RR78 - Isolation and auto-balancing techniques for portable machines

The portable engine powered strimmer is used as a case study of the application of vibration analysis and control techniques. Frequency analysis is an important tool in understanding how vibration is generated and transmitted. Modal analysis extends this to show how components can be modified and where they should be connected for controlling vibration. The theory of vibration isolation is discussed and tested. Auto-balancing is tested, and theory of auto-balancing is reviewed to show why it cannot be applied to all machines with rotating unbalance. The strimmer has two sources of vibration, the engine and the rotating unbalance of the cutting head. These are identified by frequency analysis, and resonant modes of components are shown to exist in the range of working frequencies. It is shown that better locations are possible for attaching the handles. Suggestions are given for maintaining strimmers to ensure low vibration.

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Updated 2021-04-15