Nabco Limited

Nabtesco Corporation

Jun Nakano

Kensuke Ioku

Yasunori Hatanaka

An arm direction changeover valve () is provided in an arm block (). A first pilot check valve () is provided in a first block (). A second pilot check valve () is provided in a second block (). The three blocks, i.e., the arm block (), the first block (), and the second block () are arranged side by side. The first block () and the second block () are arranged to be contiguous to each other. Accordingly, an increase in size can be prevented even if a float mechanism and a multi-direction changeover valve are formed integrally with each other.

Hydraulic control device for loader

In a multiple-switching valve having a bucket-leveling function, there are provided a diverged passage, which is diverged from a merged passage and connects with an unloading passage or a tank passage, and a switching valve to disconnect and connect the diverged passage. The switching valve allows a pressured oil drained from a rod-side chamber of a boom cylinder via a directional switching valve for boom to be supplied to the merged passage flow in the diverged passage, thereby preventing the pressure oil from being supplied to a head-side chamber of the bucket cylinder. Accordingly, the bucket-leveling function can be cancelled properly, thereby improving the operation of the multiple-directional switching valve.

Multiple-directional switching valve

There is provided a flow divider system in a hydraulic circuit for a work machine including a boom cylinder and a bucket cylinder. The flow divider system divides a pressured oil drained from a one-boom cylinder into an other-bucket cylinder and a tank via a first orifice, a second orifice and a flow dividing valve, maintaining a specified pressure difference between pressures downstream the first and second orifices. The first and second orifice are configured of a variable orifice respectively, and in the event that the oil flow from the one-boom chamber decreases, respective opening degrees of the first and second orifices are controlled so as to be reduced. Accordingly, changing of a divisional ratio of oil flow can be suppressed properly regardless of a small oil flow drained from the boom cylinder.

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Hyogo-ken, Japan

Jun Nakano