VENTILEINRICHTUNG ZUR VERHINDERUNG DES ZUSAMMENFALLENS EINES BAUMASCHINEN-ARBEITSWERKZEUGES

摘要

A valve apparatus for preventing a fall of a working machine comprises a cylinder-side passage (20) communicating with a cylinder port (19) opened in a cylinder-side mounting surface (11), a valve body (10) having a directional control valve-side passage (18) communicating with a directional control valve port (17), a check valve (24) provided in the valve body (10) and preventing the entry of a pressure oil from the cylinder-side passage (20) into the directional control valve-side passage (18), a flow rate control valve (34) provided in the valve body (10), normally shutting off the directional control valve-side passage (18) and cylinder-side passage (20) from each other, and establishing communication between these passages on receiving an external signal, and a safety valve (44) provided in the valve body (10) and adapted to relieve a high pressure in the cylinder-side passage (20). The check valve (24), flow rate control valve (34) and safety valve (44) are provided in a common plane substantially parallel to the cylinder-side mounting surface (11).