Over-sizing the drive system when selecting and replacing worn v-belt drives is one simple, commonly-made mistake that actually causes premature wear on every component in a rotating system.

How can this be? Aren’t more belts always better? Not always with v-belt drive systems.

With the high cost of parts, labor and downtime, sizing belt drives correctly will save in many ways. If you are responsible for keeping your HVAC systems up and running, it’s important to understand why bigger is not always better.

Here’s a typical situation that occurs with many belt-drive systems:

The system:

• Return air fan unit
• 5 hp, 1750 rpm motor
• 1250 rpm fan wheel speed
• Motor drive sheave, 5-inch diameter dual “B” belt
• Fan shaft driven sheave, 7-inch diameter dual “B” belt

The Problem:

• Belts wear out annually and sheaves last only 3 years
• Difficult -to-tension  belts due to flexible structure

The Solution:

I asked the maintenance manager if the drive arrangement used was as the OEM supplied it. The answer was “no” — he increased the belt section to “B” from  the “A” that was originally supplied so he could get better drive-belt life. In reality, he did just the opposite.

According to Browning grip-belt engineering data, the horsepower capacity per belt using “B” belts is about 11.5. This means the drive is capable of 23 horsepower. If “A” section belts were selected, the horsepower per belt is 7.5, for a total capacity of 15 hp.

Both situations provide more than enough capacity. The problem is the larger the drive capacity requires more belt tension to prevent slipping. The best situation would be to use a single groove “B” belt. Even one “A” belt would be enough if the diameter of both sheaves were increased.

This provides plenty of service factor and reduces the acquisition cost of the parts. The belt tension requirements are less, and the structure is more capable of maintaining the needed tension. Added capacity often means added wear and expense – proper belt-size and tension reduces noise, slip, wear, and vibration from flapping.

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Vibration analysis, with proper mechanical inspections, can make the difference between making the same ineffective repairs over and over again, or determining the precise nature of a problem and applying the proper solution once.

HVAC air handling equipment is a good example because the bearings fit to the shaft in rotating machinery can degrade over many years. We had a recent repair job in a retail building in which the HVAC system had become very noisy and begun vibrating. The customer had previously replaced the bearings several times, hoping that would solve the problem, but the noise and vibration never went away..

We performed a vibration analysis on the system and a dial indicator reading revealed a .010 run-out on the shaft, suggesting shaft wear. That conclusion was supported by a red residue in the area that seemed to indicate iron powder wearing off the shaft (fretting).

Since the system was over 60 years old, new shafts were not available. Even if one could be fabricated, it would be very difficult, time-consuming, and expensive to replace a shaft on a system that old.

Instead, we took very careful measurements, fabricated a precision sleeve to fit over the worn area and a new bearing arrangement to accommodate a larger bearing to fit over the now-larger shaft sleeve. As a result, we were able to make the repair in just five hours, instead of days, saving the customer thousands of dollars.

Hi-Tek Balancing, Inc. provides industrial balancing and vibration analysis to companies around the world.

“We replaced the bearings three times and it still makes noise”…Sound Familiar?

If you are responsible for the reliability of HVAC air handling equipment, you probably have units that rumble and make more noise than they should.

Most often this is due to the shaft to bearing fit up. Improper bearing installation can cause the bearing’s inner ring to wear a groove into the shaft.

Once the shaft is grooved it’s only a matter of time before you realize that repeated bearing changes is not the solution. You also know that shaft replacement is difficult and very expensive.

HI-TEK specializes in shaft repair of all rotating machinery.

Our innovative approach to equipment repair can save you thousands. We have numerous repair methods that allow for restoration of bearing fits without removing the shaft.

See our examples below.

Supply Fan #2 at Retail building in Harvard Square

Here is the arrangement before repair. This is a very typical Sealmaster Low Height pillow block, belt drive. The Bearing rests on a shelf with a shim under to adjust ride height.

Problem:

1. Fan unit has high vibration and elevated noise, Dial indicator reading reveals .010 run-out on shaft suggesting shaft wear. Red substance in the area is iron powder emitting from the shaft to bearing fit degradation.
2. Repeated bearing replacement has not solved the problem.
3. A new Shaft is not available as the unit is almost 60 years old. Replacing the shaft is very difficult as the blower wheels are fragile and frozen onto the shaft. Downtime could be days where summertime temperatures are almost 100 degrees.

Solution:

1. Sleeve the shaft in place.
2. Repairing the shaft involves taking careful measurements and making a precision shaft sleeve to cover over the worn area.
3. A new bearing arrangement is needed to accommodate a larger bearing as the sleeve needs to be at least ½ inch in diameter larger than the original shaft.

See photos below.

Supply Fan #3 at Retail building in Harvard Square

This is the arrangement as it was when we were called in. This is the belt drive side with the drive pulley removed. The bearing support structure was previously modified by another company. The original bearing was a four bolt flange style that bolted to the fan cabinet.

Problem:

1. The original bearing location was abandoned as the bearing had loosened and wore a deep grove in the shaft. Another company modified the structure to allow for the retrofit of the pillow block style bearing. This allowed the bearing to seat on a undamaged part of the shaft.
2. As you will see below the shaft has been previously worn in all available locations. Continued replacement of the bearing does not solve the problem.

Solution:

1. Sleeve the shaft in place.
2. Repairing the shaft involves taking careful measurements and making a precision shaft sleeve to cover over the worn area.
3. A new bearing arrangement is needed to accommodate a larger bearing as the sleeve needs to be at least ½ inch in diameter larger than the original shaft.

Improper gear assembly can have disastrous results from the smallest of mechanisms to the most enormous. When one thinks of gear assembly, a few things may come to mind. From handed clocks and automobiles to helicopters and roller coasters, gears play an integral role in each machine’s function. With gears being so important, it is apparent that improper assembly of such gears could result in the need to replace a favorite family heirloom or be the biggest tragedy imaginable, costing people their lives.

A gear is a part in a mechanism or transmission that works with its similar part or parts in order to transmit activity from one part to another to determine direction and/or power while performing a specific role. In nonprofessional terms, it means the gears make the machine go. When all these gears are working properly the result is a finely-tuned piece of machinery that will efficiently perform the task for which it is designed. When gears are not properly assembled the results can be devastating. For example:

“Sunday, April 20, 1997 – At Bell’s Amusement Park in Tulsa, Oklahoma, one person was killed and five others were injured when two roller coaster cars collided on the park’s Wildcat roller coaster. The accident happened as a car was nearing the top of the lift hill. The mechanism holding the car onto the track failed, causing the car to roll back down the hill and crash into another car which was approaching the chain lift. The victim, a 14-year-old boy, was thrown from the car during the crash and struck his head on a steel support. Two other boys were also treated at a local hospital. The Wildcat had been in operation at Bell’s Amusement Park since 1974. It was inspected just two weeks prior to the accident.”¹

This is one example of countless accidents that ensue because the gears in the machinery were not correctly functioning due to problems with assembly. Even more surprising was that the roller coaster was inspected just a couple of weeks before the accident. How could they have missed the problem? Shockingly enough, business owners will often times choose what they think is the most cost-effective maintenance without any real forethought about the mistakes that could occur, that is, until a tragedy strikes.

HI-TEK Balancing offers exceptional service on gear assembly and for over a decade has personally seen to their excellence and proper performance, becoming masters in their field.

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¹Provided by: www.rideaccidents.com

These days machines are more efficient and run more smoothly and quietly than ever before. Companies such as HI-TEK Balancing Inc. know why that is. The precision balancing for machinery is not only helpful to the effectiveness of the machinery flawlessly performing the job it was designed for, but it is vital for the safety and longevity of the machine.

HI-TEK Balancing, identifies unbalance by recognizing the distribution of mass (the dynamic) in relation to force and vibration, then minimizing force and vibration to result in correcting the unbalance. In other words “dynamic balancing.” This is achieved by either adding or removing weight from the rotating component.

Dynamic Balancing is used to lessen the effects of centrifugal force, therefore reducing vibration and minimizing the damage that is done to the rotation devices. This not only extends the life of the machine, but makes the machine easier and more comfortable to use. An example of the sort of intensity of centrifugal force is to think about an amusement park ride such as the spinning cylinder, also known as the gravity ride, where the individuals in it stand up with their backs to the wall while the ride spins at high speed. The force that people feel pushing them against the wall of the ride is centrifugal force.

Without proper balance, in a piece of machinery this force can cause extreme vibration which, in time, damages the machine. The result is a higher frequency of maintenance. The vibration from one machine can adversely affect the performance of machines nearby resulting in the need to perform maintenance and solve issues that may not have been necessary if all machines had gone through dynamic balancing. Not only are machines affected by this, but the people who use these machines during their work day can develop health issues to their continued exposure to heavy and constant vibration caused by the machine being unbalanced.

With HI-TEK Balancing offering a service that extends the life of the machine, effectively increases injury; it is apparent why HI-TEK Balancing has been a successful business since 1998 and continues to grow. While providing concentration, accuracy, and professionalism and informing their clients of the long-term benefits of dynamic balancing and its importance in the world of machinery, HI-TEK Balancing Inc., without a doubt, outweighs others in their industry.

In the present economic times, it is now more important than ever, to ensure that when you are selecting a supplier for dynamic balancing and vibration analysis services, you are choosing a stable and dedicated service company.

Quality

HI-TEK Balancing, Inc. is committed to quality. Balancing services are performed at our Lunenburg, MA facility, by our highly skilled professional staff. We pride ourselves in providing the best possible balancing service solutions tailored to meet the customer’s specific requirements. HI-TEK Balancing has taken on a project to completely re-design its core business practices in line with the requirements of ISO 9001:2008. The current project plan includes third party certification by mid 2010.

Growth

HI-TEK Balancing, Inc. has experienced continued growth. In each of the last three years HI-TEK has added staff to the company with an average staff increase of 15% per year since 2006. In 2008, when many businesses were unfortunately eliminating positions, HI-TEK increased its staff by 16%. In addition, since 2006 HI-TEK has achieved an average annual revenue growth rate of 22%. We have hired a Continuous Improvement (CIP) manager to lead projects focused on improving the effectiveness and efficiency of our business processes. His diverse background in various manufacturing roles also positions him well to act as a facilitator in our ISO commitment.

Longevity

HI-TEK Balancing, Inc. established in 1998 in the basement of the owners Luneburg home, has expanded its production operations to a new separate 4500sq ft. Industrial manufacturing facility.

Thanks to our current standing on debt free, solid financial ground, HI-TEK has been able to dedicate significant resources and money to invest in itself through expanded order processing and production capabilities. We are in the middle of an extensive renovation and remodel of our company owned facility. It includes balancing equipment installations that expand our present component size capability. In addition, we have developed a customized software database to streamline order processing, production, quality assurance processes and documentation. Because, we have no debt as a company, our customers can be confident they are making a smart and solid investment when they choose HI-TEK as their component balancing and vibration analysis service company.

Hi-Tek was at the EASTEC Trade Show recently!