JPS6128855B2 - - Google Patents
Info
- Publication number
- JPS6128855B2 JPS6128855B2 JP6522981A JP6522981A JPS6128855B2 JP S6128855 B2 JPS6128855 B2 JP S6128855B2 JP 6522981 A JP6522981 A JP 6522981A JP 6522981 A JP6522981 A JP 6522981A JP S6128855 B2 JPS6128855 B2 JP S6128855B2
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- pressure receiving
- control valve
- control
- valve
- 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.)
- Expired
Links
- 238000006073 displacement reaction Methods 0.000 claims description 20
- 230000007423 decrease Effects 0.000 description 6
- 230000007935 neutral effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Fluid Gearings (AREA)
Description
【発明の詳細な説明】
本発明は可変容量油圧ポンプとアクチユエータ
とが閉回路を形成するように接続された油圧系統
の制御装置に関し、特に油圧シヨベルなどの土
木・建設機械に好適なものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a hydraulic system in which a variable displacement hydraulic pump and an actuator are connected to form a closed circuit, and is particularly suitable for civil engineering and construction machines such as hydraulic excavators. .
第1図は従来の油圧系統の制御装置を示す。可
変容量油圧ポンプ1とアクチユエータ2とが主回
路A,Bにより閉回路を形成するように接続さ
れ、アクチユエータ2は負荷3を駆動する。可変
容量油圧ポンプ1は斜板などの押しのけ容積可変
機構4を備え、押しのけ容積可変機構4の位置
は、制御用アクチユエータ5及びサーボ弁6から
成る油圧サーボ機構7によつて制御され、押しの
け容積可変機構4の動差速度は制御弁8によつて
制御される。9は制御油圧源、10A,10Bは
操作レバー、11A,11Bはパイロツト弁、1
2はタンク、13はクロスオーバーリリーフ弁、
14はシヤトル弁である。 FIG. 1 shows a conventional hydraulic system control device. A variable displacement hydraulic pump 1 and an actuator 2 are connected to form a closed circuit through main circuits A and B, and the actuator 2 drives a load 3. The variable displacement hydraulic pump 1 is equipped with a variable displacement mechanism 4 such as a swash plate, and the position of the variable displacement mechanism 4 is controlled by a hydraulic servo mechanism 7 consisting of a control actuator 5 and a servo valve 6. The differential speed of the mechanism 4 is controlled by a control valve 8. 9 is a control hydraulic pressure source, 10A and 10B are operating levers, 11A and 11B are pilot valves, 1
2 is a tank, 13 is a crossover relief valve,
14 is a shuttle valve.
操作レバー10A又は10Bの操作によりパイ
ロツト弁11A又は11Bがパイロツト圧信号を
発生すると、油圧サーボ機構7が動作し、操作レ
バー10A又は10Bの操作量に応じて押しのけ
容積可変機構4の位置を動かす。これによつて、
アクチユエータ2は押しのけ容積可変機構4の位
置に見合う速度で動作しようとするが、例えば負
荷3の慣性が大きい場合には、直ちにその速度に
達することはできず、主回路A又はBの圧力が上
昇する。この圧力はシヤトル弁14を介して制御
弁8に切換圧として導かれ、制御弁8の設定圧力
に達すると、制御弁8を復帰位置8Bから切換位
置8Aに向つて換える。これにつて、制御油圧源
9からサーボ弁6へ供給される制御油の圧力及び
流量が低減し、押しのけ容積可変機構4の動作速
度を小さくする。一般に慣性の大きな負荷を駆動
する際の駆動圧力は駆動流量の変化速度に比例す
るので、この時、主回路A又はBの圧力は低下す
る。このようにして、結局主回路A又はBの圧力
はアクチユエータ2を加速する場合も減速する場
合も制御弁8の設定圧力以下になるように制御さ
れる。したがつて、制御弁8の設定圧力をクロス
オーバーリリーフ弁13のリリーフ設定圧力より
低く設定すれば、負荷3をリリーフによる動力損
失なしに駆動することができ、また負荷3の持つ
動力を回収することができる。 When the pilot valve 11A or 11B generates a pilot pressure signal by operating the operating lever 10A or 10B, the hydraulic servo mechanism 7 operates and moves the position of the variable displacement mechanism 4 in accordance with the amount of operation of the operating lever 10A or 10B. By this,
The actuator 2 tries to operate at a speed commensurate with the position of the variable displacement mechanism 4, but for example, if the inertia of the load 3 is large, it cannot reach that speed immediately and the pressure in the main circuit A or B increases. do. This pressure is led to the control valve 8 as a switching pressure via the shuttle valve 14, and when the set pressure of the control valve 8 is reached, the control valve 8 is switched from the return position 8B to the switching position 8A. In this regard, the pressure and flow rate of the control oil supplied from the control oil pressure source 9 to the servo valve 6 are reduced, and the operating speed of the variable displacement mechanism 4 is reduced. Generally, the driving pressure when driving a load with large inertia is proportional to the rate of change of the driving flow rate, so at this time, the pressure in the main circuit A or B decreases. In this way, the pressure in the main circuit A or B is ultimately controlled to be equal to or lower than the set pressure of the control valve 8 whether the actuator 2 is accelerated or decelerated. Therefore, by setting the set pressure of the control valve 8 lower than the relief set pressure of the crossover relief valve 13, the load 3 can be driven without power loss due to relief, and the power of the load 3 can be recovered. be able to.
しかし、第1図において、主回路A又はBの圧
力が高くて、制御弁8が動作している時に、操作
レバー10A又は10Bを中立位置へ戻す操作を
行つた場合には、制御用アクチユエータ5に供給
される制御油量が制御弁8によつてしぼられてい
る状態であるので、制御弁8が動作していない時
と比較して、応答速度が遅くなる不具合がある。 However, in FIG. 1, when the pressure in the main circuit A or B is high and the control valve 8 is operating, if the operation lever 10A or 10B is returned to the neutral position, the control actuator 5 Since the amount of control oil supplied to the control valve 8 is being throttled by the control valve 8, there is a problem that the response speed is slower than when the control valve 8 is not operating.
例えば、サーボ弁6が切換位置6Aにあつて、
制御用アクチユエータ5のピストンを右方に移動
させつつあり、且つ主回路Aの圧力が上昇して制
御弁8を切換位置8Aへ切り換えた状態におい
て、アクチユエータ2を停止させるために、操作
レバー10Aを中立位置に復帰させると、サーボ
弁6は切換位置6Bとなり、制御用アクチユエー
タ5のピストンは左方へ移動しようとする。しか
し、制御弁8の動作により制御油圧源9からの供
給制御油の圧力及び流量が低減されているので、
制御用アクチユエータ5の移動速度、即ち押しの
け容積可変機構4の動作速度は非常に遅くなる。
このため、主回路Aの圧力の減衰及びそれに続く
主回路Bの圧力の立上りが遅くなり、アクチユエ
ータ2が停止するまでの時間及び作動距離が伸び
る。したがつて操作性が著しく損われ、緊急操作
時に危険が生ずる心配がある。 For example, when the servo valve 6 is in the switching position 6A,
While the piston of the control actuator 5 is being moved to the right and the pressure in the main circuit A has increased and the control valve 8 has been switched to the switching position 8A, the operation lever 10A is pressed to stop the actuator 2. When returned to the neutral position, the servo valve 6 becomes the switching position 6B, and the piston of the control actuator 5 attempts to move to the left. However, since the pressure and flow rate of the control oil supplied from the control oil pressure source 9 are reduced by the operation of the control valve 8,
The moving speed of the control actuator 5, that is, the operating speed of the variable displacement mechanism 4 becomes extremely slow.
Therefore, the attenuation of the pressure in the main circuit A and the subsequent rise in the pressure in the main circuit B are delayed, and the time and operating distance until the actuator 2 stops is extended. Therefore, operability is significantly impaired, and there is a concern that danger may occur during emergency operations.
本発明の目的は、上述した間題点を解決し、制
御弁の動作に起因する可変容量油圧ポンプの作動
遅れを解消し、操作性を向上させることができる
油圧系統の制御装置を提供することである。 SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic system control device that can solve the above-mentioned problems, eliminate delays in the operation of a variable displacement hydraulic pump caused by the operation of a control valve, and improve operability. It is.
この目的を達成するために、本発明は、制御弁
に、高圧側の主回路の圧力が導かれる第1受圧部
と、第1受圧部に対抗する第2受圧部と、第2受
圧部に対抗する第3受圧部とを設け、第2受圧部
に操作信号に合致したパイロツト圧信号を時間遅
れ手段を経て導き、第3受圧部に操作信号に合致
したパイロツト圧信号を導くようにして、加速操
作中に減速操作に切り換えた場合に制御弁を復帰
方向に制御するようにしたことを特徴とする。 In order to achieve this object, the present invention provides a control valve with a first pressure receiving part to which the pressure of the main circuit on the high pressure side is introduced, a second pressure receiving part opposing the first pressure receiving part, and a second pressure receiving part. a third opposing pressure receiving part is provided, a pilot pressure signal matching the operating signal is guided to the second pressure receiving part through a time delay means, and a pilot pressure signal matching the operating signal is guided to the third pressure receiving part, The present invention is characterized in that the control valve is controlled in the return direction when switching to deceleration operation during acceleration operation.
なお、本発明において、操作信号に合致するパ
イロツト圧信号とは、操作信号にパイロツト圧信
号が用いられている場合には操作信号そのもの
を、操作信号に機械的変位信号や電気信号が用い
られている場合には操作信号に比例したパイロツ
ト圧信号を、意味する。 In the present invention, the pilot pressure signal that matches the operation signal refers to the operation signal itself when the pilot pressure signal is used as the operation signal, and the operation signal itself when the operation signal uses a mechanical displacement signal or an electrical signal. means a pilot pressure signal proportional to the operating signal.
以下、本発明を図示の実施例に基づいて詳細に
説明する。 Hereinafter, the present invention will be explained in detail based on illustrated embodiments.
第2図は本発明の一実施例を示す。第1図と同
様は部分は同一符号にて示す。制御弁8の復帰位
置8Bと切換位置8Aとは非連続的に区分された
位置ではなく、復帰位置8Bと切換位置8Aとの
途中では制御油圧源9からの制御油量はしぼられ
た状態で連続的に変化する。制御弁8には、シヤ
トル弁14により取り出された高圧側の主回路A
又はBの圧力が導かれる第1受圧部8aと、第1
受圧部8aに対抗する第2受圧部8bと第2受圧
部8bに対抗する第3受圧部8cとが設けられ
る。第2受圧部8bには、パイロツト弁10A又
は10Bからのパイロツト圧信号がシヤトル弁1
5及び時間遅れ手段16を経て導かれ、第3受圧
部8cにはパイロツト圧信号がシヤトル弁15を
経て導かれる。時間遅れ手段16は例えば蓄圧器
17としぼり18とから成る。 FIG. 2 shows an embodiment of the invention. Components similar to those in FIG. 1 are designated by the same reference numerals. The return position 8B and the switching position 8A of the control valve 8 are not discontinuously separated positions, and the amount of control oil from the control oil pressure source 9 is reduced in the middle between the return position 8B and the switching position 8A. Continuously changing. The control valve 8 has a main circuit A on the high pressure side taken out by the shuttle valve 14.
or the first pressure receiving part 8a to which the pressure of B is introduced, and the first
A second pressure receiving section 8b opposing the pressure receiving section 8a and a third pressure receiving section 8c opposing the second pressure receiving section 8b are provided. A pilot pressure signal from the pilot valve 10A or 10B is transmitted to the second pressure receiving portion 8b.
5 and time delay means 16, and a pilot pressure signal is guided to the third pressure receiving portion 8c via the shuttle valve 15. The time delay means 16 comprises, for example, a pressure accumulator 17 and a throttle 18.
動作について説明する。操作レバー10Aの操
作によりパイロツト弁11Aがパイロツト圧信号
を出力すると、サーボ弁6が切換位置6Aに切り
換えられ、制御油圧源9からの制御油は制御弁8
の復帰位置8B及びサーボ弁6の切換位置6Aを
通つて、制御用アクチユエータ5の左側油室5A
に入り、ピストンを右方に移動させる。これによ
つて押しのけ容積可変機構4の位置は中立位置か
ら主回路A側に吐出する方向に移動し、可変容量
油圧ポンプ1は主回路Aに圧油を吐き出す。した
がつて、アクチユエータ2は駆動される。 The operation will be explained. When the pilot valve 11A outputs a pilot pressure signal by operating the control lever 10A, the servo valve 6 is switched to the switching position 6A, and the control oil from the control oil pressure source 9 is transferred to the control valve 8.
The left oil chamber 5A of the control actuator 5 passes through the return position 8B of the servo valve 6 and the switching position 6A of the servo valve 6.
Enter and move the piston to the right. As a result, the position of the variable displacement mechanism 4 moves from the neutral position in the direction of discharging pressure oil to the main circuit A side, and the variable displacement hydraulic pump 1 discharges pressure oil to the main circuit A. Therefore, the actuator 2 is driven.
同時にパイロツト弁11Aのパイロツト圧信号
は第2受圧部8bには時間遅れ手段16を経るた
め遅れて伝えられ、第3受圧部8cには直ちに伝
えられる。このため、遅れ時間中は、第2受圧部
8bと第3受圧部8cとの圧力差が第1受圧部8
aの作用を助勢し、制御弁8の設定圧力はばねに
より設定される値より低い値となる。第2受圧部
8bの圧力が上昇することにより制御弁8の設定
圧力はばねにより設定される値に徐々に達する。 At the same time, the pilot pressure signal of the pilot valve 11A is transmitted to the second pressure receiving section 8b with a delay because it passes through the time delay means 16, and is immediately transmitted to the third pressure receiving section 8c. Therefore, during the delay time, the pressure difference between the second pressure receiving part 8b and the third pressure receiving part 8c is reduced to the first pressure receiving part 8.
This assists the action of a, and the set pressure of the control valve 8 becomes a value lower than the value set by the spring. As the pressure in the second pressure receiving part 8b increases, the set pressure of the control valve 8 gradually reaches the value set by the spring.
遅れ時間中及び遅れ時間後において、主回路A
の圧力が設定圧力より大きくなると、第1受圧部
8aが主回路Aの圧力を受けることによつて制御
弁8を切換位置8Aへ移動させ、制御油圧源9か
らの制御油の流量をしぼるので、押しのけ容積可
変機構4の動作速度は小さくなり、主回路Aの圧
力は設定圧力以下になる。この時には制御弁8の
出力側の圧力は制御油圧源9の圧力タンク圧力の
中間の所定圧力となつている。 During and after the delay time, main circuit A
When the pressure becomes higher than the set pressure, the first pressure receiving part 8a receives the pressure of the main circuit A, moves the control valve 8 to the switching position 8A, and reduces the flow rate of the control oil from the control oil pressure source 9. , the operating speed of the variable displacement mechanism 4 decreases, and the pressure in the main circuit A becomes below the set pressure. At this time, the pressure on the output side of the control valve 8 is a predetermined pressure that is between the pressure tank pressure of the control hydraulic pressure source 9.
この状態から操作レバー10Aを中立位置方向
へ戻すと、パイロツト弁11Aからのパイロツト
圧信号の大きさが低下し、第3受圧部8cが受け
ている圧力は即座に低下する。一方、第2受圧部
8bが受ける圧力は時間遅れ手段16の働きによ
り徐々に低下する。この圧力差は第1受圧部8a
の作用に対抗する力として働き、制御弁8は復帰
位置8Bへ復帰する。したがつて、制御油圧源9
から油圧サーボ機構7へ供給される制御油の圧力
及び流量は増大し、押しのけ容積可変機構4の動
作速度は速くなり、主回路Aの圧力は速やかに減
衰し、主回路Bの圧力は速やかに立ち上がり、作
動遅れは生じない。また、前述したように、操作
レバー10A又は10Bを中立位置から操作した
時に、制御弁8の設定圧力は低い値から徐々に上
昇して、ばねにより設定される規定の設定圧力に
達するので、アクチユエータ2の起動をなめらか
にすることができる。 When the operating lever 10A is returned to the neutral position from this state, the magnitude of the pilot pressure signal from the pilot valve 11A decreases, and the pressure being received by the third pressure receiving portion 8c immediately decreases. On the other hand, the pressure received by the second pressure receiving portion 8b gradually decreases due to the action of the time delay means 16. This pressure difference is caused by the first pressure receiving part 8a
The control valve 8 returns to the return position 8B. Therefore, the control hydraulic source 9
The pressure and flow rate of control oil supplied to the hydraulic servo mechanism 7 from There is no delay in startup or operation. Further, as described above, when the operating lever 10A or 10B is operated from the neutral position, the set pressure of the control valve 8 gradually increases from a low value and reaches the specified set pressure set by the spring, so that the actuator 2 can be started smoothly.
時間遅れ手段16は蓄圧器17及びしぼり18
に限定されるものではなく、他の種々のものを用
いることができる。サーボ弁6は操作レバーによ
つて直接操作されるものでもよい。その場合には
サーボ弁6の操作レバーにパイロツト弁11A,
11Bが連動するようにする。またサーボ弁6は
電気信号によつて操作されるものでよく、この場
合、パイロツト弁11A,11Bも同じ電気信号
によつて操作されるようにする。 The time delay means 16 includes a pressure accumulator 17 and a throttle 18.
It is not limited to this, and various other types can be used. The servo valve 6 may be directly operated by an operating lever. In that case, the pilot valve 11A is installed on the operating lever of the servo valve 6.
11B will be linked. Further, the servo valve 6 may be operated by an electric signal, and in this case, the pilot valves 11A and 11B are also operated by the same electric signal.
以上説明したように、本発明によれば、制御弁
に、高圧側の主回路の圧力が導かれる第1受圧部
の他に、第1受圧部に対抗する第2受圧部と、第
2受圧部に対抗する第3受圧部を設け、第2受圧
部に操作信号に合致したパイロツト圧信号を時間
遅れ手段を導き、第3受圧部に操作信号に合致し
たパイロツト圧信号を導くようにして、操作信号
の大きさが低下することに応じて時間遅れ手段の
遅れ時間だけ第2受圧部の作用により制御弁を復
帰位置方向へ戻すようにしたから、制御弁の動作
に起因する可変容量油圧ポンプの作動遅れを解消
することができ、操作性を向上させることができ
る。したがつて、緊急操作時の安全性を増すこと
ができる。また、起動時に、時間遅れ手段の遅れ
時間だけ第3受圧部が第2受圧部より早くパイロ
ツト圧信号を受けることによつて、制御弁の設定
圧力を低い値にするようにしたから、アクチユエ
ータの起動をなめらかにすることができる。 As explained above, according to the present invention, the control valve includes, in addition to the first pressure receiving part to which the pressure of the high pressure side main circuit is introduced, the second pressure receiving part opposing the first pressure receiving part, and the second pressure receiving part. A third pressure receiving part is provided opposite to the second pressure receiving part, the time delay means guides a pilot pressure signal matching the operating signal to the second pressure receiving part, and a pilot pressure signal matching the operating signal is guided to the third pressure receiving part, Since the control valve is returned to the return position by the action of the second pressure receiving part by the delay time of the time delay means in response to the decrease in the magnitude of the operation signal, the variable displacement hydraulic pump due to the operation of the control valve is It is possible to eliminate the delay in operation and improve operability. Therefore, safety during emergency operations can be increased. Furthermore, at startup, the third pressure receiving section receives the pilot pressure signal earlier than the second pressure receiving section by the delay time of the time delay means, thereby lowering the set pressure of the control valve to a low value. It can make startup smoother.
第1図は従来の油圧系統の制御装置の回路図、
第2図は本発明の一実施例の回路図である。
1……可変容量油圧ポンプ、2……アクチユエ
ータ、4……押しのけ容積可変機構、7……油圧
サーボ機構、8……制御弁、8a……第1受圧
部、8b……第2受圧部、8c……第3受圧部、
9……制御油圧源、11A,11B……パイロツ
ト弁、16……時間遅れ手段、A,B……主回
路。
Figure 1 is a circuit diagram of a conventional hydraulic system control device.
FIG. 2 is a circuit diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Variable displacement hydraulic pump, 2... Actuator, 4... Variable displacement mechanism, 7... Hydraulic servo mechanism, 8... Control valve, 8a... First pressure receiving part, 8b... Second pressure receiving part, 8c...Third pressure receiving part,
9... Control hydraulic power source, 11A, 11B... Pilot valve, 16... Time delay means, A, B... Main circuit.
Claims (1)
回路により閉回路を形成するように接続された油
圧系統に対して、可変容量油圧ポンプの押しのけ
容積可変機構の位置を操作信号によつて制御する
油圧サーボ機構と、主回路の圧力に応じて油圧サ
ーボ機構への制御油の供給を制御する制御弁とを
備えた油圧系統の制御装置において、制御弁に、
高圧側の主回路の圧力が導かれる第1受圧部と、
第1受圧部に対抗する第2受圧部と、第2受圧部
に対抗する第3受圧部とを設け、第2受圧部に操
作信号に合致したパイロツト圧信号を時間遅れ手
段を経て導き、第3受圧部に操作信号に合致した
パイロツト圧信号を導くようにしたことを特徴と
する油圧系統の制御装置。1. A hydraulic servo mechanism that controls the position of the variable displacement mechanism of the variable displacement hydraulic pump using an operation signal for a hydraulic system in which the variable displacement hydraulic pump and the actuator are connected to form a closed circuit through a main circuit. and a control valve that controls the supply of control oil to the hydraulic servo mechanism according to the pressure of the main circuit, the control valve includes:
a first pressure receiving part to which the pressure of the main circuit on the high pressure side is guided;
A second pressure receiving section opposing the first pressure receiving section and a third pressure receiving section opposing the second pressure receiving section are provided, and a pilot pressure signal matching the operation signal is guided to the second pressure receiving section via a time delay means. 3. A control device for a hydraulic system, characterized in that a pilot pressure signal matching an operation signal is guided to a pressure receiving section.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6522981A JPS57184748A (en) | 1981-05-01 | 1981-05-01 | Apparatus for controlling hydraulic system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6522981A JPS57184748A (en) | 1981-05-01 | 1981-05-01 | Apparatus for controlling hydraulic system |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS57184748A JPS57184748A (en) | 1982-11-13 |
JPS6128855B2 true JPS6128855B2 (en) | 1986-07-03 |
Family
ID=13280873
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP6522981A Granted JPS57184748A (en) | 1981-05-01 | 1981-05-01 | Apparatus for controlling hydraulic system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS57184748A (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5160245A (en) * | 1991-05-01 | 1992-11-03 | Sauer, Inc. | Displacement control feedback apparatus and method |
US5205201A (en) * | 1991-08-19 | 1993-04-27 | Sauer, Inc. | Displacement control valve |
US5561979A (en) * | 1995-02-17 | 1996-10-08 | Caterpillar Inc. | Control arrangement for a hydrostatic system |
DE19625393A1 (en) * | 1996-05-22 | 1998-01-02 | Brueninghaus Hydromatik Gmbh | Slewing gear control with double-sided braking |
-
1981
- 1981-05-01 JP JP6522981A patent/JPS57184748A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS57184748A (en) | 1982-11-13 |
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