Articles containing the keyword 'ergonomy'

The influence of horizontal whole-body vibration of fairly low intensity alone and combined with the mental load and motor action typical for the forest machine drive on heart rate variability (HRV), respiration rate (RR) and heart rate (HR) was studied by testing five subjects. Horizontal vibration had an influence on HR, HRV and RR. ’Control activities’ had the most influence on RR and HRV, but some influence on HR, too. ’Moving the control devices’ (motor action) gave the same response in HR as ’control activities’, but not in HRV and RR. ’Control activities’ together with ’vibration’ had a more effect on HRV and RR than these two factors singly, but not on HR. The possibilities of using these variables in field studies are discussed.

The PDF includes a summary in Finnish.

• Harstela, E-mail: ph@mm.unknown
• Piirainen, E-mail: kp@mm.unknown

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.

The PDF includes a summary in English.

• Rieppo, E-mail: kr@mm.unknown
• Väyrynen, E-mail: sv@mm.unknown

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.

• Wuolijoki, E-mail: ew@mm.unknown

The aim of the study was to search for differences in ergonomic effects between lateral 1, 2, 3 and 4 Hz whole-body vibrations of the forest tractor driver. Healthy male volunteers, both professional drivers and students, were exposed to 692 different vibrations in four different experiments, total number of subjects being 34.

Increase of vibration displacement affected clearly the subjects’ manipulating ability. The subjective magnitude rating of vibration correlated with energy content of vibration, but no correlation was found between subjective rating and heart rate, blood pressure or urinary catecholamine excretion, although the last variables mentioned indicate the energy consumption of the body. The professional drivers rated the vibration with smaller ratings than amateur drivers.

Frequency alteration of tractor vibration can be a possibility for reduction of vibrational effects as a tool for industrial hygiene.

The PDF includes a summary in Finnish.

• Wuolijoki, E-mail: ew@mm.unknown