logging in the mountains of

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS ROME

\ \

LOOQING IN THE MOUNTAINS

OF

CENTRAL EUROPE

by

A. T:rzesnio'l'rski

SWEDISH FUNDS-IN-TRUST FOI: ',l'F .... INT. 74 (SviE)

FOOD AND AGRICUI/1'\JRE ORGANIZ:A'riON OF THE UNITED NATIONS

Rome, 1976

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The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the. Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

The copyright in this book is vestcld in the Food and Agriculture Orga­nization of the United Nations. The book may not be reproduced, in whole or in part, by any method or process, without written permission from the copyright holder. Applications for such permission, with a statement of the purpose and extent of the reproduction desired, should be addressed to the Director, Publications Division, Food and Agriculture Organization of the United Nations, Via delle Terme di Caracalla, 00100 Rome, Italy.

© FAO 1976

iii

The Forest Logging and Transport Branch of the Forestry Department (FAO) is preparing a series of manuals and documents on specific problems in logging, transport and forest road construction. The latest in this series is the present document: "Logging in the Mountains of Central Europe 11 • The objective is to make recent developments in logging, cost and production data as widely as possible available to interested foresters all over the world.

This document is to be considered as a preliminary report and will, therefore, be published in English only. It is based on the work of Mr. A. Trzesniowski and has been worked out in collaboration with the Forest Logging and Transport Branch.

As in many developing countries more and more foresters are confronted with problems of wood harvesting in steep terrain with the concept of a sustained yield, the Logging Branch is planning to publish a mamlal on wood harvesting in steep terrain, for which this preliminary document may very well serve as background material. Readers are, therefore, invited kindly to comment, make suggestions, or give their views on the report so that the present document may be improved.

The mention of specific companies or of their products or brand names does not imply any endorsement or recommendation on the part of the Food and Agriculture Organization of the United Nations.

The Food and Agriculture Organization gratefully acknowledges its indebtedness to the Swedish International Development, Authority (SIDA) whose Funds in Trust made this report possible.

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ABSTRACT

Many types of logging techniques are used in the mountains of ~ntral Europe.

The simplest involve skidding the logs by hand and employing gravity to get them down

to the valley; the most complicated demand the use of sophisticated modern equipment

by trained crews.

A wide range of techniques is discussed in the report, together with the kind

of terrain and conditions for which each is suited. Felling and skidding patterns

are given, and forest-road density, planning and maintenance are described.

Appendixes provide detailed speGifications of equipment, step-by-step instructions

on how to set it up, and information on work procedure and methods.

1. INTRODUCTION

1.1 The Importance of Planning

·j. 2 Methods of Extraction

1-3 \'lork Procedure

1.4 The Importance of Roads

1. 5 Conversion Sites

2. EXTRACTION TECHNIQUES

2.1 Manual Skidding

2.2 Animal Skidding

2.3 Mechanical Skidding

2.4 High Lead System

2.5 Slack Line System

2.6 The Cable Crane

2.7 Pendulum Cableways

3· ROADS

3· 1 Planning

3.2 Maintenance

3.3 Strip Roads

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TABLE OF CONTENTS

3

3

3

4

4

5 6

9 10

10

14

15

15 16

16

Appendix 1: SPECIFICATION OF EQUIPMENT FDR A CABLE CRANE WITH TOPMOUNTED WINCH . 19 Appendix 2: THE SETTING-UP PROCESS 23

Appendix 3: \'lORK PROCEDURE, METHODS AND OUTPUT 25

List of Tables

1. Basic Data from Eleven Cable C~ane Installations in Kaernten, Austria

2. Average Times Taken to Set Up Cable Cranes

3. Output in One Year 1d th Two Urus Unimog by an Austrian Forest Company

4• Comparison of Extracting Times of iiell-trained and Untrained Crews

5• Output as .Affected by Length of Cable Lines and Number of Supports

List of Diagrams

1. Manual Skidding

2. Strip Roads for Mechanical Skidding

3. Lateral Skidding

4· Output as Affec·ted by Lateral Skidding Distance

26

27 28

29 30

31 32

33

34

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1. INTRODUCTION

Over the centuries a tradition of special logging techniques lms been developed in the Alpine region of Central Europe in order to obtain a sustained yield from the forests in difficult terrain conditions. Forests in this region have long been recognized as providing not only the necessary raw material for housing, construction work, heating and so forth, but also protection against soil erosion and avalanches, protection of watersheds, the regulation of stream flows, maintenance of a balanced environment and nowadays protection against industrial emanations and the preservation of wild life, as well as recreational and social facilities.

Besides the traditional logging methods in steep terrain, such as manual and animal skidding, a wide range of modern equipment- mobile cable crane units, short and long distance cable cranes, skidders, wheeled tractors, winches and so on - is now used in forest operations. Recent technological developments naturally demand highly trained and specialized forest workers.

In many countries in the world, suitable terrain and soil have increasingly to be put under food production because of the expanding population, and forestry and forest management are confined mainly to steep and difficult terrain. This intermediate report is to recall the experience gained in Central Europe and to discuss the logging techniques mostly used today, which may be of interest in forest operations in developing countries. Sometimes these would need to be modified and adapted according to local conditions.

1 • 1 THE IMPORTANCE 0 F PLANNING

As in any other work process, the success of logging in the mountains depends on good planning and organization. Different phases of the work have to be coordinated and detailed information given to the forest workers on the plans and processes they are to follow, as well as information on such important matters as prevention of accidents. At the planning stage the method of extraction is decided on. The existing network of forest roads is examined and decisions taken on the advisability of constructing others. A choice may have to be made between building strip roads for trucks or using cableways. Decisions on uphill or downhill transport are made, depending on the situation and the machines available. ·

1 • 2 METHODS OF EXTRACTION

In choosing machines and equipment the following classifications may be used as a guide:

1.2.1 Downhill Extraction

Animal skidding on level ground and on a slope of up to about 35 percent, according to the type of animal and the weight of the wood (section 2.2);

Skidding with a farm tractor, generally on slopes of up to 30 percent; over a short distance with protective chains and other special equipment on slopes of up to about 40 percent (section 2-3.2).

Skidding with an articulated four-wheel-drive S:cidder on slopes of up to about 50 percent, using ami-skid chains on the wheels. Where the ground is especially dry and even, short distances on slopes of approximately 60 percent are possible, provided a suitable place is available for the vehicle to turn around for the return journey (section 2-3-3·).

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Manual Skid~ing using conventional tools (peavies) and natural possibilities offered by the ~teight of the logs. Skidding logs with bark; generally rellllires a slope of over 80 percent; those without bark one of over 60 percent. In especially favourable conditions (ice, wet ground) a slope of only about 32 percent is required (section 2.1).

Transport with cable and valley station equipment. Used on very difficult terrain from even to steep (with rocks, steep slopes and tree stumps), also for short distances of up to 400 m and with a low lifting height and not too wide a lateral skidding (up to 30 m) (section 2.6.2).

The high lead system is seldom used in Europe. Acco+ding to manufacturers, this method may be recommended for transport of light or heavy logs, with or ~dthout bark. The working distance is up to about 300 m. It is not dependent upon the slope of the land, but the terrain profile must be more or less concave (section 2.4).

1.2.2 Uphill Extraction '

Manual extraction uphill is generally not feasible, though in special cases light logs can be carried over short atstances (section 2.1). .

·Animal skidding uphill is feasible only with a light load over ·short distances and on slopes of up to approximately 10 percent. I~ general this method is not suitable (section 2. 2).

The use of farm tractors and direct pull is feasible only on terrain with a slope of up to 20 percent. In "stepped" Skidding a slope of up to about 30 percent is practicable (section 2. 3· 2).

Skidding with an articulated four-wheel-drive skidder and adirect pull. This is practicable on slopes of up to 2'5 percent. "Stepped" Skidding is feasible on slopes of about up to 45 percent, if the skidder is powerful enough. Under favourable ground conditions a slope of 50 percent over a short distance is manageable (section 2.3.3).

Using a cable, ground Skidding is possible on any slope, but only when the terrain is free of obstructions. It is economical up to 30 lll (in special cases 100 m), if the mainline is pulled manually. With the use of a fiecond w:j.noh or a double drum ,.n.nch ,.n, th pulley, a distance of 300m may be achieved (section 2.3).

Cable transport using the gravity system and mountain stationed winch may be employed on slopes from approximately 22 percent. The steeper the terrain the better the equipment functions. Logs of any length may be transported. The use of a mobil13 to"tier cable c r a n e ;is ideal for this work. According to the working system of the cable crane, distances of up to about 2 500 m can be handled (section 2.6).

Fbr the high lead system a strong winch and a set of cables is necessary (section 2. 4) •

Slack line logging is generall¥ similar to the high lead, but better lateral extraction is possible (section 2.5)•

As a general rule it may be said that tractors with all the possibilities they offer are the best extraction equipment for downlull transport of logs. Cable systems Qf any type provide the best method on steep mountain slopes with obstructions as well as for transport down - and uphill. Traotors \veighing up to 6 t are also sui table· for use on sloping terrain. Heavy four-l'lheel-dri ve articulated skidder can be used for log Skidding on a strip road. The best of all Skidding systems for short distances and small amounts of logs is ground skidding. Attention should be paiq to the trend toward the use of mobile to1·rer cable cranes. These, used in a co:p.jWJ.ciiion with existing roads, can attain the economical extraction distance of 500 - 800 m.

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1. 3 WORK PROCE;DURE

Before fellin~ qomme~ces,~he forest workers should know what type of logging technique is to be used, flO t~i; they can fell the trees in the appropriate direction. Coordination of the felling with. tM ~id\1-ing is particularly important in the tree-length method (Diagr~m 2). Wh.ere whee~~q tractor ~idding is to be used the strip road, should be at least rougPly marked out ~o t~a~ the trees can ~e felled in the required direction.

Fbr cab~e crane transport tb.~ ~yline corridor must be surveyed before felling, the support and anoPQr tree~ m~~t be marked so that they are not accidentally felled. thinnings the q~ble cprri~or should be c1ea~felled before normal felling proceeds. way unwanted ~Ps ;i.n 'l;l;l.e :f'o~el?t cover are avoided.

1. 4 ':):'HE IMFOR~.I\N0:111 OF R()A;ps

and In ~this

Fbrest ro~df are a vita~ factor in practical forest work. From the viev~oint of silviculture, fore~t proteqtion and forestry technique, roads are the best means of m~ing the forest aooessiPle• Fbrest roads have a specific limit with a view to protecting the lan~scape, preventang eroaaon and keeping the costs down. These factors as well as the exigencies of the e;x:t:r:•p.ction metl;l.od ahould be borne in mind when the choice is made of the area and the most f?Uit'f.ble ,cOfllbinatiol:l qf forest roads, skidding trails and cable corridors. (Pl1nning, buildin~ and maintenance of roads, strip roads and tracks: section 3.)

1·5 CONVERSION SITES

Conversion sites are especially necessary in fUll tree or tree length skidding. The size of these area,s dep~nd~ u:pon tl;l.e amount of timber to be felled. 'Generally, a site would be 1. 5 - 2 tree lengths long, and 12 - 15 m ~dde. Conversion sites should be provided at the flattest avai~abie places along tb.e road and at bends.

When skiddin~ ;i.s oarr;i.ed out with a wheeled tractor, the conversion site can be laid out \'lith a spa,cing of ?00- 800 m along the road, so that as many strip roads as possible lead to the landin~. Wl;l.en cable cranes ~re used, there must be a log landing at the end of each cable corrido~ and in t~is case its shape should be as square as possible.

l'l~ll aligned, forest road

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2. EXTRACTION T~HNIQUES

2. 1 MANUAL SKIDDING

Skidding by hand is generally regarded as the most expensiye ~ethod of extracting logs. Nevertheless, there are some situations. where it is n,ecessa,ry. These occur primarily when logs are lying scattered in the woods and must be taken to the roads, storage sites or different transportation sites. With the building of ~oad networks and the use of specialized equipment, the amount of manual skiddilfg e<;tn be reduced and consequently also expensive manpower and damage to the forest floor (~nth the danger of erosion) and to the trees as 11ell.

2.1.1 Manual Skidding Without Machinery

On level ground, a man can carry the lighter wood (30- .50 kg) on his shoulder, or he may carry the butt and drag the pole. Sometimes, a pole can be carried by two or more men.

In the mountains, heavier logs may be taken to the valley by means of gravity. Here, obviously, the steeper the terrain, the easier the method. Rolling the logs down is the easiest and simplest method, but also the most destructive. Skidding a log lengthwise causes also damage to the soil and vege-tation and to the log itself although, if special precautions are taken, the damage can be limited. Leaving the bark on the log is helpful in skidding logs in very steep terrain. On gentler slopes, when it is v1et, or there is snow and ice, the logs are easier to skid without it. For manual skidding, the -trees should be felled in an upvmrd direc·tion so that the butt points toward the valley. The trunks should be cut into smaller logs at the felling site so that extraction becomes easier.

A certain slope is required to induce the logs to slide into the valley; according t0 Prof. Hafner 1/, a pine 1dthout bark requires a slope of 74 percent on o1ay soil. Under the same conditions, but with the bark, one of 88 percent is required. Once the logs are sliding, a slope of only 40 - 68 percent on dry ground and 16 - 50 percent on wet ground is sufficient. .

With veri heavy logs or where the ground is flat, skidding can be carried out by laying logs at right angles, or building wooden chutes. Mainly in mountain areas, such chutes are made by laying wood in a fishbone pattern, so that one trunk after the other can be slid over this "deck of guiding logs". The "deck" is -then dismantled from the top and the comP,onent logs slid down over the ones still in position. (See Logging and Log Transport in Manmade Forests in Developing Countries, FA0 9 Rome, 1974, page 112).

2.1. 2 Manual Skidding with Tools

Manual skidding of logs in the mountains requires the use of a hand tool with a hooked head, the peavie. This tool is well known in Alpine regions, and is invaluable. Even the heaviest trunks can be moved by four to six forest \'I'Orkers, using the appropriate methods. The peavie is so constructed that the head and the handle form an angle of 120°. The head is ~ade of steel and the handle of hard wood (approximately 1.20 m long). The nook is strongly made and therefore may be used for pulling logs.

In many oases (for example in young forests), a >vhole trunk must be transported to the valley in good condition. This is achieved with the aid of a hempen or nylon rope and a screw or hook, ;.1hich is either screwed or driven into the butt. After the tree is felled with the top pointing toward the valley, it is hung on to the stump for debranching and de-barking.

1/ Der Holztransport by Franz Hafner, published by Osterreichischer Agrarverlag , Vienna

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For the skidding, one man drags the top of the trunk with the cant hook and so guides it, while a second man winds the rope tHo or three times around a tree and in this manner controls the slow slide of the fresh smooth trunk toward the valley. After the rope and screw have been pulled up, the next tree is felled and transported in a similar fashion. Because the rope is probably only about 80 m long, trunks must be brought downward by degrees. To avoid carrying the rope, many types of winches with steel cable are used.

The speed of manual skidding depends largely on the Heather. In order to use periods of favourable weather to their best, felling and ~idding should be carried out by the same forest crew. Logs are skidded according to the weather (usually on rainy day~ or the time of day (early in the morning). On steep slopes, the trunks are skidded in . dry weather to prevent damage to themselves and to the forest floor as far as possible. In favourable conditions (ice, frozen or very wet ground), four workers can skid up to 40 m3 of wood over a distance of 500 m a

3day. In unfavourable conditions, production over

the same distance would hardly yield 5 m per day.

2.2 ANIMAL SKIDDING

According to the terrain, horses, mules and oxen may be used for skidding. On level or slightly hilly land, pairs of. oxeri can pull very heavy loads; occasionally they are used singly. In mountain forests, horses and mules are ideal for lighter loads, but these animals are becoming scarcer.

There is no machine that can, without much adjustment, work a mountain slope in all directions as can a horse, but the general trend toward mechanization and the fact that animals must be cleaned, fed and attended to, day and night, workdays and holidays, has led to their steady decrease. It is easier to find a mechanic who understands timber transport than a nature-loving animal keeper who does.

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Animal skidding is most useful in the mountains, because here it is possible for the timber-to be dragged in the' contour lines to the track, storage area or point of mechanical transport. Strip roads are generally not needed, because the animal can find its own ~dy, and the forest worker can concentrate on seeing to it that the log is not damaged by other trees or stumps. Animals are more useful than most machinery, in that they can reach almost any place, arid therefore areas Hhere there is only a little timber can also be exploited.

On a slope, it is better to skid the butt first; on even ground, the opposite is better. The distance between the load and the animal should be about 1.5 m, so that the animal is not hindered by the load.

The equipment used in animal skidding is simply a hook on a chain. Apart from this, there are various skidding sledges and logging arches; these are required more or less according to the area and the conditions.

The weight of the load that can be skidded by a horse is generally one fifth to one quarter of its body weight,· so a horse \dth a body weight of 700- 800 kg could pull a load of 140 - 180 kg.· A lighter horse is quicker, but with a body l-Teight of about 500 kg, it could pull only about 60- 80 kg at a speed of 0.8- 1.1 m/sec. Over a short distance, a horse can pull up to double the load. Oxen \d th a body \-teight of 600 - 800 kg can produce a pulling strength of 160 - 190 kg and a speed of 0.6 - 0.8 m/sec. Mules ~nth a body weight of 350 - 400 kg can pull about 50 kg at a speed of 1. 0 - 1.1 m/ sec. 11

11 For more information, see Countries, pp. 112- 119

Logging and Log Transport in Manmade Forests in Developing

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2.3 MECHANICAL SKIDDING

2. 3. 1 Ground Skidding with Winches

Ground skidding with a winch can be carried out in many ways, but it is lirni ted to a range of 300 m. The advantage of the method lies in the fact that ine~perienced personnel can >rork •d th the equipment, and tha·t small amounts of timber are profitable; because removal from one place to the next can be carried out quickly.

Its biggest disadvantage is that the mainline must be pulled out by hand. If a second •·rlnch is used, up to 100 m will be the most economical extraction distance, otherwise it >·Till be only \vi thin a range of 30 - 50 m.

The settin~ up and functioning of a cable win.ch·

Cable \'~inches for ground skidding consist of one or two steel drums with a mechanical or hydraulic drive. The ·braking equipment must be capable of s~oPping a full load and, to this end, drum or band brakes are fitted. The drive should have different forward and reverse speeds if possible, or there should be a smooth hydraulic drive. The clu~ch should be either mechanically, hydraulically, pneumatically.or elebtro-magnetically controlled. The clutch should have a safety overload that slips, if the timber weight is excessive.

The cable should be wound neatly on the d.rum, therefore a. guiding d.tw'ice shoUld be used, or a .pulley fixed at a distance of 20 times the drUm Width.

Use of the cable winch

The main types of winch used in forestry worl<: are: an unmounted winch, a winch that can be driven, one that is mounted on a wheeled or crawler tractor* and finally one mounted on a bogie (RUckewagen). In order to choose the correct type for the gi~en work the following factors should be considered:

dragging power with a full and empty drum,

drum diameter and capacity

the cable diameter, adjusted to the drum diameter

the line pull of the winch, and

the weight of the load.

The cable speed should, where possiple, be controllab~e. The cable guide should protect the cable and not impede pulling it out. The whole winch ~hould be stable, Whether mounted on a vehicle or not, and it should be easy to operate. The safety regUlations for the emergency stop must be complied rli th; the s.et of control leve:r-s should be of good design, easily operated and failproof. ·

Cable winches

In their lightest form (weight approximately 120 kg), and With an engine power of 15 hp, these are used \1here the machine has to be transported by manpOwer. This is the case rli th forest road building, v1here HOOd has to be transported above the future

road. After completion of the road, the wood can be easily extracted. These winches can also be used for the transport of light rrood from thinnings or foi' pulling up the cable of a wheel skidder. The control can be mechanical or by maa.rts 'or radio (Radioti!'-vlinch).·

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Stationary ;v:i.nches of heavy construction have engine power of approximately 60 ~150 hp. A double drum winch is used mainly for up1vard extraction of tree length logs over a distance of 300 m. The areas where these winches are used are difficult, inaccessible gulleys7 ·or places where debranching7 crosscutting and de-barking of trees at the felling site is impossible. With these ;·ri.nches, a day's output may reach up to 30 m3 of timber extracted.

2. 3· 2 ~ng ;v:i.. th Farm Traotors

liarm tractors are, because of their construction, most fitted for farm ;v-ork, and as such are of use in forest or mountain areas only under certain conditions. It should be particularly noted that these machines can easily tip over and should therefore have a rollover canopy fitted. In addition to ·this, it is necessary to protect all easily breakable parts (headlights, brake lights, radiator, valves, etc.) and also to fit a floor plate against damage from bel0>1·

For skidding light vrood loads of up to 2.5 m3

(2.0 t), a tractor of 40- 60 hp is sufficient. If the tractor is driven much off the road, especially in wet weather, a four-wheel-drive tractor ;dth chains is required. \'lith heavy loads of 3-5m3 (2.5- 4 t), a tra,ctor with at least 70 hp is necessary.

'The main advantage of the farm tractor is apparent in downhill. skidding, vrhere i·t can be driven straight d011n the slope, or on a simple strip road; but there are several ways in which a tractor can be usedt as the following discussion ;v:i..ll show.

Farm tractor without cable winch

This type of skidding is found only where the tractor can drive directly to the timber to be extracted. In many oases, the timber is manually skidded to the vehicle. For skidding individual trunks to the road (for example, out of ditches), the tractor is driven along the road and the wood is logged by means of a cable and pulley.

Farm tractor with a bui1 t-'-On op.ble 1-Tinoh

When skidding with a farm tractor it is seldom possible to get right up to all the logs, and therefore they must be gathered separately in order to get a full load. This method is an advantage in selective felling or thinnings on a slope. Farm tractors with a bu:i.l t-on cable vrinch are used both for uphill and downhill skidding; normally' the former is more practicabJ.e. On a fe\'r tractor types; the \'Tinch is mounted at the front, but mostly it is at the rear end, which is the better solution.

The \'linch is driven from the power take-off of the tractor. The cable is about 80 m long and has a diameter of 12 - 14 mm. The line pull of the winch, according to its manufacture, are 2 - 6 ·b. Cable \'ri.nches Ni th one drum are best for skidding long or heavy logs, while types >vi th ·two drums are better for small wood or bundles of short logs. ~/hen logs are being skidded to the wheeled traotor7 there is heaVy strain on the rear axle 7 ancl it is th.erefore subject to more ;vear. For reasons of safety, the tractor should be blocked to prevent its being dragged.

Farm tractors vrl th a cable winch are economic for skidding logs for up to 400 m and this is generally the distance from the felling site to the first landing. For small-sized timber, v1ith a diameter of about 15 om, a production of 1-1.5 m3 per vmrk-hou3 can be expected. With logs averaging 16-22 om in diameter production rises to 2-4 m per work­hour. With larger timber the power of the tractor is a limiting factor, and so is the condition of the ground (where there are slopes, ditches and so on).

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Farm tractor and bogie

The bogie is used as an addition to the farm tractor, where much cable work is done and also where the wheeled tractor has to be driven on strip roads and forest roads. Bogies are not used off the road, because they have a relatively high empty weight.

The main advantage of a bogie is that it takes the strain during log skidding and consequently the rear axle of the tractor is spared. Because of its connexion vrith the farm tractor hydraulics, logs can be lifted and skidded vii th the butt off the ground.

Technically, the bogie offers the advantage that, as it is connected to the tractor hydraulics, it can be quickly and easily fitted or removed, and therefore easily replaced by other equipment (for example a trailer).

A bogie may or may not be equipped with wheels, and may include a cable winch which is driven from the tractor engine and fed out over a strong support pan. The cable (length 80 - 100 m, diameter 12 - 14 mm) is guided from the vrinch over a fair-lead, so that a lifting component is available during skidding. There is a bogie for small wood (for example F.armi of Finland), for medium weight timber (Igland of Norway), and one for heavy timber (Steyr-RUckev~gen of Austria). Its use is economic over a range of a few metres up to about 1 500 m. The skidding capacity is the same as for farm tractors with a rear mounted cable winch.

Farm tractor with grapples --

Grapples are used in the transport of tree-length, usually one log at a time or, under especially good circumstances, a maximum of three. With this equipment the timber can be transported by one man, as the driver of the tractor operates the grapple. The grapple is hydraulically opened and closed from the tractor.

If a grapple is to be used, the tractor must be able to get right up to the trunk and it is important that the vehicle can be driven under load in the felling area for the complete distance because unloading and later cable extraction of the timber is not feasible. The best area for working is in a clear cut. With skidding distances of 400-600 m, excellent results can be achieved. On favourable terrain, logs with an average diameter of 30 - 40 em and a length of 15 - 30 m can be skidded at 8 - 10 m3 an hour. The limiting factors are the line pull of the tractor winch and the hydraulic power available. Grapples used with farm tractors can skid timber weighing up to 3.5 t.

2.3.3 Articulated Four-Uheel-Drive Skidders

The articulated four-vTheel-drive skidder is the most recommended machine. It gives good performance in the mountains, because it can be driven in the terrain, on s-trip roads and on forest roads without causing a lot of damage. Fully loaded, it can manage a slope of up to 30 percent with the right ground conditions (dry and not too rocky). Its best performance is in downhill skidding, where trees with or without branches can be transported The limit to the gradient of a slope that may be undertaken by an articulated four-wheel­drive skidder is 40 percent on wet and unfavourable ground,in general the limit is 50 percent and 70 percent over short distances and under the most favourable conditions. On slopes with a gradient of 50 percent and more, the skidder can be driven only when pulling a load, and the logs must have their bark intact in order to provide a braking effect.

The skidding of long timber with bark requires high line pull and good traction. For this reason, skidders have four v1heels of equal s_ize and an all-wheel drive. The cable of the winch is guided over a fair lead and this makes it easier to lift the trunk. The normal equipment of the skidder includes a blade that is hydraulically operated. The weight distribution is two thirds on the front axle and one third on the rear. Most skidders have 80-150 hp.

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It is most important that skidders are fitted with a rollover canopy and a screen behind the driving seat to protect the driver from logs that may slide forward from behind.

Articulated four-wheel-drive skidders must by European standards handle 10 000 m 3 of timber a year in order to be economic. An hourly production of 8 - 12 m3 and a daily output of 50 - 90 m3 is normal for a skidder. It should be noted that one man alone can carry out the work, and therefore labour costs are lower than with cable systems.

Generally the skidding distance is 300 - 800 m, and in special cases up to 2 000 m. The extraction capacity is not dependent so much on the distance as on the time required to hook and unhook the load. Often the trees are felled and converted in one "working chain".

In Austria, the normal working method is as follows: three forest workers equipped with three chainsaws fell the conifers independently and debranch them on the upper surface. The same workers help with the hooking-on of the trees to the skidder, which then transports up to 12 logs (8- 10 t), according to the tree size, per trip to the landing. There the driver drops the load and pushes it to thB side with the blade. One or t~~o more forest workers debranch the undersurface of the trees with chainsaws9 and measure and crosscut them into various lengths. With conifers and other roundwood with few branches, only two forest workers are required for felling.

2-3.4 Skidding vii th a Crav1ler Tractor

Timber skidding with a crawler tractor is most successful on very soft and wet ground and in woods that are being felled for the first time, and therefore have no forest roads. This method is very useful when carried out simultaneously vdth road build­ing, where the tractor both clears the road and skids the logs. Crawler tractors can skid heaviest logs. On slopes, hov1ever, there is a danger that the machine may slip

sideways. Although they are very flexible, crawler tractors have limited usefulness because of the damage they cause to tree roots and roads.

2.4 HIGH LF.AD SYSTEM

The high lead system v~s invented in America, and is used there with great success for transporting timber out of clear cuttings. Fbr many years now, this system (the Igland) has been used in northern Europe.

Originally, it required a tree used as a spar, and a double drum cable winch, a mainline and a haulback line. More recently, a mobile system has been developed, equipped with a steel mast with pulleys and cable winch attached, which can be set up in a few hours. The high lead system can be used for uphill and dovmhill transport of timber. The normal range is 300 m with a lateral extraction range of about 15 m.

The working method is simple. The vlinch is always mounted on or near a road. 'l'he mainline is guided over a pulley on the endmast. At the other end of the cable line, it is fixed to the haulback line, >vhich is also guided over a pulley on the endmast. A simple hook is used for carrying the timber, and this is fixed where the ma.inline is joined to the haulback line. Mainly simple carriages are used, mounted on the haulback line and pulled by the mainline. In order to load the timber, both cables are lowered to the grou.>1d.

l'lhen the mainline is pulled and the haulback line braked, the load is lifted and transported. Hi th concave ground, or \d th a sui table mast heighty the timber can be brought to the road without any special problems. The cable winch power ~30- 150 hp) and cable ( 18 - 34 mm in diameter) are chosen according to the terrain and timber weight. The >·mrking output varies betvmen 50 m3 and 200 m3 a day, depending on the equipment, terrain and timber weight.

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2.5 SLACK LINE SYSTEM

With this system, the skyline is tensioned directly by a winch and led over the h~ad and tail spars. It can thus be quickly lowered in order to load the timber. In steep areas an open mainline with a topmounted winch is used (double drum winch). Generally a three­drum winch is used for skyline, mainline and haulback :).ine. At the junction of .the mainline and haulback line, a simple carriage is fixed. To hook the load the skyline is slackened. After the skyline is tensioned again, the load can be transported to the road o~ storage area. The range of this system is approximately 500 m. On very good terrain (over a valley, for instance), 1 500 m is the limit.

Lateral extraction is possible over only a few metres. This is one.of the special disadvantages of the system, together vli th the un¢01ftrol:).ab:i,;Li ty of the skyline tensioning and the experience required of the operati~g crew. Thr advanta~e is that flat terrain can also be worked. Daily production varies from 20 - qO m3 of t;l.mbe.r.

2. 6 THE CABLE CRANE

2. 6.1 General

Short-range cable cranes may be defined as those ~P to 100 m long, medium range those from 100 - 1 500 m long and lon~range those more than 1 500 m long.

vlhile short-range cable cranes will be a nepessary supplement to existing forest roads in· the future, the long-range type shou~d be bor~e in mind as a substitute for missing forest roads. The lon~range equipment is suitable mainly for downhill transport. Even though road construction is normally given priority over the setting up of cable. cranes, there are special oases where such eg\l.ipment speaks for itself. Especially steep and rocky terrain, once-only timber felling, very high road-construction and maintenance costs, special forestry regulations, are a few of these oases.

Apart from economic, practical or legal reasons, other ar~ents for the use of cable cranes come to mind: the preservation of the landscape and the protection of water quality are becoming more and more important; to these ends, the use of such equipment is well suited.

Practically any wood extraction distance can be worked with the equipment for one long-range cable crane. The mainlines and skylines are merely shortened for the shorter distances, while the cable carrying oapacity of the vnnch drum is reduced. Because many different skidding line lengths are enco~tered in a forest enterprise, equipment for longer mcidding lines should be chosen in order to have a calculated reserve of Sky­line and mainline. Furthermore, it is much better to· fit strong cable winches even for short mcidding lines, the advantage being a larger power reserve, less '\'Tear, and less overloading of the equipment.

2.6.2 ~Crane with Topmounted Winch

General description

Of all the different cable crane systems, the most widely used, because of its simplicity, is the gravity cable crane system with a topmounted winch. This system i~orks •vi th a minimum gradient of abouii 20 pfilrcent and :t'unotions better as the terrain becomes steeper.

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A fixed taut Skyline, together with a 1rinch mounted on a sledge and an open mainline, is required. The carriage can be fitted vrlth a mechanical stopping device, or as is becoming more common, it can be positioned automatically. Generally speaking, this type of equipment is made for loads of 1, 2 and 5 t, but in special cases also for 10 t or more.

A particular advantage of the system appears v1hen a load is being transpo'rted uphill. The logs are transported with their tops raised and are therefore partially suspended above the ground, so the supports can pe lower. Moreover, because the cable winch stays near the road, less setting-up work is required. A further advantage is that tree length logs can be logged uphill, provided the weight limit of the cable equipment is not exceeded there is a big enough landing at the topmounted winch station. Longer setting-up times are required for do1vnhill transport. Firstly, the cable winch must be driven across the slope to the top station, and secondly, higher supports must be used because the payload has to be fully suspended above the ground. In do1vnhill transport, log lengths of up to approximately 12 m are sui table. 'i'he problem of downhill gravity transport of tree lengths by cable is under constant consideration, and first results have been achieved.

2.6.3 Cable Crane with Valley-Mounted Winch

In contrast to the cable crane vrl th a topmounted vrlnch, that with a valley-mounted winch·is not very often used, although in forestry work this type v1ould be suitable in many cases. The main reasons for the reluctance to use it are probably the complicated setting up, the high rate of wear and the higher purchase price of the equipment.

The main operating areas of the valley-mounted winch system are rooky and therefore very rough terrain (although it may not be too steep), and above all terrain which cannot be driven over (boggy, deeply eroded, and so on). The chief advantage of this equipment is that the system can be used l'lhere there are countergradients and the often very heavy winches can remain on the forest roads. The range is limited generally to about 300-400 m, although one or two designs (especially built) can be successfully operated lrith a cable corridor approximately 1 500 m long.

!Juipment

Cable cranes with valley-mounted winch usually have a small cable drum fitted on the carriage that can accept approximately 100m of cable (hoist line). The cable drum in the carriage is driven from the mainline over a parabolic pulley also in the carriage.

The cable winch must be provided vnth either a parabolic pulley and endless mainline, or there must be t1'10 cable drums. In every case, the top station must have suitable pulley equipment. With an endless mainline, the cable must .be spliced for every ne1'1 length of corridor. A winch vrl th t1-10 drums must be capable of holding double the length of a mainline cable.

To set it up, a special light Hinch that is fixed in the top station is required. This vnnch pulls up the mainline and also the Skyline. Fbr short-range cables, a thin setting-up cable that can be pulled to the top station by man or animal power is used. This is then fed into the pulley and used in other setting-up 1-10rk like :pulling up the mainline and· Skyline. Other equipment may vary, but is in general identical to that of a cable crane with topmounted vrlnch. In some designs, the equipment is radio-controlled.

Horking methods

Although the v1orking methods of a cable crane 1ri th a valley-mounted winch are much the same as one with a topmounted winch, there are one or two distinct advantages and disadvantages. Among the advantages: the Skyline profile is not restricted and all gradients, countergradients and level land can be worked. In addition, downhill transport of tree length logs is technically possible, provided the carrying capacity of the supports, cables and other pieces of equipment is adequate. Jinally, because most of the designs allow the logs to be partially suspended above the ground, the support can be built relatively low.

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The disadvantage is that either the skyline corridor must be wider or the ha.ulback line must be diverted and this requires a separate cable corridor. The lateral extraction of logs is dependent upon the height of the skyline and the length of the hoist line 11hich is limited. A further problem is that the hoist line may get stuck in the carriage dnL~. The l'lhole equipment is heavier and setting it up takes longer.

In all it can be said th.'l t the load transported daily 7 according to v10rking circumstances, \·rould fluctuate between 40 and 60 m3 of timber.

Time re~uired for setting up and dismantling

The times neces&;.ry for setting up and dismantling shoVT big differences from one cable corridor to the next. These differences are dependent on several factors: firstly, the terrain itself 7 the forest site, and its distance from the road. Next the skill and experience of the surveyor are important, as uell as a •~ell-trained crevr. Three men should be capable of doing all the cable crane 1vork alone, and Hi th the help of forest HOrkers, it should be possible to set up or dismantle the equipment (winch station, valley and mountain anchors, supports, and so on) in several places at the same time.

Good coordination of all this vrork is import3.nt in shortening the setting-up time. The same applies for shortening the dismantling time and, by the same token, the general success of the operation. Provision must be made for the correct number of appropriate tools and equipment in orgdnizing and planning cable crane \vork.

Even though the time for each setting-up and dismantling fluctuates a great deal, some basic data may be founcl in 'l'able 2.

2.6.4 Mobile 'l'oHer Cable Cranes

In forests Hi th road spacing of 300 - 500 m, a mobile tov1er cable crane is the ideal equipment for timber extraction on a slope 1 because it can reach most cutting areas from the road. In contrast to the Scandinavian design (Igland), the Austrian equipment (Urus or

3 Goesser cable crane; see Table 3) always uses a skyline, because logs of up to about 3 m or ;. t must be carried. The maximum range is 500 m. A fcvr lou supporto are built, because the logs are carried partially suspended on the cable. ·

;§Tli;Qment and tcchnir:;al report

The cable equipment can be tran8ported from one site to the next very quickly Hhen it ie built on an Un:i.mog or a lorry. The vehicle's engine, vrith 60 - 90 hp1 can also beusErl as a pov:er source for the cable winch. Tiw three-drum \'linch can carry a skyline 500 m long and 18 rrun in diameter, a mainline 550 m long and 10 mm in diameter and also a haulback line 1 100 m long and 10 mm in diameter. The tovrer is used as the endmast. H can be dismantled and set up vurtico_lly hyr1raulically. Tho height may be up to 12 m according to the design. The maGt is equipped •vi th a robust top pulley for the skyline and tvJO pulleys for the w~cinlin e e,nd the hau.lbB.ck line. Under \vorking conditions, the mast is tensioned vri th two guylineo from the back. 'rhe carriage can be of any decign preferred.

l'lorldnr< mc;thods o.ncl perform."-nce

Af tc;r ttw c:c~·:,r:ral plannine; of a cuttinrr area, eight to ten cable corridors are selecterl, st~wk,,d cut, and immediately clear cut. The distance betvwen the corridors according to tree 1 ength a.nd the elope of the terrain, ,,i_ll be from 40 - 60 m. After each corridor is surveyed, the profile is plotted on graph-paper at the site; the position of the supports iB aacertained and also stacked out. The technical data (line sag, strength of supportr; 8.n<:l anchor) arc obtv,inecl. from tables.

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Every day, two men can lay out up to five cable corridors. If necessary, the position of the mobile tower cable crane can be decided while "!;he cable planning is being prepared and then in good time the fo-rest road can b-e wi.dEmed when required,. The extraction capc.ci -t;y depends upon a large enough landing on the road, vrhich should be at leas·t

1 - 1.5 lorry >'lidth.

After clear cutting of the cable line, the remaining trees are felled in a fishbone pattern toward the cable; this method is used for selection as.vrell as clear cutting. The debranched trees are crosscut at the felling site into logs 8 - 12 m long. Further cross­cutting can be performed at the landing. According to the terrain, the size of the landing and the condition of the road, the logs are crosscut on the road or taken straight to the sawmill to be processed. Usually trees are felled in advance and then a cable crew handles the transport of the logs.

In order to coordinate the different jobs well, the felling and extraction are no\'1 often done in one "working chain". \'/hen the logs are removed continuously 1 the fellers have more space and can hook logs at the same time. This means that they are employed in chainsavl work and cable crane work as well, t-Thich is an important health factor. Since the logs are transported in bark, it is important to remove it quickly, because of the danger of bark beetles.

The setting-up time of the equipment is short, va~Jing between 5 and 50 man-hours per cable crane installation. The main reasons for the variations are the differences in terrain, and hence the number of supports that are required. The experience of the forest vwrkers (see Table 4), and the length of the cable crane corridor itself. Since these cab]e systems are geared for uphill extraction mainly, the supports can be built as low and as simple as possible. Mainly cross supports with a height of 4 - 8 m are used.

The setting up and also the cable operations ~ould be carried out by the same crew hence for all the work, payment ;.wuld be made per m of wood transported. The crew consists of a winch operator and mostly of three forest workers, who should have appropriate training. Tvlo vmrkers hook the logs on to the carriage and the third unhooks them from the cable at the top station. In some forest enterprises a hydraulic loading crane is employed near the cable equipment at the road so that the unhooked logs can be loaded directly on .to a lorry or at least away from the cable crane landing area, this being normally very narrow.

It is a special advantage of this equipment that the anchor and support trees can also be brought uphill, the reason being that the tensioning and releasing of the skyline can be carried out so quickly. A start is made with the lmvest point of the cable line, where the lowest support tree is felled, debranched and crosscut. The skyline is then again tensioned and the logs transported uphill. The valley anchor is felled a bit higher on the trunk, and also transported uphill. The cable saddles and guylines are carried along the contour line to the next cable installation. By this method, the cable corridor is completely cleared of all trees and these are transported to the landing.

The average number of machine hours which may be expected from mobile tower cable cranes per year is abou] 1 100. This includes the setting-up time. In mountainous terrain a production of 6 000 m of logs vli th bark can be expected. Naturally, production fluctuates a great deal and is dependent on the usual factors.

'.'Then this equipment is used together with a good road network, many problems are solved, and constant production can be expectGd. It is true, hov1ever, that the initial planning, felling direction, log length, training of workers and constant removal of lqes should all be Hell coordinated. The equipment pays for itself, when a minimLUn of SO m..J of v10od per co.ble installation is availg.hle 1 and it is naturally more profitable \·lhen there is more v10od per cable line (e.e. 150 m..J of Hood on a cable corridor of about 150m in length). Operation and production are more profitable, the steeper the terro.in. Per~'orma.uce is depGndent on and measured by :;he avera,se diameter of the logs and the round­viOOLl volu.rne felled per co.ble corridor.

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2. 6. 5 Two-Man Cable Equipment for Uphill Transport in Thinning Operations

Until now, thinning on steep and very steep terrain has been a matter of cost. With two-man cable equipment, the human work is considerably reduced, and good performance is still obtained. It is essential that all parts of the equipment be light, and that two men can set up and dismantle the equipment as well as extract the logs.

Equipment and technical report

The carriage has two skyline sheaves and a mainline pulley of the simplest design. The cable winch, with a motor, is built on a sledge. The traction power is 1 500 kg, the v1ire storage 250 m with a diameter of 6. 5 mm. The 500 oc engine has 15 hp and tv10 line speeds. The total weight is 130 kg. The skyline drum is built on an iron frame, and the diameter of the skyline is 10 mm. The cable corridors, 1 -2m wide, are.laid out at a spacing of about 20 - 30 m from each other. Felling is carried out tov~rd the direction of the cable and at an angle of approximately 40°. The logs are cut to a length of 3 - 6 m.

After felling, the two men set up the cable equipment - an operation taking about two to four hours. When extraction along one cable line is completed, the equipment should immediately be dismantled. .The next cable installation is easier because part of the equipment can be carried along the contour line. During transport, one man is occupied with preparing the load and hooking on the logs and the second works as winch operator and unhoo~s the load. Lateral extraction is limited because of the mainline pulley; it is carried out at half speed and is, therefore, less harmful for the remaining stand.

In an Austrian forest enterprise, 24 such cable lines were set up, from which 625 m3 of wood .were transported. The average log diameter was 11 em. The following production figures were obtained:

trees felled per cable corridor

length of cable line

production (cable extraction only)

extraction + setting up + dismantling

26 m3

112- 163m

1.14 m3 per hour

0.90 m3 per hour

In an 8-man hour day, and with two men, 8-12 m3 of soft wood with about 25 logs per m3 were extracted.

2. 7 PENDULUM CAELEWAYS

Pendulum cableways may be differentiated as follows:

(a) pendulum cableway with skyline and open mainline

(b) pendulum cable\my with skyline and closed mainline

( 0) pendulum cableway with two skyli~es and a mainline, with or without an engine drive unit.

Pendulum cableways of type (a) have a mountainside drive; type (b) with a closed mainline has a valley-mounted station and requires· a pulley at the top station. This transport system is simple and requires few machine parts to set it up. However, its transport capacity is not very high.

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Pendulum cable>-mys with two skylines and a mainline - type (c) - are more reliable and therefore are frequently used. Both skylines have the same diameter ( 22-24 mm) and are built 2m from each other. On every skyline is a carriage. Each carriage is fixed, one at either end of the mainline. The mainline is guided around a disc at the mountain station whi'ch can be d.ri ven with a mot or. unit and must have a brake. Given sufficient gradient (from 25 percent), the loaded carriage travels to the valley and pulls the empty carriage up. The running speed must be held to a constant 3 m/ s. ·

The main advantage of this type of cableway lies in the fact that.no motor drive is needed and it can therefore be used in remote areas. Because it is reliable and uncompli­cated, it can be operated by untrained forest workers. The transport production achieved by cableways of 800 - 1 000 m length is approximately 8 - 10 m3 of timber per hour.

The disadvantage is that the timber must then be transported to the loading station and can be sent downhill only. Uphill transport is possible only rli th very small loads.

3· ROADS

3. 1 PLANNING

The dimensions, location and density of forest roads in the mountains must be planned according to the type of work which is to be performed on them. The building of hillside roads .is practicable only with gradients of a maximum of 10 percent. These can usually be driven by lorries.

Where cable cranes are to be used, very simple logging equipment should be chosen if possible, because co~pared with other methods of extraction, the setting-up and labour costs are high. The simplest type is uphill extraction with the logs partially suspended above _the ground. Extraction by cable crane from a distance of 400 - 500 m would require a road net density of 25/20 m/ha. The spacing between roads should be about 350-450 m. Within certain distances (about 60- 80 m), roads should be made wider, so that mobile cable cranes can be set up along them. Because the logs are generally brought to the cable line at an angle of 45°, the skyline corridors should be planned with a spacing of 60- 80 m.

Where the terrain is not too steep and wheeled tractors are to be used, the road should be so planned that the wood is skidded downhill. Over short distances (80- 100 m), however, a wheeled tractor can pull the logs uphill to the road. Wheered tractors, especially four-wheel articulated skidders, sRid logs dovmhill best when they are in the form of tree lengths.

Strip roads should be laid out so that logs can be skidded downhill along them, and joined up at the acutest possible angle to the road. On steep slopes, the strip road must be planned so that the gradient is at the most 35 - 40 percent. Because of the danger of erosion, it is important to plan for adequate Mater drainage.

R~sults of a questionnaire from forestry enterprises in Austria gave the following picture of the density of forest road net11orks:

Number of enterprises questioned: 355

Total forest area of the enterprises: 419 900 ha

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Area of productive forest 200 - 1 800 ha 000 - 5 000 ha over 5 OCO ha

Average area of forest holding

Road network existing up to 1973

Average density of road netvTorks at that time

Average planned density of roads

Percentage completed

Range of road density

Minimum

f.!aximum

500 ha

646 km

35 m/ha

47 m/ha

75 5~

2 340 ha

2 691 km

31 m/ha

43 m/ha

72 ~;

14 m/ha

75 m/ha

10 700 ha

2 353 km

21 m/ha

34 m/ha

6:'%

10 m/ha

40 m/ha

The results of this questionnaire shOI> tr..at the largest enterprises have feNer roads than the smaller ones. The former are more mechanized and can make better use ·Jf their equipment.

3.2 !>lAINTEH.FJICE

Every forest road is subject to unrelenting wear, and also damage through the type of use to which it is put. It must be constantly maintained.

Surface deterioration can be noticed as the surface material is with the p~ssage of time throVTn to the side and ground to dust; heavy rainfall, floodine, fast driving and the work itself can all cause damage and lead to its destruction.

Maintaining the road in usable condition involves the e·ssential task of draining off the water. Surface water may quickly drain to the road sides if the road is built vii th a camber. Apart from this, a drain must be built on the upper side to take not only the surface v/3.ter but also that which flovTS dovm from the slope. According to the gradient of the road,culverts or open top culverts should be built approximately 40- 50 m apart. ~lliere there is heavy rainfall, they may be closer together.

The renev/3.1 of a road surface is best carried out with a gre,der 1 and rolling aftervl3.rds is of great advantage.

3· 3 S'E-1IP ROADS

Strip roads are required to transport the 1vood from the forest to the forest road and to storage areas (page 27 1 Logging and Log Transport in Manmade Forests in Developing Countries). Strip roads are laid out vlith regard to the skidding equipment that is to be used. ·

3-3· 1 Strip Ro::..ds for Animal Skidding

These are from 1 - 1. 5 m \Tide, on even ground or running along the contour lines 1-1i th a maximum gradient of 40 percent for dovmhill and 6 percent for J.phill skidding.

3. 3. 2 Strip no8.ds for l;/h<: el"' 1 'l'r'ldor Sl:iridint:a

The strip ro'3-rl r:houlrJ. be 3 - 4 m vli"l.e. Brush and tree cle:1-rance should be 1 - 1. 5 m ~Tider than the vehicle. 'rhe gr<dien-t is depend~nt on the climbing capacity of the vehicle 1'he road should join the main road at an acute angle. J:.'or strip roads straight dovmhill the tree stumps need to be cut only at ground level. F'or hill side strip ro<.Hl.s, it is necessOtry not only to clr;ar Gut thE: roud 8i te but also to excavate Hith an a:1gledozer or an articulated. four-wheel- dr i vo f:kidder. 'J:'h(: sj>:~.cing of the strip roads HOUl·!. be about t\-10 tree-lengths, approximately 20-50 m in thirmir,gs <mcJ. approxirn::.teJy 60-f;o rn in fim.l cuts.

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3· 3· 3 Cable Lines for Cable Cre.ne EXtraction

For setting up a cable crane a 1 - 1,5-m-•dde cleared strip is needed, measured from tree to tree. The minimum slope of 20 percent for a gravity cable crane must be maintained. Generally, this cable line runs up and down the slope, forming a right angle w-ith the road. In very steep areas, the corridors are led to the road at an angle of 45° 1 so that more wood can be collected per corridor and the logs stored in a more efficient \V<>Y• In many cases, it may be useful to set up the cable corridors in fan form, as this is more economic. 'rhe spacing from one corridor to the next may be 10 - 60 m1 according to the tree leng-ths.

Cable lines should be plarilled and laid out before the first logging operation is carried out. In many cases of reforestation, the proposed cable lines are not planted v1i th ne1;r trees. However, until the harvesting, branches from the side trees may reach the cable line and may have to be cleared. Tests 1dth quick-growing trees to be planted in the cable lines are carried out. In highly organized forest enterprises, the trees at the corner idwre a corridor meets a road are protected \U th stakes. In cable logging, the supports and anchor trees are protected \d th a thick layer of branches, \'lhich are then saved for use in other cable crane installations.

3-3·4 General Advant.?.ges of Strip Roads

SkiddL1g damage can be kept to a minimum. The logs obtain a better price. The ivood can be skidded in tree lengths. Various v1ork such as delimbing 1 de-barking, measuring and crosscutting can be carried out in a place where the necessary equipment is available instead of at the felling site. The trees are easily accessible, and therefore smaller amounts of timber felling are also profitable.

3· 3· 5 Strip lloar.ls in 'l'hinnings

Together idth the criteria already mentioned for strip roads, the latter are especially important in thi1mings 1 so that the forest floor is not damaged. Careful planning of the layout of strip roads is important here, because these roads will be used over and over again in the course of the years. The working methods are as follows:

Firstly, tho terrain is examined for the best junction point vri. th the forest road. Bach strip road is then stacked out and all the trees on the strip road are felled. After the clearing of the strip road, the thinning itself is carried out. The strip road network is very narrow (approximately 10m apart) to correspond with the height of the young trees. As the tree height increases, every second, and later every third, strip road is used for log Skidding.

3.3.6 Strip Roads in Clear Cuttings

Strip roads in clear cuttings are planned mainly for special Skidding. The chief motive for their existence is to obtain an economic means of transporting logs. For Skidding idth a vlheeli'!O. tractor only, a suitable and safe driving path is required. For transport id th a cable crane, it is important to plan the cable line and to determine the a.'1chor and support trees in good time to prevent their accidental felling. ·

Strip roads in a clear cutting are often subject to the danger of erosion. For this reason, after the work, v~ter bars should be made across the strip road at a distance of 10 - 15 m. In many cases, it is enough to lay dovm branches or sow grass to prevent erosion.

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Gravelled forest road

- 19 -

Appendix

SPECIFICATION OF EQUIPMENT FOR A CABLE CRANE WITH TOPMOUNTED WINCH'

Carriage

According to requirements, with carriage stopping device or fully automatic.

Cable winch mounted on sledge

The minimum line pull, with a full drum in the lowest gear, is approximately half the calculated cable breaking load of the mainline. The capacity of the drum depends upon the required mainline length and its diameter. The speed of the mainline with a full drum should not be less than 0.5 m/s and not more than 5 m/s. It is an advantage if all gears operate in forward and reverse drive.

Skyline

The skyline is of stranded wire with 42 wires in a clean .left or right handed uniform lay. The material is twi~t- and strain-free and made of impregnated fibres. .It has a strength of 160 - 180 kg/mm • The outside of the cable is protected with grease. The diameter can be calculated from the theoretical breaking strain, which is the total load x 7 x'3 to 2.5. The total load is the weight of the carriage+ payload+ mainline weight. Usually, cables with diameters of 22 - 25 mm are used. When the cable is more than 26 mm in diameter, it is possible to use the Seale type, 114-wire cable. The length of the skyline is determined from the maximum cable corridor length + 100 m.

This is of stranded wire and the steel specification is the same as for the skyline. For lighter loads, the mainline is 9.5 mm in diameter, for heavy loads 10.5 mm. When the winch drum diameter is small, the main2ine may be 10 or 11 mm in diameter. Seale cable of 114 wires with a strength of 160 kg/mm is used. The length of the mainline is equal to the maximum corridor length + 200 m.

Anchor cables

These are of 114 stranded wires, zinc plated, with a material strength of 160 kg/mm2

• Theoretical breaking strength with a four cable anchorage = theoretical breaking strength of the skyline devided by 2.4. The rope lexigths depend on the anchorage system.

Sisiline saddles

One or two of these are required at every intermediate support, They must be adjusted to tJ.:le type of carriage used.

Endmast pulleys

_ Endmast pulleys are necessary for every endmast with a high pressure and a high buckling angle.

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Mainline guide pulleys

These are needed to steer the mainline in the same direction as the skyline. Recommended for this use ?-re 3 - 5 t guide pulleys (with ball bearings enclosed, and a round groove with an opening angle). Groove radius =mainline radius +at least 10 percent.

Grooves that are too wide do less damage to the cable than those that are too narrovi·

Skyline anchor clamps

These should have a built-on pulley block.

Communication equipment

A three-v~y field telephone should be providea for the winch operator, the loading crew and the unloading crew. There should be a loudspeaker telephone ;rith one or two fine, insulated, steel multi-wire cables, with a copper earth wire 2.6 or 3.1 mm-in diameter. Field telephones with one thin cable and earth feed must have a relay for a signal lamp or horn, fitted separately, near_the winch. Walkie-talkies are not suitable because they are neither loud nor robust enough.

Other materials

Guylines should be zinc plated, with the same specifications and workmanship as the mainline, and not over 160 kg/mm2 in strength. The number and length required are according to the number of supports and the building method. The usual length of guylines used in log transport is 40 - 60 m. Fbr less important purposes, discarded mainlines can be used. Riggin&' c~ble used for saddles is usually of 216-;-;:l.re Warrington-Seale manufacture, 160 kgjmm , zinc plated and 14 - 17 mm in diameter. lt can also be made from conventional. 114-•dre, 14 mm diameter cable. The length of cable required for the rigging of crossbeams is 8 - 10 m, for the saddle 5 m, and for the. endmast pulleys 6 - 8 m.

Cross cables are made from 114-stranded wire cable 1 cross-laid, 160 or 180 kg/mm2

bright (greased )or zinc plated, and 14 - 18 mm in diameter, according to buckling resistance. A "transport cable" is used to transport the winch to the top station, and save the mainlines, in which case the mainline is taken off1 and the transport cable put on the winch. The specification is as for the mainline: 14 mm in diameter, 150 - 250 m long, or of the Seale type, 12 - 14 mm in diameter.

Setting-up cables are of the same specifications as the mainlines, 6.2 - 6.5 mm in diameter, and are as long as the fficylines. Small parts that are used are climbing clamps from round iron 10- 12 mm in diameter, bolts 20 mm in diameter, both ends screw-threaded for 20 em, and square underlay washers and nuts, cable clamps, twisted annealed wire, 4 - 5 mm in diameter, and setting-up clamps.

Setting-up equipm~nt and tools

The following equipment is carried by the setting-up crew on their backs: two or three safety belts and extension chain with tivO spring hooks (especially adjustable for cable crane work); one or two pairs of tree-climbing irons, one 1. 5-kg hammer per climbing set, •rith a knob and leather sling on the end of the handle, to drive in climbing clamps; hand saw for debranohing;' a two-man hand saw or a light chain saw; forest axes according to requirements; two wood drills, one 24 mm in diameter and 40 om long, the other 22 mm in diameter and-80 em long.

- 21 -

Other setting-up equipment and tools are: setting-up cords, hempen cord 8 - 10 mm in diameter, 30 to 40 m long; setting-up pulleys with a hood that can be opened or clasp pulley for 1.~ 3 or 5 t; other pulleys according to requirements; Tirfor block and tackle 1.5 or 3 t, "Lug-all" block and tackle with 6-m cable; wedge clamps (size No.1 for guylines, sizes 2 and 3 for cross rope or cable slings and chokers) - these items according to requirements.

Small tools are needed like cranked ring spanners for the cable clamps, fork spanner set, screwdriver set, hammer, chisels, etcetera; splice tool, with an assortment of large and small splicing needles, two hand-hammers, a copper or plastic hammer, v10oden cable­winder, various rigging wires, hemp for cable core, measuring tape; safety helmet for use in various work, protective gloves, bandages and first aid kit for all cable crane stations.

URUS-UNiri!OG cable crane and loader

-22-

U~hill transport of a cable winch for a cable crane with topmounted winch

-~-

Appendix 2

THE SETTING-UP PROCESS

After the cable corridor has been carefully surveyed and it has been ascertained that the carriage can·be repaired and maintained at the ground level at either the topmounted or the valley station, the cable line profile is calculated and the support points are staked out in the nature, the setting-up instructions are written down:

Technical data required for the cable rigging

These are: the total length, the difference in height between the valley and top­mounted stations, the average slope in degrees, the span-distance between each of the supports, the gradient for each of the spans, the height of each support, the maximum pressures on supports, minimum distance between skyline and ground, skyline pull (maximum, normal, ratio between load and line pull), payload in tons.

General data for the cable crane installations

Anchor and support specifications with general measurements are needed, together with position of winch and the length of time in seconds for one skyline swing in order to measure the cable tension. A material list of the parts used in the installation of the cable line.should be available as well as installation tools. The work is divided into various parts, giving methods, alternatives and priorities.

Instructions for setting up cable cranes

A cable crane is set up as follows: Transport material to site. Set up the skyline drum! Drive the winch, trailing sledge with material to the top station, laying the support material at the best points on the way. Set up the winch and anchor in position. Remove the transport cable, wind the setting-up cable on the winch for further use. After the telephone is installed and tested, the mainline and skyline can be pulled up. Anchor the'skyline in position. Sort out the other support material, build the supports, lay the skyline in the saddles and tension it. If the mainline is to be used .to tension the skyline, it should be pulled to the valley; if it is required, it can be pulled by the winch from support to support and used for their setting up on the way, (It is worth noting that the mainline can also be tensioned to one quarter of the breaking strength before the skyline is pulled up, and a carriage can be hung on and used to transport material to the support points, using the setting-up cable as a mainline. The total load in this case is about one seventh of the basic line pull, or it can be separately calculated according to every cable installation).

Lastly hang the carriage on the skyline and attach the mainline to the hook. It may be necessary to hang the carriage on before tensioning, in order to make the work easier. After the test run with a light load, the cable crane should be run with a gradually increasing load. By this method, line pull on the skyline and the pressure on anchors and supports can be ascertained and tested.

Dismantling is carried out in the reverse order using the same methods and tools. The most important part of the dismantling is the transport of the skyline downhill. This is fixed on the mainline because it· must always be under a slight pull. The speed of the skyline drum has to correspond to the speed of the mainline and the winch. The pulling-in of the skyline should be watched and cheoked by means of telephones or walkie-talkies.

- 24-

Preparatory work for setting up cable cranes

In forest areas strips of up to approximately 2 m wide should be cut for the cable lines. Through dense forests and where the skyline is well clear of the tree tops, a narrower cleared strip for the cable line is sufficient. The trees to be as artificial supports should be felled early and left to dry; in any case, the mainline has to hang free of all obstacles such as stones and branches.

Cable crane carriage

- 25-

Appendix 3

WORK PROCEDURE, METHODS AND OUTPUT

V/here cable crane equipment is concerned, every effort should be made to see that every machine is fully utilized, and for this reason, the correct ere>.; size should be chosen. The number of workers in the crevr depends on different working conditions; for example, ho.., far the payload has to be pulled until it is under the cable, the length of the cable line, the amount of logs to be transported, the amount of sorting and storing vmrk. Three to five men are required for a cable crane crevr:

foreman, who is also the chief setting-up and winch operator

or 2 forest vmrkers at the log landing, one of whom must be trained for cable crane operations

1 or 2 forest >vorkers at the loading station, one of >'lhom must be capable of at least helping >·Ji th cable crane operations.

It is essential for good vmrking conditions that the trees are felled_ in a fishbone patiern, lying uphill,· to shorten lateral skidding (see Diagram 3). Lateral fficidding over a distance of more than ~0 m is not economic, because the work output is reduced. If lateral skidding of 10 m from both sides to the skyline is assumed to give a work output of 100 percent 1 ~hen at _20 m, the output will be 80 percent, at 30 m 65 percent, and at 40 m 42 percent \Diagram Lt).

It may be seen from these figures that a maximum lateral extraction width of 60 m can be planned. However, single logs can be laterally dragged from a distance of 100 m if the terrain is not too steep. It haR been learnt from practical experience that it is better to extract small amounts of logs to the skyline by hand or by using animals. With large amounts, it is cheaper to seo up several cable cranes over the working area. In some cases, cable lines may be arranged in a fan pattern in order to have the same anchor for the skylines and winch in the same position, thus saving setting-up time.

With respec~ to transport capacity, this may be calculated on the basis of a day's load of 40- 50 m for transport uphill, with an average log diameter of 18 em. A load of 1 - 1.5 m3 of wood per trip may be assumed, although the usual cable crane equipment is built for a load of 2 t, which corresponds to approximately 2 m3 of fresh softvtood. The reason that the crane is only.50- 75 percent loaded lies in the fact that the logs must be collected and laterally extracted to the cable line. This would lead to long waiting times, so that the carriage is sent lightly loaded, and full utilization is almost impossible. This situation occurs especially with logs of s~all diameter; that is, in thinnings~,vthere the payload collected would be about 0.70- 1 m • With poles of 4 m in length, 1 m would comprise 20 - 70 pieces; as one choker can at most carry three logs irrelevant of size, without the logs slipping out during transport, the payload is limited. In a 9-hour day the maximum work period on mountains is 6.5 - 7 man-hours, so a practical cable crane use of 30 - 50 loads can be counted on.

Under Central European forestry conditions a cable crane is profitable when at least 4 000 m3 of wood per year are transported.

Crew No. size

4- 6

2 5 - 6

3 5-7

4 4- 8

5 8

6 8 - 9

4- 7

2 5 - 6

3 5

4 6 - 7

5 6 - 8

Length of

Table 1

BASIC DATA FROM ELEVEN CABLE CRANE INSTALLATIONS IN KAERNTEN, AUSTRIA

(Cable winch Nessler MSA 27 carriage Hinteregger D 2)

Setting-up Dis- Repairs Winch Transport Total Output time mantling operating time

No. of

cable line (work- (work- (work- (work- (work-per

( work- cable _3ine loads (m) hours) hours) hours) hours) hours) hours) (m ) per day

250 85 63 40 42 190 420 259 46

300 178 75 88 85 415 841 350 42

300 223 96 43 152 1 010 1 524 626 45

150 110 71 - 30 254 465 140 68

500 224 48 25 59 480 836 320 40

300 154 125 66 108 782 1 235 624 30

700 342 161 116 172 1 012 1 803 1 004 49

350 174 77 38 110 471 869 534 43

700 283 149 5 114 465 1 015 615 39

650 512 160 244 272 1 470 "2 658 1 345 39

675 331 186 270 198 1 240 2 225 940 37

Average Harvest load per

(m3) da~ ( m )

1-25 58 >:! 'd

0.98 41 p: I-' I-'

0.92 41 d-'1 [ll

0.68 46 :3 Ul 'd 0

1. 25 49 '1 d-

1\)

1. 50 45 ~

I

1. 20 59 p.. 0

~ 1.12 49 p:

I-' I-'

1. 32 51 d-'1

1. 25 50 g rn

48 'd

1. 29 0 '1 d-

- 27-

Ta,ble 2

AVE:{AGE Tll~w TAKEN TO SET UP CABLE CRANES

Cable line lengths:

Cable line clearing (2 - 3 men)

Surveying (1 man)

Construction supervision (1 man)

Material: loading lorry (5 men)

p.aterial: m1loading lorry (5 men)

Driving winch uphill (3 - 5 men)

Setting Hinch in place, anchoring with base (3- 5 men)

Transport support material with winch sledge (3- 5 men)

Laying telephone lines (2 men)

Erecting endmast 8 - 12 m high (2 men)

Preparing one support, 1 tree 10 - 16 m ( 2 men)

Transport mainline do>mhill (3 men)

Transport skyline uphill with ;'/inch and anchoring (3 men)

Feeding skyline into saddles (2 men)

Tensioning the skyline (4 - 5 men)

Setting up carriage and fixing mainline ( 3 men)

Adjusting guy line tension ( 2 men)

Other y10rk ( ;varning signs) (5 men)

Dismantling ( 30 - 50% of setting-up time)

•rotal

300 m

1E + 1S.1/

8

4

4

3

3 - 12

2 - 20

8- 12

2

10 - 20

10 - 30

3

2

3

2

4

0- 19

80 -150

25 - 75

105 -225

700 m Time in man-hours

1E + 2S

12

5

5

4

15 - 30

2 - 20

10 - 20

6

10 - 20

20- 50

3

5

4

8

2

6

2 - 49

120 -250

40 -125

160 -3'75

1 200 m

1E + 3S

20

7

2

8

6

20 - 50

2 - 20

15 - 30

10

10 - 30

50 -120

6

9

8

15

2

8

2 - 49

200 -400

70 -200

'270 -600 ===~~=~===========~=====~==~==~====~========~=

1/ E ~~. KYJ.dma.st 1 S Support

- 28-

Table 3

OUTPUT IN ONE YEAR WITH TWO URU3-UNIMOG BY AN AUSTRIAN FOREST COMPANY

Urus I Urus II Total

Harvest output (m3) 5 598 6 995 12 593

Average diameter (om) 28.8 26.6 27.6

Number of areas worked 26 36 62

Average length of corridor 188 186 187

Average in m3 per corridor 215 194 203

Transport work ( ore\v-hours) 749 970 719

Setting up and dismantling time (crew hours) 166 322 488

Total working time 915 292 2 207

Harvested out~1t including setting up and dismantling (m3 per machine hour) 6.11 5·21 5·71

Harvested output without setting-up an~ dismantling time (m3 per machine hour) 7 ·47 7·21 7-32

- 29-

Table 4

COMPARISON OF EXTRACTING TIMES OF WELL-TRAINED AND UNTRAINED CREWS

Machine operating (Urus mobHe tower cable crane )

Hooking the logs at the stump area and unhooking at the landing

Drawing the hook to the logs

Travel of the stop device from one point of lo~ pick-up to the next

Control and watching

Repairs

Waiting in connexion with repairs

Going to the working place and returning

Working-and personal delay

Pr~paration

Recreation

Total

Well-trained crew

(minutes per m3)

2.22

3·31

0.97

0.67

3.16

5·69

o •. 19

1. 37

0.54

0.64

19-3

Untrained creH

(minutes per m3)

0.70

18.84

0.54

3·24

0.90

0.13

43·5 c=====c=

The well-trained crew received instructions at a forest training centre. They attended a course on setting up and dismantling cable cranes, winch operation, correct hooking of the logs, preventing accidents'and coordinating the different jobs in the most efficiE?nt 'l'[ay. Besides this, they visited the manufacturer of the cable crane for special instructions. All members of the crew had good experience in cable crane \·rork.

The forest workers without special training, on the other hand, had experience only in cutting ~rees and in manual Skidding. The winch operator of this crew '~'[as trained only on the job and was given brief instructions on using the cable cranes.

Comparison of their extraction times shows clearly the importance of appropriate training and of specialized instructions where this is relevant.

Length of traces

( m)

90

124

181

26,]

330

1?0

300

Lj'JO

Table 5

OUTPlJT AS AFF'l!X::TED BY LEtJGTH OF CABLE LINES AND NUMBER OF SUPPORTS

Uphill extraction with Urus-Unimog

Harvested Harvested out-Gradient Number of output per Average put, installation Cutting

('f~) supports cable corridor diameter time included volume (m3) (em) (m3 /man-hour) (m3 /man-h.)

56 1 312 35 9·75 2. 11

54 1 216 32 13.50 5·53

68 2 262 34 6.72 1. 72

68 3 278 32 1 o. 11 1-55

64 4 252 32 4·34 2. 11

Compare with the extraction of logs using an articulated four-wheel-drive £kidder (Timber jack 209 D)

10

12

10-24

267

520

263

33

33

33

12.71

10.50

9-50

2.48

3·27

3-20

Installation time between 5 and 30 man-

hours

Average

time from

62 traces 7.86 '

man-hours VJ 0

I per trace

uphill

downhill

downhill

- 31-

Diagram 1 MANUAL SKIDDING

Branches

Road

Diagram 2

Landing

STRIP ROADS FOR MECHANICAL SKIDDING Felling directions for tree-length method

~

Road

VJ 1\)

I

Diagram 3

- 33-

LATERAL SKIDDING

Road

Cable crane uphill and downhill

-

Log landing == length of the logs

- 34-

Diagram 4 OUTPUT AS AFFECTED BY DISTANCE

I I

30m

65% >

I -<E--<---1----+I- ___ 40 m

1 42%

I

MR!H 7631/E/3.76/1/1500