March 2, 2012
Plan Your Work, Then Work Your Plan
By Patrick Lawrence
In my last two classes, we (well, they) aligned a couple pumps that were a little finicky. OK, they were pains. But they were alignable. The process and troubleshooting steps we practiced in class were applied to real-world, flimsy-based, soft foot-ridden, base/bolt-bounded equipment. Completing the pre-alignment steps, using the Verti-Zontal compound move, knowing what to troubleshoot and exercising some patience made all the difference in the success of our shaft alignment.
One of the best things about our alignment training classes is going out in the field and aligning something. The stock needs to be scraped off, the grease and oil need to be cleaned up, the bases need to be inspected, etc. So how did we tackle this 3HP, 1750 rpm motor? We had a plan and stuck to it. You only have to do a couple of these to know that something this small can be touchy. Here’s what we did–hopefully it will help you, too.
- Rough it in
- Check obvious soft foot
- Establish a torque sequence
- Final soft foot check
Do you think they found any soft foot? You bet they did. These little guys with the stamped out bases are usually a problem. A few shims had to be cut to correct the angle on the back left foot.
Measure and Correct with the Verti-Zontal Compound Move
With the alignment condition measured, the vertical misalignment was corrected first. After the shims were adjusted the horizontal correction was performed. As light as this little motor was, the bolts were snugged just a bit to make moving and adjusting it easier. Once the horizontal alignment was in tolerance, the bolts were tightened back down in the same sequence nice and easy. This is where the patience comes in. Take another look at that motor base. Being overly aggressive with the bolt tightening will walk the motor all around. Use some finesse.
After remeasuring, we still weren’t fully within our 1800 rpm tolerance. Some troubleshooting was in order–this was part of the plan. The big culprits are typically soft foot and looseness. Bracket tightness was checked and was fine. The motor bolts were tight. The motor base was actually on a plate bolted to the rest of the base–a couple of those bolts were tightened. Another check of soft foot (one foot at a time) and some minor corrections had to be made again. One of the issues with soft foot is that it can creep back into the equation–as shims are added and removed, the motor feet may respond differently to the base.
The lessons they
learned taught themselves about how these little motors respond to things like soft foot and base issues will go a long way in troubleshooting the next shaft alignment. Excuses weren’t tolerated–we found issues, corrected them and moved on. We stuck to our plan. And the cherry on top of this sundae? It was aligned within 3600 rpm tolerances.