Observing a training class of new mechanics can sometimes be a stressful proposition for a former field Millwright. Especially when said millwright has control issues. As part of our Precision Shaft Alignment Training, the trainees move from the classroom setting into the field to practice what they have learned. Transferring the knowledge gained in a class setting to a field setting can be difficult for the trainees. They can revert to past practices forgetting all they learned and demonstrated understanding of in previous day’s training. After a mechanic performs a task in the field, things make more sense and are practiced as such in perpetuity.
As a mechanic, I can tell you that adding technology to a process can sometimes cause confusion in mechanics mind. We will forget to look for the simplest, most basic “best practices” in the alignment process.
As an observer accustomed to laser alignment, I see the most common installation errors as they occur during training classes. Most of the following observations have little to do with the actual alignment, but more to do with precision practices when aligning basic close coupled pump and motor combinations. Some are procedural, some relate to other aspects of reliability, but all relate to the prolonged operation of both man and machine!
Safety First! Lock out- Don’t start a job before the lock out procedure is complete and verified!
NO HAMMERS, especially on the coupling! Hitting any part of a motor or pump assembly will damage bearings. Failure is a direct result of this action. Maybe not today, but it will cause failure in time. To learn more, look up False Brinelling. When searching for alternative means of moving a motor, see our blog “Use Your Head Not Your Hammer”
“Move the equipment into the operating position ensuring the gap between the shaft ends matches the ‘G’, or Gap dimension in Table-X.”
Figure 1- Incorrect
It should be noted that this is a very small amount of weight. It would more critical to replace this set screw in machines that can tolerate no imbalance induced vibration.
The formula for determining the proper key length is; Length of keyway on hub + length of keyway on shaft; divided by 2. Then multiply by .95. (hub key length + shaft key length = X, X ÷ 2 = Y, Y x .95 = proper key length) For more info on This see “Balance Your Couplings” in our Alignment Blog.
Stay tuned for additional episodes of “Installation Errors”.
Installation Errors Part 2- Shim handling and Shims under pump?
Installation Errors Part 3- Pump bowl torque and Torqueing of hold down bolts. Torqueing Bolts in General!
Installation Errors Part 4- Base bolts and Jack bolts.