مجله جنگل ایران (Nov 2017)
Assessment of hand-arm vibration caused by chainsaw in beech tree felling and bucking operations
Abstract
Nowadays, one of the most popular tools to cut and process the trees in northern forests of Iran is chainsaw. One of its most important defects is constant vibration during operation. The aim of this study was to investigate the hand-arm vibration in beech tree cutting and bucking in Kheyrud forest, Nowshahr, Mazandaran Province. Three beech trees and bucks were selected and hand-arm vibration was measured by using vibrometer Bruel & Kjear 2237 in the back and front handles of chainsaw in three directions x, y, and z. The index of vibration equal value (aeq), vibration total value (ahv), transmitted vibration coefficient (Tr) and daily exposure duration (A(8)) were used to explain the chainsaw vibration. In cutting stage, the value of aeq on the x-axis was significantly higher than the two others in front and back handles (P= 0.010) and in bucking stage, the value of aeq on x-axis is significantly more than z-axis, (P= 0.008). The value of ahv during logging (P= 0.017) and bucking (P=0.013) in the back handle is significantly higher than front handle. Tr coefficient in the back handle of chainsaw while cutting (2.78) was significantly higher than the same handle in bucking (2.75) mode (P= 0.011). The results showed that the values of Tr, aeq and ahv in the back handle is more than front one, hence it needs immediate operation to improve it ergonomically.
