Hydraulic control arrangement for operating a winch with easing, hoisting and mooring modes

FIELD AND BACKGROUND OF THE INVENTION

The invention is based on a hydraulic control arrangement which is used to operate a winch in easing, hoisting and mooring modes and which has an adjustable hydraulic motor (

12

) to drive the winch (

10

), a proportionally adjustable directional control valve (

35

), spring-centered in a mid position, to control the flow paths of a pressure medium between a pressure medium source (

25

), the hydraulic motor (

12

) and a pressure medium supply container (

26

), a pilot controller (

65

) which is used to control the adjustment of the directional control valve (

35

) and of the hydraulic motor (

12

) and has a control lever (

81

) which can be actuated as desired and can be deflected from a neutral position in one direction over a specific easing angle range (

85

) for easing at different speeds and can be deflected in the opposite direction over a specific hoisting angle range (

86

) for hoisting at different speeds, during a deflection of the control lever (

81

) over the entire hoisting angle range (

86

), the directional control valve (

35

) being fully opened and the hydraulic motor (

12

) being adjusted to a minimum absorption volume.

A hydraulic control arrangement of this type is disclosed by the typesheet RD 65 050/03.96 from the applicant. In such a control arrangement, the winch is preferably driven by an adjustable hydraulic motor. Using a directional control valve which is pilot-controlled, proportionally adjustable and spring-centered in a mid position, the flow paths of a pressure medium are controlled between a pressure medium source, the hydraulic motor and a pressure medium storage container. To control the adjustment of the directional control valve and of the hydraulic motor, use is made of a pilot controller having a control lever which can be actuated as desired and can be deflected from a neutral position in one direction over a specific easing angle range for easing at different speeds, and can be deflected in the opposite direction over a specific hoisting angle range for hoisting at different speeds. In the process, two adjustments are involved in changing the speed of the winch. Firstly, during a deflection of the control lever, the directional control valve is opened further and further, so that the amount of pressure medium flowing to the hydraulic motor is increased further and further. Secondly, the absorption volume of the hydraulic motor is reduced. It is conceivable to change the opening cross section of the directional control valve and the absorption volume of the hydraulic motor in parallel with each other. In the prior art, however, provision is made that, up to a pilot control pressure of 18 bar, for example, only the hydraulically pilot-controlled directional control valve is adjusted and, in the range of a pilot control pressure from 20 to 30 bar, for example, only the adjustable hydraulic motor is adjusted.

In the mooring mode, the hawser is to be kept under a predefinable tension. This tension can be set by means of the absorption volume of the hydraulic motor. In the prior art, the control lever of the pilot controller is deflected from a neutral position counter to the force of a restoring spring in one direction for the hoisting mode of the winch and in the other direction for the easing mode of the winch. For the mooring mode, which is generally intended to be maintained over a relatively long time period without the control lever being held in a specific position by hand, a fixing brake is provided for the control lever in the known hydraulic control arrangement, said brake holding the control lever within the hoisting angle range, counter to the force of the restoring spring, in a position corresponding to a specific absorption volume of the hydraulic motor.

In the case of the known hydraulic control arrangement, in the hoisting mode, the variable to be set, namely the speed of the hawser, becomes greater as the deflection angle of the control lever increases. In the mooring mode, the variable to be set is the torque exerted by the hydraulic motor. This torque decreases with increasing deflection angle of the control lever, a behavior which contradicts the usual concepts of setting a variable via a control lever, and can therefore lead to wrong setting. Another drawback of the known hydraulic control is that the hoisting mode and mooring mode cannot be distinguished by using the position of the control lever.

SUMMARY OF THE INVENTION

The invention is based on the object of constructing a hydraulic control arrangement which has the introductory-mentioned features in such a way that a type of mooring mode corresponding to the usual concept is possible.

In a hydraulic control having the introductory-mentioned features, according to the invention, the intended object is achieved wherein, the control lever, as viewed from the neutral position, can be deflected over a mooring angle range on the other side of the hoisting angle range, wherein and, with increasing deflection of the control lever in the mooring angle range, the hydraulic motor is adjusted in the direction of a greater absorption volume. Therefore, with increasing deflection of the control lever, the torque that can be exerted by the hydraulic motor increases, which corresponds to the usual concept of a control system and reduces the probability of wrong control. In addition, the angle range in which the control lever is located for hoisting and the angle range for the mooring mode are separated from each other, so that a reference to a different mode of operation can already be taken from the position of the control lever.

Thus according to another feature of the invention, during an adjustment of the control lever from the hoisting angle range into the mooring angle range a considerable rise in torque is preferably detectable, so that it is clearly pointed out to the operator that he is leaving the hoisting angle range with the control lever and passing into the mooring angle range.

As already outlined, a winch is often operated in the mooring mode over a relatively long time period, for example during the period during which a ship is lying in a harbor. In order that a person does not have to hold the control lever fixed during this entire time, provision is expediently also made in a control arrangement according to the invention as in the known hydraulic control arrangement, for the control lever to be capable of being brought into a position for the mooring mode from which it does not automatically return into the neutral position. The possibility of leaving the control lever in a specific position provides a temptation to operate a winch contrary to the regulations. This is because a person can use the mooring mode to haul in the hawser by the person first moving the control lever into a specific position in the mooring angle range and then attempting to do something at the hawser or at the load. It is therefore beneficial if, in the mooring mode, the speed with which the hawser can be hauled in is limited to a small value. According to a feature of the invention, a hydraulic control arrangement according to the invention is equipped with a nozzle and a second directional control valve for such a speed limitation, it being possible for this second directional control valve, at the transition of the control lever from the hoisting angle range to the mooring angle range, to be changed over into a mooring position in which the nozzle is located in the flow path of the pressure medium leading via the hydraulic motor, with the effect of limiting the rotational speed of the hydraulic motor to small values. Such a limitation on the rotational speed of the hydraulic motor is primarily advantageous for the direction of rotation in which the hawser is wound up. If a hawser breaks, for example in the mooring mode, then winding up takes place only at the limited speed so that the loose cable does not thrash about wildly in the surrounding area and endanger personnel. In addition, in the case of the winch being operated contrary to the regulations, during which operation a load is moved in the mooring mode, the speed is only low and therefore the hazard to personnel is low.

According to other features of the invention, the nozzle and the second directional control valve are preferably arranged in series with each other and in a bypass line to the first directional control valve, the first directional control valve, at the transition of the control lever from the hoisting angle range to the mooring angle range, being brought into a mid position in which the feed of pressure medium to the hydraulic motor under pressure is blocked by the first directional control valve. It is intrinsically also conceivable to arrange the parallel circuit of a nozzle and of the second directional control valve in series with the first directional control valve. The second directional control valve would then be completely open in the hoisting mode and closed in the mooring mode. However, it would have to be designed for the maximum quantity of pressure medium flowing to the hydraulic motor and to be dimensioned to be accordingly large. By contrast, in the case of a construction according to features of the invention, the second directional control valve can be relatively small.

According to

FIG. 5

, the pilot controller is a hydraulic pilot controller and the first directional control valve can be actuated hydraulically. As a result, in the event of an adjustment of the control lever into the mooring angle range, said first directional control valve is moved into its mid position by both pilot control chambers being acted on with the same pilot control pressure, also present on the hydraulic motor. This simplifies the control arrangement as compared with a different solution, in which, in order to return the first directional control valve into the mid position, its two pilot control chambers are relieved of pressure. This is because the two control lines leading from the pilot controller to the first directional control valve are usually also connected to the two inputs of a changeover valve, from the output of which a control line leads to the adjusting device of the hydraulic motor. Via the changeover valve, a pilot control pressure present in the one pilot control chamber or in the other pilot control chamber of the first directional control valve is supplied to the adjusting device of the hydraulic motor. If it were then desired to relieve the two pilot control chambers of the directional control valve to the tank, then the second directional control valve would have to be used to separate the input of the changeover valve on which a pilot control pressure for the hydraulic motor prevails in the hoisting mode, from the corresponding pilot control chamber of the directional control valve, and the pilot control chambers could be relieved separately to the tank. This would make a tank connection on the directional control valve and a tank duct necessary. Particularly advantageous in this case is the construction according to further features of the invention if, the pilot controller comprises an adjustable pilot valve with a pilot control pressure connection which can be connected to various pilot control chambers of the first directional control valve via a directional control valve that is operated by the deflection of the control lever. A pilot controller with a pilot valve whose pilot control pressure connection can be connected via a directional control valve to one or the other pilot control chamber of a proportionally adjustable directional control valve provides the advantage that the behavior of the pilot control is not influenced in a different way by tolerances in the pilot valve, irrespective of the direction in which the control lever is deflected from its neutral position. If, therefore, for example the pilot control valve is in each case actuated in the same way as a function of the angle, irrespective of the direction, during a deflection of the control lever from the neutral position then, in the event of the same deflection angle, the pilot control pressures are also equal. When the pilot valve is set, the pilot control pressure in the two deflection directions are influenced in the same way.

For load-independent control of the rotational speed of a winch, a feed metering diaphragm of the proportionally adjustable directional control valve is assigned a pressure compensator that maintains a fixed pressure difference across the feed metering diaphragm. The bypass line then advantageously circumvents both the pressure compensator and the directional control valve. One control side of the pressure compensator can then be connected in a straightforward way to a connection of the directional control valve, via which a brake on the winch can have pressure applied to it and which, in the mid position of the directional control valve, is relieved of pressure in order that the brake can engage. However, it is also conceivable to connect one control side of the pressure compensator via a changeover valve to one or the other connection of the hydraulic motor and to permit the bypass line to branch off downstream of the pressure compensator, so that only the directional control valve is circumvented. The pressure compensator and nozzle in the bypass line then together form a flow control valve, so that in the mooring mode, one has flow regulation for the pressure medium flowing from the pressure medium source to the hydraulic motor.

In the bypass line, according to features of the invention, there is advantageously a nonreturn valve, which opens in the direction of the flow of pressure medium from the pressure medium source to the hydraulic motor. In addition, there is a pressure limiting valve, which is arranged between the two connections of the hydraulic motor and by means of which the pressure of the connection of the hydraulic motor to which pressure is applied in the mooring mode is limited to a maximum value. When the cable is being let out in the mooring mode, pressure medium flows from the connection of the hydraulic motor to which pressure is applied to the other connection on a short path, via the pressure limiting valve. The hydraulic motor does not have to take up a large quantity of pressure medium via long lines, which would be associated with the risk of cavitation. If the control pressure is supplied internally via a pressure reducing valve, then the latter is connected by its pressure connection to the bypass line, specifically upstream of the nozzle, according to features of the invention the nonreturn valve being arranged between the pressure connection and the pressure medium source.

In the known hydraulic control arrangement for a winch, a hydraulically vented mechanical brake is supplied with pressure medium via a changeover valve from the two motor valve connections of the proportionally adjustable directional control valve. In the mid position of the directional control valve, both motor valve connections of the directional control valve, and therefore also the brake, are relieved to the tank, so that the brake can engage. In accordance with the construction according to features of the invention, the proportionally adjustable directional control valve is in its mid position in the mooring mode, the intention being for a supply of pressure medium to the hydraulic motor to be possible via the bypass line, and therefore one motor valve connection of the proportional directional control valve is advantageously not relieved to the tank when in its mid position, in order not to need a further valve between this motor valve connection and the branch point of the bypass line. According to further features of the invention, therefore, in the mooring mode, the brake is advantageously supplied with pressure medium via the second directional control valve and can also be relieved of pressure via the second directional control valve when the control lever is put into its neutral position. It is therefore essential here that the hydraulic brake actuator can have pressure applied to it and can be relieved of pressure in the mid position of the proportional directional control valve, independently of the latter.

As in the prior art, according to features of the invention, there is a nonreturn device for the control lever, which comprises a restoring spring which, in the easing and hoisting angle range, is prestressed to a greater extent as the deflection of the control lever increases, so that in the aforementioned angle ranges, a restoring force is exerted on the control lever. Adjusting the control lever in the mooring angle range, on the other hand, is indifferent with regard to the prestressing of the restoring spring. Therefore, in the mooring angle range, the latter does not exert any restoring force on the control lever either. This renders a separate fixing brake for the control lever superfluous. Advantageous refinements of the restoring device, referring to the presence and absence of a restoring force, and a cam disk which is coupled to the control lever so as to be secure against rotation and collaborates with the restoring spring are provided. Here, reference is made in particular to the configuration according to features of the invention, according to which, in the mooring angle range, a pressure piece of the restoring device is pressed against the cam disk by a second spring in addition to the restoring spring. This increases the frictional force between the pressure piece and the cam disk, so that a small torque exerted on the control lever by a pilot valve certainly does not lead to any adjustment of the control lever.

The hydraulic control arrangement according to the invention is used for the purpose of operating a winch in the easing, hoisting and mooring mode. For many winches, however, no mooring mode is envisaged. In order to be able to use the same components in the pilot controller as those for a winch with a mooring mode, in the development of a hydraulic control arrangement according to the invention and according to further features of the invention, provision is made for the deflection of the control lever at the end of the easing angle range and at the end of the mooring angle range in each case to be limited by a stop face on a part that corotates with the control lever, and an opposing stop, and for the pressure piece to have an additional stop which, depending on the type of installation of the pressure piece and/or of an opposing stop, limits the path of the pressure piece in the direction of more intensive prestressing of the restoring spring at the end of the hoisting angle range (winch without mooring mode) or does not limit the same (winch with mooring mode).

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous refinements of a hydraulic control arrangement according to the invention emerge from the description which now follows of an exemplary embodiment which is illustrated in the drawing, in which:

FIG. 1

shows the exemplary embodiment in a circuit diagram, in which the control lever and the angle ranges in which the control lever is located during the various modes of operation are also shown schematically,

FIG. 2

shows a partial section through a pilot controller at right angles to the axis of the control lever, the section plane for the restoring device and the housing being a different one from that for the pilot control valve,

FIG. 3

shows the shaft that can be rotated with the control lever and has cam tracks, the pressure piece of the restoring device and a plunger of the pilot control valve in a position which the parts assume when the control lever is deflected to the greatest extent in the easing direction,

FIG. 4

shows the same parts as in

FIG. 3

, in a position in which the control lever has been deflected through 15 degrees from its neutral position into the hoisting angle range,

FIG. 5

shows the same parts as in

FIG. 4

after a deflection of the control lever through 25 degrees,

FIG. 6

shows the parts from

FIG. 5

after a deflection of the control lever through 45 degrees, as far as the end of the hoisting angle range,

FIG. 7

shows the parts from

FIG. 6

after a deflection of the control lever through 57 degrees as far as the start of the mooring angle range, and

FIG. 8

shows the parts from

FIG. 7

after the control lever has been pivoted through 100 degrees as far as the end of the mooring angle range.

A DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1

reveals a winch

10

, which can be driven in opposite directions via a gearbox

11

via an adjustable hydraulic motor

12

. Arranged between the output shaft of the hydraulic motor and the gearbox is a brake

13

, which can be actuated via a single-acting hydraulic cylinder

14

. The hydraulic cylinder

14

is constructed in the manner of a differential cylinder, whose piston and piston rod can be displaced by a spring with the effect of engaging the brake. By applying pressure medium to the annular chamber

15

of the hydraulic cylinder

14

, piston and piston rod are moved back counter to the force of the spring and, as a result, the brake

13

is released. The absorption volume of the hydraulic motor

12

may be adjusted continuously on the basis of a control pressure applied to the control input

16

, and is smaller the greater the control pressure. For the adjustment, there are an actuating cylinder

17

constructed as a differential cylinder and a pump control valve

18

. The latter has a tank connection, which is connected to a leakage oil line

19

, a pressure connection which is connected via two nonreturn valves

20

to the motor connection

21

or

22

, respectively, and a cylinder connection connected to the pressure chamber, on the side remote from the piston rod, of the actuating cylinder

17

. The pressure chamber on the piston rod side of the actuating cylinder

17

is connected to the pressure connection of the pump control valve

18

. The piston slide of the pump control valve

18

is acted on with the effect of connecting the cylinder connection to the pressure connection of the control pressure and with the effect of connecting the cylinder connection to the tank connection by a first compression spring, set to a fixed value, and by a second compression spring whose prestress changes with the position of the piston and the piston rod of the actuating cylinder

17

. The piston and piston rod of the actuating cylinder

17

therefore in each case assume a position such that the force generated as a result of the applied control pressure and the pressure generated by the springs maintain the equilibrium of the piston of the pump control valve

18

. In this way, a specific absorption volume of the hydraulic motor

12

can be set by means of the control pressure.

The source for the pressure medium which is fed to the hydraulic motor

12

is a displacement pump

25

, which takes hydraulic oil from a tank

26

and discharges it into a feed line

27

. The displacement pump

25

is provided with a pressure controller

28

, and therefore, when the pressure set on the pressure regulator

28

is reached in the feed line

27

, pivots back to a swept volume which is sufficient to maintain the set pressure in the feed line

27

. In order to safeguard the entire control arrangement against excessively high pressures, a pressure limiting valve

29

is connected to the feed line

27

. The maximum swept volume of the displacement pump is designed in such a way that said pump is not pivoted as far as the stop even if, taking account of a simultaneous actuation of a plurality of hydraulic loads, the maximum quantity of pressure medium is requested.

The rotational speed at which the hydraulic motor

12

rotates and the direction of rotation can be controlled by a proportionally adjustable directional control valve

35

. This is spring-centered into a mid position and can be actuated hydraulically. It has a total of six connections, namely a feed connection

36

, to which pressure medium can flow from the feed line

27

via a pressure compensator

37

, an outlet connection

38

, which is connected directly to a tank line

39

, a second outlet connection

40

, which is connected via a brake valve

14

to the tank line

39

, a first load connection

42

, which is connected via a load line

43

to the motor connection

21

, a second load line

44

, which is connected via a load line

45

to the motor connection

22

, and a brake connection

46

, via which pressure medium can be applied to the annular chamber

15

of the hydraulic cylinder

14

.

In the spring-centered mid position of the directional control valve

35

, its connections

36

,

40

and

44

are blocked off. The connections

42

and

46

are connected to the connection

38

and therefore to the tank

26

. By applying a control pressure to a first control chamber

47

, the valve piston of the directional control valve

35

is displaced to a different extent, depending on the level of the control pressure, into a first operating position, in which the outlet connection

38

is blocked off. The load connection

42

and the brake connection

46

are jointly connected to the feed connection

36

via a feed metering diaphragm

48

, whose opening cross section depends on the extent of the displacement of the valve piston. The load connection

44

is connected via an outlet restrictor

49

to the outlet connection

40

. If the control chamber

47

is relieved of pressure, and if a second control chamber

50

has a control pressure applied to it, then the valve piston of the directional control valve

35

passes to a different extent from the mid position into a second operating position, in which the load connection

42

is connected in an unrestricted manner to the outlet connection

38

. The brake connection and the other load connection

44

are jointly connected to the feed connection

36

via the feed metering diaphragm

48

. The outlet connection

40

is blocked off. The maximum displacement travel of the valve piston in the two opposite directions is limited by adjustable stops

51

.

According to the connections outlined, the pressure compensator

37

is arranged between the various connections of the directional control valve

35

in the two operating positions of the latter, in each case upstream of the feed metering diaphragm

48

. The control piston of the pressure compensator

37

is acted on in the closing direction by the pressure upstream of the feed metering diaphragm and in the opening direction by a compression spring

52

and by a pressure which is applied via a control line

53

, which is connected to the brake connection of the directional control valve and therefore in each case to the load connection

42

or

44

of the directional control valve

35

in the flow to the hydraulic motor

12

. The pressure is therefore in each case equal to the pressure downstream of the feed metering diaphragm

48

. The pressure compensator

37

therefore controls a specific pressure difference, equivalent to the force of the spring

52

, across the feed metering throttle

48

. The quantity of pressure medium flowing via the feed metering diaphragm

48

therefore depends only on the opening cross section of the feed metering diaphragm and is independent of the load pressure and of the pump pressure.

The control piston of the brake valve

41

is acted on in the opening direction by the pressure present on the load connection

42

of the directional control valve

44

and therefore also present in the load line

43

and at the motor connection

21

, and is acted on in the closing direction by the force of a compression spring

54

and by a pilot control pressure applied via a control line

55

, which is constantly in the region of 40 bar, for example. The two pressures act on equally large areas, so that under a pulling load, the brake valve

41

, together with the restrictor

49

, restricts the outflow of pressure medium from the hydraulic motor

12

via the load line

45

in each case to such a great extent that, in the load line

43

, a pressure is built up which produces a force on the control piston of the brake valve which maintains the equilibrium of the force of the compression spring

54

and the force generated by the pilot control pressure. The rotational speed of the hydraulic motor

12

is therefore also determined by the opening cross section of the feed metering diaphragm

48

when under a pulling load. In addition, the pressure on the brake connection

46

of the directional control valve

35

is so high under a pulling load that the brake

13

remains released.

Arranged between the two load lines

43

and

45

is a pressure limiting valve

60

, which is set to a pressure which is about 10-20 bar above the pressure controlled by the displacement pump

25

, but below the set pressure of the pressure limiting valve

29

.

The directional control valve

35

, the pressure compensator

37

, the brake valve

41

and the pressure limiting valve

60

are accommodated in a valve plate

61

. Built up on the latter is a pilot controller

65

, via which a bypass line

66

which can be blocked off leads, which originates from the feed line

27

upstream of the pressure compensator

37

and opens into the load line

45

, that is to say circumvents the pressure compensator

37

and the directional control valve

35

. Located in the bypass line

66

is a throttle

67

, which is located in the plate

61

and through which the quantity of pressure medium which can flow to the hydraulic motor

12

via the bypass line

66

is limited to about 10% of the quantity of pressure medium which flows to the hydraulic motor

12

via the directional control valve

35

when the feed metering diaphragm

48

is at its maximum opening.

The pilot controller

65

contains two pressure reducing valves

68

and

69

, a directional control valve

70

, a nonreturn valve

71

, various changeover valves

72

,

73

,

74

and

75

, two damping nozzles

76

, two relief nozzles

77

and various ducts for connecting the valves to one another. The nonreturn valve

71

is in the bypass line

66

and blocks toward the feed line

27

. Downstream of the nonreturn valve

71

, the pressure reducing valve

68

is connected to the bypass line

66

by its pressure connection. A relief connection of the pressure control valve

68

is connected to a leakage duct

78

. The pressure reducing valve

68

is set to a fixed value and, at its control output and in a pilot control pressure supply duct

79

, to which the control line

55

leading to the brake valve

41

is also connected, for example controls the aforementioned pressure at the level of 40 bar. The second pressure reducing valve

69

, which is connected by its pressure connection to the duct

79

, by its relief connection to the duct

78

and by its control output to a pilot control pressure duct

80

, can be adjusted by pivoting a control lever

81

from a neutral position. The pivot axis of the control lever

81

is designated by

82

. Fixed to the control lever is a control disk

83

having a control cam on which an actuating plunger

84

of the pressure reducing valve

69

bears. The control cam is configured such that when the control lever is pivoted from the neutral position, first of all the pressure reducing valve

69

is adjusted in the same way, irrespective of the pivoting direction. To be specific, the pilot control pressure in the duct

80

increases continuously, starting from a pivoting angle of about 8 degrees up to a pivoting angle of 45 degrees, even if not necessarily with the same slope everywhere. The pivoting angle of the control lever

81

is limited to about 50 degrees for the pivoting in one direction. In this direction, the control lever is pivoted for the purpose of easing, that is to say for unwinding the hawser from the winch

10

. Pivoting the control lever in the other direction is carried out for the purpose of hoisting, that is to say when the hawser is to be wound up on the winch

10

. In this case, both when being pivoted in the direction of easing and when being pivoted in the direction of hoisting, the control lever

81

pivots back into its neutral position again, because of a restoring device acting on it, when it is released. In the hoisting direction, however, the control lever can be pivoted up to a pivoting angle of about 100 degrees, remaining in the position assumed by it when it is pivoted over about 54 degrees, even when it is released. In this range, the winch

10

is operated in the mooring mode. The three angular ranges of easing, hoisting and mooring are indicated hatched in FIG.

1

and provided with reference numbers

85

for easing,

86

for hoisting and

87

for mooring. Here, the control disk

83

is configured such that in the mooring angle range

87

the pressure in the duct

80

decreases as the pivoting angle of the control lever

81

increases.

The directional control valve

70

is actuated mechanically by the control lever

81

. Its movable valve element is not specifically illustrated, but is preferably constructed as a rotary disk, whose axis of rotation coincides with the axis

82

of the control lever

81

. It can assume a total of four functionally distinguishable switching positions and has 7 connections, of which two connections

88

and

89

are downstream of the nonreturn valve

71

and upstream of the nozzle

67

in the bypass line

66

. The pilot control pressure duct

80

leads to one connection

90

. One connection

91

is connected to the leakage duct

78

. The three remaining connections

92

,

93

and

94

each lead to a first input of a changeover valve

72

,

73

and

74

, respectively. The second input of the changeover valve

74

is connected to the brake connection

46

of the directional control valve

35

. A line

95

leads from the output of the changeover valve to the annular chamber

15

of the hydraulic cylinder

14

. The second input of each of the two changeover valves

72

and

73

is respectively connected to an external connection

95

, which is closed in the present case but offers the possibility of controlling the winch with a second pilot controller, which is arranged at a distance from the block comprising the plate

61

and the pilot controller

65

. For the case of this remote control, and for the case of small pilot control pressures, the line between the connection

46

of the directional control valve

35

and the changeover valve

74

is needed, since the annular chamber

15

of the hydraulic cylinder

14

can then be pressurized via this line. From the output of the changeover valve

72

, a control line

96

leads via a damping nozzle

76

to the control chamber

50

, and from the output of the changeover valve

73

, likewise via a damping nozzle

76

, a control line

97

leads to the control chamber

47

of the directional control valve

35

. The changeover valve

75

is connected by one input to the output of the changeover valve

72

and by its other input to the output of the changeover valve

73

. Its output is connected via a control line

98

to the control input

16

of the hydraulic motor

12

.

In the neutral position of the control lever

81

, the directional control valve

70

assumes a position in which the connections

88

,

89

and

90

are blocked off and the other connections are connected to the tank duct

78

. The bypass line

66

is therefore blocked. The control lines

95

,

96

,

97

and

98

are relieved of pressure in relation to the duct

78

. The directional control valve

35

is therefore in its mid position. The hydraulic motor

12

is at maximum absorption volume. The brake

13

is engaged.

The control lever is then adjusted into the angle range

85

for easing. As a result, the directional control valve

70

moves into a switching position, in which the connections

89

and

94

, the connections

90

and

93

and the connections

91

and

92

are respectively connected to each other. Therefore, the control chamber

47

of the directional control valve

35

has a control pressure applied to it via the connections

90

and

93

and the changeover valve

73

and the control line

97

. This control pressure is also present on the control input

16

of the hydraulic motor

12

via the changeover valve

75

and the control line

98

. The control chamber

50

of the directional control valve

35

is relieved of pressure via the control line

96

, the changeover valve

72

and the connections

91

and

92

of the directional control valve

70

, and via a relief nozzle

77

. The directional control valve

35

is therefore moved into a position in which the feed connection

36

is connected via the feed metering diaphragm

48

to the load connection

42

and to the brake connection

46

. In the load line

43

and in the feed line

27

, a pressure builds up which, via the changeover valve

74

, is also present in the annular chamber

15

of the hydraulic cylinder

14

and is finally sufficient to release the brake. Pressure medium delivered by the hydraulic pump

25

can then flow via the feed line

27

, the pressure compensator

37

, the directional control valve

35

and the load line

43

to the hydraulic motor

12

and, from there, via the load line

25

, the restrictor opening

49

of the directional control valve

35

and via the brake valve

41

, to the tank

26

. The hawser is unwound from the winch

10

. In the process, even when a pulling load hangs on the hawser, the brake valve

41

ensures that the outflow of pressure medium from the hydraulic motor

12

to the tank can only take place in a restricted manner so that a specific pressure is maintained in the load line

43

. This pressure is sufficient to hold the brake

13

released. In addition, the speed at which the hawser is paid out is determined only by the control pressure, which depends on the deflection of the control lever

81

. In this case, the speed of the winch

10

is influenced in two ways. Up to about a deflection angle of 25 degrees, only the directional control valve

35

is adjusted, but not the hydraulic motor

12

. The latter remains at the maximum absorption volume and maximum torque. The torque is indicated in

FIG. 1

by the radial extent of the fields

85

,

86

and

87

. After a deflection of the control lever

81

of 25 degrees, the directional control valve

35

is completely open. During further deflection of the control lever

81

, the absorption volume of the hydraulic motor

12

is then reduced, as a result of which its rotational speed is increased, but its torque is reduced. This is indicated by the decreasing radial extent of the field

85

in FIG.

1

.

If, starting from the neutral position shown, the control lever

81

is pivoted into the hoisting angle range

86

, then the directional control valve

70

comes into a position in which the connections

89

and

94

are again connected to each other. However, the connection

90

is now connected to the connection

92

and the connection

91

to the connection

93

. The control chamber

47

is therefore depressurized, and the control chamber

50

of the directional control valve

35

has applied to it the pilot control pressure dependent on the deflection angle of the control lever

81

. This pressure is also present on the control input

16

of the hydraulic motor

12

. The directional control valve moves into its second operating position, in which the pressure medium delivered by the displacement pump

25

can flow via the feed line

27

, the pressure compensator

37

, the connections

36

and

44

with the feed metering diaphragm

48

located between them, and via the load line

45

, to the hydraulic motor

12

. The outflow of the pressure medium from the hydraulic motor

12

takes place via the load line

43

and the connections

42

and

38

of the directional control valve

35

to the tank

26

. In the load line

45

and in the feed line

27

, a load-dependent pressure is built up which is sufficient to release the brake

13

. The hawser is then wound up on the winch

10

.

If the control lever

81

is pivoted still further into the mooring angle range

87

, then the directional control valve

70

passes into a switching position in which the connections

88

and

94

are connected to the connection

89

. Accordingly, the bypass line

66

is open for the flow of pressure medium, and the annular space

15

of the hydraulic cylinder

14

is connected to the bypass line downstream of the nonreturn valve

71

. The connection

91

of the directional control valve

70

is blocked off. The connections

92

and

93

are connected to the connection

90

, and therefore to the control output on the pressure reducing valve

69

. The same pilot control pressure is therefore present in both the control chambers of the directional control valve

35

, so that the latter returns into the mid position on account of its spring centering. The pilot control pressure is also present on the inlet

16

of the hydraulic motor

12

. In this case, the control cam of the control disk

83

is configured in such a way that, at the start of the mooring angle range, the pilot control pressure is so high that the hydraulic motor is set to its minimum absorption volume. The torque that can be exerted by the hydraulic motor

12

is therefore also a minimum. As the deflection of the control lever

81

increases in the mooring angle range

87

, the pilot control pressure decreases continuously, so that the absorption volume and therefore the torque that can be exerted by the hydraulic motor

12

increases continuously. This is beneficial in terms of working physiology.

In the mooring angle range

87

, pressure medium can still flow to the connection

22

of the hydraulic motor

12

only via the bypass line

66

. This feed flow is limited by the nozzle

67

, so that in the mooring mode, the rotational speed of the hydraulic motor and therefore the speed with which the hawser is wound up is limited. This is important for operational safety. This is because, since the control lever

81

in the mooring angle range

87

maintains its position, even without the action of an external force, there is the possibility that a person will firstly place the control lever in the mooring angle range and then do something with the hawser or stay in the area of the hawser. As a result of the nozzle

67

, the speed at which the hawser is moved is now limited to a low speed. Even if the hawser breaks, the speed at which the hawser is then wound up is low, because of the nozzle

67

, even though it may be somewhat higher than under load.

The control lever

81

is fixed to a shaft which is not specifically illustrated in the figures but projects from the housing

101

of the pilot controller

65

and with which, as

FIG. 2

reveals, within the housing

101

a cam disk

102

with a cam track

104

cooperating with a restoring device

103

, and the control disk

83

axially immediately adjacent to the cam disk

102

and having a control cam

105

cooperating with the plunger

84

of the pressure reducing valve

67

are coupled in a rotationally secure manner. The cam track

104

and the control cam

105

are in each case part-cylindrical surfaces which extend axially over a certain distance. The cam disk

102

and the control disk

83

are located in a relatively large cavity

99

in the housing

101

, into which there open two housing bores

106

and

107

which are located diametrically opposite but, in accordance with the axial offset of the cam disk

102

and control disk

83

, are likewise offset axially in relation to each other. The housing bore

106

accommodates the parts of the restoring device

103

. The pressure reducing valve

69

is inserted into the housing bore

107

.

This pressure reducing valve

69

can be adjusted externally in such a way that a quite specific pilot control pressure prevails in the duct

80

at a selected deflection angle of the control lever

81

. At this selected deflection angle, the intention is for the directional control valve

35

to be fully open and for the displacement of the hydraulic motor

12

to begin. For the purpose of adjustment, the pressure reducing valve

69

has a control sleeve

108

, which is screwed into the housing bore

107

from the externally open end of the latter. The control sleeve

108

is stepped three times on the outside and, at each step, has a seal

109

,

110

and

111

. Formed between the seal

109

with the smallest diameter and the middle seal

110

, between the control sleeve

108

and the housing

110

, is an annular chamber, which is part of the control pressure supply duct designated by

79

in FIG.

1

and in which there prevails the pressure regulated by the pressure reducing valve

68

at the level of 40 bar. Axially between the two seals

110

and

111

, on the outside of the control sleeve

108

, there is a further annular chamber, which belongs to the pilot control pressure duct

80

from

FIG. 1. A

further annular chamber between the control sleeve

108

and the housing

101

is created in front of the seal

109

, this annular chamber belonging to the leakage duct

78

from FIG.

1

.

The central passage

112

through the control sleeve

108

has sections lying axially one behind another with different cross sections. A bore section with the smallest diameter is located axially approximately between the seals

109

and

110

and, via two radial holes

113

, is open to the annular chamber

79

. It merges outward into a bore section which is somewhat larger and partially provided with an internal thread and from which there lead radial holes

114

which open into the annular chamber

80

. Screwed into the bore section is a grub screw

115

, by means of which the aforementioned bore sections are closed off to the outside. On the other side of the grub screw

115

, the passage is formed as an internal polygon, on which a tool can be attached for the purpose of rotating and therefore for the purpose of axial adjustment of the control sleeve

108

. The bore section into which the radial holes

113

open merges inward into an accommodation chamber

116

, which is again stepped and from which radial holes

117

lead into the annular chamber

78

. Inserted into this accommodation chamber

116

is a guide bush

118

for the plunger

84

of the pressure regulating valve

69

, said plunger being captively secured therein by a grub screw

121

. The guide bush has radial holes

119

, via which, together with an annular chamber placed between the control sleeve

108

and the guide bush

118

, a spring chamber

120

formed between the control sleeve

108

, the guide bush

118

and the plunger

84

is connected to the annular chamber

78

and therefore to the tank.

The passage section into which the radial holes

113

open is used as a guide bore for a control piston

125

and, together with the control piston, controls the connections between the various annular chambers

78

,

79

and

80

. The edges between the radial holes

113

and the bore section, on the one hand, and the edge between the bore section and the relatively large spring chamber

120

, on the other hand, form the control edges in this case. The control piston

125

is a hollow piston having an axial blind bore

126

, which is open toward the radial holes

114

and is connected via a plurality of radial holes

127

to the outer side of the control piston. The radial holes

127

merge on the outside into an annular groove

128

. The axial extent of the annular groove, including the radial holes

127

, is slightly smaller than the clear axial spacing between the control edges on the control sleeve

108

, so that it is possible to separate the blind bore

26

with a positive overlap both from the radial holes

113

and from the spring chamber

120

. The control piston

125

extends through the spring chamber

120

and projects with a head

129

into a blind bore

130

in the plunger

84

. With the head

129

, it engages behind a disk

131

, which is arranged between the plunger

84

and a spring plate

132

, and holds the head

129

in the manner of a slotted securing ring. A restoring spring

133

accommodated by the spring chamber

120

and intended for the plunger

84

is supported at one end on the control sleeve

108

and at the other end, via the spring plate

132

and the disk

131

, on the plunger

84

and presses the plunger against the control cam

105

. Also accommodated by the spring chamber

120

is a control spring

134

, which is clamped in between a spring plate