The portable petrol driven grass trimmer is identified as a type of machine whose operator can be
subjected to large magnitude of hand-arm vibration. These vibrations can cause complex vascular,
neurological and musculoskeletal disorder, collectively named as hand-arm vibration syndrome. The
vibration total level on the handle of grass trimmer of 11.30 m/s2 was measured, and it has reached the
exposure limit value of 5.0 m/s2 for daily vibration exposure A(8). New suspended handles were designed
to reduce the vibration level. Three different prototype handles with rubber mounts were designed.
Handles were made of different materials, and the distance of rubber mounts were varied. From the
study, it was observed that not all the handles with rubber mounts were effective in reducing hand-arm
vibration. The reduction of vibration depended on the handle material and distance installed between
rubber mount and vibration transmissibility of handle-isolation system. Subjective ratings of perception
of vibration were measured, and the results indicated that operators were not fully aware of the level of
vibration. A prototype handle that is made of heavier material results in the lowest hand-arm vibration of
2.69 m/s2. The new handle has significantly reduced the vibration total value by 76% compare with the
existing commercial handle.
Relevance to industry: Large numbers of workers are employed to perform grass trimming job in many
developing countries. This paper presents the effect of handle types (commercial and prototype) on the
commonly used grass trimmer.
The portable petrol driven grass trimmer is identified as a type of machine whose operator can besubjected to large magnitude of hand-arm vibration. These vibrations can cause complex vascular,neurological and musculoskeletal disorder, collectively named as hand-arm vibration syndrome. Thevibration total level on the handle of grass trimmer of 11.30 m/s2 was measured, and it has reached theexposure limit value of 5.0 m/s2 for daily vibration exposure A(8). New suspended handles were designedto reduce the vibration level. Three different prototype handles with rubber mounts were designed.Handles were made of different materials, and the distance of rubber mounts were varied. From thestudy, it was observed that not all the handles with rubber mounts were effective in reducing hand-armvibration. The reduction of vibration depended on the handle material and distance installed betweenrubber mount and vibration transmissibility of handle-isolation system. Subjective ratings of perceptionof vibration were measured, and the results indicated that operators were not fully aware of the level ofvibration. A prototype handle that is made of heavier material results in the lowest hand-arm vibration of2.69 m/s2. The new handle has significantly reduced the vibration total value by 76% compare with theexisting commercial handle.Relevance to industry: Large numbers of workers are employed to perform grass trimming job in manydeveloping countries. This paper presents the effect of handle types (commercial and prototype) on thecommonly used grass trimmer.
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