Having been monitoring these Lamson blowers with semi-annual visits for the past three years, I was able to chart how the vibration levels of the #1 motor/blower unit were steadily rising. The 2-100 HP, Model 1268 blowers were operating alternately on a regular basis, so the vibration levels of each were normally pretty close to the same levels. 

The motor of the #1 unit began showing an increase in noise, and the bearing temperatures rose from a normal 95° F to 140° F. Since I had previously laser aligned both of these units, I expected the bearings had simply reached the end of their life span--nine years! We decided it was time to replace the motor bearings.

We entertained the idea of removing and sending the motor out to a local repair shop for reconditioning. But after closely looking at the estimated time to disconnect and reconnect the relatively large wiring, and the bearing & winding RTD sensors, we elected to replace the bearings without removing the motor.  This would also limit the machine downtime to only 1 day. 

Since we were disconnecting the coupling and moving the motor, we decided to replace the blower bearings also. Although the vibration and temperature levels did not indicate any real problems with the bearings, they are part of the same drive train as the motor bearings. For the minimal extra cost of a couple more bearings and a couple more hours of labor, the complete motor/blower drive train now has all new bearings and the shafts are laser aligned. 

The motor bearings were found to be in very bad shape from too much grease & dirt buildup, especially in the motor windings. Overgreasing motor bearings is a very common cause of motor failures. When the relatively small space in the bearing housing fills with grease, the extra grease is forced into the motor windings, which are not designed to operate with grease packed into them.  Replacing the bearings and cleaning the windings easily prevented a catastrophic failure of the motor, which would have cost many thousands of $$ to replace. 

The opposite drive(outlet) end bearing on the blower was also found to have been damaged by excessive heat. A blower bearing failure could result in impeller damage that would require an expensive rebuild of the complete blower. The reconditioning of the motor/blower drive train, including cleanup of the motor windings, should give this unit at least another 10 years of trouble free life.

Regular monitoring is the key.  Invest in PM, it will save you money.