PROBLEM TO BE SOLVED: To reduce weight and cost of a machine body in a travel device directly-mounted boom sprayer with a horizontal mechanism.SOLUTION: A boom sprayer includes a horizontal mechanism for maintaining a horizontal state of a boom using a weight balance of the boom horizontally developed in the left and right by pivotally supporting a support frame to support the boom with respect to a body frame directly mounted on a travel device. The horizontal mechanism includes a rotary shaft for rotatably supporting the support frame with respect to the body frame, and a double-acting hydraulic cylinder arranged between the body frame and the support frame and making the support frame swing around the rotary shaft. A directly-connected flow path for directly connecting a hydraulic oil gateway at both sides of the cylinder in the hydraulic cylinder is provided, and an opening/closing switching valve for opening and closing the directly-connected flow path is provided.SELECTED DRAWING: Figure 4COPYRIGHT: (C)2020,JPO&INPIT【課題】水平機構を備えた走行装置直装式のブームスプレーヤにおいて、機体の軽量化と低コスト化を図る。【解決手段】ブームスプレーヤは、走行装置に直装される機体枠に対してブームを支持する支持枠を軸支して左右水平方向に展開したブームの重量バランスでブームの水平状態を維持する水平機構を備え、水平機構は、機体枠に対して支持枠を回転自在に支持する回転軸と、機体枠と支持枠との間に配備されて回転軸回りに支持枠を揺動させる複動型の油圧シリンダとを備え、油圧シリンダにおけるシリンダ両側の作動油出入口を直結させる直結流路を設けると共に、直結流路を開閉する開閉切換弁を設けた。【選択図】図４
