PROBLEM TO BE SOLVED: To provide a tractor capable of avoiding an engine stall due to a rapid rise of a traction load.SOLUTION: A tractor includes: a hydraulic lifting/lowering drive unit 17 driving and lifting/lowering a tillage device of traction type and a mechanical linkage unit 18 for automatic lifting/lowering converting a change amount of a traction load to a lifting/lowering operation amount to be transmitted to the lifting/lowering drive unit 17. The mechanical linkage unit 18 includes: a change amount conversion mechanism 33 including a load detection member 36 oscillating front/back according to a traction load and a link mechanism 34 interlocking and connecting the change amount conversion mechanism 33 and lifting/lowering drive unit 17. The change amount conversion mechanism 33 includes an oscillation member 38 supported so as to oscillate by the load detection member 36 and interlocked/connected to the lifting/lowering drive unit 17 through the link mechanism 34 and converts a change amount of a traction load obtained by front/back oscillation of the load detection member 36 to a lifting/lowering operation amount after amplification by relative oscillation of the load detection member 36 and oscillation member 38.SELECTED DRAWING: Figure 15COPYRIGHT: (C)2018,JPO&INPIT【課題】牽引負荷の急激な上昇に起因したエンジンストールを回避できるトラクタを提供する。【解決手段】牽引式の耕耘装置を昇降駆動する油圧式の昇降駆動ユニット17と、牽引負荷の変化量を昇降操作量に変換して昇降駆動ユニット17に伝える自動昇降用の機械式連係ユニット18とを備え、機械式連係ユニット18は、牽引負荷に応じて前後揺動する負荷検出部材36を有する変化量変換機構33と、変化量変換機構33と昇降駆動ユニット17とを連動連結するリンク機構34とを備え、変化量変換機構33は、負荷検出部材36に揺動可能に支持されるとともにリンク機構34を介して昇降駆動ユニット17に連動連結される揺動部材38を有して、負荷検出部材36の前後揺動で得られる牽引負荷の変化量を、負荷検出部材36と揺動部材38との相対揺動によって増幅してから昇降操作量に変換する。【選択図】図15
