The aim of this concise interview survey was to collect information about the servicing properties of forest tractors. Ten interviewees gave grades (in a scale from 4 to 10) concerning two servicing properties of various types of forest tractor. The rating covered the general safety during servicing (structural serviceability) and work postures during the work. Four types of forest tractor widely-used in Finland were chosen. The forwarders were of different size and structure.
According to the rating, the lightest forwarder was clearly superior to the other types. This machine was also the smallest in size and the most modern. Differences between the other three forwarders were not quite so clear. The variation between the machines as regards both so-called easy and troublesome tasks was considerable. Lubrication of the articulated shafts and supporting bearings was, however, very troublesome regardless the machine type. The heaviest tractor was considered the most difficult to service.
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The paper deals mainly with the effects of jolting of forest tractors and processors on the health and working capacity of the driver. The literature surveyed presents especially the following points of interest: Jolting of the machine may hamper the focusing of the eyes and mastery of the controls. Long-term exposure to jolting may result in reduced sympathetic nervous activity at rest, and may impair an already existing back problem. Workers exposed to vibration, get more frequently gastric changes and changes in reproductive functions than usual. Jolting, as also the other negative physical factors of working environment, must be minimized as early as possible during the design of the machines.
The PDF includes a summary in English.