Action detection device for operating valve for hydraulic machinery

摘要

The operating valve action detection device includes a pressure reduction valve (3). This valve, which supplies fluid to the operating valve (4), is made so that it is pressed in the direction reducing the aperture upstream of the operating valve becomes smaller, and in the direction in which the aperture is made larger by downstream pressure from the operating valve. An auxiliary aperture (10) allows fluid to drain out when the aperture in the pressure reduction valve exceeds a certain size. The auxiliary aperture has a pressure detector (15) producing signals detecting the action of the operating valve.