Volume 17
Issue 2
Forestry
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Available Online: http://www.ejpau.media.pl/volume17/issue2/art-02.html
PRODUCTION RATE AND ECONOMIC EFFICIENCY OF MID-CLASS HARVESTERS IN THINNINGS OF MOUNTAINOUS TERRAINS OF CENTRAL SLOVAKIA
Jozef Tajbo¹, Valéria Messingerová
Faculty of Forestry, Department of Forest Harvesting, Logistics and Ameliorations Technical University in Zvolen, Slovakia
In this paper we introduced an analysis of technological parameters of the
mid-class harvesters John Deere 770D and Valmet 911.1. We focused on their production
rate, movement and work in relation to ecological effects of their activity in
forest stands. In the next part we offered a brief analysis of the economic efficiency
of these mid-class harvesters in comparison with classic methods of timber harvesting
and skidding in thinnings in mountainous terrains of Central Slovakia – Forest
Enterprise Kriváň and Čierny Balog. We obtained primary data
during the realization of premature logging in the thinning forest stands of
the mountainous terrains. This work also contained a brief description of technical
parameters of the harvesters and a proposal of an optimal or suboptimal technology
in thinnings. The results confirmed the economic efficiency of presented harvesters
in premature felling of conifer forest stands. Results of performances – Valmet
6.5 m3·h-1 and John Deere 5.7 m3·h-1 are
comparable with the results of the others authors in similar production conditions.
Key words: harvester, technology, production rate, thinning, economic efficiency.
INTRODUCTION
High production rate and relatively small scale of damage to the soil and stand, high slope accessibility and manoeuvrability (the adaptation of a bogie wheel has up to a 45–50% accessibility, a wheeled-tracked and tracked ones up to a 60% accessibility and a walking one, in principle, has an unlimited accessibility), high level of mechanization, automatization and humanization of work and adequate costs for timber production in comparison with the classic technologies are the most significant advantages of harvester technology [2–6, 9–11, 13–15].
In this paper we introduce an analysis of operation and the possibilities of using harvesters in the mountainous terrains in thinnings, during which majority of harvested assortments are used in energy biomass production. This process is the most time and money consuming activity of the logging process. Mountain forests create up to 60% of the forests of the Slovak Republic. Premature logging is made once or twice per decennium, approximately from the age of 40 to 80 years of the forest stand and the share of the mechanization of operations from felling to cross-cutting is considerably lower than in mature logging or premature logging in the forests in plains and uplands.
MATERIALS AND METHODS
We carried out the research in the Forest Enterprise (FE) Kriváň, Forest Management Unit (FMU) Málinec, in 357A and 358 forest stands and in FE Čierny Balog, FMU Sihla, in 224 and 326A forest stands. We carried out the research during the first thinnings in the spruce forest stands. The harvesters produced 4 meter-long assortments and compact logging residues for wood chips.
In Tables 1 and 2 there we can see basic mensurational characteristics of forest stands. In both cases the harvester worked in the first thinnings in the spruce forest stands. John Deere 770D worked in younger forest stands where there was a higher share of logging residues.
Table 1. Basic mensurational characteristics of forest stands (Valmet) |
[m] |
[cm] |
[m3] |
[years] |
[%] |
||||
jd 50 |
11 |
10 |
0,25 |
26 |
||||
sc 30 |
12 |
15 |
0,36 |
26 |
||||
sm=spruce, jd=fir, sm=spruce, sc=larch |
||||||||
Table 2. Basic mensurational characteristics of forest stands (John Deere) |
forest stand |
tree species |
height |
thickness |
volume |
quality |
stand density |
age |
slope |
sc 10 |
12 |
15 |
26 |
|||||
sc 2 br 2 jd 2 |
10 6 3 |
7 6 – |
0,01 0,01 – |
26 12 24 |
||||
sm=spruce, sc=larch, br= birch, jd=fir |
||||||||
In order to record time measurement of work of the harvester,we used the chronometry method. We recorded time consumption of operations of the harvester:
-
Movement of the harvester to the next working site, during which the operator cleaned the line, he put the logging residues under the wheels, moving into optimal position. The operation started when the harvester started to move and finished when it stopped.
-
Moving out the boom, grabbing the tree and felling. The operation started when the harvester stopped and finished when the tree-top reached the ground. We could clearly measure the end of the operation only by measuring time when the tree-top hit the ground, because operators had to start delimbing the lowest branches on many occasions in order release the tree from the dense remaining stand.
-
Manipulation. According to the length of the tree two to three pieces of four meter assortments and one to two pieces of wood chip assortments were made. The operation started after the tree-top hit the ground, it finished as follows:
- with moving out the boom to the next tree- the beginning of the second operation; the operator felled multiple trees from one site,
- with the movement of the harvester to the next position,
- with the stoppage of the harvester for a break.
-
Shift times – technical (e.g. changing the chain), technological (marking the direction of the continuing of the working line, telephonic or direct consultation with a forester or the forwarder operator), relax (getting the operator off the cabin and the short-term psycho-physiological relaxation). Shift time started with turning off the harvester’s engine or the operator stepping out of the cabin. They finished with turning on harvester’s engine or the operator stepping into the cabin.
We recorded the time intervals with the accuracy of 3 seconds. With regard to the fact that we carried out the research in the first thinning where the operations were rapid a more precise division of particular operations would not be effective. Moreover, on the basis of the previous measurements it could cause an informational noise in connection with the interdigitation of the partial operations with the registration of their beginning and ending and therefore it could significantly decrease the relevance of the processed data.
We processed the data with standard mathematical-statistical methods, the calculation of the basic statistical characteristics, regression analysis, testing the significance of the parameters, etc.
We evaluated the economic efficiency through comparison of calculation of the costs for production of 1 m3 of assortments according to the average volume of the trees.We evaluated the whole logging process, i.e. the operations as logging (pre-felling, delimbing), skidding and cross-cutting.
Technical parameters of the harvesters
The Valmet 911.1 harvester, according to criteria FPP Harvester/Forwarder
1998 [4, 12, 16–18] and its performance, it belongs to the mid/heavy class.
Due to its parameters it is more convenient for later or last thinnings. The
John Deere harvester belongs to light/mid class. It is convenient for the first
or second thinnings.
Basic technical parameters:
| Valmet 911.1 | John Deere 770D | ||
| Weight | 16 900 kg | 11 550 kg | |
| Width | 2750–2900 mm | 2630 mm | |
| Height | 3950 mm | 3620 mm | |
| Length | 7250 mm | 5900 mm | |
| Engine | 6 cylinder turbo diesel | 4 cylinder turbo diesel | |
| Capacity | 6.6 l | 4.5 l | |
| Output | 140 kW (2200 rev·min-1) | 86 kW (2200 rev·min-1) | |
| Peak torque | 740 Nm (1400 rev·min-1) | 500 Nm (1400 rev·min-1) | |
| Hydrostatic transmission | 133 kN | 100 kN | |
| Hydraulic system: | Flow | 0–255 l·min-1 | 0–208 l·min-1 |
| Pressure | 25 Mpa | 24 Mpa | |
| Length of hydraulic manipulator | 8.5–11 m | 10 m | |
| Harvester head: | Weight | 1155 kg | 780 kg |
| Maximum cutting diameter | 650 mm | 620 mm | |
| Feeding power on cylinders | 19.6 kN | 15.1 kN | |
RESULTS AND DISCUSSION
We show the basic statistical characteristics of the time measurements and other parameters in Table 3 (Valmet) and 4 (John Deere). The structure of the work time consumption of Valmet is on Figure 1 and of John Deere is on Figure 2.
Table 3. The basic statistical characteristics (Valmet) |
[m] |
[m3] |
[hundredths of a minute] |
|||||
av=average, s=standard deviation
|
|||||||
Table 4. The basic statistical characteristics (John Deere) |
[m] |
[m3] |
[hundredths of a minute] |
|||||
av=average, s=standard deviation
|
|||||||
|
| Fig. 1. The structure of the work time consumption (Valmet) |
|
| Fig. 2. The structure of the work time consumption (John Deere) |
Average hourly output:
- Valmet – 6.5 m3·h-1
- John Deere – 5.7 m3·h-1
As with other harvesters of this class, the delimbing, cross-cutting and piling the assortments operations form almost half of the time consumption – 38 and 45% of the operation cycle. Then there are breaks – technical breaks, technological, relaxation.
We can see the dependence of the time consumption on voluminosity on Figure 3 (Valmet) and on Figure 4 (John Deere). After transformation of the regression equation the development of time consumption based on voluminosity can we seen on Figures 5 and 6. The results approximately correspond to the parameters of the harvesters, all in all the stronger Valmet has higher production rate and therefore lower time consumption for processing the given volume of the tree mass. On the other hand, John Deere has better results within very thin mass – up to the diameter of 10–15 cm, approximately 0.10–0.15 m3. In both cases there is very close dependence, stem volume explains 35% of variance of time consumption for Valmet (Fig. 3) and 23% for John Deere (Fig. 4).
|
| Fig. 3. Time of operation cycle in dependence on voluminosity (Valmet) where: y = 1,0549 0 2,3522 · x – regression equation, R2 – coefficient of determination, R – correlation coefficient, n – observed number of operating cycles, F – statistical characteristics of the F – distribution, α – significance level (results from F). |
|
| Fig. 4. Time of operation cycle in dependence on voluminosity (John Deere) |
|
| Fig. 5. Development of time consumption in dependence on voluminosity (Valmet) |
|
| Fig. 6. Development of time consumption in dependence on voluminosity (John Deere) |
The results we present (mainly output per hour in the range 4–8 m3) correspond to the works of the authors [1, 5, 7, 8, 10, 17]. On Figures 7 to 10 we show the dependence of movement time on distance and the dependence of the time of the cross-cutting on the number of the logs. On Figure 15 we shows a comparison of our results with the results of authors [1], of the comparable harvesters classes 1 and 2.
|
| Fig. 7. Movement time consumption dependence on the distance (Valmet) |
|
| Fig. 8. Movement time consumption dependence on the distance (John Deere) |
|
| Fig. 9. The dependence of manipulation time consumption on the number of assortments (Valmet) |
|
| Fig. 10. The dependence of manipulation time consumption on the number of assortments (John Deere) |
The harvesters moved through the forest stand with comparable speed. Valmet approximately at 17 m·min-1, John Deere at 21 m·min-1. John Deere is a smaller, more manoeuvreable harvester, therefore it is faster than Valmet. On the other hand, in connection with its higher performance, Valmet is faster in manipulation despite the higher voluminosity of the processed trees. Valmet was able to produce approximately 4 assortments in 0.75 minutes, John Deere in 0.85 minutes.
Economic efficiency of the thinnings carried out by harvesters
in comparison with motormanual method
Valmet 911.1 and forwarder Valmet
840.1
On Figure
11 we show a calculation of the classic motor-manual logging
(pre-felling, delimbing, skidding and cross-cutting) and skidding of the assortments
with a wheeled skidder in comparison with harvesting and forwarding of the assortments
with integrated technology. Based on the comparison of the technologies we can
say that the costs in SKK for 1 m3 of the timber to the voluminosity of
0.15 m3 lower by 12% when using harvester technology. From the voluminosity
of 0.15 m3 the harvester technology is more expensive on average by 17%.
|
| Fig. 11. Comparison of prices of the classic and harvester technology – Valmet 911.1 |
The price of processed assortments on the forest landing is approximately 10–12 €·m-3 when logging with a portable chainsaw and choker skidding with a wheeled skidder. When harvester technology is used, the price is approximately 15–17 €·m-3. The prices depend on various conditions (type of logging, intensity of silvicultural access, etc.). When dealing with the harvesting technology the prices are set after direct inspection of the forest stand.
John Deere 770D and forwarder John Deere 810D eco III
On Figures 12 and 13 we show a calculation of motormanual logging (pre-felling,
delimbing, skidding and cross-cutting) and skidding of the assortments with a
wheeled skidder in comparison with harvesting and forwarding the assortments
with integrated technology.
|
| Fig. 12. Calculation of motor-rmanual and harvester technology – Valmet 911.1, forwarding down hill |
|
| Fig. 13. Calculation of motor-rmanual and harvester technology – Valmet 911.1, forwarding uphill |
The calculation of individual logging methods confirms the advantages of using integrated technology mostly in young forest stands up to the growing period of thin stem (approximately up to 0.22 m3). In these forest stands the labour content (time consumption for the production of 1 m3 of the assortment) decreases exponentially with increasing voluminosity, which has proportional impact on the costs for the production of 1 m3 of coniferous assortments.
The efficiency of using the integrated technology is more significant when forwarding uphill. From the point of the costs for the production of 1 m3, using integrated technology is more profitable approximately to 0.5 m3 average volume.
When forwarding down hill, integrated technology is 4.5 €·m-3 cheaper than the motor manual method, i.e. by 2.25 €·m-3 on average for voluminosity of 0.2 m3. When forwarding uphill, integrated technology is 6.2 €·m-3 cheaper, by 3.1 €·m-3 on average for voluminosity of 0.2 m3 (approximately of 0.4 m3), the total average difference is 2.67 € in favour of integrated technology.
Full tree method is almost universaly used for biomass preparation in young stands. The calculation is mentioned on Figure 14. Integrated technology is advantageous to use in stands with voluminosity up to 1 m3, as can be seen from the results section.
|
| Fig. 14. Calculation of motor-rmanual and harvester technology – Valmet 911.1, full tree method |
|
| Fig. 15. Comparison of our results with the results of authors Dvorak et al. 2012 |
DISCUSSION
The production rate of the technology is three to ten times higher than the production rate of the classic technologies. Also in relatively demanding conditions in which the research was done, the potential production rate of the harvester was from 50 to 100 m3 per working day (one to two working shifts). The output of Valmet (6.5 m3·h-1) and John Deere (5.7 m3·h-1) was close to the mean values of long-term averages presented by foreign companies and correspond to the works of the authors listed previously. Providing access to forest stands and the width of working fields in our conditions are comparable to those abroad, which allows using standard and commonly used the harvesters.
Harvester technology is economically efficient mostly in young forest stands up to the growing period of thin stem (John Deere approximately up to 0.3–0.4 m3 according to used technology, Valmet up to 0.15–0.20 m3). In these forest stands the labour content increases exponentially with the decreasing voluminosity, which has proportionate impact on the costs for the production of 1 m3 of coniferous assortments.
Generally the appropriateness of integrated technologies on the basis of multi-operational machines for premature logging in mountain and submountain areas of Slovakia was proven. Besides the economic efficiency there are other significant attributes – humanization of work, high production rate, environment aspects, work operativeness when liquidating relatively big amount of timber from disasters windthrow and snowfall, there are no costs for constructing, running and maintaining of handling-dispatch store and cross-cutting line.
CONCLUSION
As within the analysis of operation of other harvesters, we can say that an effective application of harvesters requires careful planning and technological preparation of the workplace. Among the most important measures besides the selection of an appropriate type of harvester, is choosing an appropriate forest accessing method and a choosing methods with sufficient volume of the trees – concentration of timber and complex adjustment of the transporting lines and knots (marking lines for harvester, forwarder, etc.). These facts are closely connected with the fluency of timber hauling – ensuring adquate hauling capacity and functioning relations among suppliers and customers. From the point of view of time control, the solution of intensity and range of work time during the day is important. The harvester and forwarder are technically equipped to work non-stop. The amount of productive operational hours is a decisive factor of the production rate. Continuous operation also sets extra demands on wider logistic support of such efficient production system.
Acknowledgement
This paper is the result of the project implementation: Extension of the centre of Excellence „Adaptive Forest Ecosystems“, ITMS: 26220120049, supported by the Research & Development Operational Programme funded by the ERDF.“ and of project “Analysis of the impact of the forest technology chassis on soil surface and determination of maximum limits of damage”. VEGA 1/0323/011.
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Accepted for print: 07.04.2014
Jozef Tajbo¹
Faculty of Forestry, Department of Forest Harvesting, Logistics and Ameliorations Technical University in Zvolen, Slovakia
T.G.Masaryka 24
960 53 Zvolen
Slovakia
email: tajbos@vsld.tuzvo.sk
Valéria Messingerová
Faculty of Forestry, Department of Forest Harvesting, Logistics and Ameliorations Technical University in Zvolen, Slovakia
T.G.Masaryka 24
960 53 Zvolen
Slovakia
email: messin@vsld.tuzvo.sk
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