Ketaskoorel "Nabra" parendamine

Ketaskoorel on traktoriga järelveetav mullaharimismasin, mis kobestab mulda. Tema põhiülesanneteks on kevadel seemnesängi ettevalmistamine ja mehhaaniline umbrohutõrje ning sügisel kõrrekoorimine. Nabra-t kasutatakse samuti hooldusniidukina, libistina, kultivaatorina ning saab ette valmistada ka turbaväljasid. Käesoleva lõputöö käigus konstrueeriti ketaskoorel Nabra-le uus konstruktsioon, milles kasutati eelnevalt väljatöötatud tööseadiseid. Ketaskoorel koosneb neljast hüdraulilise pingestamisega tööseadisest, mis asetsevad eraldi neljal külgraamil. Külgraamid kinnituvad omakorda pearaamile, mis jaotub kaheks ning mille vahele on projekteeritud keskliigend seadme kompaktsesse transpordiasendisse viimiseks. Külgraamide, tööseadiste, rattaraami ja tagumise pearaami liigutamiseks kasutatakse ketaskoorelil kokku 16 hüdraulilist silindrit, mis töötavad nominaalrõhuga 175 bar-i. Ketaskoorelil Nabra parendati lõputöö käigus transpordiasendisse pakkimise mehhanismi ning uuenenud konstruktsiooni tõttu ei kuluta tööseadise kettad selle konstruktsioone nii nagu see juhtus eelmisel mudelil. Samuti vähendati ketaskooreli massi 23,5%, 10 700 kg-lt 8 500 kg-le. Kuigi see polnud lõputöös eraldi eesmärk, siis töölaiust suurendati 1 meetri võrra, kuid seejuures saavutati kompaktsem transpordiasend, kus transpordipikkus on 2,7 m (23,7%) lühem, transpordikõrgus 0,8 m (20%) madalam ja transpordilaius on endiselt 3 m. Ratta teljest tahapoole üleulatuv osa on kõigest 1,32 m, mis võimaldab parendatud ketaskoorelit mugavamalt transportida.

Chain-disc Harrow is an agricultural machine which is pulled behind tractor and which breaks down rinds in soil and mollifies the dirt. The main purposes of chain-disc harrow in spring season are to prepare seedbed and do the mechanical weed-killing to parry noxious plants. In fall season it’s main purpose is straw hulling. Also „Nabra“ could be used as maintenance mower, cultivator and to prepare peat fields. There were engineered new construction for the Nabra Chain-Disc Harrow 7,5M in the current diploma thesis, using working units which were developed earlier. Chain-disc harrow consist of four working units with hydraulic tensioning, which are located individually on side-frames. Side-frames are clamped to main frame and are divided into two separate sections. There is a constructed joint-frame between them to allow compact transportation positioning. On chain-disc harrow there are 16 hydraulic cylinders used in total to operate between working and transportation positions. The nominal pressure of the system is 175 bar. Through the current diploma thesis the unfolding mechanism of „Nabra“ chain-disc harrow has been improved and due to improved constructions there is no damage done by discs like it was in previous model. Also, the mass of chain-disc harrow was lessened 20,5%, from 10 700 kg to 8 500 kg. Though there was no such goal set, working width got widened by 1 meter. Thereat the transportation dimensions were greatly scaled down. Improved Chain-disc harrow’s tranportation lenght is 2,7 m (23,5%) shorter, transportation height 0,8 m (20%) lower and tranportation width remains 3 m. Device parts are hanging rearwards only 1,32 m from the wheel axle so it is more comfortable to transport the improved chain-disc harrow.