JPS59222601A - Oil hydraulic cylinder control device - Google Patents
Oil hydraulic cylinder control deviceInfo
- Publication number
- JPS59222601A JPS59222601A JP58097498A JP9749883A JPS59222601A JP S59222601 A JPS59222601 A JP S59222601A JP 58097498 A JP58097498 A JP 58097498A JP 9749883 A JP9749883 A JP 9749883A JP S59222601 A JPS59222601 A JP S59222601A
- Authority
- JP
- Japan
- Prior art keywords
- valve
- piston
- cylinder
- pressure
- hydraulic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Fluid-Pressure Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
この発明はショベルローダの駆動用油圧シリンダ、クレ
ーンのブーム駆りｖｌ用シリンダ或は工作機械のテーブ
ル送り、刃物送り用などの各種機器の駆動用油圧シリン
ダの制御装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a hydraulic cylinder for driving a shovel loader, a cylinder for driving a boom of a crane, a hydraulic cylinder for driving various equipment such as a machine tool table feeder, a cutter feeder, etc. It is.
このような油圧シリンダ（こおいて、そのピストン杆に
より作動させる負荷が軽いとき、あるいは無負荷のとき
は油圧が低くとも十分に作動するが、低圧でピストンを
高速前進させるためには油圧ポンプの流量を大きくして
短時間の間にシリンダ内に大量の油を送り込み、シリン
ダの前部内の油を油タンクに戻丁必要がある。また、ピ
ストン杆に大きな荷重が加わったときにピストン杆を低
速前進させる１こめにはポンプ流量を小さくして高圧の
油をシリンダ内に送り込む必要がある。This kind of hydraulic cylinder (in this case, when the load operated by the piston rod is light or when there is no load, it can operate satisfactorily even if the oil pressure is low, but in order to move the piston forward at high speed with low pressure, it is necessary to use a hydraulic pump) It is necessary to increase the flow rate to send a large amount of oil into the cylinder in a short period of time, and return the oil in the front of the cylinder to the oil tank.Also, when a large load is applied to the piston rod, it is necessary to The first time the engine moves forward at low speed, it is necessary to reduce the pump flow rate and send high-pressure oil into the cylinder.
しかし、このような作用を行なわせるＴこめには、ピス
トン杆に加わる負荷の゛：′凌動に応じて、吐出流量が
自動的に変ｆヒてる可変吐出量ポンプが必要となるが、
このポンプはｉ構がきわめて複雑で高価であり、保守に
も手数がかη・るという問題がある。However, in order to perform such an action, a variable discharge pump is required, which can automatically change the discharge flow rate according to the fluctuation of the load applied to the piston rod.
The problem with this pump is that its structure is extremely complicated and expensive, and maintenance is also labor intensive.
、ｌ この発明は上記のような油圧制御装置の
問題を解決することを目的とするもので、従来の油圧回
路の切換弁と油圧シリンダの途中に簡単な構造の１個の
自動制御弁とシーケンス弁と逆止弁を附加するだけで定
流量油圧ポンプを用いて、可変吐出量ポンプを用いた場
合と殆んど変ることのない円滑な運転が行なえる油圧シ
リンダ制御回路を提供でるものである。, l The purpose of this invention is to solve the problems of the hydraulic control device as described above, and the present invention is to install one automatic control valve of a simple structure and a sequence control valve in the middle of the switching valve and hydraulic cylinder of the conventional hydraulic circuit. By simply adding valves and check valves, it is possible to provide a hydraulic cylinder control circuit that uses a constant flow rate hydraulic pump and can perform smooth operation almost the same as when using a variable discharge rate pump. .
丁なわち、この発明は油圧ポンプの吐出口と油タンクと
を油圧シリンダの両端に通じる配管の途中に４方口３位
置切換弁を介在させた油圧回路において、前記４方口３
位置切換弁の２ツのボートをシリンダの両端に通じる配
管の途中に、パイ・により押動されるスプールと、一定
圧力以力の油圧が後端に加わったとき、前記バネに抗し
てスプールを押動するスプール作動ピストンを有でる自
動制御弁を設け、この自動制御弁には、別記４方口３位
置切換弁とシリンダに通じる４ツのボートの他に、前記
スプール作動ピストンの後端に油圧を加える制御ポート
を設け、前記切換弁をピストン前進位置とし１ことき油
圧ポンプに通じる自動制御弁の油圧ポンプ側のボートと
、前記制御ポート間に油岑ポンプの吐出圧力が一定圧以
上になつ１ことき進じるシーダンス弁と、制御ポート側
の圧力が高いときにのみ開となる逆止弁とを並列に接続
して、前記切換弁をピストン前進位置とし、油圧ポンプ
の吐出圧力が一定圧以下のときは、シーケンス弁と逆止
弁がＩｌｌじ、ポンプの吐出口とシリンダの両端を連通
させ（第２図の状態〕油圧ポンプの吐出圧力が一定圧以
上のときはシーケンス弁が開き、スプール作動ピストン
が作動してポンプの吐出口がシリンダの後部に通じると
ともにシリンダの前と１；が、１１１タンクに辿じ（第
３図の扶助前記切換弁をピストン後退位置としＴことき
はシリンダのｎｄ部がポンプの吐出口に通じ、シリンダ
の後部が油タンクにｊｗしる（第４図の状態）ように構
成しＴこものでピストン杆に加わる負荷の変動に応じて
自動制御弁内のスプールが自動的に切換えらｎて負荷が
一定圧以下のときはピストンのｎｉ、ｒ後の面積差によ
る押圧力の差によってピストン杆を前進させることによ
りポンプ吐出流量が小さいシこも刀・刀・わらず高速で
ピストン杆を前進させることができるものである。Specifically, the present invention provides a hydraulic circuit in which a four-way, three-position switching valve is interposed in the middle of a pipe connecting a discharge port of a hydraulic pump and an oil tank to both ends of a hydraulic cylinder.
In the middle of the piping that connects the two boats of the position switching valve to both ends of the cylinder, there is a spool that is pushed by the pipe, and when hydraulic pressure above a certain pressure is applied to the rear end, the spool moves against the spring. An automatic control valve having a spool actuating piston that pushes the spool actuating piston is provided, and this automatic control valve includes a four-way three-position switching valve and four boats communicating with the cylinder, as well as a rear end of the spool actuating piston. A control port for applying hydraulic pressure is provided, and when the switching valve is set to the piston forward position, the discharge pressure of the oil pump is equal to or higher than a certain pressure between the boat on the hydraulic pump side of the automatic control valve communicating with the hydraulic pump and the control port. By connecting in parallel a seedance valve that advances each year with a check valve that opens only when the pressure on the control port side is high, the switching valve is placed in the piston forward position, and the hydraulic pump discharges. When the pressure is below a certain pressure, the sequence valve and the check valve are activated to communicate the pump discharge port and both ends of the cylinder (the state shown in Figure 2).When the hydraulic pump discharge pressure is above a certain pressure, the sequence valve and the check valve are activated. The valve opens, the spool actuating piston operates, and the discharge port of the pump communicates with the rear part of the cylinder, and the front of the cylinder and 1; The cylinder is configured so that the nd part of the cylinder communicates with the discharge port of the pump, and the rear part of the cylinder contacts the oil tank (as shown in Figure 4). The spool in the control valve is automatically switched, and when the load is below a certain pressure, the piston rod is moved forward by the difference in pressing force due to the difference in area after the piston, thereby reducing the pump discharge flow rate. It is capable of moving the piston rod forward at high speed regardless of whether it is a sword or sword.
以下にこの発明の詳細を添（＝Ｊ図面に示す実施例に基
づいて説明する。The details of this invention will be explained below based on the embodiments shown in the accompanying drawings.
図において１は油タンク、２は定流量型油圧ポンプでモ
ータあるいはエンジンなどの駆動装置３により駆動され
る。In the figure, 1 is an oil tank, 2 is a constant flow type hydraulic pump, which is driven by a drive device 3 such as a motor or an engine.
４は４方口３位置切換弁で手動式、電磁式、油圧式など
の任意の操作機構を有してお・す、この切換弁のＰポー
トには前記油圧ポンプ２の吐出口に通じる配管が連結さ
れ、ＴボートにはりＣはこの発明の要点である自動制御
弁で、弁箱６の一方に設けたボート７．８と前記切換弁
４のＡポートとＢボートを配管により連結し。4 is a 4-way, 3-position switching valve that has any operating mechanism such as manual, electromagnetic, or hydraulic. The P port of this switching valve is connected to a pipe that leads to the discharge port of the hydraulic pump 2. The beam C is an automatic control valve which is the main point of this invention, and the boat 7.8 provided on one side of the valve box 6 is connected to the A port and B boat of the switching valve 4 by piping.
他方に設けたボート９．１０を油圧シリンダ１１の両端
のボートに配管により連通させる。The boats 9 and 10 provided on the other side are connected to the boats at both ends of the hydraulic cylinder 11 by piping.
１４．１５．１６．１７、は弁箱６の内周に設けた周溝
であって、周溝１４はボート７．９を通じ、周溝１５は
ボート１０に、周溝１６はボート８に通じ、周溝１７は
制御ホード１８に通じている。14.15.16.17 are circumferential grooves provided on the inner circumference of the valve body 6, in which the circumferential groove 14 communicates with the boat 7.9, the circumferential groove 15 communicates with the boat 10, and the circumferential groove 16 communicates with the boat 8. , the circumferential groove 17 communicates with the control housing 18 .
１９は弁箱６内にはめたスプールで、その外周には前記
周溝１４．１５を連通させる周溝２０を設け、スプール
１９のボート７．９側の一部には押バネ２１をはめる凹
所と、この凹所と周溝１４を通じる油路を設けである。Reference numeral 19 denotes a spool fitted in the valve box 6, and its outer periphery is provided with a circumferential groove 20 that communicates the circumferential grooves 14 and 15, and a part of the spool 19 on the boat 7.9 side is provided with a recess into which a push spring 21 is fitted. At this point, an oil passage is provided which communicates with this recess and the circumferential groove 14.
２３は弁箱６同のバ、ネ取付側と反対の側にはめたスプ
ール作動ピストンで、外径はスプール１９より大きくと
り、このピストン２３のスプール側には小径の突軸２４
が一体に設けである。Reference numeral 23 denotes a spool actuating piston fitted on the side opposite to the side where the spring and screw are attached in the same valve box 6. The outer diameter is larger than the spool 19, and a small diameter protruding shaft 24 is attached to the spool side of this piston 23.
is provided in one piece.
前記制御ボート１８には前記ボート７に通どる並列の配
管を設けてこの各配管にシーケンス弁２５と逆止弁２６
を設ける。The control boat 18 is provided with parallel piping leading to the boat 7, and each piping is equipped with a sequence valve 25 and a check valve 26.
will be established.
この発明は上記のｌｊｔ ＤＬであり、第１図は切換弁
４が中立位置にある。このとき、油圧ポンプ２から送り
出さｎた圧力油は、切換弁４の短絡油路を通って油タン
ク１へ戻っている。まＴこ、１ スプール１９は
バネ２１でピストン２３の方へ押付けられているから自
動制御弁Ｃのホード７．８間は遮断さｎ、スプール１９
の周溝２０が弁、萌６の周溝１４．１５を連通させてい
るが、油圧は働いていない。This invention is the above ljt DL, and in FIG. 1, the switching valve 4 is in the neutral position. At this time, the pressure oil sent out from the hydraulic pump 2 returns to the oil tank 1 through the short circuit oil path of the switching valve 4. Since the spool 19 is pressed toward the piston 23 by the spring 21, the connection between the automatic control valve C's hoard 7 and 8 is cut off.
The circumferential groove 20 of the valve communicates with the circumferential grooves 14 and 15 of the moe 6, but hydraulic pressure is not working.
つぎに第２ ＠ （７，、） Ｊ：うに切換弁４を切換
えると、 ゛ポンプ２からの油は切換弁４を通り
、ボート７→周溝１４→ポート９を経てシリンダ１１の
後端に加わり同時にスプール１９の周溝２ｏをｊ止って
ボート】０がらシリンダ１１の前部にも加わる。Next, when the second @ (7,,) J: sea urchin switching valve 4 is switched, the oil from the pump 2 passes through the switching valve 4, passes through the boat 7 → circumferential groove 14 → port 9, and reaches the rear end of the cylinder 11. At the same time, it stops at the circumferential groove 2o of the spool 19 and also applies to the front part of the cylinder 11.
このようにピストン１２の前後に同圧の油圧が加わると
、ピストン１２の前面はピストン杆１３の断面だけ面積
が小さいので、ピストン１２の後部に加わる押圧力の方
が前部に加わる押圧力より大となるため、ピストン１２
は前進する。このときシーケンス弁２５にも油圧が加わ
っているが、ピストン杆１３に加わる負荷が小さいとき
は油圧が低いので、シーケンス弁２５は閉じており、従
ってスプール１９、ピストン２３は第２図の位置を保っ
ている。In this way, when the same hydraulic pressure is applied to the front and rear of the piston 12, the area of the front surface of the piston 12 is smaller by the cross section of the piston rod 13, so the pressing force applied to the rear part of the piston 12 is greater than the pressing force applied to the front part. Due to the large size, the piston 12
moves forward. At this time, oil pressure is also applied to the sequence valve 25, but when the load applied to the piston rod 13 is small, the oil pressure is low, so the sequence valve 25 is closed, and therefore the spool 19 and piston 23 are in the position shown in FIG. I keep it.
上記の作用によりピストン杆１３がある程度前進してピ
ストン杆１３に加わる負荷が増大すると、そゎに応じて
油圧が増大し、シーケンス弁２５が開いて制御ボート１
８からピストン２ン２３カｆ４］進し、その突軸２４に
よりスプール１９を押して第３図の位置とする。このた
め、スプール１９の外周で周溝１４．１５は遮断さイ１
、周溝１５．１６が連通ずる刀）ら、シリンダ１１の前
部の油がタンク１へ戻る。一方、シリンダ１１の後部に
は圧力油の供給がｉ読いているのでピストン杆１３は大
きな力で前進して所要の仕事を行なう。When the piston rod 13 moves forward to some extent due to the above action and the load applied to the piston rod 13 increases, the oil pressure increases accordingly, the sequence valve 25 opens, and the control boat 1
8, the piston 23 (f4) advances forward, and its protruding shaft 24 pushes the spool 19 to the position shown in FIG. Therefore, the circumferential grooves 14 and 15 are cut off at the outer periphery of the spool 19.
, the oil at the front of the cylinder 11 returns to the tank 1 through the peripheral grooves 15 and 16 communicating with each other. On the other hand, since pressure oil is supplied to the rear of the cylinder 11, the piston rod 13 moves forward with great force to perform the required work.
こうして仕事が終っ１このち、第４図のように切換弁４
を位置させると、弁箱６のボート７がタンク１に通し、
ボート８に油圧が加わりピストン２３の後部に加わって
いた押圧力はなくなり、スプール１９の後備とピストン
２３の前部に油圧が加わる。このため、ピストン２３の
後部の油は制御ポー）１８ｉ＞ら逆止弁２６を通ってタ
ンク１に戻り、第４図のようにピストン２３は後退し、
スプール１９はバ４２１ｍＪへ寄ったままとなり、シリ
ンダ１１の後部の油はタンク１に戻り、ピストン１２の
前部には油圧が加わるからピストン杆１３は速やかに後
退する。After the work is completed, the switching valve 4 is opened as shown in Figure 4.
When the boat 7 of the valve box 6 passes through the tank 1,
Hydraulic pressure is applied to the boat 8, the pressing force applied to the rear of the piston 23 disappears, and hydraulic pressure is applied to the rear of the spool 19 and the front of the piston 23. Therefore, the oil at the rear of the piston 23 returns to the tank 1 through the control port 18i> and the check valve 26, and the piston 23 retreats as shown in FIG.
The spool 19 remains close to the bar 421mJ, the oil at the rear of the cylinder 11 returns to the tank 1, and since oil pressure is applied to the front of the piston 12, the piston rod 13 quickly retreats.
この発明の操作装置は上記のようにピストンの前進時に
おいてはピストンの前後に油圧を加えてピストンの前後
面の面積差による押圧力の差によってピストンとピスト
ン杆を前進させ、シリンダ前部の油はシリンダ後部に流
ｎ込むのでポンプから送り出丁油は一定でもピストンは
高速で移動する。マＴこ、負荷が働いてピストンの動き
が遅くなって油圧が上ると、シリンダの前部がタンクへ
通じてピストンの前部の油がタンクへ戻るのでシリンダ
後部に流入する油による押圧力が全てピストンを前進さ
せる力となるからピストンは大きな力で前進する。As described above, when the piston moves forward, the operating device of the present invention applies hydraulic pressure to the front and rear of the piston, moves the piston and the piston rod forward by the difference in pressing force caused by the difference in area between the front and rear surfaces of the piston, and applies oil pressure to the front of the cylinder. Since the oil flows into the rear of the cylinder, the piston moves at high speed even if the amount of oil delivered from the pump is constant. When a load is applied and the movement of the piston slows down and the oil pressure increases, the front of the cylinder opens to the tank and the oil at the front of the piston returns to the tank, so the pressing force from the oil flowing into the rear of the cylinder increases. The piston moves forward with great force because all of this acts as a force to move the piston forward.
この発明は上記のように無負荷のときは油圧ポンプの吐
出量が一定であっても速い速度でピストンが動き、負荷
が増大したのちは力は増加するが、速度は遅くなる。従
って油圧ポンプとして安価な定流量ポンプを用いても高
価な可変吐出量ポンプを用いた場合と同様の円滑な運転
が行なえる。As described above, in this invention, when there is no load, the piston moves at a high speed even if the discharge amount of the hydraulic pump is constant, and after the load increases, the force increases but the speed becomes slower. Therefore, even if an inexpensive constant flow rate pump is used as the hydraulic pump, smooth operation can be achieved similar to when an expensive variable discharge rate pump is used.
第１図ないし第４図はこの発明の油圧制御装置の自動制
御弁の縦断面図を含む各状態の回路図である。
１・・・油タンク、２・・・油圧ポンプ、４・・・４方
口３位置切換弁、１１・・・油圧シリンダ、１８・・・
ＩＱ御ボート、１９・・・スプール、２１・・・押バネ
、２３・・・スプール作動ピストン、２５・・・シーケ
ンス弁、２６・・・逆止弁、Ｃ・・・自動制御弁。
同代理人 鎌 １）文 二
第１図
１
第３図
１1 to 4 are circuit diagrams of the automatic control valve of the hydraulic control device of the present invention in various states, including longitudinal cross-sectional views. DESCRIPTION OF SYMBOLS 1...Oil tank, 2...Hydraulic pump, 4...4-way 3-position switching valve, 11...Hydraulic cylinder, 18...
IQ control boat, 19... Spool, 21... Push spring, 23... Spool operating piston, 25... Sequence valve, 26... Check valve, C... Automatic control valve. Same agent sickle 1) Text 2 Figure 1 1 Figure 3 1
Claims (1)
に通じる配管の途中に４方口３位置切換弁を介在させＴ
こ油圧回路において、前記４方口３位１に切換弁の２つ
のホードをシリンダの両端に通じる配管の途中に、バネ
により押動さｎるスプールと、一定圧力以上の油圧が後
端に加わつ１ことき前記バネに抗してスプールを押動す
るスプール作動ピストンを有する自動制御弁を設け、こ
の自動制御弁には、前記４方口３位置切換弁とシリンダ
に通じる４つのボートの他に、前記スプール作動ピスト
ンの後端に油圧を加える制御ボートを設け、前記切換弁
をピストン前進位置としＴことき油圧ボン？“に通じる
自動制御弁の油圧ポンプｈのボートと、前記制御ボート
間に油圧ポンプの吐出圧力が一定以上になつＴことき通
じるシーケンス弁と一制御ボート側の圧力が高いときに
のみ開となる逆止弁とを並列に接続して、前記切換弁を
ピストン前進位置とし、油圧ポンプの吐出圧力が一定圧
以下のときは、シーケンス弁と逆止弁が閉じ、ポンプの
吐出口とシリンダの両端を連通させ、油圧ポンプの吐出
圧力が一定圧以」二のときはシーケンス弁が開き、スプ
ール作動ピストンが作動してポンプの吐出口がシリンダ
の後部に通じるとともにシリンダの前部が油タンクに通
じ、前記切換弁をピストン後退位置としＴこときはシリ
ンダの前部がポンプの吐出口に辿じ、シリンダの後部が
油タンクにｊｌｆ−しるように構成した油圧シリンダ制
御装置。A 4-way, 3-position switching valve is interposed in the middle of the piping that connects the discharge port of the hydraulic pump and the oil tank to both ends of the hydraulic cylinder.
In this hydraulic circuit, there is a spool pushed by a spring in the middle of the piping that connects the two ports of the switching valve to both ends of the cylinder at the 4-way port 3 position 1, and a hydraulic pressure above a certain pressure is applied to the rear end. (1) An automatic control valve having a spool actuating piston that pushes the spool against the spring; A control boat is provided to apply hydraulic pressure to the rear end of the spool operating piston, and the switching valve is set to the piston forward position. ``The hydraulic pump h boat of the automatic control valve connected to ``T'' opens only when the pressure on the control boat side is high, and the discharge pressure of the hydraulic pump becomes above a certain level. A check valve and a check valve are connected in parallel, and the switching valve is in the piston forward position, and when the discharge pressure of the hydraulic pump is below a certain pressure, the sequence valve and the check valve are closed, and the discharge port of the pump and both ends of the cylinder are closed. When the discharge pressure of the hydraulic pump is equal to or higher than a certain pressure, the sequence valve opens and the spool operating piston operates, allowing the discharge port of the pump to communicate with the rear part of the cylinder and the front part of the cylinder communicating with the oil tank. , a hydraulic cylinder control device configured such that the switching valve is in the piston retracted position, the front part of the cylinder follows the discharge port of the pump, and the rear part of the cylinder connects to the oil tank.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58097498A JPS59222601A (en) | 1983-05-30 | 1983-05-30 | Oil hydraulic cylinder control device |
| DE19833346235 DE3346235A1 (en) | 1982-12-27 | 1983-12-21 | Control device for hydraulic cylinders |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58097498A JPS59222601A (en) | 1983-05-30 | 1983-05-30 | Oil hydraulic cylinder control device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS59222601A true JPS59222601A (en) | 1984-12-14 |
Family
ID=14193924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58097498A Pending JPS59222601A (en) | 1982-12-27 | 1983-05-30 | Oil hydraulic cylinder control device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59222601A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03103344U (en) * | 1990-02-09 | 1991-10-28 | ||
| JP2010203500A (en) * | 2009-03-02 | 2010-09-16 | Ckd Corp | Air cylinder |
| CN103990992A (en) * | 2014-05-15 | 2014-08-20 | 鹰普（中国）有限公司 | Pneumatic control structure of full-automatic pneumatic clamp |
-
1983
- 1983-05-30 JP JP58097498A patent/JPS59222601A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03103344U (en) * | 1990-02-09 | 1991-10-28 | ||
| JPH0540126Y2 (en) * | 1990-02-09 | 1993-10-12 | ||
| JP2010203500A (en) * | 2009-03-02 | 2010-09-16 | Ckd Corp | Air cylinder |
| CN103990992A (en) * | 2014-05-15 | 2014-08-20 | 鹰普（中国）有限公司 | Pneumatic control structure of full-automatic pneumatic clamp |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| GB2313413A (en) | Variable-regeneration directional control valve for constructional vehicles | |
| JPS6059443B2 (en) | Rapid discharge circuit of double-acting hydraulic cylinder | |
| US6453585B1 (en) | Hydraulic drive device of working machine | |
| US5907991A (en) | Quick drop valve control | |
| US3906727A (en) | Hydrostatic drive with direction memory | |
| US3746040A (en) | Directional control valve | |
| JPS59222601A (en) | Oil hydraulic cylinder control device | |
| JPS6058338B2 (en) | Construction machinery engine control device | |
| JP2511629Y2 (en) | Hydraulic circuit | |
| US5003776A (en) | Hydraulic drive system | |
| KR900016555A (en) | Backhoe Hydraulic Circuit | |
| CN115370628A (en) | Rotary hydraulic system, rotary device and working machine | |
| US3776273A (en) | Directional control valve | |
| JPS59121204A (en) | Hydraulic cylinder control device | |
| US3775980A (en) | Hydrostatic transmission | |
| JPH0660644B2 (en) | Hydraulic circuit of hydraulic excavator | |
| US5746108A (en) | Hydraulic control system of transfer system for machine tools | |
| JPS58133451A (en) | Engine controller | |
| JPS59226288A (en) | Hydraulic pressure operating device of piston pump for sending fluid body by pressure | |
| JPH07127601A (en) | Intensifying circuit for oil pressure | |
| JP2006258237A (en) | Hydraulic motor unit | |
| JPH0723588Y2 (en) | Variable pump flow control valve device | |
| JP2000346007A (en) | Two speed hydraulic motor control circuit and sequence valve | |
| JP2871886B2 (en) | Hydraulic circuit of excavator | |
| KR890007173Y1 (en) | Remote control-type excavator having sequence valve |