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FAIR-CT97-3381
Excavators as base machines in forest operations |
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Contract No: | FAIR-CT97-3381 |
| Date Prepared: | March 2001 | |
| Source: | Final Report Abstract |
Introduction
Within this project, that started in August 1998, three annual meetings took place. During the meetings were presented papers, video films etc on relevant subjects. Excursions were carried out also and further information provided through a webpage (see above).
The aim of this Concerted Action was to support, develop, and increase mechanisation in forestry, using excavators and backhoe loaders as base machines in procedures that are environmentally, technically, and economically sound, leading to an overall better European Competitiveness. Conventional forest machines are expensive and can normally, do only one type of job. A lot of the machines have a bad impact on the environment, often related to their impact on ground and soil disturbance. In countries outside Europe, such as USA, Canada, and New Zealand excavators are commonly used as base machines in forest operations. One potential advantage considering the technology in this CA-proposal is increased utilisation (multiple-use). Through this Concerted Action new and existing information about the proposed technique will be distributed to the participating countries and made available for further use and development in each country. It will also be clearly identified within which areas further research is necessary and in which way these efforts can be co-ordinated and thus carried out in an effective and economically sound way. Socio-economic impact would be considerable.
This project is of great interest for most countries within the EU, since the suggested harvesting technique is appropriate for any country with forestry. The project fits the work programme very well. It highlights very much the impact on economic, socio-economic, environmental, and industrial matters. The partners and associated partners have been chosen because of their professional capabilities and for their ability to represent individual links within this area. The participants show a broad variety of enterprises and organisations - SME's (e.g. manufacturers and users), large enterprises, research organisations, and universities. Exchange of expertise and experience between these different organisations is of utmost importance in bringing the concept to a successful end.
Activities
The work was divided into a number of task areas as follows:
Mobility and harvesting performance. Mobility in deep snow, in steep terrain, on peat land, or ground with low bearing capacity. Harvesting performance in stands with large softwood and hardwood trees, and in stands with small trees. Harvesting performance in thinning on mineral soils or on peat land (including damage to remaining trees).
Reliability and harvesting productivity. Reliability and harvesting productivity in the long term. Economic potential.
Computer based analysis and modelling. Computer based analysis of ground damage (using parameters gathered in the field). Modelling of the machine stability and of the operator's work.
Environmental impacts. Environmental impacts (e.g. erosion), socio-economic impact.
Work environment, ergonomics New concepts.
In all over 100 participants, presented over 50 papers and attended excursions to 10 different places. In addition to presented papers two video films were also presented during the first meeting and one video film was produced
Results
The project has so far shown that most excavator based forest machines are operating in Ireland and Great Britain. However, this type of machine exists in many other European countries, but in much lower numbers. Initially modifications to the machines were quite simple, and many bases were rather small. Today the modifications are of a higher standard, and the bases are larger. What is high standard for one factor can, however, mean lowered standard for another factor. As for example, raised ground clearance for better mobility causes increased problems for entering/exiting the machine. The modifications are required/desired for a number of reasons, such as:
In general there are three types of machines (harvesters) considered as base machines:
Lately purpose built tracked machines, such as Timbco, Impex, and Neuson, have appeared on the European market. These are supposed to combine the best qualities from both the wheeled machines and the tracked machines. One good quality is the levelling cab. However, the price is rather high, about the same as for wheeled machines. Ergonomics and work environment have not yet been examined/assessed, but some people suggest that this should be done.
This project has shown that productivity for excavator based harvesters is good, especially considering stands with large trees. Larger excavators are needed to handle large trees. The situation is about the same in USA, where the amount of large logs are decreasing in some places leading to that the number of large machines sold is also decreasing. In cases where productivity seems lower than for purpose built machines this largely seems to depend on a lower travel speed. Advantages given for tracked machines include:
Economy seem to be good also, at least when bases promoting good productivity are used, given the investment level is not too high. The investment level is given to be approximately 50 % - 80 % of that of purpose-built machines. Economy was in many cases at about the same level as that of purpose built wheeled machines.
It also seems that the price for purpose built wheeled machines has decreased during the last few years. When talking with operators, machine owners, forest owners etc. there are also indications that the decreased price for purpose built wheeled machines might depend on the competition from excavator based machines.
On the other hand ergonomics are considered to be poorer. Cheaper and less modified machines seem to have even poorer ergonomics and work environment. Experience considering ergonomics, work environment etc is very limited to only a few participants. However, the need for this issue was thought to be large. This includes topics such as work organisation and education/training, not at least as parts of logistic problems.
A lot is done (and being done) regarding damage/impact to the ground. But it is not enough, a lot still needs to be done. This is largely due to the complex nature of this matter, due to e.g. organic soils versus different mineral soils and the whole scale in between. Other factors are stones and roots in the ground and on the ground, and grass and herbs on the ground. Water content is another important factor. It is very important to ecology and environment, e.g. erosion, soil compaction and water stagnation. Damage to the ground was at about the same level as that of purpose built wheeled machines. It varied but can in many cases be considered to depend on the work method used. The level of damage to roots in thinnings has in some case been high, but tracked machines should not be used in stands with shallow root systems. There are also indications that tracked machines should not be used in thinnings at all.
Tracked harvesters offer forestry further possibilities for rationalisation in harvesting heavy timber, young trees arid on slopes. Transport of these machines is difficult in comparison with wheeled machines and requires greater volume of felling at each site. More research is necessary to investigate damage to the soil and the roots caused by the tracks.
The picture considering socio-economic impact and rural development is today a little less blurred compared to state of art at the start of the project. However, a lot still needs to be further investigated.
During the meeting the need for bases which, already at the factory, are better prepared for different forestry use and attachments, and why not include a ladder? This would make modifications much easier and cheaper. Modifying companies will have to be supported in their efforts by the large manufacturers of excavators in order for the excavator harvester to gain the market penetration it could have. Operators who have been using both purpose built machines and modified excavators have judged both to be equivalent. However, a big effort from the excavator manufacturer in designing, is needed in order to improve certain aspects mentioned above.
The modifications in converting an excavator to a harvester should aim to improve the properties of the present units as regard to their mobility, especially the steering of the vehicle, to avoid the damages caused during the operation and to the ergonomics from the operator's point of view. Something might be done in these areas, but due to technical reasons the hands of the designing engineers seem to be tied in aiming at those goals.
The competitiveness of excavator-based harvesters may be improved in the future. Some of these improvements are connected with modifications of the base carrier when introducing it to the cutting work. Since the operating conditions greatly vary in different countries, it might be possible to design excavator base carriers especially for certain limited, very demanding work conditions. Cutting really large trees, several cubic meters in size, could be one example where the high total mass of the carrier would be beneficial.
Machine manufactures should take a leading role in machine design to improve ergonomics of the machine, in particular those which will improve the working posture and the environment in all working conditions. Managers should ensure that those actions and practices which will relieve the stresses of the operator are implemented. This relates to both the safety issues and whole body vibration.
The excavator based harvester is a multi-functional and economical alternative for harvesting purposes which has the potential to meet the increased demands on competitive harvesting costs as being shown in this report. The reason for this being a lower purchase price, a lower maintenance cost than the purpose built rubber tired machine, in addition to the possibilities of the excavator to function in the areas it was originally designed for. Other factors influencing the contractor when deciding what to buy will have to be attended to by the suppliers of excavators to a larger extent than what has been the case so far.
The excavators can be used in harvesting full time as well as part time. If it is used part time in harvesting it can be used in other work rest of the time. The cost in the other work can then be reduced due to a high degree of utilisation.
Forestry imposes new limits on how an excavator can be used, but this does not mean that the excavator cannot do a good job. On the contrary, this machine can reach a fairly high productivity - often higher than obtained from other alternatives like the farm tractor. A good knowledge of how the machine will be used makes it possible choosing the most suitable model for each task, and fitting it properly. Excavators used in forestry carry out very peculiar jobs, which follow specific work routines. These routines hardly compare to the standard digging cycle that the excavator was designed to perform. Log loading is the only job that resembles digging, while all other tasks are significantly different.
Backhoe loaders seem to be of less importance as base machines for forestry use. There is a limited number in mainly Sweden and Finland while a few machines have also been purchased in The Netherlands and Germany. The future for excavators is today relatively difficult to foresee. We know enough about productivity. But there are other areas that need further research, not only about excavators but in a wider and more general respect. We can, however, foresee that once standard (excavator-) based harvesters are introduced in forestry - they are, more or less, there to stay. Excavator technology will probably not be used to some larger extent in the Nordic countries, maybe with an exception for steep areas. This is probably due to the strong traditions considering purpose built wheeled machines. In the rest of Europe development/use will C> increase, or at least not decrease very much. The excavator based machines will be modified all the way from very simple modifications to more expensive ones. The number of excavator based machines are in some countries likely to increase and in some others to decrease. A certain increase will, most likely, be on the number of tracked purpose built machines. These are now being tested in some countries. What machines will be bought in the future is up to each buyer, but it is worth mentioning that each type of machine has its' advantages, over the other types, in its own area. However, for the final decision the level of investment will be very important.
During one discussion, it was pointed out that research often delivers the results late - research is sometimes confirming what practice already knows. During this project, however, we have an opportunity to be ahead of practice. Important areas to investigate further are:
Another important task is standardisation. This depends on the fact that it is difficult to make various comparisons between different countries due to e.g. varying tree species, tree size, modifications, work methods, work Organisation, machine size, and output product. Some kind of standardisation would make it easier for all to make comparisons, since now it is difficult to know what is being compared or what methods are used. During the project there were opportunities to meet others working in this area, an some started to co-operate, and this level of co-operation will probably increase in the future.
© Copyright 2006 Policy Statements
Updated
by CPL Press:
03/07/2007
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