# Vibration Isolation Isolators have a natural frequency, fn, which is derived from a formula that includes the spring rate of the isolating material and the weight of the equipment. The natural frequency at maximum capacity is listed in the Anti-Vibe® and Mighty Mount™ tables for each part number. The natural frequency of an isolated system and the disturbing frequency it is subject to can be used to determine the amount of isolation achieved, as shown below. If transmissibility, T, is plotted against the ratio of the frequency of a machine fo (its output frequency), and the natural frequency of the isolating mount fn, a graph as shown in Figure 1 is generated. Any values above 1.0 on the T axis indicate amplification and values below indicate isolation. Resonance occurs at a ratio of 1.414, so any ratio above that will provide isolation. From the graph you can see that at a 2:1 ratio T = 33%, at a 3:1 ratio T = 12.5% and so forth. You can use this chart as a shortcut to determine either the amount of isolation achieved or to determine the mount to use for a desired T. For example, if you have a 4200 lb machine on 6 Mighty Mounts™ with a capacity of 700 lbs each (P/N MM80136) the natural frequency, fn, of each mount would be 8Hz. If the system frequency, fo, is 35Hz, then the ratio of output frequency to natural frequency is 35/8 or 4.38. Using the chart, this translates into a T of approximately .05 or 95% isolation. In equation form: 