JPH04102762A - Hydraulic circuit for closed-circuit hydraulic transmission - Google Patents
Hydraulic circuit for closed-circuit hydraulic transmissionInfo
- Publication number
- JPH04102762A JPH04102762A JP2218096A JP21809690A JPH04102762A JP H04102762 A JPH04102762 A JP H04102762A JP 2218096 A JP2218096 A JP 2218096A JP 21809690 A JP21809690 A JP 21809690A JP H04102762 A JPH04102762 A JP H04102762A
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- Prior art keywords
- hydraulic
- pressure
- circuit
- valve
- pressure oil
- 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
- 230000005540 biological transmission Effects 0.000 title claims description 25
- 230000007935 neutral effect Effects 0.000 claims abstract description 33
- 238000001514 detection method Methods 0.000 claims description 16
- 238000006073 displacement reaction Methods 0.000 claims description 15
- 239000003921 oil Substances 0.000 description 44
- 230000008602 contraction Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、可変容量型油圧ポンプと油圧モータを閉回路
接続した油圧トランスミッションを左右一対備えた油圧
駆動車両における閉回路油圧トランスミッションの油圧
回路、特に車両停止時に閉回路を構成する第１・第２主
回路を短絡する中立バイパス弁と駐車ブレーキに関する
。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic circuit of a closed circuit hydraulic transmission in a hydraulically driven vehicle equipped with a pair of left and right hydraulic transmissions in which a variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit; In particular, the present invention relates to a neutral bypass valve and a parking brake that short-circuit the first and second main circuits forming a closed circuit when the vehicle is stopped.
特開昭５８−１２８５５８号公報に示す閉回路油圧トラ
ンスミッションの油圧回路が知られている。A hydraulic circuit for a closed circuit hydraulic transmission disclosed in Japanese Patent Application Laid-open No. 58-128558 is known.
つまり、可変容量型油圧ポンプと油圧モータを第１・第
２主回路で閉回路接続した油圧トランスミッションを左
右一対設け、左右の油圧トランスミッションの可変容量
型油圧ポンプの容量、吐出方向を制御して左右の油圧ト
ランスミッションの回転速度、回転速度を異ならせるこ
とで前進、後進、左右旋回走行する油圧回路である。In other words, a pair of left and right hydraulic transmissions are provided, in which a variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit through the first and second main circuits, and the capacity and discharge direction of the variable displacement hydraulic pumps of the left and right hydraulic transmissions are controlled. This is a hydraulic circuit that allows the vehicle to travel forward, backward, and turn left and right by varying the rotational speed of the hydraulic transmission.
かかる油圧回路においては車両停止時に左右可変容量型
ポンプの容量をゼロとして左右油圧モータを停止してい
るが、左右可変容量型ポンプの容量制御レバーを操作し
てから容量がゼロになるまでに時間遅れがあるので、例
えば実開昭５６−１５５９３２号公報に示すように左右
油圧トランスミッションの閉回路を構成する第１・第２
主回路を中立バイパス弁で短絡して左右油圧モータを停
止させている。In such a hydraulic circuit, when the vehicle is stopped, the capacity of the left and right variable displacement pumps is set to zero and the left and right hydraulic motors are stopped.However, it takes time after the capacity control lever of the left and right variable displacement pumps is operated until the capacity becomes zero. Since there is a delay, for example, as shown in Japanese Utility Model Application Publication No. 56-155932, the first and second
The main circuit is shorted with a neutral bypass valve to stop the left and right hydraulic motors.
前述の中立バイパス弁は油圧モータのブレーキ制御圧力
を利用して駐車ブレーキを制動する時に開とし、駐車ブ
レーキを解放する時に閉としているので、中立バイパス
弁と駐車ブレーキは連動して作動する。The neutral bypass valve described above is opened when the parking brake is applied using the brake control pressure of the hydraulic motor, and closed when the parking brake is released, so the neutral bypass valve and the parking brake operate in conjunction.
他方、車両発進時には中立バイパス弁を閉としてから駐
車ブレーキを解放しないと坂道発進時に車両が一担降板
するので危険であり、車両停止時には駐車ブレーキを制
動してから中立バイパス弁を開としないと坂道停止時に
車両が−担降するので危険である。On the other hand, when starting the vehicle, the neutral bypass valve must be closed before the parking brake is released, otherwise when starting on a slope the vehicle will dismount, which is dangerous.When the vehicle is stopped, the parking brake must be applied before opening the neutral bypass valve. It is dangerous because the vehicle will be lifted off the ground when stopped on a slope.
しかしながら、前述のように従来の中立バイパス弁はブ
レーキ制御圧力を利用して開・閉しているので、前述の
ように中立バイパス弁と駐車ブレーキの作動順序を２通
り満足することはできない。However, as described above, since the conventional neutral bypass valve opens and closes using brake control pressure, it is not possible to satisfy the two operating orders of the neutral bypass valve and the parking brake as described above.
そこで、本発明は前述の課題を解決できるようにした閉
回路油圧トランスミッションの油圧回路を提供すること
を目的とする。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic circuit for a closed-circuit hydraulic transmission that can solve the above-mentioned problems.
〔課題を解決するための手段及び作用〕閉回路を構成す
る第１・第２主回路を連通。[Means and effects for solving the problem] The first and second main circuits forming a closed circuit are communicated.
遮断する中立バイパス弁と駐車ブレーキを制動。Shuts off the neutral bypass valve and brakes the parking brake.
解放する切換弁を、可変容量型油圧ポンプの容量を変更
する圧油で切換作動し、その圧油が供給される圧力検出
回路にスローリターン弁を設けてブレーキ保持圧が圧力
検出回路よりゆっくり排出され、車両発進時には第１・
第２主回路が遮断された後に駐車ブレーキが解放状態と
なり、車両停止時には駐車ブレーキが制動状態となった
後に第１・第２主回路が連通ずるようにしたものである
。The switching valve to be released is operated by pressure oil that changes the capacity of the variable displacement hydraulic pump, and a slow return valve is installed in the pressure detection circuit to which the pressure oil is supplied, so that the brake holding pressure is slowly discharged from the pressure detection circuit. When the vehicle starts, the first
After the second main circuit is cut off, the parking brake is brought into a released state, and when the vehicle is stopped, the first and second main circuits are brought into communication after the parking brake is brought into a braking state.
以下本発明の実施例を図面を参照して説明する。 Embodiments of the present invention will be described below with reference to the drawings.
第１図に示すように、左油圧トランスミッションＡと右
油圧トランスミッションＢと操向操作部Ｃとより閉回路
油圧トランスミッションを構成し、操向操作部Ｃを操作
することで左右油圧トランスミッションＡ、Ｂの回転速
度９回転方向を制御することで左スプロケットＤと右ス
プロケットＥを回転して直進、旋回走行するようにしで
ある。As shown in Fig. 1, a left hydraulic transmission A, a right hydraulic transmission B, and a steering operation section C constitute a closed-circuit hydraulic transmission, and by operating the steering operation section C, the left and right hydraulic transmissions A and B can be operated. By controlling the rotation speed 9 and the direction of rotation, the left sprocket D and the right sprocket E are rotated to move straight and turn.
前記左油圧トランスミッションＡは左可変容量型油圧ポ
ンプ１（以下左油圧ポンプ１という）と左油圧モータ２
を左第１．第２主回路３，４で閉回路接続して成り、右
油圧トランスミッションＢは右可変容量型油圧ポンプ５
（以下右油圧ポンプ５という）と右油圧モータ６を右第
１・第２主回路７，８で閉回路接続しである。The left hydraulic transmission A includes a left variable displacement hydraulic pump 1 (hereinafter referred to as left hydraulic pump 1) and a left hydraulic motor 2.
1 on the left. The second main circuit 3 and 4 are connected in a closed circuit, and the right hydraulic transmission B is connected to the right variable displacement hydraulic pump 5.
(hereinafter referred to as right hydraulic pump 5) and right hydraulic motor 6 are connected in a closed circuit through right first and second main circuits 7 and 8.
前記左右油圧ポンプ１，５は斜板１ａ、５ｇの角度を変
更することで容量、つまり１回転当り吐出量を可変とす
る斜板式の可変容量型油圧ポンプとなり、その斜板１ａ
、５ａは左右サーボシリンダ９，１０で傾動され、左右
サーボシリンダ９．１０には左右制御弁１１．１２によ
って補助油圧ポンプ１３の吐出圧油が供給される。The left and right hydraulic pumps 1 and 5 are variable displacement hydraulic pumps of the swash plate type in which the capacity, that is, the discharge amount per rotation, can be varied by changing the angles of the swash plates 1a and 5g.
, 5a are tilted by left and right servo cylinders 9, 10, and the left and right servo cylinders 9.10 are supplied with pressure oil discharged from an auxiliary hydraulic pump 13 by left and right control valves 11.12.
前記操向操作部Ｃは油圧パイロット弁１４となり、その
油圧パイロット弁１４は１本のレバー１５を前後に揺動
することで第１・第２減圧弁１６．１７を作動し、レバ
ー１５を左右に揺動すると第３・第４減圧弁１８．１９
を作動する構成であり、各減圧弁は前記補助油圧ポンプ
１３の吐出圧油をレバー１５の操作ストロークに比例し
て出力する構成である。The steering operation section C becomes a hydraulic pilot valve 14, and the hydraulic pilot valve 14 operates the first and second pressure reducing valves 16 and 17 by swinging one lever 15 back and forth, and the lever 15 is moved left and right. 3rd and 4th pressure reducing valves 18.19
Each pressure reducing valve is configured to output pressure oil discharged from the auxiliary hydraulic pump 13 in proportion to the operation stroke of the lever 15.
次に各部の詳細を説明する。Next, details of each part will be explained.
前記左第１・第２主回路３，４には一対のチエツク弁２
０．２０を介して左チャージ回路２１が接続し、左高圧
回路２２と左低圧回路２３が左シャトル弁２４で高圧側
主回路、低圧側主路に接続されて左第１・第２主回路３
，４における高圧油を左高圧回路２２に、低圧油を左低
圧回路２３にそれぞれ導入できるようにしである。A pair of check valves 2 are provided in the left first and second main circuits 3 and 4.
0.20, the left charge circuit 21 is connected, and the left high pressure circuit 22 and left low pressure circuit 23 are connected to the high pressure side main circuit and the low pressure side main path through the left shuttle valve 24, and the left first and second main circuits are connected. 3
, 4 can be introduced into the left high pressure circuit 22 and low pressure oil can be introduced into the left low pressure circuit 23, respectively.
前記右第１・第２主回路７，８には一対のチエツク弁２
５．２５を介して右チャージ回路２Ｂが接続し、右高圧
回路２７と右低圧回路２３が右シャトル弁２９で高圧側
主回路、低圧側主路に接続されて右第１・第２主回路７
．８における高圧油を右高圧回路２７に、低圧油を右低
圧回路２８にそれぞれ導入できるようにしである。A pair of check valves 2 are provided in the right first and second main circuits 7 and 8.
5.25, the right charge circuit 2B is connected, and the right high pressure circuit 27 and right low pressure circuit 23 are connected to the high pressure side main circuit and the low pressure side main path by the right shuttle valve 29, and the right first and second main circuits are connected. 7
．． The high-pressure oil at 8 can be introduced into the right high-pressure circuit 27 and the low-pressure oil can be introduced into the right low-pressure circuit 28, respectively.
前記左チャージ回路２１と右チャージ回路２６は前記補
助油圧ポンプ１３の吐出路１３ａに接続し、かつ安全弁
３０が設けである。The left charge circuit 21 and the right charge circuit 26 are connected to the discharge passage 13a of the auxiliary hydraulic pump 13, and are provided with a safety valve 30.
前記左高圧回路２２と右高圧回路２７は一対のチエツク
弁３１．３１を介して接続し、さらに左高圧回路２２と
右高圧回路２７における前記一対のチエツク弁３１．３
１の入口側がイコライズ弁３２を介して連通している。The left high voltage circuit 22 and the right high voltage circuit 27 are connected via a pair of check valves 31.31, and the pair of check valves 31.3 in the left high voltage circuit 22 and the right high voltage circuit 27 are connected to each other via a pair of check valves 31.31.
The inlet side of the valve 1 is connected to the valve 1 through an equalization valve 32.
該イコライズ弁３２は左右高圧回路２２．２７の左右高
圧油の圧力差がない時には絞り３２ａを有する連通位置
ａに保持され、圧力差がある時には遮断位置すに切換わ
る構成となっている。The equalizing valve 32 is held at the communicating position a with the throttle 32a when there is no pressure difference between the left and right high pressure oils in the left and right high pressure circuits 22, 27, and is switched to the blocking position when there is a pressure difference.
前記左低圧回路２３と右低圧回路２８は接続し、かつ低
圧リリーフ弁３３．オイルクーラ３４を経て前記左右油
圧モータ２，６の冷却回路２ａ。The left low pressure circuit 23 and the right low pressure circuit 28 are connected, and the low pressure relief valve 33. The cooling circuit 2a for the left and right hydraulic motors 2, 6 passes through the oil cooler 34.
６ａに接続している。Connected to 6a.
前記左右高圧回路２２．２７における一対のチエツク弁
３１．３１間は中立バイパス弁３５で前記左右チャージ
回路２１，２６、つまり補助油圧ポンプ１３の吐出路１
３ａに接続し、かつ安全弁３６で前記低圧゛リリーフ弁
３３の入口側に接続している。A neutral bypass valve 35 is connected between the pair of check valves 31 and 31 in the left and right high pressure circuits 22 and 27 to connect the left and right charge circuits 21 and 26, that is, the discharge path 1 of the auxiliary hydraulic pump 13.
3a, and is connected to the inlet side of the low pressure relief valve 33 through a safety valve 36.
前記中立バイパス弁３５はバネ３５ａで連通位置Ｃに保
持され、受圧部３５ｂのパイロット圧油で遮断位置ｄに
切換わる構成である。The neutral bypass valve 35 is held in the communication position C by a spring 35a, and is switched to the cutoff position d by pilot pressure oil in the pressure receiving part 35b.
前記安全弁３０の低圧側は左右油圧ポンプ１゜５の冷却
回路１ｂ、５ｂに接続している。The low pressure side of the safety valve 30 is connected to the cooling circuits 1b and 5b of the left and right hydraulic pumps 1.5.
前記左右制御弁１１．１２はバネ力でドレーン位置ｅに
保持され、第１・第２受圧部１１ａ。The left and right control valves 11.12 are held at the drain position e by spring force, and the first and second pressure receiving portions 11a.
１１ｂ、１２ａ、１２ｂと第３・第４受圧部１１ｃ、ｌ
ｉｄ、１２ｃ、１２ｄのパイｏ−７ト圧油の圧力差で前
進位置ｆ、後進位置ｇに切換えられる構成となり、左右
制御弁１１．１２が前進位置ｆとなると前記補助油圧ポ
ンプ１３の吐出圧油が左右サーボシリンダ９，１０のＷ
４１室９ａ、１０ａに供給されて左右油圧モータ１゜５
の斜板１ａ、５ａが前進側に傾動して左右第１主回路３
．７に高圧油を吐出し、左右油圧モータ２，６が正転し
て車両は前進し、左右制御弁１１．１２が後進位置ｇと
なると補助油圧ポンプ１３の吐出圧油が左右サーボシリ
ンダ９゜１０の第２室９ｂ、１０ｂに供給されて左右油
圧モータ１，５の斜板１ａ、５ｂが後進側傾動して左右
第２主回路４．８に高圧油を吐出し、左右油圧モータ２
，６が逆転して車両は後進する。11b, 12a, 12b and the third and fourth pressure receiving parts 11c, l
The structure is such that the forward position f and the reverse position g are switched by the pressure difference between the pipe O-7 pressure oils of id, 12c, and 12d, and when the left and right control valves 11 and 12 are in the forward position f, the discharge pressure of the auxiliary hydraulic pump 13 changes. Oil is in W of left and right servo cylinders 9 and 10.
41 Chambers 9a and 10a are supplied to the left and right hydraulic motors 1°5
The swash plates 1a and 5a tilt toward the forward side, and the left and right first main circuits 3
．． 7, the left and right hydraulic motors 2 and 6 rotate forward, and the vehicle moves forward. When the left and right control valves 11 and 12 reach the reverse position g, the pressure oil discharged from the auxiliary hydraulic pump 13 is applied to the left and right servo cylinders 9 degrees. 10 second chambers 9b, 10b, the swash plates 1a, 5b of the left and right hydraulic motors 1, 5 tilt to the reverse side, and discharge high pressure oil to the left and right second main circuits 4.8.
, 6 are reversed and the vehicle moves backward.
前記油圧パイロット弁１４の各減圧弁の入口ポート４０
は第１切換弁４１．ダブルチエツク弁４２を介して前記
補助油圧ポンプ１３の吐出路１３ａに接続し、その入口
ポート４０はレバー１５を操作しない時には遮断され、
レバー１５を操作することで出口ボート４３に連通され
、第１減圧弁１６の出口ポート４３に第１パイロツト路
４４が接続され、第２・第３・第４減圧弁１７．１８．
１９の出口ボート４３に第２・第３・第４パイロット路
４５，４６．４７がそれぞれ接続しである。Inlet port 40 of each pressure reducing valve of the hydraulic pilot valve 14
is the first switching valve 41. It is connected to the discharge passage 13a of the auxiliary hydraulic pump 13 via a double check valve 42, and its inlet port 40 is shut off when the lever 15 is not operated.
By operating the lever 15, it is communicated with the outlet boat 43, the first pilot passage 44 is connected to the outlet port 43 of the first pressure reducing valve 16, and the second, third, fourth pressure reducing valves 17, 18, .
The second, third, and fourth pilot paths 45, 46, and 47 are connected to the exit boat 43 of No. 19, respectively.
なお、第１・第２減圧弁１６．１７のタンクポート４８
は絞り４９を経てタンク側に接続している。In addition, the tank port 48 of the first and second pressure reducing valves 16 and 17
is connected to the tank side through a throttle 49.
前記第１パイロツト路４４は左制御弁１１の第１受圧部
１１ａと右制御弁１２の第１受圧部１２ａに接続し、第
２パイロツト路４５は左制御弁１１の第３受圧部１１ｃ
と右制御弁１２の第３受圧部１２ｃに接続し、第３パイ
ロツト路４６は左制御弁１１の第２・第４受圧部１１ｂ
。The first pilot passage 44 is connected to the first pressure receiving part 11a of the left control valve 11 and the first pressure receiving part 12a of the right control valve 12, and the second pilot passage 45 is connected to the third pressure receiving part 11c of the left control valve 11.
and the third pressure receiving portion 12c of the right control valve 12, and the third pilot path 46 is connected to the second and fourth pressure receiving portions 11b of the left control valve 11.
.
ｌｉｄに接続し、第４パイロツト路４７は右制御弁１２
の第２・第４受圧部１２ｂ、１２ｄに接続している。The fourth pilot passage 47 is connected to the right control valve 12.
It is connected to the second and fourth pressure receiving parts 12b and 12d.
これにより、レバー１５は前側に揺動して第１減圧弁１
６を作動すると第１パイロツト４４から左右制御弁１１
．１２の第１受圧部１１ａ。As a result, the lever 15 swings forward and the first pressure reducing valve 1
6, the left and right control valves 11 are operated from the first pilot 44.
．． 12 first pressure receiving portions 11a.
１２ａにパイロット圧油が供給されて左右制御弁１１．
１２が前進位置ｆとなるので、前述のように車両は前進
する。Pilot pressure oil is supplied to the left and right control valves 11.12a.
12 is the forward position f, so the vehicle moves forward as described above.
レバー１５を後側に揺動して第２減圧弁１７を作動する
と第２パイロツト路４５から左右制御弁１１．１２の第
３受圧部１１ｃ、１２ｃにパイロット圧油が供給されて
左右制御弁１１゜１２が後進位置ｇとなるので、前述の
ように車両は後進する。When the lever 15 is swung rearward to operate the second pressure reducing valve 17, pilot pressure oil is supplied from the second pilot passage 45 to the third pressure receiving portions 11c and 12c of the left and right control valves 11.12. Since °12 is the reverse position g, the vehicle travels backward as described above.
レバー１５は斜め左側前方に揺動して第１・第３減圧弁
１６．１８を作動すると、第１・第３パイロット路４４
．４６にパイロット圧油が供給されて左右制御弁１１．
１２の第１受圧部１１ａ、１２ａと左制御弁第２・第４
受圧部１１ｂ、ｌｉｄにパイロット圧油がそれぞれ供給
され、左右制御弁１１．１２は前進位置ｆに切換えられ
るが、左制御弁１１の切換えストロークが右制御弁１２
の切換えストロークより短かくなって左油圧ポンプ１の
斜板角度が右油圧ポンプ５の斜板角度より小さくなって
容量が少なくなり、左油圧トランスミッションＡの回転
速度が右油圧トランスミッションＢの回転速度より遅く
なるので、車両は前進左旋回走行する。When the lever 15 swings diagonally forward to the left and operates the first and third pressure reducing valves 16 and 18, the first and third pilot passages 44
．． Pilot pressure oil is supplied to the left and right control valves 11.
12 first pressure receiving parts 11a, 12a and the second and fourth left control valves
Pilot pressure oil is supplied to the pressure receiving part 11b and the lid, respectively, and the left and right control valves 11.12 are switched to the forward position f, but the switching stroke of the left control valve 11 is the same as that of the right control valve 12.
As a result, the swash plate angle of the left hydraulic pump 1 becomes smaller than the swash plate angle of the right hydraulic pump 5, resulting in a smaller capacity, and the rotation speed of the left hydraulic transmission A becomes lower than the rotation speed of the right hydraulic transmission B. As the speed becomes slower, the vehicle moves forward and turns left.
レバー１５を斜め左側後方に揺動して第２・第３減圧弁
１７．’１８を作動すると前述と同様に左右制御弁１１
．１２が後進位置ｇとなると共に、左制御弁１１の切換
えストロークが右制御弁１２の切換えストロークより短
かくなって左油圧ポンプ１の容量が右油圧ポンプ５の容
量より少なくなるので、車両は後進左旋回走行する。Swing the lever 15 diagonally to the left and rear to release the second and third pressure reducing valves 17. When '18 is activated, the left and right control valves 11
．． 12 becomes the reverse position g, the switching stroke of the left control valve 11 becomes shorter than the switching stroke of the right control valve 12, and the capacity of the left hydraulic pump 1 becomes smaller than the capacity of the right hydraulic pump 5, so the vehicle moves in reverse. Turn left.
レバー１５を斜め右側前方に揺動して第１・第４減圧弁
１６．１９を作動すると第１・第４パイロット路４４．
４７にパイロット圧油が供給され、左右制御弁１１．１
２の第１受圧部１１ａ、１２ａと右制御弁１２の第２・
第４受圧部１２ｂ、１２ｄにパイロット圧油が供給され
るので、左右制御弁１１．１２は前進位置ｆに切換わる
と共に、右制御弁１２の切換えストロークが左制御弁１
１の切換えストロークより短かくなって右油圧ポンプ５
の斜板角度が左油圧ポンプ１の斜板角度より小さくなり
、右油圧ポンプ５の容量が左油圧ポンプ５の容量より少
なくなって、右油圧トランスミッションＢの回転速度が
左油圧トランスミッションＡの回転速度より遅くなり、
車両は前進右旋回走行する。When the lever 15 is swung forward diagonally to the right and the first and fourth pressure reducing valves 16.19 are actuated, the first and fourth pilot paths 44.
Pilot pressure oil is supplied to 47, and the left and right control valves 11.1
2 first pressure receiving parts 11a, 12a and the second pressure receiving part 12a of the right control valve 12.
Since pilot pressure oil is supplied to the fourth pressure receiving parts 12b and 12d, the left and right control valves 11.12 are switched to the forward position f, and the switching stroke of the right control valve 12 is changed to the left control valve 1.
The right hydraulic pump 5 is shorter than the switching stroke of 1.
The swash plate angle of the left hydraulic pump 1 becomes smaller than the swash plate angle of the left hydraulic pump 1, the capacity of the right hydraulic pump 5 becomes smaller than the capacity of the left hydraulic pump 5, and the rotational speed of the right hydraulic transmission B becomes the rotational speed of the left hydraulic transmission A. slower,
The vehicle moves forward and turns to the right.
レバー１５を斜め右側後方に揺動して第２・第４減圧弁
１７．１９を作動すると、第２・第４パイロット４５．
４７にパイロット圧油が供給されて前述と同様に左右制
御弁１１．１２が後進位置ｇに切換わると共に、右制御
弁１２の切換えストロークが左制御弁１１の切換えスト
ロークより短かくなって右油圧ポンプ５の容量が左油圧
ポンプ１の容量より少なくなり、車両は後進右旋回走行
する。When the lever 15 is swung diagonally to the right and backward to operate the second and fourth pressure reducing valves 17.19, the second and fourth pilots 45.
Pilot pressure oil is supplied to 47, and the left and right control valves 11 and 12 are switched to the reverse position g in the same manner as described above, and the switching stroke of the right control valve 12 becomes shorter than the switching stroke of the left control valve 11, so that the right hydraulic pressure is reduced. The capacity of the pump 5 becomes smaller than the capacity of the left hydraulic pump 1, and the vehicle moves backward and turns to the right.
前記第１切換弁４１は連通位置ｉに保持され、操作部材
、例えばインチング・ブレーキペダルで遮断位置ｊに向
けて操作され、第１切換弁４１を遮断位置ｊとする油圧
パイロット弁１４の各減圧弁の入口ポート４０がドレー
ンに連通し、左右制御弁１１．１２の各受圧部がドレー
ンに連通されて左右制御弁１１．１２はドレーン位置ｅ
となり、左右油圧モータ１，５の斜板１ａ。The first switching valve 41 is held in the communication position i and is operated toward the cutoff position j by an operating member, such as an inching brake pedal, to reduce the pressure of the hydraulic pilot valve 14 to set the first switching valve 41 to the cutoff position j. The inlet port 40 of the valve communicates with the drain, and each pressure receiving part of the left and right control valves 11.12 communicates with the drain, so that the left and right control valves 11.12 are in the drain position e.
Thus, the swash plate 1a of the left and right hydraulic motors 1 and 5.
５ａは最小角度位置となって最小容量となる。5a is the minimum angular position and has the minimum capacity.
前記第１や第２パイロット４４．４５はシャトル弁５０
で圧力検出回路５１に接続し、その圧力検出回路５１は
スローリターン弁５２を経て前記中立バイパス弁３５の
受圧部３５ｂに接続し、レバー１５を前後に揺動して前
述のように車両を走行する時には第１パイロツト路４４
又は第２パイロツト路４５のパイロット圧油がシャトル
弁５０て圧力検出回路５１に検出され、その圧油が中立
バイパス弁３５の受圧部３５ｂに供給されて遮断位置ｄ
とする。The first and second pilots 44 and 45 are shuttle valves 50
The pressure detection circuit 51 is connected to the pressure receiving part 35b of the neutral bypass valve 35 through the slow return valve 52, and the lever 15 is swung back and forth to drive the vehicle as described above. When doing so, the first pilot path 44
Alternatively, the pilot pressure oil in the second pilot path 45 is detected by the pressure detection circuit 51 through the shuttle valve 50, and the pressure oil is supplied to the pressure receiving part 35b of the neutral bypass valve 35 to reach the cutoff position d.
shall be.
前記左右スプロケットＤ、Ｅは駐車ブレーキ６０を備え
、その駐車ブレーキ６０はブレーキ板６１をブレーキシ
リンダ６２より成り、ブレーキシリンダ６２をバネ６３
で伸長付勢して制動状態とし、縮少室６４に圧油を供給
することでブレーキシリンダ６２を縮少すると解除状態
となり、その縮少室６４はブレーキ回路６５に接続して
いる。The left and right sprockets D and E are equipped with a parking brake 60, which consists of a brake plate 61 and a brake cylinder 62, which is connected to a spring 63.
When the brake cylinder 62 is compressed by supplying pressurized oil to the contraction chamber 64 and the brake cylinder 62 is compressed, the brake cylinder 62 is brought into a released state, and the contraction chamber 64 is connected to a brake circuit 65 .
該ブレーキ回路６５は第２切換弁６６で前記補助油圧ポ
ンプ１３の吐出路１３ａと圧力検出回路５１に連通制御
され、その第２切換弁６６はバネ力で第１装置ｋに保持
され、第１・第２受圧部６６ａ、６６ｂのパイロット圧
油で第２位置ｇとなる構成で、その第１・第２受圧部６
６ａ、６６ｂは前記圧力検出回路５１．ブレーキ回路６
５に接続されている。The brake circuit 65 is controlled to communicate with the discharge passage 13a of the auxiliary hydraulic pump 13 and the pressure detection circuit 51 by a second switching valve 66, and the second switching valve 66 is held by the first device k by a spring force,・With a configuration in which the pilot pressure oil of the second pressure receiving parts 66a and 66b takes the second position g, the first and second pressure receiving parts 6
6a and 66b are the pressure detection circuits 51. Brake circuit 6
5.
前記第１切換弁４１の入口側にはチエツク弁６７を備え
た圧油供給口６８が設けてあり、別の油圧源より圧油を
′ｉｓｌ切換弁４１の入口側に供給できるようにしであ
る。A pressure oil supply port 68 equipped with a check valve 67 is provided on the inlet side of the first switching valve 41, so that pressure oil can be supplied to the inlet side of the 'isl switching valve 41 from another hydraulic pressure source. .
次に本発明に係る中立バイパス弁について説明する。Next, a neutral bypass valve according to the present invention will be explained.
前記中立バイパス弁３５は第２図に示すように、弁本体
７０のスプール孔７１にスプール７２を嵌挿し、スプー
ル孔７１の両端部に第１・第２プラグ７３．７４を設け
て第１プラグ７３とスプール７２の一端部との間に受圧
部３５ｂを構成し、第２プラグ７４とスプール７２の他
端部との間にバネ３５ｇを設けて第１ボート７５と第２
ポート７６を連通する位置に保持し、第１プラグ７４の
軸孔７７より受圧部３５ｂに圧油を供給することでスプ
ール７２を第１ボート７３と第２ポート７４を遮断する
位置に移動できるようにし、前記第２プラグ７４にネジ
杆７８をネジ込んでロックナツト７９で固定し、ロック
ナツト７９を弛めてネジ杆７８を締込むことでスプール
７２を連通位置に手動操作で保持できるようにしてあり
、前記第１ポート７５が一対のチエツク弁３１．３１間
に接続し、第２ボート７６が安全弁３０の高圧側に接続
し、軸孔７７に検出回路５１が接続している。As shown in FIG. 2, the neutral bypass valve 35 has a spool 72 inserted into a spool hole 71 of a valve body 70, and first and second plugs 73 and 74 are provided at both ends of the spool hole 71 to form a first plug. 73 and one end of the spool 72, and a spring 35g is provided between the second plug 74 and the other end of the spool 72.
By holding the port 76 in a communicating position and supplying pressure oil from the shaft hole 77 of the first plug 74 to the pressure receiving part 35b, the spool 72 can be moved to a position that blocks the first boat 73 and the second port 74. A screw rod 78 is screwed into the second plug 74 and fixed with a lock nut 79, and by loosening the lock nut 79 and tightening the screw rod 78, the spool 72 can be held in the communicating position by manual operation. , the first port 75 is connected between the pair of check valves 31 and 31, the second boat 76 is connected to the high pressure side of the safety valve 30, and the detection circuit 51 is connected to the shaft hole 77.
前記第２切換弁６６は第３図のように、弁本体８０内に
スプール８１を嵌挿し、そのスプール８１をバネ８２で
上方に押して第１位置にとして第１ポート８３をスプー
ル８１の第１油孔８４、***８５．第２油孔８６を経て
第２ポート８７に連通し、さらにスプール８１の上端部
を小径として第１受圧部６６ａを構成し、かつスプール
８１の上端部に形成した盲穴８８内にロードピストン８
９を嵌挿して第２受圧部６６ｂを構成し、その第１受圧
部６６ａを第２ポート８７に開口させ、第２受圧部６６
ｂを***８５に開口させて第１・第２受圧部６６ａ、６
６ｂの圧力でスプール８１を下方に押して第３ボート９
０を第１ポート８３に連通する第２位置ｇとなるように
してあり、第１ポート８３がブレーキ回路６５．第２ポ
ート８７が圧力検出回路５１、第３ポート９０が補助油
圧ポンプ１３の吐出路１３ａにそれぞれ接続している。As shown in FIG. 3, the second switching valve 66 is constructed by fitting a spool 81 into a valve body 80, pushing the spool 81 upward with a spring 82 to the first position, and then switching the first port 83 to the first position of the spool 81. Oil hole 84, small hole 85. The load piston 8 is connected to the second port 87 via the second oil hole 86, and the upper end of the spool 81 has a small diameter to form the first pressure receiving part 66a.
9 is inserted and inserted to form the second pressure receiving part 66b, and the first pressure receiving part 66a is opened to the second port 87, and the second pressure receiving part 66 is opened.
b into the small hole 85 and the first and second pressure receiving parts 66a, 6
Push the spool 81 downward with the pressure of the third boat 9
0 to the first port 83, and the first port 83 is connected to the brake circuit 65. The second port 87 and the third port 90 are connected to the pressure detection circuit 51 and the discharge path 13a of the auxiliary hydraulic pump 13, respectively.
次に中立バイパス弁３５と駐車ブレーキ６０の作動を説
明する。Next, the operation of the neutral bypass valve 35 and the parking brake 60 will be explained.
車両を発進する時にはレバー１５を揺動操作して第１又
は第２減圧弁１６．１７を作動して第１又は第２パイロ
ット路４４．４５にパイロット圧油を供給するので、そ
の第１パイロツト路４４又は第２パイロツト路４５のパ
イロット圧油がシャトル弁５０で圧力検出回路５１に導
入され、その検出回路５１から中立バイパス弁３５の受
圧部３５ｂにパイロット圧油が供給されて遮断位置ｄと
なると共（こ、前記検出回路５１のパイロット圧油は第
２切換弁６６の第１位置によりブレーキシリンダ６２の
縮少室６４に供給されるが、その圧力が低いのでブレー
キシリンダ６２が作動せずに駐車ブレーキ６０は制動状
態のままであり、更に操作レバー１５を操作してパイロ
ット弁の出力圧を高くすると第２受圧部６６ａ内の圧力
も上昇して第２切換弁６６が第２位置ｇとなって補助油
圧ポンプ１３の吐出圧油がブレーキシリンダ６２の縮小
室６４に供給され、これによりブレーキシリンダ６２が
縮小して駐車ブレーキ６０が解放状態となる。When starting the vehicle, the lever 15 is swung to operate the first or second pressure reducing valve 16.17 to supply pilot pressure oil to the first or second pilot path 44.45. The pilot pressure oil in the passage 44 or the second pilot passage 45 is introduced into the pressure detection circuit 51 by the shuttle valve 50, and the pilot pressure oil is supplied from the detection circuit 51 to the pressure receiving part 35b of the neutral bypass valve 35 to reach the cutoff position d. (The pilot pressure oil of the detection circuit 51 is supplied to the reduction chamber 64 of the brake cylinder 62 by the first position of the second switching valve 66, but since the pressure is low, the brake cylinder 62 does not operate. , the parking brake 60 remains in the braking state, and when the operating lever 15 is further operated to increase the output pressure of the pilot valve, the pressure in the second pressure receiving part 66a also increases, and the second switching valve 66 moves to the second position g. The pressure oil discharged from the auxiliary hydraulic pump 13 is supplied to the contraction chamber 64 of the brake cylinder 62, whereby the brake cylinder 62 is contracted and the parking brake 60 is released.
このように駐車ブレーキ６０は中立バイパス弁３５が遮
断位置ｄとなってから若干の時間経過後に解放状態とな
り、坂道発進時に車両が一旦降板することがない。In this way, the parking brake 60 becomes released after a certain amount of time has passed after the neutral bypass valve 35 reaches the cutoff position d, so that the vehicle does not temporarily dismount when starting on a slope.
車両を停止する時には油圧パイロット弁１４のレバー１
５を中立位置として各パイロット路をタンクに連通する
ので、前記検出回路５１のパイロット圧油が低下し、第
２切換弁６６の第１受圧部６６ｇの圧力が低下してスプ
ール８１が第１装置ｋに向けて移動し始めるが、駐車ブ
レーキ６のブレーキシリンダ６２の縮小室６４内にはバ
ネ６３の戻し力に応じた圧力が生じ、その圧油が第２切
換弁６６を通って圧力検出回路５１に流出し、かつその
圧力はスローリターン弁５２で駐車ブレーキ６０が制動
するまである圧力に保持され、その保持された圧力で中
立バイパス弁３５は遮断位置ｄに保持されて駐車ブレー
キ６０が制動状態となってから所定の時間経過後に中立
バイパス弁３５が連通位置Ｃとなる。When stopping the vehicle, press lever 1 of the hydraulic pilot valve 14.
5 is set at the neutral position and each pilot path is communicated with the tank, the pilot pressure oil in the detection circuit 51 decreases, the pressure in the first pressure receiving portion 66g of the second switching valve 66 decreases, and the spool 81 is placed in the first device. However, pressure corresponding to the return force of the spring 63 is generated in the reduction chamber 64 of the brake cylinder 62 of the parking brake 6, and the pressure oil passes through the second switching valve 66 to the pressure detection circuit. 51, and its pressure is held at a certain pressure by the slow return valve 52 until the parking brake 60 is braked, and with the maintained pressure, the neutral bypass valve 35 is held at the cutoff position d, and the parking brake 60 is braked. After a predetermined period of time has elapsed, the neutral bypass valve 35 enters the communication position C.
中立バイパス弁３５が連通位置Ｃとなると左右高圧回路
２２．２７と左右チャージ回路２１゜２６が連通するの
で、左右油圧トランスミッションＡ、Ｂの閉回路を構成
する左第１・第２主回路３．４及び右第１・第２主回路
７，８はそれぞれ短絡して左右油圧モータ２，６は停止
する。When the neutral bypass valve 35 is in the communication position C, the left and right high pressure circuits 22,27 and the left and right charge circuits 21.26 communicate with each other, so that the left first and second main circuits 3. 4 and the right first and second main circuits 7 and 8 are short-circuited, respectively, and the left and right hydraulic motors 2 and 6 are stopped.
このように、駐車ブレーキ６０が解放状態となってから
若干の時間遅れをもって中立バイパス弁３５が連通位置
Ｃとなるので、左右油圧トランスミッションＡ、Ｂの閉
回路を構成する第１・第２主回路が連通される以前に駐
車ブレーキ６０が解放状態となり、坂道停止時に車両が
一旦降板することがない。In this way, the neutral bypass valve 35 reaches the communication position C with a slight time delay after the parking brake 60 is released, so that the first and second main circuits forming a closed circuit for the left and right hydraulic transmissions A and B are closed. The parking brake 60 is released before the parking brake 60 is connected, and the vehicle does not once get off when stopped on a slope.
また、エンジン故障時に車両をけん引走行する際には補
助油圧ポンプ１３の吐出圧油がゼロとなり、駐車ブレー
キ６０を解放状態にできないので、圧油供給口６８より
圧油を供給し、油圧パイロットバルブ１４のレバー１５
を前側に揺動して第１減圧弁１６を作動し、
第１パイロット路４４．チエツク弁５０より検出回路５
１に圧油を導入して前述と同様に第２切換弁６６を第２
位置ｇとして前記圧油供給口６８より供給した圧油をブ
レーキシリンダ６２の縮小室６４に供給して駐車ブレー
キ６０を解放状態とする。Furthermore, when the vehicle is towed in the event of an engine failure, the pressure oil discharged from the auxiliary hydraulic pump 13 becomes zero and the parking brake 60 cannot be released, so pressure oil is supplied from the pressure oil supply port 68 and the hydraulic pilot valve 14 levers 15
is swung forward to operate the first pressure reducing valve 16, and the first pilot path 44. Detection circuit 5 from check valve 50
1, and the second switching valve 66 is switched to the second switching valve 66 as described above.
At position g, the pressure oil supplied from the pressure oil supply port 68 is supplied to the reduction chamber 64 of the brake cylinder 62 to bring the parking brake 60 into the released state.
この時、中立バイパス弁３５の受圧部３５ｂにも圧油が
供給されるが、ネジ杆７８を締付けてスプール７２を連
通位置に保持することで中立バイパス弁３５を連通位置
Ｃに保持できるから、けん引走行がスムーズにできる。At this time, pressure oil is also supplied to the pressure receiving part 35b of the neutral bypass valve 35, but the neutral bypass valve 35 can be held in the communication position C by tightening the threaded rod 78 and holding the spool 72 in the communication position. Towing can be done smoothly.
車両発進時にはパイロット圧油で中立バイパス弁３５が
遮断位置となった時に切換弁６６が第２位置になって駐
車ブレーキ６０が解放状態となり、車両停止時にはブレ
ーキシリンダ６２の保持圧で中立バイパス弁３５が遮断
位置に保持され、かつその保持圧はスローリターン弁５
２を通って排出されるから切換弁６６が第１位置となっ
た後に中立バイパス弁３５が連通位置となり、駐車ブレ
ーキ６０が制動状態となった後に閉回路を構成する第１
・第２主回路が連通される。When the vehicle starts, when the pilot pressure oil causes the neutral bypass valve 35 to enter the cutoff position, the switching valve 66 becomes the second position, and the parking brake 60 becomes released, and when the vehicle stops, the neutral bypass valve 35 operates using the holding pressure of the brake cylinder 62. is held at the cutoff position, and the holding pressure is maintained at the slow return valve 5.
2, so after the switching valve 66 becomes the first position, the neutral bypass valve 35 becomes the communication position, and after the parking brake 60 enters the braking state, the first
- The second main circuit is connected.
したがって、坂道発進１発進時に車両が一旦降板するこ
とを防止できる。Therefore, it is possible to prevent the vehicle from temporarily dismounting when starting on a slope.
第１図は本発明の実施例を示す油圧回路図、第２図は中
立バイパス弁の断面図、第３図は切換弁の断面図である
。
Ａは左油圧トランスミッション、Ｂは右油圧トランスミ
ッション、１は左可変容量型油圧ボンブ、２は左油圧モ
ータ、３は左第１主回路、４は左第２主回路、５は右可
変容量型油圧ポンプ、６は右油圧モータ、３５は中立バ
イパス弁、６０は駐車ブレーキ、６２はブレーキシリン
ダ、６６は切換弁。FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, FIG. 2 is a sectional view of a neutral bypass valve, and FIG. 3 is a sectional view of a switching valve. A is left hydraulic transmission, B is right hydraulic transmission, 1 is left variable displacement hydraulic bomb, 2 is left hydraulic motor, 3 is left first main circuit, 4 is left second main circuit, 5 is right variable displacement hydraulic 6 is a right hydraulic motor, 35 is a neutral bypass valve, 60 is a parking brake, 62 is a brake cylinder, and 66 is a switching valve.
Claims (1)
第２主回路３、４で閉回路接続した左油圧トランスミッ
ションＡと、右可変容量型油圧ポンプ５と右油圧モータ
６を右第１・第２主回路７、８で閉回路接続した右油圧
トランスミッションＢを備えた閉回路油圧トランスミッ
ションの油圧回路において、 前記左右の第１・第２主回路を連通・遮断する中立バイ
パス弁３５と、左右の油圧モータの出力側を制動する駐
車ブレーキ６０を設け、該駐車ブレーキ６０を常時制動
状態とし、かつブレーキシリンダ６２に圧油を供給する
ことで解放状態となる構成とし、そのブレーキシリンダ
６２に圧油を供給する切換弁６６を設け、 前記中立バイパス弁３５をバネ力で連通位置に保持し、
かつ前記左右の可変容量型油圧ポンプの容量を変更する
パイロット圧油で遮断位置となる構成とし、 前記切換弁６６を、ブレーキシリンダ６２の圧油を前記
パイロット圧油の圧力検出回路に流出する第１位置と補
助油圧ポンプ１３の吐出圧油をブレーキシリンダ６２に
供給する第２位置を有し、かつバネ力で第１位置に保持
し、パイロット圧油で第２位置となるようにし、 前記圧力検出回路にスローリターン弁５２を設けたこと
を特徴とする閉回路油圧トランスミッションの油圧回路
。[Claims] The left variable displacement hydraulic pump 1 and the left hydraulic motor 2 are connected to the left variable displacement hydraulic pump 1 and the left hydraulic motor 2.
The left hydraulic transmission A is connected in a closed circuit through the second main circuits 3 and 4, and the right hydraulic transmission is connected in a closed circuit between the right variable displacement hydraulic pump 5 and the right hydraulic motor 6 through the right first and second main circuits 7 and 8. In the hydraulic circuit of the closed circuit hydraulic transmission equipped with B, a neutral bypass valve 35 that connects and blocks the left and right first and second main circuits, and a parking brake 60 that brakes the output side of the left and right hydraulic motors are provided, The parking brake 60 is always in a braking state and released by supplying pressure oil to the brake cylinder 62, and a switching valve 66 is provided for supplying pressure oil to the brake cylinder 62, and the neutral bypass valve 35 is held in the communicating position by spring force,
and the left and right variable displacement hydraulic pumps are configured to be in a shutoff position with pilot pressure oil that changes the capacity, and the switching valve 66 is configured to be in a shutoff position to allow the pressure oil of the brake cylinder 62 to flow out to the pressure detection circuit of the pilot pressure oil. 1 position and a second position for supplying pressure oil discharged from the auxiliary hydraulic pump 13 to the brake cylinder 62, and is held at the first position by a spring force and set at the second position by pilot pressure oil, and the pressure is A hydraulic circuit for a closed circuit hydraulic transmission, characterized in that a slow return valve 52 is provided in the detection circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2218096A JPH04102762A (en) | 1990-08-21 | 1990-08-21 | Hydraulic circuit for closed-circuit hydraulic transmission |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2218096A JPH04102762A (en) | 1990-08-21 | 1990-08-21 | Hydraulic circuit for closed-circuit hydraulic transmission |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04102762A true JPH04102762A (en) | 1992-04-03 |
Family
ID=16714570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2218096A Pending JPH04102762A (en) | 1990-08-21 | 1990-08-21 | Hydraulic circuit for closed-circuit hydraulic transmission |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04102762A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6675576B2 (en) * | 2001-04-23 | 2004-01-13 | Poclain Hydraulics Industrie | Hydraulic circuit having a hydraulic motor equipped with a brake for a vehicle suitable for being towed |
| WO2007052692A1 (en) * | 2005-11-02 | 2007-05-10 | Hitachi Construction Machinery Co., Ltd. | Travel control device for working vehicle and working vehicle |
| US7722131B2 (en) | 2006-02-02 | 2010-05-25 | White Drive Products, Inc. | Control component for a spring applied-pressure released hydraulic brake and hydraulic motor |
| US7909414B2 (en) | 2006-03-10 | 2011-03-22 | White Drive Products, Inc. | Hydraulic circuit for spring applied-hydraulically released brake and hydraulic motor |
| US8240779B2 (en) | 2006-02-02 | 2012-08-14 | White Drive Products, Inc. | Control component for hydraulic circuit including spring applied-hydraulically released brake |
-
1990
- 1990-08-21 JP JP2218096A patent/JPH04102762A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6675576B2 (en) * | 2001-04-23 | 2004-01-13 | Poclain Hydraulics Industrie | Hydraulic circuit having a hydraulic motor equipped with a brake for a vehicle suitable for being towed |
| WO2007052692A1 (en) * | 2005-11-02 | 2007-05-10 | Hitachi Construction Machinery Co., Ltd. | Travel control device for working vehicle and working vehicle |
| US8585156B2 (en) | 2005-11-02 | 2013-11-19 | Hitachi Construction Machinery Co., Ltd. | Travel control device for work vehicle and work vehicle |
| US7722131B2 (en) | 2006-02-02 | 2010-05-25 | White Drive Products, Inc. | Control component for a spring applied-pressure released hydraulic brake and hydraulic motor |
| US8240779B2 (en) | 2006-02-02 | 2012-08-14 | White Drive Products, Inc. | Control component for hydraulic circuit including spring applied-hydraulically released brake |
| US7909414B2 (en) | 2006-03-10 | 2011-03-22 | White Drive Products, Inc. | Hydraulic circuit for spring applied-hydraulically released brake and hydraulic motor |
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