If the need for vibration protection is so obvious, why isnt it standard practice for all large machines to have protective devices specified?
1. Vibration is a difficult element to measure, comprehend or compare because it is composed of a variety of fundamental frequencies, higher harmonics and aperiodic components (transients), all of which vary greatly across different machines as well as across different locations on the same machine. The typical prospective user assumes that the only significant quantity to measure is mils (displacement), and even then may have no idea as to what level of mils would be safe. 2. Many potential users rely on the ability of their machinery operators to detect any changes in the sounds their machinery is making, which might indicate mechanical trouble. This dependence on sound is better than nothing, but has important disadvantages: (1) sound, at the fundamental (low) frequency of rotation, is usually inaudible; (2) the human ear is very poor in remembering and comparing sound levels; (3) the sound of a machine is frequently masked by extraneous noise. Another great disadvantage is that con
