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Nedslag i skogsbrukets teknikhistoria

del 1. skotarens tillkomst, del 2. gripskördarens tillkomst, del 3. aktörer, beteenden och förlopp i den skogstekniska utvecklingen

Ager, Bengt (2017). Nedslag i skogsbrukets teknikhistoria. Umeå: (S) > Department of Forest Biomaterials and Technology (from 131204), Sveriges lantbruksuniversitet. Rapport från Institutionen för skogens biomaterial och teknologi ; 2017:11
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Abstract

Del 1. Skotarens tillkomst
Skotaren definieras som ett traktorekipage som består av en del som bär motor och förare och en del som bär lasset, med vridmidja mellan delarna och drift på alla markkontaktorgan samt med en griplastare för på- och avlastning. Detta koncept växte fram i östra Kanada under 1950-talet med hjulskotaren Bonnard Forwarder som fungerande prototyp 1958 och Dowty Forwarder som den första serietillverkade maskinen, lanserad på marknaden 1961.
Medan den utvecklingen pågick i Kanada började i vårt land i slutet av 50-talet ett skotarkoncept växa fram med en halvband- eller helbandtraktor som främre enhet och en dragen kälke eller kärra som bakre enhet, med ”svansstyrning” som en form av midjestyrning. Slutprodukten av den skotarutvecklingen blev ”trekvartsbandaren”, med midjestyrning och drift runtom, som började serietillverkas 1964. Men den utvecklingslinjen fick överraskande konkurrens när den vid Värmlands Skogsarbetsstudier (VSA) nyanställde konstruktören Lars Bruun hösten 1962 lanserade hjulskotaren Brunetten. Trots ljumt intresse från de stora skogsföretagen och negativt bemötande från det skogstekniska etablissemanget fick Brunetten fotfäste på marknaden och följdes snabbt av andra tillverkares varianter av hjulskotare. Trekvartsbandaren och hjulskotaren konkurrerade en period men i början av 70-talet framstod hjulskotaren som det vinnande konceptet. Men bandet fortsatte att användas som komplement.
Frågor som diskuteras är dels orsakerna till att den kanadensiska utvecklingen inte gjorde några tydliga avtryck i Sverige och dels turerna kring Brunetten, som trots motståndet blev en framgång. Den gängse historiken har justerats och kompletterats på några punkter.

Del 2. Gripskördarens tillkomst
Först med att sätta ett avverkningsdon i spetsen på en traktormonterad kran var man, även i detta fall, i Kanada - året var 1958. Men det blev en udda företeelse utan fortsättning. I den intensiva mekanisering av drivningsarbetet som skedde i Nordamerika på 1960-talet blev fällning-kvistning-kapning med kranspetsmonterade don ett av de utvecklingsspår som prövades. Funktionsdugliga prototyper av ”one-grip-harvesters” fanns 1966 men ingen av dem kom i serieproduktion och spåret övergavs. Konceptet sågs och beskrevs av svenska utvecklingsaktörer men det gav ingen synlig stimulans för vår inhemska skogstekniska FoU.
Utvecklingen av vårt högeffektiva och idag helt dominerande skördarkoncept i form av gripskördaren/engrepparen gick stegvis och långsamt under 15-20 år. Fällklippen Garpnäven 1966, följd av ÖSA:s fällare–läggare samt gripsågen på skotare som kapade på marken liggande stammar var tidiga steg, fram till 70-talets början. Sedan blev intresset för gallringens mekanisering en stor drivkraft. Ett franskt koncept med fäll- och kapklipp samt kvistdon i kranens vipparm, uppfångat av Husqvarna, gav stimulans. Jan ”Skogs-Jan” Erikssons gripprocessor, som 1978 började arbeta på stickvägarna i mellansvenska gallringar, var ett mycket stort kliv. Jan Eriksson hade också ett gripskördaraggregat med i sin patentansökan. Det dröjde dock till 1982 innan hans skördarkoncept blev en kommersiell produkt, tillverkad av Volvo BM Valmet och vidareutvecklad till Valmet 901 med valbar storlek på gripskördaraggregatet, som blev en storsäljare. Sandahl/Pedersens SP 21:a, lanserad 1980 och som blev en gripskördarlösning i motormanuellt svårdrivna täta granungskogar i södra Sverige, blev relativt snabbt en framgång. 1983-84 kan ses som genombrottsår för den relativt färdiga gripskördartekniken.
Men det stora genomslaget för gripskördarkonceptet kom att dröja – av flera skäl. Lågkonjunktur, allmän teknikpessimism, negativa expertbedömningar och storsatsning på skogsbränslesortiment var några av dem. Trotsande bedömningar och prognoser åt sig gripskördaren dock in i gallringsskogen och var i slutet av 80-talet där den dominerande tekniken. Gripskördaren började också användas i klena slutavverkningar. På 90-talet fullbordades gripskördarens genomslag i slutavverkningarna och dominansen blev total.

Del 3. Aktörer, beteenden och förlopp i den skogstekniska utvecklingen
Som inledning till detta kapitel kommenteras några viktiga skrifter som beskriver den skogstekniska utvecklingen under gången tid. Den första frågan som sedan belyses är om den tekniska utvecklingen i skogsbrukets operativa verksamhet har anpassat sig till samhällets, skogsvårdens och naturvårdens krav eller om den möjligen varit ”deterministisk” d v s hänsynslöst självgående. Mitt svar är att den tekniska utvecklingen var relativt självgående i mekaniseringens tidiga skede men att anpassningen successivt förbättrades och i sin helhet kan ses som relativt god. En förklaring är att vi utvecklade ett mångsidigt skogstekniskt innovationssystem som fungerade väl, på nationell nivå. Innovationssystemet bottnade i ”den svenska modellen” och hade utvecklingstriangeln tillverkare-brukare-forskare som kärna. Aktörerna och mekanismerna i nämnda utvecklingstriangel åren 1938-2000 beskrivs. Aktörernas roller och tyngd förändrades ständigt. Skapandeprocessen för såväl skotarkoncepten (trekvartsbandaren och hjulskotaren) som de gripmonterade bearbetningskoncepten indikerar att den skogstekniska utvecklingen i vårt land skedde organiskt, med ”gräsrotsinnovatörer” som nyckelpersoner. Det stödjer också tesen att den tekniska utvecklingen i skogsbruket i huvudsak varit anpassad och inte deterministisk. Utvecklingstriangeln började falla sönder under 90-talet, samtidigt som resurserna för skogsteknisk FoU minskade kraftigt – såväl penningmässigt som personellt. Alla tre aktörskategorier i triangeln krympte drastiskt. Den tekniska utvecklingen stannade av.
Den tekniska utvecklingen under förra seklets andra hälft präglades av aktörernas mångfald och flera perioder av stor osäkerhet med inslag av oväntade ändringar i omvärldsbetingelserna samt felbedömningar eller missade utvecklingspotentialer i lanserad teknik. I ett försök att identifiera och kategorisera inslag av ”mänsklig faktor” i utvecklingsarbetet prövar jag ”perceptionsblindhet” och ”sekterism” som två tänkbara fenomen. Med inspiration från uppsatser på 1960-talet av C R Ross Silversides och Ivar Samset granskas tidsförloppen för viktiga teknikskiften i drivningsarbetet under perioden 1950-1999, i kortvirkesmetoden. Diffusionstiden har beräknats som tiden för den nya tekniken att gå från tio procent (”etablering”) till 90 procent (”stor dominans”) av avverkningsvolymen i det industriella skogsbruket. Det tog 15 år (1953-68) för motorsågen att bli allroundredskapet i den ”motormanuella huggningen”. Terrängtransportens mekanisering genom det alltmera utvecklade skotarkonceptet tog tio år (1958-68). Avverkningsarbetets helmekanisering, med en basmaskinmonterad processor som grund, hann på tolv år (1973-85) nå ca 75-80 % av volymen – innan gripskördaren tog över. Gripskördaren hade en diffusionstid på nio år när den slog igenom i gallring och en total diffusionstid på 15 år (1984-99) för att nå stor dominans som avverkningskoncept för hela avverkningsvolymen i det industriella skogsbruket. Mekaniseringen av skogsbrukets drivningsarbete tog omkring 40 år. Sist i denna del föreslår jag att ett seniornätverk för skogsteknisk FoU bildas som resurs i innovationssystemet.

Authors/Creators:Ager, Bengt
Title:Nedslag i skogsbrukets teknikhistoria
Subtitle:del 1. skotarens tillkomst, del 2. gripskördarens tillkomst, del 3. aktörer, beteenden och förlopp i den skogstekniska utvecklingen
Alternative abstract:
LanguageAbstract
English

This report is a study of the emergence of the forwarder and the (one)-grip-harvester – the central concepts in the cut-to-length system in logging today. Some general aspects on the technical development in logging are also given.

Part 1. The emergence of the forwarder

The forwarder is a logging vehicle consisting of one unit carrying the engine and the driver and one unit carrying the load, with articulated steering between the two units, all ground contacts powered and a grapple loader for handling of the wood.
The first forwarder concept was developed step by step in eastern Canada in the 1950´s, beginning 1951 with a modified farm tractor. Bonnard Forwarder, a prototype machine tested in 1958, can be seen as the first well performing forwarder fulfilling the central criteria for a forwarder. The commercial end product of this development was Dowty Forwarder, presented at the historic summer meeting of the Canadian Pulp and Paper Association in 1961 when the first fully mechanized logging systems in Canada were shown. These first Canadian forwarders all had big wheels. In Sweden systematic trials and development of tractors for logging under winter conditions started in 1954 by the work study organisation SDA, serving the forest industry companies in northern Sweden. Farm tractors equipped with half-tracks or full tracks was the most common type of vehicle tested. The first step – inspired by an odd two-unit vehicle for compaction of snow roads - towards a forwarder was to link the pulling vehicle to the pulled sleigh with an articulated steering device, called “tail steering”. In the years 1958-64 this concept developed. The sleigh was replaced by a powered and tracked wheeled unit as load carrier. The “three-quarter-track” was the end solution for the front unit, which still was a converted farm tractor. This forwarder concept became mature and commercial in 1964. But a fierce competitor had already entered the logging scene.
In the summer of 1962 the work study organisation VSA, serving the forest industry companies in western Sweden, hired a young machine constructor named Lars Bruun. He had moderate formal education in engineering but a solid practical experience. VSA had been experimenting with a Garrett Tree Farmer (a wheel skidder) pulling a wheeled log carriage. The new employee was supposed to develop that concept. But Lars Bruun brought his own ideas and realized them in a two-unit four wheel forwarder. The farm tractor was still the base for the front unit and the back unit was equipped with auxiliary hydraulic power. The machine was named “The Brunette”. In spite of low interest among the VSA member companies and poor ratings from the established expertise, the Brunette got foothold on the market. VSA sold 12 machines in 1963 and another 37 in 1964. The selling then increased very rapidly.
Other machine producers started to deliver similar versions of wheel forwarders and together with three-quarter-track forwarders and wheel skidders they completed mechanization of the off-road transport in Swedish forestry in the sixties. In the beginning of the seventies the wheel forwarder was strongly dominating the market and the three-quarter-track concept disappeared. But the track survived as supplement to the wheels under certain ground conditions. In the concluding discussion chapter the author tries to explain why the early Canadian forwarder development did not have any noticeable influence on the development in Sweden. The mechanisms behind the success of the Brunette, despite bad odds, is also discussed.

Part 2. The emergence and breakthrough of the (one-)grip harvester

An early (1958) experiment, in eastern Canada, was to mount a felling device (hydraulically torn steel wire) on the boom of a tractor. It worked but stayed as an odd event without continuation. In the intense mechanization process of logging in North America in the 1960`s boom-mounted devices for felling, limbing and bucking were tried. Successfully operating prototypes of “one-grip harvesters” appeared in 1966, but none of them became commercial and this track of development was abandoned. Swedish logging experts reported home about these advancements but the knowledge did not show any influence on Swedish R&D in logging. As was the case in the forwarder development the Swedish development went its own way.
The development of the grip harvester, today the very efficient and completely dominating tree harvesting concept in Sweden (and Scandinavia), occurred stepwise during a period of 15-20 years. Early steps were the boom mounted felling shear “The Garp Fist” appearing in 1966, the ÖSA feller-buncher and the gripsaw on forwarders, used for bucking of tree lengths - the latter two both appearing in the beginning of the seventies. The increasing interest in mechanization of the thinning operations then became a thriving ground for further development, while the full mechanization of the clear fellings was completed with the harvester using two units on the base machine – one for felling and one for processing (the two-grip harvester).
A french outfit with a boom-end-mounted shear for felling plus a limbing device mounted on the boom itself was imported to Sweden by the equipment producer Husqvarna. The concept was not successful on the market but it stimulated the creativity of domestic entrepreneurs.
One entrepreneur was the logging contractor Jan Eriksson who constructed a grip processor (Skogsjan RK450) that from 1978 operated successfully on the strip roads in late thinnings in central Sweden, processing trees that had been felled with the power saw. His concept became successful despite negative opinions from the established expertise. In his patent application 1977 Eriksson also had a construction of a complete grip harvesting device. The realization of that concept, however, also met resistance from the labor union. But in 1982 the first commercial grip harvester based on Jan Erikssons concept appeared, produced by VolvoBMValmet in Umeå. The final version – Valmet 901, appearing in 1984 - became a best seller.
A complete grip harvester, especially aimed for operation in dense early spruce thinnings in southern Sweden, was (after some experimenting 1979) introduced in 1980 by the practitioners Ingmar Sandahl and Lars Pedersen and named SP 21. It became quite successful despite unfavourable conditions such as bad economy in Sweden, increasing unemployment in forestry and bad times for logging equipment producers. Their concept was adopted by larger equipment producers, initially Bruun Systems and later ÖSA.
Despite low odds for a number of reasons, the grip harvester concept gradually won ground and by the end of the 1980`s it was used in more than half of all thinnings in the country and also in part of the clear fellings. The concept continued to exceed all forecasts and at the end of the nineties it was the greatly dominating harvesting techniques in Sweden – and still is.

Part 3. Some general aspects on the development of technology in Swedish
forestry

The first aspect is the influence that the technology developed in industrial forestry has had on society, nature, silviculture and forest workers.
The organized rationalization, starting at the end of the 1930´s, of manual operations and horse logging did not have any negative effects in the context mentioned. On the contrary, it had rather positive effects, especially for the forest workers. When mechanization began in the 50´s and then accelerated in the 60´s several signs of uncontrolled self-development appeared. Very large clear felling sites, great damages of the forest floor, damages of valuable timber assortments and rapidly rising number and seriousness of accidents among the forest workers were examples of detrimental effects. The problems peaked in the beginning of the 70´s
About 10-15 years later most of these problems were solved. To a large degree this can be attributed to a well operating innovation system. The core of this innovation system was “the golden triangle” with machine producers, users and researchers, cooperating closely and transparently. The users were represented by both forest industry companies and the forest worker union. Other interest groups – such as company health services, nature conservation organisations, the National Board of Occupational Health and the National Board of Forestry - did also increasingly influence the development and use of technology. This broad innovation system peaked in the 80´s and then by and by broke down to fractions of its past.
As part of the study the author gives a review of the inputs of the three actor categories in the golden triangle during the period of 1938-2000. “Grass-root-innovators” – emerging from both the user category and the workshop category - has been identified as important actors. By the end of the 90´s the role of the technological innovation actors was strongly reduced as were the fundings for technological development. At that time mechanisation of the cut-to-length logging system had reached some kind of final stage, with well working grip harvesters and forwarders.
As a possible contribution to better understanding of technological development processes the author has identified two types of phenomenon – “perceptional blindness” and “secterism” - as human shortcomings that may reduce rational action in the innovation system.
The rate of diffusion of new technology during the period of 1950-99 has been investigated, mainly inspired by C R Ross Silversides (1966) and limited to the CTL method. The time of diffusion is defined as the time elapsed between reaching 10 % (technology “established”) and 90 % (reaching “strong dominance”) of the volume harvested in industrial forestry. It took 15 years (1963-68) for the powersaw to become the allround tool for “motormanual” cutting. The time for the forwarder concept to replace the horse was about ten years (1958-68). The fully mechanized harvesting concept based on a processor mounted on the base machine – developing from feller/buncher + processor system to the two grip harvester – reached a dominance of 75-80 % in about twelve years before it was replaced by the runner up system the (one) grip harvester. The grip harvester had a diffusion time of nine years in thinnings and of 15 years to become the dominant harvesting technology. The overall time for mechanization of logging in Sweden was about 40 years.

Series/Journal:Rapport från Institutionen för skogens biomaterial och teknologi (BIB14845294)
Year of publishing :29 June 2017
Number:2017:11
Number of Pages:74
Place of Publication:Umeå
Publisher:Institutionen för skogens biomaterial och teknologi, Sveriges lantbruksuniversitet
Language:Swedish
Publication Type:Report
Article category:Other scientific
Full Text Status:Public
Agris subject categories.:K Forestry > K01 Forestry - General aspects
K Forestry > K11 Forest engineering
Subjects:(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 203 Mechanical Engineering > Vehicle Engineering
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
Agrovoc terms:forestry equipment, forestry, history, sweden
Keywords:Skogsbruk, teknikhistoria, avverkning, terrängtransport, skotare, gripskördare, diffusionstider
URN:NBN:urn:nbn:se:slu:epsilon-e-4259
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4259
ID Code:14417
Faculty:S - Faculty of Forest Sciences
Department:(S) > Department of Forest Biomaterials and Technology (from 131204)
Deposited By: Malin Sandberg
Deposited On:11 Jul 2017 10:28
Metadata Last Modified:11 Jul 2017 10:28

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