1997 Volume 12 Issue 3 Pages 183-192
The operation efficiency of a wheel grapple-bunk skidder is higher than that of the present winch skidder, the time for grappring the tree length log being 4.6% of total operation time. The work intensity level was light physiological loads, the average heart rate being 84 beats/min. The HRmax appears when skidder grapping the tree length log in looking the rear. The main objects of the field that were invisible to the front were cabin, bonnet, and exhaust pipe. The results that the solid angles for dozers and wheel are small in spite of the operators concentrating their fixations on them, are considered a serious problem. As the seat facing 17° to the right-rear, the operator can face easily just to the rear, looking at the tree length log in grapping and at the skidded logs in skidding with load. But, there was 55.8% of all operating time in operator's twisted body posture. The vibration on the seat in 3 directions were allowable below the "Fatigue-Decreased Proficiency Boundary" according to the ISO-proposal. When going back to the felling site and skidding with load, the noise level at the operator's ear is higher than noise limits at the frequencies of 1-4 kHz prescribed in "Japan Association of Industrial Health". These noise level of the equivalent continuous sound level is 80-93dB(A) over the limit of occupational noise level in "Occupational Safety and Health Regulation". Comparing the position of the levers and pedals with JIS-proposal, these are arranged at suitable positions. As the height of step being higher than the standard value proposed, operator access to and from cab with any discomfortable postures.
