PROBLEM TO BE SOLVED: To provide a controller for lifting and lowering of an implement of a work vehicle designed to stably perform sufficient deceleration to the lowering side with an inexpensive motor.SOLUTION: The controller 60 for lifting and lowering of the implement of the work vehicle is equipped with a hydraulic cylinder 6 for lifting and lowering the implement 14 supported on the work vehicle 1, a position controlling valve 90 changing over the oil supply of a hydraulic oil to the hydraulic cylinder by operating a lifting and lowering operation means, a normally and reversibly rotatable electric motor 95 connected to an operation part of the position controlling valve 90 and further a means 85 for detecting the rotation position of an output shaft of the electric motor 95 therein. The implement 14 supported on a traveling machine body is freely liftably and lowerably controlled corresponding to the operation position of the electric motor 95 with the hydraulic cylinder 6. In the controller 60, the motor 95 is connected to the controller 60. When the rotational speed of the motor reaches a value not higher than a first threshold value S1 at a low speed, control is performed so that the amount of output for the motor 95 is maintained at the rotational speed thereof irrespective of the rotation position of the motor.COPYRIGHT: (C)2007,JPO&INPIT【課題】安価なモータを用いて下降側に十分な減速が安定して行われることを可能にする作業車の作業機昇降制御装置を提供する。【解決手段】作業車両1に支持された作業機14を昇降する油圧シリンダ6と、該油圧シリンダへの圧油の送油を昇降操作手段の操作により切り換えるポジション制御バルブ90と、該ポジション制御バルブ90の操作部に連繋された正逆回転可能な電動モータ95を備え、該モータ95にはその出力軸の回転位置を検出する手段85を備え、前記油圧シリンダ6により走行機体に支持された作業機14を、前記電動モータ95の操作位置に対応して昇降自在に制御する作業車の昇降制御装置60において、前記モータ95を制御装置60と接続し、前記モータの回転速度が低速の第一閾値S1以下に達したならば、モータ回転位置に関わらず前記モータ95に対する出力量をその回転速度に保持するように制御する。【選択図】図12
