PROBLEM TO BE SOLVED: To provide a hand-held bush cutter having light weight, easy to use, having toughness and durability, producible at a reduced cost, remarkably reducing risk of splashed soil and pebble and amount of remained crops after harvest, and enabling easy attaching and detaching of a cutting blade.SOLUTION: A speed reducing mechanism in a gear case 11 has a two-stage speed reduction mechanism including a former stage speed reduction by meshing a small-diameter bevel gear 41 for power input with a large-diameter bevel gear 40 and a latter stage speed reduction by meshing a small-diameter spur gear 31 with the first large-diameter spur gear 22 attached to the first short axis 17 and meshing the small-diameter spur gear 31 with the second large-diameter spur gear 23 freely supported on the first short axis 17, wherein the small-diameter spur gear 31 is interlocked with the large-diameter bevel gear 40. An intermediate spur gear 36 for reverse rotation is inserted in the meshing of the small-diameter spur gear 31 with the second large-diameter spur gear 23. An upper blade 7 is made to be freely rotatable together with the second large-diameter spur gear 23, and a lower blade 8 is inserted into and engaged with an attaching part 17a at a lower end of the first short axis 17 and clamped from under with a single bolt 25.COPYRIGHT: (C)2010,JPO&INPIT【課題】軽量で使い易く、丈夫で耐久性があり、製造コストが抑えられた手持ち式刈払機にすることと、土や小石の跳ね飛ばしによる危険性と刈り残しが大幅に改善され、刈刃の着脱操作が容易に行なえる手持ち式刈払機にすることを同時に実現させることにある。【解決手段】ギヤケース11内の減速機構を、入力用の小径傘歯車41と大径傘歯車40との噛合による前段の減速と、大径傘歯車40と連動する小径平歯車31と第1短軸17に装着された第1大径平歯車22との噛合及び、小径平歯車31と第1短軸17に遊嵌支持された第2大径平歯車23との噛合による後段の減速とからなる、2段の減速を経る機構にした。そして、小径平歯車31と第2大径平歯車23とによる噛合を、逆転用の中間平歯車36を間に介在させた噛合にした。上刃7を第2大径平歯車23と連れ回り自在にさせ、下刃8を第1短軸17下端の装着部17aに嵌入係合させて、下方から1本のボルト25で挟み付けた。【選択図】図2
