JPH0254901U

JPH0254901U -

Info

Publication number: JPH0254901U
Application number: JP13344788U
Authority: JP
Priority date: 1988-10-14
Filing date: 1988-10-14
Publication date: 1990-04-20

Description

[Brief explanation of the drawing]

第１図は本考案の一実施例の回路図、第２図は
同実施例の具体的構成を示す断面図である。Ａ……上昇制御弁（第１の切換弁）、Ｂ……ア
ンロード弁、Ｃ……チエツク弁、Ｄ……下降制御
弁（第２の切換弁）、Ｓ……シリンダ（アクチユ
エータ）、Ｓａ……作動油室、１……供給通路、
１Ａ……シリンダ側通路、２……排出通路、２Ａ
……タンク側通路、３……ポンプ、４……タンク
、４０……上昇制御弁のスプール、５０……下降
制御弁のスプール、６０……アンロード弁体、８
０……チエツク弁体。 FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a sectional view showing a specific configuration of the embodiment. A... Ascent control valve (first switching valve), B... Unloading valve, C... Check valve, D... Descending control valve (second switching valve), S... Cylinder (actuator), Sa ... Hydraulic oil chamber, 1 ... Supply passage,
1A...Cylinder side passage, 2...Discharge passage, 2A
... Tank side passage, 3 ... Pump, 4 ... Tank, 40 ... Rise control valve spool, 50 ... Descent control valve spool, 60 ... Unload valve body, 8
0...Check valve body.

Claims

[Claims for Utility Model Registration] A supply passage that supplies pressure oil discharged from the pump to the hydraulic oil chamber of the actuator, a discharge passage that returns oil from the hydraulic oil chamber to the tank, and a first switching valve that opens and closes a passage;
an unload valve that circulates the pressure oil discharged from the pump to the tank without load according to the switching position of the switching valve; a check valve that is interposed in the supply passage; and a check valve that is disposed in the discharge passage and that controls the passage. In a hydraulic control valve equipped with a second switching valve that opens and closes, the unload valve is built into the spool of the first switching valve, and the supply passage is passed through the spool of the second switching valve. A hydraulic control valve characterized in that the check valve is incorporated inside the spool.