| Abstract |
- In recent years, inflation and a growing concern for soil compaction and environmental damage have affected both the forest manager and the logger. Balloons, helicopters, and skylines have been used to harvest timber and the results have been promising
(Dykstra, 1975, 1976). However, the high cost of using these aerial systems is often prohibitive, particularly in areas of relatively low timber volumes.
Ground base logging systems have been limited to the familiar crawler-type tractor and the rubber-tired skidder. Few changes have been made in these systems to reduce compaction and environmental damage, and major improvements appear unlikely.
In 1974, FMC Corporation introduced a radically new design in logging equipment. Two models of a tracked skidder were introduced, the model 200 BG and the model 200 CA.. The 200 BG was designed mainly to skid large quantities of small wood rapidly, and a study of its capabilities has been completed (Legault and Powell, 1975). The model 200 CA was designed to move larger timber at speeds equivalent to those of the rubber-tired skidder, but with reduced soil compaction. Some maintenance problems were encountered with the suspension system of the model 200 CA and in July of 1976, the model 210 CA was introduced. The basic differences between the two models were a heavier suspension system and new design criteria on the road wheels. The acceptance of this machine has been remarkable, with well over 200 now being used throughout the western and southern United States. In researching the literature, no evidence was found that production and cost studies have been conducted on this machine. This makes the acceptance of the FMC skidder even more remarkable •.
Various studies have been conducted to determine factors that are important in explaining turn time and yarding costs for tractor skidding. Adams (1967), Aulerich, et al. (1974), Mccraw (1964), and McDonald (1972) found skidding distance and number
of logs per turn to be the most important variables in explaining turn time for tractors and skidders. McIntosh and Johnson (1974) found that for rubber-tired skidders, average tree size, stand • and terrain characteristics,, and the skidder operator's skill and motivation have the most effect on production rates. Suprisingly, skidding distance was not a significant variable in their study. Schillings {1969) devised a method of estimating skidding costs if skidding distance, terrain type, slope, and operating efficiency could be determined or estimated beforehand. This paper investigates production rates and costs of the· FMC model 210 CA skidder. Four variables have been identified hat are considered important in affecting skidding production. Time study procedures, regression analysis, skidding costs, and uphill skidding capabilities are described. It is hoped that more accurate cost allowances can be determined for skidding with the FMC by correct application of the information found in this paper.
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