevron pulleys deflect it out and away.

Texas Industries Inc. (TXI) is one of the largest suppliers of cement, aggregate and consumer building products in its primary markets of Texas and California. To enhance its market position, TXI management stresses a focus on expansion, modernization and production efficiency. TXI replaced its conventional wing pulleys with Chevron wing pulleys at its Bridgeport, Texas, limestone operation and at its Mill Creek, Okla., limestone processing location.

“The Chevron pulley is ideal as a tail pulley in limestone applications. We need a highly durable and heavy-duty wing pulley as a tail pulley. Certainly that is where you will typically see the most wear and tear,” said TXI Senior Buyer Larry Ennis. “Since we upgraded to these pulleys, we have eliminated a lot of downtime. When rocks get wedged in the traditional wing pulley, it causes major tracking problems – and trying to retrack a belt causes considerable downtime, and potential damage to a very expensive belt,” he said.

Upgrade Multiple System Locations

The Chevron pulley is ideal as a tail pulley in limestone applications.

According to Felton, operations are specifying the Chevron pulley in multiple system locations that include the tail, gravity take-up, bend, and snub functions. “While wing pulleys are traditionally thought of as tail pulleys only, the round-end design of the Chevron pulley allows it to be applied in a number of applications,” said Felton. “CEMA said that a wing pulley should be used in a non-drive situation (either as a tail or take-up pulley) where there is 180-degrees of wrap angle. However, since the round surface of the Chevron pulley allows it to operate so much differently that the conventional wing pulley, we can use it successfully in non-180-degree wrap angle applications, such as bends and snubs,” he said.

Conduct an Audit

Take the opportunity to fully examine your material handling systems. Are you maximizing uptime? Are you getting the maximum wear life from costly belts? Are you best allocating your maintenance manpower? Upgrading key conveyor components throughout the entire material handling system is certainly one of the most cost-efficient ways to ensure profitability and peak performance.

Information courtesy of Superior Industries.