Misalignment of shafts, couplings, bearings, or gears causes noise and vibration, and thus accelerated wear. The wear is the effect that is to be avoided; the noise and vibration are the symptoms. We have two very sensitive transducers on the sides of our heads to detect the noise. The noise is generated mostly from the bearings and the coupling. For vibration, we have pressure sensors in our skin. Our on-board transducers are completely adequate to detect the symptoms of even the slightest misalignment. The problem we have is interpreting the information in a noisy environment. In a quiet room and with some training and calibration, anyone with normal sensors can diagnose misalignment. The noise and vibration can be detected only if the machine is operating and the signal-to-noise ratio is high enough. These operating diagnostics will be discussed in a later section of this chapter. There are also some indicators of misalignment when the machine is stopped. These will be covered first.

Static Diagnosis

The easiest diagnostic procedure is to simply ask questions about recent maintenance work. The shaft-to-shaft alignment is what gets disturbed when the machines are unbolted from their foundations. The bearing alignment certainly changes if new bearings are installed. This investigation can be done without even visiting the machine, but by just asking the right questions, like:

• Was the alignment checked after work was completed?

• What method of alignment was used?

• How did the machine sound and feel during start-up?

• Was growth compensated for?

• What is the...