Chipping hammer vibration.

An investigation was carried out to determine the factors influencing the vibration of chipping hammers and to find ways of reducing the vibration at the operator's hand. It showed that substantially higher vibration levels are produced at the chisel of a chipping hammer than at its handle. Typical weighted values for the two areas were 24 and 8 m/s2, respectively. This finding agrees with medical observations showing that invariably the hand holding the chisel exhibits the more severe symptoms of vibration-induced white finger. A sleeve which fits onto the chisel was developed which can effect a reduction in vibration of up to 66%. A prototype hammer was developed incorporating an isolating material which reduced the weighted vibration value from 7 to 3 m/s2. Vibration isolating gloves were tested and resulted in an additional reduction in vibration of up to 63% when used with the chisel sleeve. A unique mounting device using rubber isolators was designed which protects the accelerometer from very intense high-frequency vibration but allows accurate measurement of chisel vibration in the frequency range of interest.