PROBLEM TO BE SOLVED: To provide a tractor that enables draft control with high control accuracy while being made advantageous in terms of productivity.SOLUTION: A tractor includes: a lift arm 15 for suspending and supporting a towed working device a hydraulic actuator 16 for vertically swinging and driving the lift arm 15 a control valve 17 for controlling the operation of the hydraulic actuator 16 a load detection member 21 supported to a supporting member 37 fixed at the rear of a vehicle body in a displacing manner a biasing mechanism 60 for displacing and biasing the load detection member 21 in the direction against a towing load applied on the load detection member 21 and a link mechanism 22 for interlocking a spool 17A of the control valve 17 to the load detection member 21. The biasing mechanism 60 includes a coil spring 61 for permitting displacement of the load detection member 21 according to the towing load when the towing load exceeds a set value.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2018,JPO&INPIT【課題】生産性の面において有利にしながら制御精度の高いドラフト制御を可能にする。【解決手段】トラクタは、牽引式の作業装置を吊り下げ支持するリフトアーム15と、リフトアーム15を上下方向に揺動駆動する油圧アクチュエータ16と、油圧アクチュエータ16の作動を制御する制御バルブ17と、車体後部に固定された支持部材37に変位可能に支持される負荷検出部材21と、負荷検出部材21にかかる牽引負荷に抗する方向に負荷検出部材21を変位付勢する付勢機構60と、制御バルブ17のスプール17Aを負荷検出部材21に連動させるリンク機構22とを備え、付勢機構60は、牽引負荷が設定値を超えた場合に牽引負荷に応じた負荷検出部材21の変位を許容するコイルバネ61を備えている。【選択図】図2
