“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.