It has been well documented that over long periods of time, people who regularly operate hand tools powered by small internal-combustion engines can become affected by a debilitating set of clinically irreversible effects, collectively referred to as hand-arm vibration syndrome (HAVS). Although HAVS cannot be cured, the onset of the disorder can be delayed or, in fact, prevented, by restricting the duration of the exposure and/or the magnitude of the vibration transmitted from the tool to an operator’s hands and arms (per OSHA and similar standards). Measurements have confirmed that vibration components along all three tool coordinate directions (axial, radial and circumferential) are significant, but vary in amplitude and frequency content as a function of location. The challenge is to find passive approaches capable of filtering out the most harmful low frequency components simultaneously along all three directions that do not impede the use of the string trimmer. Preliminary results show that adding lightweight, low density (lodengraf) particles to the string trimmer along its shaft reduces the amplitude of the measured radial and axial acceleration components at the grip and the loop handle. However, when the perlite particles are added only to the loop handle, there is an increase in measured circumferential acceleration component at the grip, likely due to the additional weight asymmetry introduced.

This content is only available via PDF.
You do not currently have access to this content.