JPH02504376A - Marine power steering system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Ship power steering system Fusetsu Corporation TECHNICAL FIELD The present invention relates to marine power steering systems, and more particularly to hydraulic power steering systems. An accumulator or pressurized series is used to supply fluid to the power steering system. related to systems that use printers.

next day drum distortion Typical examples include outboard motor and stern drive marine power steering systems. The system uses a steering link that can be extended and retracted. Ru. This link is connected to the ship's transom and propulsion unit, and is connected to the steering link. The propulsion unit can be moved by extending or retracting the piston rod of the Rotate to steer the ship.

Such units are useful when moving the handle quickly from one side to the other Requires a relatively large amount of hydraulic fluid, so a relatively large hydraulic pump is required. Ru. Such systems also require that the hydraulic pump not be powered by the engine. The engine must be running to activate the steering system. There is.

This marine hydraulic system for operating the power steering assembly consists of a the pump to provide pressurized hydraulic fluid from the reservoir and to selectively operate the pump. and a control system that places the device in active mode or inactive mode.

R plate Ω plate In particular, the present invention provides a hydraulic cylinder containing a piston head and a piston rod. Pressurized hydraulic fluid is applied to extend and retract the piston, which causes the outboard For rotating the propulsion unit and operating the power steering assembly. In marine hydraulic systems, a pump that provides pressurized hydraulic fluid from a fluid reservoir means for controlling the pumping means in an active or inactive mode; and a pressurized fluid. actuating said pumping means to store pressurized fluid and maintain said fluid at a desired pressure; a pressure accumulating means connected to the pressure accumulating means, and a rod side of the piston communicating with the pressure accumulating means and The pressurized hydraulic fluid is connected to the rod of the cylinder so that it is constantly exposed to the pressurized fluid from the pressure means. Pressure is applied to the first port of the hydraulic cylinder, which is introduced to the side, and the head side of the cylinder. To extend the stone rod, apply pressurized fluid from the rod side of the cylinder to the head of the cylinder. a first valve means disposed within the cylinder for selectively shifting the cylinder to the We provide hydraulic systems that

Advantageously, this marine hydraulic system operates even when the engine is stopped. and eliminates the need for large, continuously operating hydraulic pumps.

Place plate 2 Goko 2 and skin The figure below shows a marine power source mounted on a vessel and operatively connected to an outboard motor. 2 is a perspective view of the steering assembly, FIG. 2 showing the hydraulic system and the steer of FIG. 1; FIG. FIG. 2 is a schematic diagram of a ring assembly; FIG. 3 is a cross-sectional view of the valve-cylinder assembly in a neutral position, and FIG. 2 is a cross-sectional view of the valve-cylinder assembly with the piston rod in an extended position; Figure 5 shows the valve-cylinder assembly in the position where the valve retracts the piston rod. A cross-sectional view, FIG. 6 is a cross-sectional view of an accumulator used in a hydraulic system; Figure 7 connects the hydraulic pump, accumulator, and flow lines to the valves and cylinders. FIG. 2 is a schematic diagram of a hydraulic system.

Good form for performing B Figure 1 shows an outboard motor l rotatably mounted in the usual manner on the transom 12 of a ship. O is illustrated.

The outboard motor has a transom bracket (not shown) secured to the transom 12 of the ship. The propulsion unit 11 is rotatably attached to a swivel bracket (not shown). constitutes the steering axis. Swivel bracket to stern beam bracket It is rotatably mounted and forms a tilt axis.

A hydraulic cylinder 14 has a piston rod 16 that can be extended and retracted. , is fixed to the swivel bracket so as to tilt together with the drive unit 11, and the piston The linear movement of the connecting rod 16 is coupled to the rotational movement of the drive unit 11 via the link 18. converted.

An accumulator 20 is also attached to the stern beam 12, and this accumulator a port 22 for supplying pressurized hydraulic fluid to the cylinder 14 through a hose 24; Port 26 receives hydraulic fluid discharged from cylinder 14 through hose 28 and has.

The valve of the hydraulic cylinder 14 is housed within the cylinder body, and the actuation of this valve is controlled by the hand. A steering mechanism consisting of a gear 30 operatively connected to a wheel and a movable rack 32. controlled and determined by the movement of. The movement of the rack 32 is controlled by the link 36. is transmitted to the yoke 34. This causes the control stem 38 to rotate, thereby The control rod 40 is then moved linearly. The remainder of the hydraulic system in Figure 2 includes: Activates the accumulator 20, the electric motor 44 and its associated hydraulic pump 46. A control package 42 associated with an accumulator is shown. electric power is provided to control package 42 via cable 47.

As mentioned above, the valve of the hydraulic cylinder 14 is housed within the cylinder body; are best illustrated in FIGS. 3, 4, and 5.

In FIG. 3, the piston head 48 is in its leftmost position, thus The connecting rod 50 is in a fully retracted position.

In this position, there is no hydraulic fluid flow and the fluid in chamber 52 acting on surfaces 54 and 56 Only the hydraulic pressure from the pressure fluid is applied to the piston head 48, causing the piston head 48 to move. Try to move from right to left.

The pressurized hydraulic fluid in the chamber 52 is transferred from the accumulator 20 to the hydraulic flow through the check valve 60. The body is discharged through the receiving port 58.

To move the piston head 48 from left to right (see Figure 4), the control rod is 40 must be moved from right to left from the position shown in Figure 3 to the position shown in Figure 4. Must be. When the control rod 40 moves to the right, the poppet actuator 62 The inclined portion 64 of the recess 66 is moved upward to engage the bottom surface of the poppet 68, and the poppet 68 from its seat 70. When the poppet 68 leaves the seat 70, the pressurized fluid Pressurized fluid flows from chamber 52 to poppet 68 and poppet chamber 7 around actuator 62. 2 and flows into the recess 62 .

From here, the pressurized hydraulic fluid passes through passageway 74 and ultimately to the head of the piston assembly. It flows into the side chamber 76. In this chamber, pressurized hydraulic fluid is applied to the face 78 of the piston head 48. and since this surface is larger than the combination of surfaces 54 and 56, the piston head 48 is moved in the left-to-right direction, extending the piston rods 5,0. write As the piston head moves from left to right, the hydraulic fluid beam servo in chamber 52 This is used in chamber 76, which makes the hydraulic fluid more efficient. use of less fluid from the actuator 20.

To retract the piston rod 50 and thus move the marine unit 10 to the opposite side. In order to rotate the control rod 40 from the position shown in FIG. 4 to the position shown in FIG. It is necessary to move it from left to right until it reaches the desired position. In the position shown in Figure 5, the poppet The actuator 62 returns to its lowermost position within the recess 66 and then collapses. At the same time as the pet 68 is reseated, the poppet actuator 80 moves the tilt of the recess 84. Move the beveled portion 82 upwardly to engage the bottom surface of the poppet 86 and place the poppet 86 in its seat. Lift up from 88. When poppet 86 leaves seat 88, hydraulic fluid flows into chamber 76. from the poppet chamber 92 along the flow path 90 to the poppet 86 and the actuator 8. 0 and flows into the recess 84. Hydraulic fluid passes from recess 84 to passageway 96. The water flows through the connecting passageway 94 that flows through the connecting passageway 94. Passage 96 is in communication with outlet port 104. Hole 100 communicating with passage 102 drains hydraulic fluid into reservoir 98 . write In this position, all hydraulic pressure acting on surface 78 is released, and in this case the port Since the pet 68 is in the seated position, the accumulator 2 acting on the surfaces 54 and 56 There is no force against the constant fluid pressure from 0, and the piston head 48 moves from right to left. Move to.

As shown in FIG. 6, the accumulator 20 has a hydraulic fluid reservoir 10B. The mulletator 200 has an outer casing 106 formed in the lower portion.

The accumulator 20 is opened when the pressurized gas in the chamber 110 presses the piston 112 and It is filled with gas so as to be in contact with the hydraulic fluid within 14.

The position of the piston 112 is located within the chamber 110 and at the center of the piston 12. a magnetically sensitive switch disposed within an arm 120 extending downwardly into the cavity 120; 116 and 118. Magnet 122 is on the wall of cavity 120 124. Thus, the vertical position of piston 112 2 and magnetically sensitive switches 116 and 118.

In FIG. 7, the piston 112 is shown in its lower end position with only the reserve oil remaining below. It's nearby. This position is detected by magnetic switch 118. This position is When detected, the electrical control package 42 generates an electrical signal to cause the electric motor 44 and and associated hydraulic pump 46 are activated. Hydraulic pump 46 then pumps hydraulic fluid. It is pumped upwardly from reservoir 108 through filter 126 and into chamber 114 . Room 1 Backflow of hydraulic fluid from 14 back to pump 46 is prevented by check valve 127 . Hydraulic pump 46 is powered by magnet 122 energizing switch 116 to drive electric motor 44 and hydraulic fluid until cylinder 112 reaches an upper position which de-energizes pump 46. Continue pumping to chamber 114.

The accumulator 20 supplies pressurized hydraulic fluid to a hydraulic cylinder via a working port 28. Used to add to 14. The hydraulic fluid discharged from the hydraulic cylinder 14 is The data in accumulator 20 is returned to server 108 by port 130 .

A sufficient amount of hydraulic fluid is stored under pressure in the chamber 114 of the accumulator 20. 1; Pressurized hydraulic fluid is supplied to the hydraulic cylinder 14 without operating the hydraulic pump 46. can be added. Transfers pressurized hydraulic fluid from the rod side of the piston 48 to the head side. Since the piston head 48 can be moved from left to right by Therefore, such movement can be performed without external power.

Submission of translation of written amendment (Article 184-8 of the Patent Law) 1.　Display of international application PCT/US 88102396 2. Name of the invention Marine power steering system 3. Patent applicant Address: Brunswick, Sneaky, Illinois, USA Plaza (no street address) Name: Brunswick, Corporation 4, Agent Man (Postal code 100) 3-2 Marunouchi, Chiyoda-ku, Tokyo, Patent The scope of the claims ■In the power steering system of a marine propulsion unit, the driver operates the and a front steering mechanism for rotating the marine propulsion unit. a steering link responsive to the steering actuation mechanism; and a steering link responsive to the steering actuation mechanism; responsive to said steering actuating mechanism to provide assistance in effecting movement of said steering wheel; Pressurized fluid operated power steering means comprising a substantially stationary cylinder and a pressurized fluid operated power supply having a piston slidably mounted within the cylinder; - steering means; pressurized fluid supply means for supplying pressurized fluid to the power steering means; a block attached to the piston for movement with the piston; and the block has a structure in which the block and the steerer are moved by the movement of the piston. the link such that the marine propulsion system is rotated via the ring link; The power steering system is connected to the

2. further comprising a control means movably attached to the block, the control means being movably attached to the block; The control means is moved by movement of the actuating mechanism to control the pressurized fluid in the cylinder. The power steering system according to claim 1, characterized in that the power steering system controls the supply of Mu.

3. The movement of the control means causes the rod connected to the piston to The axially movable actuating rod disposed in the inner passageway is moved to perform the aforementioned operation. A dynamic rod is connected to the piston to control the supply of pressurized fluid within the cylinder. 3. The power of claim 2, wherein the power selectively engages associated valve means. steering system.

4. When the piston moves in one direction within the cylinder, fluid flows into the cylinder. and the fluid discharged from the cylinder is connected to the block and the pressurized flow. through a conduit extending between a reservoir associated with the body supply means and said block. The power steering system according to claim 1, characterized in that:

5. A control mechanism for a marine power steering system, which control mechanism includes: a steering actuation plate groove and a piston associated with said power steering system; Axial power steer for extending and retracting the rod A control mechanism disposed between the ring actuator and the piston rod. A block with a cavity and a a portion disposed within the cavity and a portion extending outwardly from the block; a control stem movably attached to the block; means for coupling an outwardly extending portion of the control stem to the steering actuation mechanism; and, A portion of the control stem disposed within the cavity is movable in the axial direction. means for coupling to an existing power steering actuator; and wherein the control stem is forward to effect movement of the power steering actuator. A control mechanism movably responsive to the steering actuation mechanism.

6. The control stem is rotatably attached to the block. The control mechanism according to claim 5, characterized in that:

7. The rotational movement of the control stem within the cavity is caused by the walls of the cavity. 7. The control mechanism according to claim 6, wherein the control mechanism is limited by:

8. The control stem is formed by a collar member having an opening through which the control stem passes. is attached to the block, and the control stem is rotatably attached to the collar member. 7. The control mechanism according to claim 6, wherein the control mechanism is attached to.

9. The collar member is attached to the block for attaching the control stem to the block. The receiver is adapted to be inserted into a recess formed in the lock. 9. The control mechanism according to claim 8.

10. The control stem extends through an opening formed in the control stem and has an end portion. is rotatably attached to the collar by a pin fixed to the collar member. The control mechanism according to claim 8, characterized in that:

11. The power steering actuation device has an actuation rod, and the control stem and The means for connecting to the power steering actuator is a ball-pocket connection. 7. The control mechanism according to claim 6, wherein the control mechanism has a portion therebetween.

12. A ball is provided at the inner end of the control stem, and the actuating rod is connected to the ball. The receiver has a pocket for receiving the control rod, so that the rotational movement of the control rod is The actuating rod is converted into an axial movement via the actuating rod. The control mechanism according to item 11.

13. connecting an outwardly extending portion of the control stem to the steering actuation mechanism; said means attached to the outer end of said control stem and said means for controlling said steering actuating mechanism; 7. The control mechanism according to claim 6, further comprising a yoke connected to the control mechanism.

14. The power steering system has a pressurized fluid actuation system, and the control a steering connected through a control stem to and to said block; movement of the steering actuation mechanism transmitted from the block through a link; Therefore, even if the fluid pressure to the steering system is cut off, the system cannot be operated. The control mechanism according to claim 5, characterized in that it is capable of steering.

15. In the power steering system of a marine propulsion unit, the driver a steering cable operatively connected to a vertical steering gear mechanism; , a control assembly coupled to and responsive to the steering cable; a cylinder and a piston slidably mounted within the cylinder; To perform steering by selectively extending or retracting the rod connected to the stone. a pressurized fluid operated power steering unit responsive to said control assembly; Eliminating the effect of the propulsion torque acting on the steering actuation device operated by the driver. In order to facilitate operation of the power steering system by a propulsion link from a marine propulsion unit to a steering actuation device operated by the driver; a power steering system having a means for eliminating torque feedback; Tem.

16. The power steering unit applies a predetermined fluid pressure to the piston. pressurized fluid supply means for supplying fluid pressure to either side of said piston; internal valve means associated with said piston for adding to said feedback The means for eliminating the self-locking means associated with the internal valve means for blocking fluid flow through the internal valve means; and by kneading, the position of the piston relative to the cylinder is determined by the operator. The propulsion torque applied to the propulsion unit is maintained until further actuation, and the propulsion torque applied to the propulsion unit is is absorbed by the steering unit, thereby increasing the 16. The power source according to claim 15, characterized in that approaching the cable is avoided. tearing system.

17. In the power steering system of a marine propulsion unit, the propulsion A steering link connected to the unit and a steering link fixed to the propulsion unit. and a piston rod connected to the steering link. , a piston slidably mounted within the cylinder, and a pressurized fluid supplied to the piston. pressurized fluid supply means for supplying the first side of the pump; Normally, fluid pressure from the second side of the piston is transferred to the first side of the piston. valve means associated with said piston for isolating from fluid pressure supplied to said piston; The valve means allows fluid to flow from the first side of the piston to the second side of the piston. , the force due to the pressure acting on the second side acts on the first side. overcoming the force due to the pressure caused by the piston rod and thereby moving said piston rod. a first position in which the steering link is moved; and a second position in which the piston is moved. The fluid pressure acting on the first side of the piston is released and therefore acts on the first side of the piston. A force due to fluid pressure moving said piston causes said valve means to displace said piston. a second position for discharging fluid acting on said second side through said valve means; a power steering system comprising actuating means for selectively moving; .

18. The valve means is disposed within a cavity formed in the piston and is a first passage means communicating the first side of the piston with the cavity; second passage means communicating the second side of the piston and the cavity; and the valve means normally blocks communication between the first passage means and the cavity. The power steering system according to claim 17, characterized in that: .

19, said first passage means communicates with said cavity through a port, and said first passage means communicates with said cavity through a port; a valve associated with said valve means to constantly press said valve means so as to normally close said valve means; 19. The power steering wheel according to claim 18, further comprising a pressing means. system.

20, the portion of said valve means which normally closes said port is closed to the flow within said cavity; exposed to body pressure, said fluid pressure exerting an opposing force on said valve means; said valve means provides an area substantially equal to fluid pressure within said cavity; Therefore, the force due to fluid pressure which tends to open said valve and the force due to fluid pressure which tends to close said valve means. 20. The force of claim 19, wherein the force due to the fluid pressure that Power steering system as described.

21, said actuating means directing fluid from said first side of said piston through said port; and into said cavity and from said cavity through said second passage means. counteracting the force of the pushing means to allow the flow to the second side of the piston. and actuated to move said valve means from a normally closed position to said first position. The power steering system according to claim 20, characterized in that: stem.

22. The actuating means is a shaft disposed within an inner passage provided within the piston. It has a linearly movable rod that responds to the steering actuation mechanism. and the actuating rod is moved by the steering actuator of the driver. said valve means for moving said valve means to its first position in response to actuation of said valve means; 22. The power steering of claim 21, wherein the power steering selectively engages the system.

23, comprising third passage means communicating the cavity and the fluid reservoir; The valve means normally blocks communication between the cavity and the third passage means. The power steering system according to claim 18, characterized in that:

24, said third passage means communicates with said cavity through a port, and said third passage means communicates with said cavity through a port; a valve associated with said valve means to constantly press said valve means so as to normally close said valve means; 24. The power steering according to claim 23, further comprising a pressing means. ring system.

25, the portion of said valve means which normally closes said port is closed to the flow within said cavity; body pressure, said fluid pressure producing an opposing force acting on said valve means. and the valve means has substantially the same area relative to the fluid pressure within the cavity. providing a force due to fluid pressure tending to open said valve means and said valve hand. characterized in that the force due to fluid pressure that tends to close the stage is substantially canceled out. The power steering system according to claim 24.

26, said actuation means being actuated by fluid pressure acting on said first side of said piston; said piston is moved, and during this movement, said piston is adjacent to said second side of said piston. fluid is discharged into the reservoir through the second passage means and the third passage means. to release fluid pressure acting on the second side of the piston to the body from the second side of the piston through the second passage means into the cavity. and from said cavity through said port to said third passageway means. The force of the pushing means is overcome to allow the valve means to return to its normally closed position. the second position. The power steering system according to claim 20.

27. The actuation means is movable in response to the steering actuation mechanism. and moves in the axial direction disposed within an inner passage provided in the piston rod. a movable rod and a valve means, said actuating rod displacing said valve means in its second position; In response to the driver's actuation of the steering actuation mechanism, the 27. The valve according to claim 26, wherein the valve means is selectively engageable with the valve means. power steering system.

2B, in a power steering system for a marine propulsion unit, the propulsion unit Steering link connected to the unit and steering operation operated by the driver a mechanism, a cylinder fixed to the propulsion unit, and the steering control. said series having an inner cavity having a piston rod connected to the cylinder; a piston slidably mounted within the cylinder; a first passage communicating between a first side of the piston and the cavity; a second passage communicating between a second side of the piston and the cavity; a third passage communicating between the cavity and a fluid reservoir; fluid pressure supply means for applying fluid pressure to said piston; communication between the first side and the second side of the ton and the cavity and the third side; a valve hand disposed within the main cavity of the piston so as to interrupt communication with the piston; and the pressure on one side of the piston is transmitted to the other side of the piston. to move the piston rod in a first direction relative to the cylinder. between the first side and the second side of the piston by selectively activating a valve marking means. are in selective communication with the reservoir, and one side of the piston is in communication with the reservoir, and one side of the piston is in communication with the reservoir; The piston is moved in a second direction by fluid pressure acting on the other side of the piston. and directing fluid through the third passageway from the side of the piston that communicates with the reservoir. selectively activating said valve means to vent pressure through said cavity and said third A power steering system comprising: actuating means for selectively communicating with the passage means; system.

29, said valve means providing communication between said first side and said second side of said piston; communication between the first valve member and the cavity and the third passageway, which is normally shut off; 29. A second valve member that normally shuts off the flow. Power steering system.

30, the first passageway communicates with the cavity through a first port, and the third passageway communicates with the cavity through a first port; a passageway communicates with said cavity through a second port, and a first valve member normally communicates with said first valve member. 1 port, and the second valve member normally seals the second port. The power steering system according to claim 29.

3) acts on the first valve member to seal the first port; further developing a restraining means acting on said second valve member to seal said second valve member. The power steering system according to claim 3o, characterized in that the power steering system comprises:

32, the first and second valve members being exposed to fluid pressure within the cavity; and the fluid pressure creates a force acting against the valve member and the first and second valve members. each of the valve members of provides a substantially equal area to fluid pressure within the cavity; Therefore, when the first and second ports are trying to seal the first and second ports, the force due to the fluid pressure applied to the second valve member and the first port and the second port, respectively. Each of the forces due to the fluid pressure applied to the first and second valve members to try to open is 32. The power steering system of claim 31, wherein the power steering system substantially cancels. stem.

33, the first port and the second port are axial rods of the cavity; and the pressing means is arranged between the first valve member and the second valve member. and pressing the first valve member against the first port causes the second valve member to press against the second port. 33. The power according to claim 32, characterized in that it has one spring that presses against the seat. steering system.

34, said actuation means comprising an axial rod responsive to said steering actuation mechanism; the rod has a portion passing through the first and second valve members; a first valve member for selectively moving the first valve member out of engagement with the first port; selectively moving the first actuating member and the second valve member into engagement with the second port; 31. A second actuating member for removing the pad according to claim 30. power steering system.

35, the actuation rod is disposed within a passage provided in the piston rod; The power steering system according to claim 34, characterized in that:

36, the third passage is a passage provided in the actuation rod and the piston rod; communicating with the reservoir through a space formed between the reservoir and the reservoir. The power steering system according to claim 35.

37. In the power steering system of marine propulsion units including engines hand, steering link and a rod connected to said link for providing hydraulic assistance for movement of said link; a fluid pressure actuated cylinder having a slidable piston; fluid pressure supply means for applying fluid pressure to the cylinder; The means operate separately from said engine, so that whether the engine is running or not, A power steering wheel in which fluid pressure is constantly supplied to said cylinder whether it is in operation or not. system.

38, an action for the fluid pressure supply means to apply a predetermined fluid pressure to the cylinder; an accumulator and an electrically actuated pump for applying pressurized fluid to said accumulator. 38. The power steering system according to claim 37, comprising: .

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Claims (5)

[Claims] 1. Hydraulic cylinder housing piston head (48) and piston rod (50) Pressurized hydraulic fluid is applied to the cylinder (14) to extend and retract the piston, which actuates the power steering assembly, which rotates the outboard propulsion unit. In a marine hydraulic system intended to provide pressurized hydraulic fluid from a fluid reservoir, pumping means (46) for providing and placing the pumping means in an active or inactive mode; control means (42) for storing pressurized hydraulic fluid and maintaining this fluid at a desired pressure; pressure accumulator means (20) operatively connected to said pump means for The rod side of the piston is in communication with the stage and is constantly exposed to pressurized fluid from the pressure accumulating means. The first port of the hydraulic cylinder introduces pressurized hydraulic fluid into the rod side of the cylinder. (58) and pressurize the head side of the cylinder to extend the piston rod. To selectively transfer pressure fluid from the rod side of the cylinder to the head side of the cylinder. a first valve means disposed within the cylinder of the hydraulic system. 2. a second port (104) on the hydraulic cylinder, the second port being connected to the hydraulic reservoir; passages (92, 9) connecting the bar (98) and the head side of the cylinder with the second port; 4) and further includes a second valve means (86) for selectively opening said passageway. located within the cylinder so that the pressurized fluid is discharged from the head side of the cylinder and 2. A device according to claim 1, characterized in that the stone rod is retractable. Hydraulic system. 3. The pressure accumulating means includes a liquid storage chamber (114) for holding hydraulic fluid, and the liquid storage chamber. the hydraulic fluid is slidably disposed within the storage chamber and maintains the hydraulic fluid under pressure within the reservoir chamber; a piston (112) that is forced into contact with the hydraulic fluid; and sensing means (116, 118) for sensing, and the sensing means is configured to sense the inside of the liquid storage chamber. When a piston position indicating a low hydraulic fluid level is detected, additional fluid is added. placing the pump in an operating mode to supply pressurized fluid to the reservoir; When the piston position is detected, which indicates that the level of the hydraulic fluid in the piston is appropriate, operatively coupled to the control means to place the pump in an inactive mode; Hydraulic system according to claim 1, characterized in that: . 4. Selectively disengaging any of said valve means to direct hydraulic fluid to said lock. A mechanism for flowing from the head side to the head side or from the head side to the reservoir. Hydraulic system according to claim 2, characterized in that it has motion means (40). 5. At least one magnet (122) is positioned forward to follow the movement of said piston. at least one magnetic field sensing switch (116, 118) disposed on the piston; ) disposed along the travel path of the magnet and operatively connected to the control means. Hydraulic system according to claim 2, characterized in that: