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Photo 10. Logging by construction crane after a windthrow where trees were lying tangled and in all directions.

APPENDIX 1. SLIDE SET - to accompany the FAO Forest Harvesting Case Study,



1. Forests of Austria

Austria is a mountainous country rich in forests: 46% of the land area is covered with forests dominated by coniferous trees; only 36% are broadleafed and mixed forests. The annual increment in timber estimated by the forest inventory is about 19 million m3, but the annual harvesting is only approximately 12 million m3 of timber.

2. Location of the case study

The case study was carried out at two harvesting areas with a 105-year-old and a 75-year-old stands of Spruce and Picea abies, respectively, amply supplied with natural regeneration in the understory. The areas were located between 470 and 480 m in altitude in Carinthia, the southernmost federal state of Austria. The average volume of the trees logged by means of construction crane was 1.24 m3.

3. Forest roads

Forest accessibility is provided by approximately 55 m of road per ha with a formation width of 6 m, carriageway width of 4 m and types of construction corresponding to the usual forest road standard in Austria. Construction cranes like the FAUN RTF 40-3 can certainly be used on these forest roads during dry seasons or when the ground is frozen. Problems concerning the road-bearing capacities might arise during wet seasons.

4. Felling

The trees have to be felled so that they point toward the location where the construc-tion crane is set up. In this case the distance from which the crane operates would be the extraction distance plus the length of the felled trees. The felling operation must be carried out very carefully so that natural regeneration is preserved. Felling has to be finished before the logging phase starts in order to avoid interference in the logging operation.

5. Setting up at the forest road

Once the driver has reached the place where the crane is to be set up, he must manoeuvre the vehicle so that it stands at a right angle to the road's center line; this will provide maximum machine stability during the operation. The front of the vehicle should be pointing opposite the work area since over-front lifting might damage the driver's cab.

6. Setting up at the final cut area

Provided the terrain is accessible and the ground is frozen, the construction crane can be set up on the felling site, about one boom length from the road thereby extending the radius of crane action.

7. Supported operation

Once the vehicle is in the correct position, the outriggers must be extended and set up on firm level ground so as to stabilize the operation, hence providing maximum lifting capacity.

8. Outriggers

The ground may need to be prepared so as to be level in case the outriggers have to be set up on forest ground. Square-sawn timber between outriggers and ground create a level surface and help to distribute the pressure evenly.

9. Extraction distance

The optimum extraction distances are within the radius of boom length plus the hoisting equipment's length.

10. Hooking

The assistant at the felling site is hooking the trees or assortments with log tongs. The tree diameters determine the proper size of the log tongs.

11. Unhooking

The log tongs can easily be removed by the assistant at the landing. Protective gloves and helmet are absolutely necessary for the assistant in handling the metal log tongs and as a safety measure against the danger of falling limbs from the lifted load.

12. Driver's cab

The construction crane is suitable for the operator because it meets ergonomic principles and requirements. Its design and safety features assure convenient and safe operation which are prerequisites for the operator's sustained performance.

13. Dismantling

The average time required for the dismantling operation is 15 minutes, which is about half the time needed for setting up the crane.

14. Telescoping boom

After joining the hoisting equipment to the hook block of the stabilized crane the telescoping boom can be extended (maximum boom length 30 m, radius 28 m).

15. Manoeuvrability

Different steering possibilities provide high manoeuvrability and small turning radius of the 3 axle all-terrain crane FAUN RTF 40-3.

16. Final cut area

The assistant who will be hooking the load has to arrange the trees or assortments for logging; in order to avoid lateral pulling he also has to direct the operator by radio so that the boom is aligned to the felled trees which have to get logged.

17. Load size

It is not advisable to transport more than one tree or assortment simultaneously. One reason is the impos-sibility to align the boom to more than one tree at the same time and avoid lateral pulling. Another reason is the difficulty during touch down of a load consisting of logs with different lengths.

18. Landing area

The crane driver is able to place the tree or assortment exactly in the desired direction.

19. Lifting the load

Lifting the load is the critical phase of the logging operation. A swinging boom caused by lifting a tangled tree makes the driver apprehensive of overturning the vehicle and increases his mental strain as well.

20. Load transported: vertical

To transport the trees or long logs in a vertical position means with "raised head".

21. Load transported: horizontal

The log tongs are fixed at both ends. This could be useful in preserving natural regenera-tion from damage but it requires that the trees lie in the optimal radius; otherwise the trees have to be transported in a vertical position first and rehooked afterwards.

22. Hoisting equipment

The hoisting equipment used consists of two 6 m long ropes with log tongs of different sizes on the one end and are connected with a loop on the other end to a 6 m long synthetic sling which is joined to the hook block. The hook block hangs from a rope about 5 m from the top of the boom; this increases the effective radius of action to 45 m, depending on the slope of the terrain.

23. Length of assortments

In relation to the height of the natural regeneration, maximum transportable length should not always be completely made use of so as to assure the best possible preservation of the young trees.

24. Load volume

A significant advantage of the FAUN RTF 40-3 and other comparable types of construction cranes is that they have a fully automatic overload protection device so that the safety hazards are reduced to a minimum.

25. Infeed pile

When the whole-tree method is used a wood processor should be selected according to its maximum design capacity and the tree diameters at the harvesting areas. A sufficient supply of trees for processing has to be assured so as to fully utilize the wood processor.

26. Wood processor

The one-grip crane processor STEYR KP 40 is a machine designed for continuous operation with trees up to 40 cm butt-diameter and can be used in combinaiton with other machines.

27. Carrier vehicles

The one-grip crane processor can be mounted on different carrier vehicles such as trucks, skidders or excavators. Here it is mounted on a wheeled excavator.

28. Site after operation

When setting up the wood processor on a forest road, the operator has to carefully pile the produced assortments and debris so as to keep a clear work space for the machine.

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