| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent the abrupt rotation of a turning device when switching a travelling device/working device changeover valve and a turning device changeover valve. <P>SOLUTION: This construction equipment hydraulic circuit comprises first, second, third and fourth hydraulic pumps, first, second, third and fourth changeover valves corresponding to the hydraulic pumps, respectively, and a combined flow changeover valve for supplying operating oil from the third hydraulic pump to working devices of the first and second hydraulic pumps. The circuit has a first valve having one end connected to a working device signal line where signal pressure is generated and to a travelling device signal line and the other end connected to a crossing point between a combined flow changeover valve signal line and a tank line when switching the working device first and second changeover valves, and a second valve closeably provided in a flow path between the first valve and the tank line for opening the flow path to discharge to the tank line pressure formed in the combined flow changeover valve signal line when switching by the supply of signal pressure, and for shutting off the flow path to generate the signal pressure in the combined flow changeover valve signal line when the signal pressure is not supplied. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
