EP2142808B1 - Hydraulic control arrangement - Google Patents

Abstract

The invention relates to a hydraulic control arrangement for a mobile machine tool, particularly for a forklift, comprising at least two hydraulic loads (10, 12), one of them having a lifting function. According to the invention, the two loads are each controlled via a LUDV valve with inflow measuring diaphragm (36, 44) and LUDV pressure regulator (46) connected downstream.

Description

Hydraulic control arrangement

The invention relates to a hydraulic control arrangement for a mobile work machine with at least two hydraulic consumers, one of which is provided for a lifting function

Examples are in document DE 19703997 and US 6293099 to find.

In the US 6,293,099 B1 Such a control arrangement is described, which is provided for controlling the consumers of a forklift. A forklift usually has a mast along which a fork is movable to raise or lower a load. The mast can also be tilted and moved laterally, these functions are each operated by hydraulic cylinders. For controlling the pressure medium volume flow to the respective hydraulic cylinder proportional valves are provided in the known solution, via which the pressure medium volume flow to the respective hydraulic cylinder can be adjusted. The pressure medium supply usually takes place via an LS variable displacement pump or a fixed displacement pump with bypass pressure compensator. Depending on the highest load pressure of all consumers, the variable displacement pump or the bypass pressure compensator can be controlled such that the pump pressure is above the highest load pressure by a predetermined Δp.

In such control arrangements, for example, a problem may occur when, for example, raised the empty, unloaded fork and at the same time the mast tilt is to be changed. The load pressure at the tilting cylinder in this case is greater than the load pressure of the lifting cylinder, so that the latter is preferably supplied with pressure medium and the fork is raised relatively quickly, while the tilting movement is very slow or even stopped. This problem occurs in virtually all conventional forklifts.

One could now try to arrange in the pressure medium flow path to the tilting cylinder LS valve with a metering orifice and a pressure balance, which is acted upon by the pressure before and after the metering orifice. In this case, raising the fork and tilting the mast could be done simultaneously as long as the maximum possible pump flow rate is not exceeded. In case of a shortage ie, in the case where the pump can not deliver enough pressure medium, the load pressure higher consumer is slower again, because the pending before the metering orifice pump pressure drops and thus the pressure difference across this metering orifice is smaller again - it poses the same problem as in the aforementioned control arrangement with proportional valves.

On the other hand, the object of the invention is to provide a hydraulic control arrangement for a mobile work machine in which several consumers can be controlled simultaneously.

This object is achieved by a hydraulic control arrangement for a mobile work machine having the features of patent claim 1.

According to the invention, the at least two consumers of the mobile working machine are supplied with pressure medium via a pump as a function of the highest load pressure. The pressure medium volume flow to an effective in the direction of lifting the consumer and the pressure medium flow to another consumer are each controlled by a LUDV valve with a Zulaufmessblende and a downstream pressure compensator in the closing direction of a pressure corresponding to about the highest load pressure of the consumer and in the opening direction downstream of the inlet orifice is acted upon.

In such LUDV controls (load pressure-independent flow distribution) arranged downstream of the metering orifice LUDV pressure compensators throttle the pressure medium flow rate so strong that the pressure after all Zumessblenden same, preferably equal to the highest load pressure or slightly above this. When undersatured, the pressure downstream of the metering orifice does not change. In front of all metering orifices, the pump pressure is applied in the same way, so that the pressure difference changes in all metering orifices in the same way, if the pump pressure is lower at unsaturation - thus ensuring a proportional flow distribution of the flow to the consumers, so that, for example, an unloaded Fork of a forklift truck can be raised and at the same time a mast of the forklift can be tilted.

In a simply constructed solution, it may be sufficient if another consumer is controlled via a proportional valve.

In a particularly simple embodiment, a LUDV valve with a metering orifice and a LUDV pressure compensator two consumers are assigned, which are provided, for example, for tilting and moving a mast of a forklift.

The pressure medium flow direction to and from the consumer is then controlled via a respective directional control valve. D. h., In this solution, the metering orifices of the LUDV valves are very simple, designed to be continuously adjustable in one direction, so that the circuit can be implemented very inexpensively.

In the case in which the working pressure of the consumers controlled via a common LUDV valve is less than the working pressure of the other consumers, the pressure compensator of the common LUDV valve can be assigned a pressure reducing valve.

The hydraulic actuation of a steering of the mobile work machine is preferably carried out via an LS valve with an inlet orifice and a steering pressure compensator.

In one variant, the steering pressure compensator in the closing direction is acted upon by the pressure in front of the associated inlet orifice and in the opening direction by a spring and the pressure in a control line. This control line is connected to a line section leading the load pressure of the steering.

In this case, it is preferable for a line section located downstream of the steering pressure scale to be connected via a control channel and a check valve closing in the direction of the steering to a LS line leading to the highest load pressure of the loads.

In an alternative solution, the control line (118) leads from a pressure medium flow path upstream of the steering pressure balance (112) to a line section carrying the load pressure of the steering, wherein two nozzles (120, 122) are arranged in the control line (118) and in the area between the two two nozzles (120, 122) branches off to an effective in the opening direction of the steering pressure balance (112) control chamber control channel (124) which is connected via a check valve (126) with a highest load pressure leading LS line (60).

The control arrangement can be implemented particularly easily if the pump for supplying pressure medium is a constant-displacement pump to which a bypass pressure compensator is assigned, which is acted upon in the opening direction by the pump pressure and in the closing direction by the highest load pressure of the consumers.

The LS line can be connected to a pressure relief valve via a relief valve with a tank. This relief valve is designed as a flow control valve.

To protect the LS line can be provided in this LS pressure relief valve.

The control arrangement according to the invention is preferably used for controlling a forklift, wherein a LUDV valve for controlling the lifting function and a LUDV valve for controlling the tilting and the lateral displacement of a mast of the forklift are provided.

Other advantageous developments of the invention are the subject of further subclaims.

• Figur 1 ein Schaltschema einer Steueranordnung eines Gabelstaplers mit einer Heben-, einer Neigen- und einer Verschiebenfunktion;
• Figur 2 eine Detaildarstellung der Steueranordnung aus Figur 1;
• Figur 3 die Steueranordnung gemäß Figur 1 mit integrierter LS-Lenkung und
• Figur 4 eine Variante der Schaltung gemäß Figur 3.

In the following preferred embodiments of the invention will be explained in more detail with reference to schematic drawings. Show it:

• FIG. 1 a schematic diagram of a control arrangement of a forklift with a lift, a tilt and a shift function;
• FIG. 2 a detailed representation of the control arrangement FIG. 1 ;
• FIG. 3 the control arrangement according to FIG. 1 with integrated LS steering and
• FIG. 4 a variant of the circuit according to FIG. 3 ,

In FIG. 1 a circuit diagram of a hydraulic control arrangement of a forklift is shown. This control arrangement is formed for example by a mobile control block 1, which consists essentially of a LUDV section 2, two-way valve sections 4, 6 and an end plate 8. In the illustrated embodiment, the mobile control block 1 has a pressure port P, a tank port T and a working port A at the LUDV section 2 and each working ports A, B at the two-way valve sections 4, 6. The illustrated mobile control block 1 is for driving a mast and the fork of the forklift provided, via a lifting cylinder 10, the fork can be raised or lowered. A tilting cylinder 12 is provided for tilting the fork leading the fork and a displacement cylinder 14 for laterally displacing the mast. The lifting cylinder 10 is a differential cylinder, wherein a bottom-side cylinder chamber 16 is connected via a working line 18 to the working port A of the LUDV section 2. The tilting cylinder 12 is designed as a double cylinder with two parallel-connected differential cylinders, wherein the bottom-side cylinder chambers are connected via a consumer line 20 and the two piston rod-side annular spaces via a further consumer line 22 to the working ports B and A of the directional valve section 4.

In the further consumer line 22, a lowering brake valve 24 is arranged, which allows a pressure medium supply from the working port A to the two annular spaces unhindered and throttles the return of the two annular spaces to the working port A, so that a controlled tilting of the mast is made possible. Such lowering brake valves or counter-balance valves are known from the prior art, so that further explanations are unnecessary.

The displacement cylinder 14 is designed as a synchronous cylinder, wherein the two annular spaces are connected via a working line 26 and a further working line 28 to the working ports A, B of the directional valve section 6.

In both directional valve sections 4, 6, a 4/3-way switching valve 34 and 32 is respectively provided, which are biased in the blocking position shown and over - as will be explained in more detail - the pressure fluid flow direction to and from the cylinders 12, 14 adjustable is.

The LUDV section 2 has an LUDV valve 34 which is assigned to the two cylinders 12, 14 and consists of a metering orifice 36 and a LUDV pressure compensator 38 connected downstream thereof. In such LUDV valves 34, the LUDV pressure compensator 38 is acted upon in the direction of its closed position by the highest load pressure or a pressure approximately corresponding thereto and in the opening direction by the pressure downstream of the respective upstream metering orifice 36. In the illustrated embodiment, the metering orifice 36 is designed by a continuously adjustable 212-way valve, which is biased in its illustrated closed position. The metering orifice can be opened by energizing a proportional magnet 40 for adjusting the pressure medium volume flow to the consumers 12, 14.

The pressure medium volume flow to the lifting cylinder 10 is also set via a LUDV valve, which is referred to below as lifting LUDV valve 42. Its basic structure corresponds to that of the LUDV valve 34 - it thus consists essentially of a lifting metering orifice 44 and one of these downstream lifting LUDV pressure compensator 46. The lifting metering orifice 44 is also designed by a continuously adjustable 2/2-way valve, whose opening cross-section is in turn adjustable via a proportional magnet 48. As will be explained in more detail below, the lifting of a load by supplying pressure medium in the bottom-side cylinder chamber 16 of the lifting cylinder 10. The lowering of the load or the fork is done solely by their weight, the lowering speed is controlled by a LS-valve 50 , Such a LS-valve consists essentially of a continuously adjustable LS metering orifice 52, which is associated with a LS-pressure compensator 54. This is the LS metering orifice upstream 52 and applied in the direction of its closed position by the force of a spring and the pressure after the LS metering orifice and in the opening direction of the pressure upstream of the LS metering orifice 52. The LS metering orifice 52 is designed as a 2/2-way seat valve, which allows a leakage-free shutoff of the working line 18 in its illustrated blocking position. The LS metering orifice 52 can be adjusted by means of a proportional solenoid 56 or by hand. Further details of the described LS / LUDV valves are based on FIG. 2 explained.

The pressure port P of the mobile control block 1 is designed to the output port of a LS pump, which may be formed for example as a fixed displacement pump. The flow of this constant pump, not shown, is then adjusted via a bypass pressure compensator 58, which is acted upon in the opening direction by the pump pressure and in the closing direction of the highest load pressure of all consumers and by the force of a pressure compensator spring. In the control position of the bypass pressure compensator 58, the pump pressure is always adjusted by a force corresponding to the spring corresponding pump-Δ above the highest load pressure, which is tapped in an LS line 60. In order to relieve the LS line 60, this is connected via a designed as a flow control valve relief valve 62 connected to the tank port T of the mobile control block 1 drain line 64. About this relief valve 62 always flows a very low control oil flow to the tank, not shown. To protect the pressure in the LS line 60, a LS pressure relief valve 66 is provided.

Further details of the LUDV section 2 will be described with reference to the enlarged view in FIG FIG. 2 explained.

The pressure medium flows from the pressure port P via an inlet channel 68 to the input port of the lifting metering orifice 44 and the LUDV metering orifice 36. The output port of the LUDV metering orifice 36 is connected via a pressure compensator channel 70 to the input port of the LUDV pressure compensator 38, so that these in Opening direction of the pressure downstream of the LUDV metering orifice 36 is acted upon. As mentioned above, this opening cross section is set via the proportional magnet 40.

A rear control chamber 72 of the LUDV pressure compensator 38 is connected to the LS line 60, so that acts on the back of the pressure compensator piston, the pressure in the LS line 60 in the closing direction. Since the highest load pressure of all consumers or at least a corresponding pressure is present in this, the highest load pressure also arises at the entrance of the LUDV pressure compensator 38 in the control position. This highest load pressure is throttled over the LUDV pressure compensator 38 to the actual load pressure of the associated consumer and guided via the connected to the output terminal of the LUDV pressure compensator 38 feed line 74 to the associated consumer. In the flow line 74 a in the direction of the two cylinders 12, 14 opening check valve 76 is arranged, so that a pressure medium backflow to the LUDV valve 34 is prevented. The displaced from the cylinders 12, 14 pressure fluid flows through the drain passage 64 and the tank port T to the tank down.

The lift-LUDV valve 42 has in principle the same structure as the LUDV valve 34. The input of the lifting metering orifice 44 is connected to the inlet channel 68 and the output via another pressure compensator channel 74 to the input of the lifting LUDV pressure compensator 46 connected. Their rear control chamber 76 is also connected to the LS line 60, so that the pressure compensator piston of the lifting LUDV pressure compensator 46 is acted upon in the closing direction by the highest load pressure and in the opening direction by the pressure downstream of the lifting metering orifice 44. The adjustment of this lifting metering orifice 44 takes place via the proportional magnet 48. The output connection of the lifting LUDV pressure compensator 46 is connected to the working connection A via a feed channel 82 and a check valve 84 which opens in the direction of the working connection A. In the area between the Working port A and the check valve 84 branches from the feed channel 82 from a return channel 86, in which the effective in the lowering direction LS-valve 50 is arranged.

The input of the LS inlet orifice 52 is connected to the return channel 86. The output is connected via a pressure compensator channel 88 to the input of the LS-pressure compensator 54. Their pressure compensator piston is acted upon in the closing direction by the force of a spring 90 and the pressure at the outlet of the LS inlet orifice 52. This control pressure is tapped via a control channel 92 in the pressure compensator channel 88. In the opening direction, the pressure acts upstream of the LS Zulaufmessbrende 52. This pressure is tapped via a control channel 94, wherein a part of the control oil flow path, in FIG. 2 labeled 94a, is integrated into the LS metering orifice 52. As already shown FIG. 1 1, the adjustment of the opening cross-section of the LS metering orifice 52 takes place via the proportional magnet 56 or by hand via a handle 96.

About the LS-valve 50 running off the lifting cylinder 10 pressure medium flow rate is held constant load pressure independent. As already explained, the LS metering orifice 52 is designed as a seat valve, so that in the illustrated closed position a leakage-free support of the lifting cylinder 10 takes place. To lower the load, the LS Zumeßblende 52 is opened, the lowering speed can be kept constant load pressure independent, since in the control position of the LS-pressure compensator 54 a constant, the force of the spring 90 corresponding pressure difference across the LS Zulaufmessblende 52 is adjusted.

The bypass pressure compensator 58 is, as already mentioned, acted upon by the force of a pressure compensator spring 98 and the pressure in the LS line in the closing direction and in the opening direction by the pressure in the inlet channel 68, which is tapped off via a channel 100. The relief valve 62 and the LS pressure relief valve 66 each extend between the LS line 60 and the drain channel 64.

The in the FIGS. 1 and 2 illustrated circuit makes it possible, for example, the lifting cylinder 16 and either the tilting cylinder 12 or the displacement cylinder 14 to operate simultaneously.

As in particular from FIG. 1 shows, the two cylinders 12, 14 connected in parallel, it being provided that only one of the two consumers is closed. The two cylinders 12, 14 upstream directional control valves 30, 32 are each designed as 4/3-way valves and biased by a centering spring assembly in its illustrated basic position. The adjustment in the switching positions a, b via switching magnets. When switching the Wegevntils 30 in the switching position a of the flow channel 74 is connected to the working port A and the drain line 64 to the working port B. As a result, the two tilting cylinders 12 are extended and the mast tilt is correspondingly reduced. When switching the directional control valve 32 in the switching position a is then corresponding to the displacement cylinder 14 as shown in FIG FIG. 1 moved to the right.

When switching the directional control valve 30 in the switching position b, the two working ports A, B of the cylinder 12 are connected to the flow channel 64 and the feed channel 74 so that, for example, the mast is tilted over the tilting cylinder 12, wherein the tilting speed over that in the return located lowering brake valve 24 is determined.

If one switches the directional control valve 32 in the switching position b, the displacement cylinder 14 in the illustration in accordance with FIG. 1 moved to the left. As already mentioned, either the displacement cylinder 14 or the tilting cylinder 12 is always actuated, so that the corresponding consumer is supplied with pressure medium via the LUDV valve 34.

With simultaneous actuation of the lifting cylinder 10 and the tilting cylinder 12, the pressure medium volume flow through the LUDV valves 34 and 42 is kept constant depending on the set opening cross section of the metering orifices 44 and 36, even at sub-saturation, the distribution of the pressure medium volume flow remains constant load independent, so even then still both consumers 16, 12 or 14 can be controlled in parallel. As described above, this is not possible with conventional control arrangements for forklifts.

In FIG. 3 an embodiment is shown in which in the circuit according to the FIGS. 1 and 2 a steering 102 is integrated. Such steering usually has a steering cylinder 104 which is supplied for steering via a steering unit 106 with pressure medium. Such steering units 106, also called Orbitrol, are described for example in the data sheet RD 14 365 Bosch Rexroth AG. The steering unit 106 consists essentially of a metering pump and a hand-operated servo valve in rotary valve construction. The size of the metering pump is chosen so that with three to five steering wheel turns from the stop to the stop of the steering can be steered. About the servo valve while a metering orifice is set. The pressure medium supply of the steering unit 106 via a branched off from the inlet channel 68 steering line 108 which is connected via a steering port C and a working line 110 to the steering unit 106. In the steering line 108, a steering pressure compensator 112 is arranged, which forms an LS valve together with the integrated into the steering unit 106 metering orifice, via which the pressure medium flow rate for adjusting the steering cylinder 104 can be kept constant independent of load.

The steering pressure gauge 112 is in the closing direction from the upstream pressure, i. acted upon by the pressure in the region of the terminal C. This control pressure is tapped via a steering control line 114. In the opening direction acts on the steering pressure compensator 112, an adjustable pressure compensator spring 116 and a steering control pressure, which is tapped on a control line 118. This extends from the steering unit 106 to an upstream of the steering pressure balance 112 located portion of the steering line 108. About this control line 118, the load pressure of the steering can be tapped. In the illustrated embodiment, two nozzles 120, 122 are arranged in the control line 118, which together form a pressure divider. In the area between the two nozzles 120, 122 branches off a control channel 124 which is also connected to a spring-side control chamber of the steering pressure balance 112, so that the pressure in the control channel 124 acts in the opening direction on the piston of the steering pressure balance 112. In the illustrated embodiment, the control channel 124 is connected via a further check valve 126 to the LS line 60.

In the FIG. 3 lower nozzle 122 forms when actuated steering together with the bypass pressure compensator 58 a flow regulator, via which the control oil volume flow through the nozzle 122 can be kept constant. By suitable design of the further nozzle 120, a predetermined pressure can then be set in the area between the nozzles 120, 122, which is a certain pressure difference above the steering load pressure. With such a circuit it is ensured that at a supersaturation, the steering 102 is supplied with pressure medium, wherein above the two orifices 36 and 44 of the LUDV consumers 10, 12, 14 no Δ is present, since with a suitable choice of the nozzle 120 at the entrance of associated LUDV pressure compensator 38, 46, the same pressure as in the control channel 124 is adjusted and this pressure with a suitable nozzle selection (nozzle 120) corresponds to the pump pressure, so that no Pressure medium or only a small volume flow to the other LUDV consumers flows, but the steering remains fully functional.

Another special feature of in FIG. 3 illustrated embodiment is that in the flow channel 74, a pressure reducing valve 128 is provided, via which in the directional control valve sections 4, 6 a lower working pressure than in the LUDV section 2 can be set. The pressure reducing valve 128 is preferably arranged in the region between the LUDV pressure compensator 38 and the check valve 76.

FIG. 4 shows another way, the steering 102 in the circuit according to FIG. 1 integrate the differences between the embodiments in FIG. 3 and 4 lie only in the tap of the load pressure acting on the steering pressure balance 112.

At the in FIG. 4 illustrated variant, the load pressure of the steering unit 106 is tapped via a channel 130, which has no connection to the steering line 108 in contrast to the control line 118 from the above-described embodiment. The control channel 124 connects in this embodiment, the LS line 60 to the working line 110, so that the pressure downstream of the steering pressure gauge 112 is reported via the check valve 126 in the LS line 60. This pressure is higher than the load pressure of the steering. In turn, the pressure balance spring 116 and the pressure in the channel 130 act on the steering pressure balance 112 in the opening direction. This pressure corresponds approximately to the load pressure of the steering (pressure downstream of the steering metering orifice).

In the case of a supersaturation, ie when the pump can not deliver enough pressure medium, the pressure in the inlet channel 68 decreases and the respective load pressure of the LUDV consumers via the LUDV pressure compensators at the outlet of the inlet orifice, so that corresponding to the pressure difference over the LUDV measuring orifices sinks and less pressure medium flows to the LUDV consumers or these are no longer supplied with pressure medium. However, the steering unit 106 is supplied with pressure medium fully open steering pressure balance 112, so that the steering can still be operated. Such integration of a steering in a LUDV control arrangement is per se from the DE 101 19 276 A1 known, so that further statements are unnecessary.

In principle, the above-described control arrangements can also be applied to other mobile machines, such as wheel loaders, mini excavators, etc.

Disclosed is a hydraulic control arrangement for a mobile work machine, in particular for a forklift, with at least two hydraulic consumers, one of which has a lifting function. According to the invention, the two consumers are each controlled via a LUDV valve with inlet orifice plate and downstream LUDV pressure compensator.

LIST OF REFERENCE NUMBERS

1

control block

2

LUDV section

4

Directional control valve section

6

Directional control valve section

8th

endplate

10

lifting cylinder

12

tilt cylinder

14

displacement cylinder

16

cylinder space

18

working line

20

consumer line

22

further consumer guidance

24

lowering valve

26

working line

28

working line

30

way valve

32

way valve

34

LIFD valve

36

LUDV metering orifice

38

LUDV pressure

40

proportional solenoid

42

Lift-LIFD valve

44

Lift-metering orifice

46

Lift-LUDV pressure

48

proportional solenoid

50

LS-valve

52

LS metering orifice

54

LS pressure

56

proportional solenoid

58

Bypass pressure compensator

60

LS line

62

relief valve

64

drain line

66

LS pressure relief valve

68

inlet channel

70

Pressure balance channel

72

control room

74

forward channel

76

check valve

78

control room

80

forward channel

82

forward channel

84

check valve

86

Return channel

88

Pressure balance channel

90

feather

92

control channel

94

control channel

96

handle

98

Compensator spring

100

channel

102

steering

104

steering cylinder

106

steering unit

108

steering line

110

working line

112

Steering pressure

114

Steering control line

116

Compensator spring

118

control line

120

jet

122

jet

124

control channel

126

another check valve

128

Pressure reducing valve

130

channel

Claims (15)

1. A hydraulic control arrangement for a mobile machine comprising at least two hydraulic loads (10, 12, 14) which can be supplied with pressure fluid by a pump in response to the maximum load pressure, wherein the pressure fluid volume flow to one of the loads (10) for a lifting function and to a load (12, 14) actuating another function of the machine is defined via a respective inflow metering orifice (36, 44) and an LUDV pressure regulator (38, 46) allocated thereto, each of which is pressurized in the opening direction by the pressure downstream of the allocated inflow metering orifice (36, 44) and in the closing direction by pressure approximately corresponding to the maximum load pressure of the loads (10, 12, 14), characterized in that in a return line from the load (10) provided for lifting to the control of lowering an LS valve (50) an including LS metering orifice (52) and an LS pressure regulator (54) is arranged.
2. The hydraulic control arrangement according to claim 1, wherein another load, for instance for tilting a boom, is controlled via a proportional valve.
3. The hydraulic control arrangement according to claim 1, wherein an inflow metering orifice (36) and the pertinent LUDV pressure regulator (38) are allocated to at least two loads (12, 14).
4. The hydraulic control arrangement according to claim 3, wherein a directional valve (30, 32) for adjusting the pressure fluid flow direction to and from the load (12, 14) is allocated to at least one of the loads (12, 14).
5. The hydraulic control arrangement according to any one of the preceding claims, wherein the inflow metering orifice (36, 44) is formed by a continuously variable two-way valve.
6. The hydraulic control arrangement according to any one of the claims 3 to 5, wherein a pressure relief valve (128) is provided downstream of the LUDV pressure regulator (38).
7. The hydraulic control arrangement according to any one of the preceding claims, wherein downstream of the LUDV pressure regulator (46) of the load (10) provided for lifting, a check valve (84) opening toward the latter is disposed and a return passage (86) branches off between the check valve (84) and the load (10).
8. The hydraulic control arrangement according to any one of the preceding claims, comprising a steering unit (120) which has an LS inflow metering orifice for the pressure fluid supply of an actuator (104) of the steering (102) and to which a steering pressure regulator (112) is allocated.
9. The hydraulic control arrangement according to claim 8, wherein the steering pressure regulator (112) is pressurized in the closing direction by the pressure prevailing upstream of the LS inflow metering orifice of the steering unit (106) and in the opening direction by a spring (116) and the pressure prevailing in a control line (118, 130) connected to a line portion conducting a load pressure of the steering.
10. The hydraulic control arrangement according to claim 9, wherein a line portion located downstream of the steering pressure regulator (112) is connected, via a control passage (124) and a check valve blocking in the direction of the steering unit (106), to an LS line (60) conducting the maximum load pressure of the loads (10, 12, 14).
11. The hydraulic control arrangement according to claim 9, wherein the control line (118) leads from a pressure fluid flow path upstream of the steering pressure regulator (112) to a line portion conducting the load pressure of the steering, two nozzles (120, 122) being arranged in the control line (118), and in the area between the two nozzles (120, 122) a control passage (124) leading to a control chamber active in the opening direction of the steering pressure regulator (112) branches off which is connected to an LS line (60) conducting the maximum load pressure via a check valve (126).
12. The hydraulic control arrangement according to any one of the preceding claims, wherein the pump is a constant displacement pump to which a bypass pressure regulator (58) is allocated which is pressurized in the opening direction by the pump pressure and in the closing direction by the maximum load pressure prevailing in the LS line (60) and a pressure regulator spring.
13. The hydraulic control arrangement according to claim 8 or 9, wherein the LS line (60) is connected to a tank via a relief valve (62).
14. The hydraulic control arrangement according to any one of claims 8, 9 or 11, wherein the pressure prevailing in the LS line (60) is limited via an LS pressure limiting valve (66).
15. The hydraulic control arrangement according to any one of the preceding claims, wherein the mobile machine is a forklift, with a lifting cylinder (10) for lifting a load, a tilting cylinder (12) for tilting and a displacement cylinder (14) for laterally displacing a boom being provided, wherein a common LUDV valve (34) is preferably associated to the two latter loads.

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