Browsing by Author "Malisa,Emilson Jeremiah"

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Productivity and physical workload of cutting crews in sao hill softwood plantations
(Sokoine University of Agriculture, 1996) Malisa,Emilson Jeremiah
Physical workload and cutting of productivity two-man raker and peg toothed saws were compared when clearfelling a Pinus elliottii compartment in Sao Hill forest plantation. Three logging crews working with the two types of saw were studied between July and October 1990. Heart rate data was collected after every 30 seconds using a SPORT TESTER while maximum aerobic power was estimated using sub-maximal tests on a cycle ergometer respectively. A total of 1271 trees with an average Dbh of 25 cm were felled and bucked into logs. Analysis of the data revealed that: (a) Effective cutting time when using raker and peg toothed saws were 8.8 and 9.6 min/tree respectively. For a 7 hour workday only about 4.7 hours were spent for productive work. (b) Raker-toothed saws had higher rates than peg-toothed saws. cutting production Production rates raker and peg- toothed saws ranged from 3.25 for 3.6 and 2.98 - 3.16 m3/crew - h respectively. (c) The heart rates of the workers during effective cutting time were 112 - 117 and 115 - 118 beats/minIll when using raker and peg-toothed saws respectively. Maximum aerobic power of the workers averaged 2.54 1/min ranging from 2.37 to 2.74 1/min. (d) Oxygen consumption rate was on the average 1.23 1/min ranging from 1.11 1.30 1/min when using raker- toothed saws. The demand averaged 1.28 1/min with peg-toothed saws ranging from 1.14 - 1.38 1/min. Thus energy demand when using peg-toothed saws was about 28% higher than for raker-toothed saw cutting. This indicated that raker- toothed saws could be a better choice for cutting operation. (e) Physical workload on the workers when cutting using the two types differences. of saws showed no significant The workload indices during effective cutting time using raker and peg-toothed saws were 43.7 52.6 % and 44.8 53.6% respectively. This showed that the cutting operation was a moderate energy demanding job.