Influence of forest machine function on operator exposure to whole-body vibration in a cut-to-length timber harvester

Abstract

The influence of machine function (tree felling and processing, and machine movement over the terrain) on operator exposure to whole-body vibration in a cut-to-length (CTL) timber harvester was evaluated. Vibrations were measured on the seat and the cabin chassis in three orthogonal (x, y, z) axes for the tree felling and processing, and during motion on a test track. It was found that the level of vibration transmitted to the operator during felling and processing was mainly affected by the tree size (diameter). For tree diameter at breast height (dbh) range of 0.25-0.35 m that was investigated, the vertical (z-axis) vibration component during processing increased by up to 300%, and increased by 50% during felling. However, the associated vibration levels were not sufficient to pose any serious health risks to the operator for an exposure limit of 8 h. Vibration at the operator seat and cabin chassis was predominant in the lateral (y-axis) and vertical (z-axis) respectively, during vehicle motion over the standard test track. Vibration peaks of approximately 0.20 and 0.17 ms(-2) occurred at 5 and 3.2 Hz respectively.

Timber harvester operators’ working technique in first thinning and the importance of cognitive abilities on work productivity

“…Rating is based on the physical and mental capacities of the operator. Today, the main physical factors causing strain are whole-body vibration and static muscle load causing pain in the neck, shoulder and lower-back area (Axelsson and Pontén 1990, Hanson 1990, Sherwin et al 2004). The senses, especially sight, are exposed to a large amount of information from the surroundings (Vuorinen 1978, Harstela 1979 as well as from the harvester monitor (Forsberg 2003).…”

Visuospatial cognitive abilities in cut-to-length single-grip timber harvester work

“…Today, the main physical factors causing strain on the operators are whole-body vibration and static muscle load causing pain in the neck, shoulder and low-back area (Axelsson and Ponte´n, 1990;Hanson, 1990;Sherwin et al, 2004). In addition, significant information flow from the surroundings (trees, ground obstacles, etc.…”

Influence of Vehicle Size, Haulage Capacity and Ride Control on Vibration Exposure and Predicted Health Risks for LHD Vehicle Operators

“…Over time, vibration exposure can lead to structural damage and health problems including: lower-back pain, spinal degeneration, gastro-intestinal tract problems, sleep problems, headaches, neck problems, autonomic nervous system dysfunction, hearing loss, and nausea 4,5,6,7 . Occupational vibration exposure has been documented for agricultural vehicles 5, 8, 9 10 , construction vehicles 9,11,12 , forestry vehicles 13,14,15,16 , transportation vehicles including cars 9,17 , trucks 9,18 helicopters 9,19 , busses 9,20 , subways 21 , and trains 22 . Despite health concerns related to WBV exposure, a limited number of studies have evaluated the health risk associated with WBV during the operation of underground LHD vehicles 1,2 .…”