EP1729014B1 - Control block and section of a control block - Google Patents

Description

The invention relates to a control block for supplying pressure medium to a plurality of consumers according to the preamble of patent claim 1 and a control block section suitable for such a control block.

Such, for example, from the data published by the applicant data sheet RD 64 278 / 05.03 and RD 64 282 / 10.99 control blocks are used to control hydraulic consumers of mobile machines. For example, in a forklift can be controlled via such a control block, the steering, as well as hydraulic cylinder for raising or lowering the fork and tilting the fork-carrying mast. Usually, the nominal size of the control block is designed as a function of the consumer with the greatest pressure medium requirement. For example, in forklifts, the pressure medium requirement of the hydraulic cylinder assembly for lifting the fork is much greater than the pressure medium requirement of other consumers (steering, mast tilt), so that the nominal size of the control block is selected in response to the maximum pressure medium requirement and the smaller consumers associated control block sections are oversized. Since the costs of the hydraulic system are not insignificantly determined by the control block, it is endeavored to carry out this with possible small nominal size. A way out of this problem might be to design the nominal size of the control block as a function of the smaller consumers and then to allocate two or more directional valve sections to compensate for the larger load, due to the additional directional valve section the investment costs for such a solution too high. The document DE 44 00 760 A1 describes a multi-way valve with multiple switch positions, which can be used for various valve functions.

In contrast, the invention has for its object to provide a control block and a suitable control block for such a control block section, with the consumer with high pressure medium demand and consumers with relatively lower pressure medium requirement with low device complexity with pressure medium can be supplied.

This object is achieved with regard to the control block by the combination of features of claim 1 and with respect to the control block section by the combination of features of claim 4.

According to the larger consumers, ie the consumer with a larger pressure medium required associated control block section is executed with two working ports, which are connected depending on the setting of a directional valve control block section either with a pressure medium source or a pressure medium sink to actuate the associated consumer. According to the invention, the flow cross section from the directional control valve is doubled up to a common supply line to the connected consumer or consumers, so that the hydraulic resistance compared to the conventional solutions is substantially reduced and the valve section is suitable for larger flow rates than in the prior art.

A directional control valve, via which two control chambers connected to a working connection can be connected either to a pressure connection or to a tank connection, is per se already out of the JP 2093104 However, this valve has only a single working port and moreover, it is not executed as part of a control block section. Through this single working port of the directional control valve, the pressure loss at high flow rate is large, so that a larger nominal size must be used.

The control block section for such a control block is designed with a continuously adjustable directional valve, the valve slide has piston collars, via the control edges, the connection between the two working ports and the pressure medium source or the pressure medium sink is adjustable.

This construction makes it possible to make the directional valve with a small axial length and thus extremely compact, so that integration into conventional control blocks can be carried out in a simple manner.

The controlled via the control block consumer can have a pressure chamber or two pressure chambers, in which case each of the pressure chambers is assigned its own control block section according to the invention.

The control block can be designed as an LS or LUDV control block.

In the control block section according to the invention, the piston collar of the valve slide is completely covered by the housing web in the central position. This piston collar has a control edge, via which the connection between a control port associated with a working port and a pressure control chamber associated with the pressure port is adjustable.

A second piston collar is in one embodiment with two control edges designed to adjust the connection between another working control chamber and a connected to a tank port tank control chamber or the pressure control chamber and the other working control chamber. The third piston collar is also provided in this embodiment with a control edge to adjust the connection between the first working control chamber and a second tank control chamber.

A second piston collar is designed with a control edge over which the connection between the further working control chamber and the pressure control chamber is adjusted. The third piston collar is designed with a control edge for adjusting the connection between the latter working control chamber and a further control chamber.

In this embodiment, the valve spool is designed with three adjacent to said piston collars piston necks.

In the case where the control block section is designed as an LS control block section, the directional control valve has an LS control chamber, which can be acted upon by a passage passing through the valve spool with the load pressure in one of the working control chambers.

This channel opens in a preferred embodiment, on the one hand in a in a working control chamber (54, 58) movable piston collar section.

In an LS or LUDV control block section, it is preferred if the valve spool is designed with an LS control edge, via which one to the LS control chamber adjacent LS communication chamber in the middle position or in displacement of the valve spool in one direction with an adjacent tank control chamber is connectable.

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

• Figur 1 ein stark vereinfachtes Schaltschema eines erfindungsgemäßen Steuerblocks für einen Gabelstapler;
• Figur 2 eine Schnittdarstellung eines Wegeventils des Steuerblocks aus Figur 1;
• Figur 3 das Wegeventil gemäß Figur 2 in unterschiedlichen Positionen;
• Figur 4 einen Schnitt durch ein vereinfachtes Ausführungsbeispiel eines Wegeventils des Steuerblocks aus Figur 1 und
• Figur 5 das Wegeventil aus Figur 4 in unterschiedlichen Schaltstellungen.

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

• FIG. 1 a highly simplified circuit diagram of a control block according to the invention for a forklift truck;
• FIG. 2 a sectional view of a directional control valve of the control block FIG. 1 ;
• FIG. 3 the directional control valve according FIG. 2 in different positions;
• FIG. 4 a section through a simplified embodiment of a directional control valve of the control block FIG. 1 and
• FIG. 5 the directional control valve off FIG. 4 in different switching positions.

FIG. 1 shows a highly simplified circuit diagram of an LS control block 1 of a forklift. The basic structure of such a mobile control block 1 is known from the aforementioned data sheets RD 74 278 / 05.03 and RD 64 282 / 10.99, so that only the essential components for understanding the invention will be discussed. Such an LS control block 1 has a pressure port P, a tank port T, a LS port LS and not shown control oil ports and external LS ports. The tank connection T is via a tank line 2 with a tank T and the pump connection P is connected via a pump line 4 to the pressure port of a pump in the present case a variable displacement pump 6, the pump pressure is adjusted via a pump regulator 8 in response to the highest load pressure of the driven consumers so that it is always a predetermined Δp above the highest load pressure. This highest load pressure is picked up at the LS connection and routed to the pump regulator 8. Within the control block 1, this highest load pressure is tapped via a shuttle valve cascade, not shown, from the actuated consumers and is applied to the LS connection.

The designed in disc design control block 1 consists essentially of an input element 10, on which the terminals P, T, LS and the other terminals (external LS terminals) are formed and a plurality of control block sections 12, 14, N and an end member 16th on which, for example, the control oil supply (stroke the front), pressure protection elements, filters and connections for supplying other control blocks with control oil (all connections not shown) may be formed. Each of the directional valve or control block sections 12, 14, ... N is associated with a consumer of the forklift. In the illustrated embodiment, the section 12 is two parallel plunger cylinders 18, 20 for lifting a fork of the forklift and the section 14, for example, a tilting device 22, consisting of two parallel-connected differential cylinder for a fork-carrying mast of the forklift assigned. Other sections may for example be associated with the hydraulic steering of the forklift or optional consumers. In practice, the plunger cylinders 18, 20 have a higher pressure medium requirement than the other consumers (Steering, tilting device), for example, the pressure medium flow rate to the plunger cylinders is 180 1 / min, while the other consumers only need to be supplied with a lower pressure medium flow rate, for example, 50 1 / min. The control section 12 described in more detail below is designed so that with a comparatively small nominal size of the control block, a sufficient supply of the plunger cylinders 18, 20 is ensured.

Each of the sections 12, 14, N for controlling a consumer consists in an LS control block essentially of a proportionally adjustable directional control valve 24, the pilot valves (pressure reducing valves), not shown, are assigned to control the position of a valve spool of the directional control valve 24. The pressure medium volume flow over the controlled on an adjustment of the valve spool of the directional valves inlet orifice plates is kept constant independent of load at LS control blocks 1 via an upstream individual pressure compensator 26. A pressure compensator piston is acted upon by a pressure compensator spring 28 and the load pressure on the associated consumer in the opening direction and by the pressure in front of the metering orifice in the closing direction. In the control block section 14, the individual pressure compensator 26 is located in an inlet channel 30, which is connected on the one hand to the pressure port P to the input element 10 and on the other hand to an input port P of the directional control valve. A tank connection T of the directional control valve 24 is connected via a discharge channel 32 to the tank connection T of the input element 10. The directional control valve 24 of the section 12 further has two working ports A, B, which are connected via a first flow channel 34 and a second flow channel 36 with the two working ports A, B of the section 12. These two working ports A, B are connected via a branching flow line 38 with the two cylinder chambers 40, 42 of the plunger cylinder 18, 20. That is, in the control block section 12, the pressure medium supply of the two plungers 18, 20 connected in parallel takes place via the summed pressure medium volume flows conducted via the working ports A, B of the section, the pressure medium volume flows being brought together outside the section 12. In the control block section 12 are further hydraulic components, such as pressure relief valves with combined feed function, shuttle valves for tapping the highest load pressure, LS-pressure relief valves, the aforementioned pressure reducing valves for controlling the directional control valve 24, etc. arranged. Since these hydraulic devices contribute nothing to the understanding of the invention, their description and illustration can be dispensed with.

As is apparent from the switching symbol of the drawn in the section 12 directional control valve 24, the four ports P, T, A, B are shut off (closed center) in its spring-biased (centering spring not shown) middle position. When controlling the pressure reducing valves, not shown, the valve spool in the illustration according to FIG. 1 down (position a) are shifted, so that the pressure port P of the directional control valve 24 is connected to the two working or output ports A, B and funded by the variable displacement pump 6 pressure medium volume flow on the individual pressure compensator 28, the open-way valve 24 and the two working ports A, B of the section 12 to the cylinder chambers 40, 42 of the plunger cylinder 18, 20 flows to extend this and lift the fork of the forklift accordingly. About the valve spool are doing practically two parallel flow cross-sections, each with a Zulaufmessblende 44, 46 controlled, so that the pressure medium in two substantially equal partial volume flows through the two parallel flow channels 34, 36 to the associated consumer (plunger cylinder 18, 20) flows. This doubling of the flow cross section from the metering orifices 44, 46 to the merging of the supply line 38, the hydraulic resistance of the section 12 can be minimized, so that a control block of comparatively small size is used, with respect to the smaller consumer (tilting device 22, optional Consumer) is optimized. To lower the fork of the valve spool of the continuously variable directional control valve 24 is shifted upward (position b), so that the pressure port P of the directional control valve 24 is shut off and the working ports A, B are connected via the drain passage 32 to the tank port T, so that the Pressure fluid from the two cylinder chambers 40, 42 can flow out to the tank T and the plunger cylinders 18, 20 retract by the weight of the fork and, if necessary, the load carried by it.

Accordingly, both working ports A, B of the section 12 can be connected depending on the position of the directional control valve 24 with the pressure medium source or the pressure medium sinks by the directional control valve arrangement according to the invention, so that each parallel partial flows are conveyed in the direction of the plunger cylinders 18, 20 or run from them.

Based on the sectional view according to FIG. 2 the basic structure of the continuously variable directional valve 24 will be explained. This has a valve spool 48 which is guided in a valve bore 50 of the disk-block-executed control block section 12. The valve bore 50 is shown in the illustration FIG. 2 left to right to a tank control chamber 52 connected to the tank connection T (the connection designations below relate to the directional control valve 24), a work control chamber 54 connected to the working connection B, a pressure control chamber 56 connected to the pressure connection P, a further work control chamber 58, a further tank control chamber 60 , and a connected to a LS connection LS control chamber 62 extended. On both sides of the LS control chamber 62, two LS connection chambers 64, 66 are formed. Such a constructed valve bore 50 is also used in the aforementioned prior art according to the data sheet RD 64 278 and RD 64 282. The guided within the valve bore valve slide 48 has two end-side end collars 68, 70, between which a central piston collar 72, a second piston collar 74 and a left of the piston collar 72 arranged third piston collar 76 is formed, the piston collars on four piston necks 78, 80, 82, 84 are spaced from each other. The second piston collar 74 has a substantially greater axial length than the two piston collars 76, 72 which are spaced apart from the piston neck 80. At the end collar, which is likewise designed with a comparatively large axial length (left in FIG FIG. 2 ), an annular groove 86 is formed, via which in the illustrated center position of the valve slide 48, the LS control chamber 62 is connected to the two adjacent LS communication chambers 64, 66. In the illustrated embodiment, the central piston collar 72 is covered in the middle position shown by a housing web 88 between the working control chamber 58 and the pressure control chamber 56, so that the pressure control chamber 56 can be performed with a relatively small axial length and thus the directional control valve 24 is relatively short. The valve spool 48 is penetrated by a channel, of which in FIG. 2 only the mouth areas 90, 92 are visible. Accordingly, the channel opens in the Center position of the directional control valve 24 on the one hand in the LS control chamber 62 and on the other hand in the piston collar 74 portion of a housing web 94 between the working control chamber 58 and the pressure control chamber 56. The channel mouth 90 arranged there is thus covered by the housing web 94 in the middle position. At the annular end faces of the second piston collar 74 two control edges 96, 98 are formed. At the two mutually facing end faces of the two piston collars 72, 76 two further control edges 98, 100 are formed and at the in FIG. 2 Right end face of the end collar 70 is formed a fourth control edge 102, via which in the center position, the pressure medium connection between the adjacent tank control chamber 60 and the LS connection chamber 64 is opened. As in the switching symbol of the directional control valve 24 in FIG FIG. 1 shown, in the middle position by the aforementioned control edges 96, 98, 100, the ports A, B, P and T of the directional control valve shut off. The control edges are each designed with fine control notches.

In FIG. 3 is the directional control valve 24 in two positions a, b adjusted, wherein in the upper position (a), the two working ports A, B of the directional valve 24 with the pressure port P and in the lower position (b) the two working ports A, B with the tank or drain port T of the directional control valve 24 are connected.

In the illustration according to FIG. 3 above is the valve spool 48 from the in FIG. 2 shown middle position shifted to the right. This is done in which a limited by the end collar 70 control chamber 104 is acted upon by the pilot valves (pressure reducing valves), not shown, with a control pressure, so that the valve spool 48 by acting on the end face of the end collar 70 control pressure against the force of also not shown Zentrierfederanordnung is moved. By this axial displacement in dependence on the height of the control pressure, an opening cross section between the pressure control chamber 56 and the two adjacent work control chambers 58 and 54 is opened by the control edges 98, 99. That is, by the two control edges 98, 99, the two in FIG. 1 indicated feed orifices 44, 46 and thus opened the pressure medium volume flow to the plunger cylinders 18, 20. The two tank control chambers 52, 60 remain shut off from the respectively adjacent work control chambers 54 and 58, respectively. The connection of the LS communication chamber 64 to the tank control chamber 60 is closed by the control edge 102. The load pressure applied in the working control chamber 54 downstream of the inlet orifice 46 is tapped via the channel with the channel mouths 90, 92 and signaled into the LS connection chamber 64, which is connected to the LS control chamber 62 via the annular groove 86. As already mentioned, the pressure drop in the flow to the connected consumer compared to conventional solutions can be substantially reduced by the parallel opened inlet orifice plates 44, 46 and the subsequent parallel pressure medium paths.

In FIG. 3 Below a position (b) of the directional control valve 24 is shown, in which the pressure medium flows from the plunger cylinders 18, 20 to the tank T out. For this purpose, the valve slide 48 from the in FIG. 2 shown center position shifted to the left, in which via the pilot control a limited by the right end collar 68 control chamber 106 is subjected to a control pressure. This axial displacement to the left via the control edge 96, the connection from the working control chamber 54 to the tank control chamber 52 and the control edge 100, the connection between the other working control chamber 58th and the further tank control chamber 60, while the pressure medium connection between the pressure control chamber 56 and the adjacent work control chambers 58, 54 is blocked by the control edges 98 and 99, respectively. The channel opens via the channel mouth 92 in the LS connection chamber 66, which is connected via the annular groove 86 with the LS control chamber 62. In the FIG. 3 The right-most holes of the channel mouth 90 is covered by the housing web 94. The LS control chamber 62 may be connected in the illustrated position via the control edge 102 of the left end collar 70 and the LS connection chamber 64 with the tank control chamber 60 of the directional control valve 24, so that in the LS control chamber 62 of the section 12 the tank pressure is applied.

In FIG. 4 an embodiment with a modified valve spool 48 is shown. The structure of the valve bore 50 is substantially the same as in the above-described embodiment, so that corresponding components are provided with the same reference numerals and a repeated description to avoid repetition is omitted.

In the modified valve spool 48, the two control edges 99, 100 are formed on a single, comparatively long central piston collar 108. The control edge 98 is formed on a comparatively short further piston collar 110 and the control edge 96 is formed in this embodiment on the right Stirnbund 68, which is designed with a larger axial length than in the above-described embodiment. The short piston collar 110 is substantially covered by a housing web 111 between the pressure control chamber 56 and the working control chamber 54. The other Stirnbund 70 (left in FIG. 4 ) has the same structure as in the above-described embodiment. The channel for tapping the load pressure opens at the in FIG. 4 illustrated embodiment with its channel mouth 90 in the large central piston collar 108, the other channel mouth 92 opens in turn in the region of the annular groove 86. In the illustrated center position, the ports A, P, B, T of the directional valve are shut off, the LS control chamber 62 is over the annular groove 86 and the control edge 102 are connected to the tank control chamber 60.

According to FIG. 5 below, is to extend the plunger cylinder 18, 20 of the valve slide 48 by applying the right control chamber 106 with a control pressure from the in FIG. 4 shown center position to the left position (a) shifted, so that the comparatively short further piston collar 110 is completely accommodated in the pressure control chamber 56, whose axial length is greater than that of the other piston collar 110. That is, via the control edge 98, the pressure medium connection of the pressure control chamber 56 to the working control chamber 54 and the control edge 99 of the piston collar 108, the pressure control chamber 56 is opened with the other working control chamber 58 and correspondingly opened the two inlet orifices 44, 46 at the axial displacement of the valve spool 48. The connection of the two tank control chambers 52, 60 to the adjacent work control chambers 54, 58 remains shut off. The load pressure downstream of the inlet orifice 44 is reported via the channel with the channel mouths 90,92 and the annular groove 86 in the LS control chamber 62. As in the above-described embodiment, two pressure medium volume flows are conveyed via the directional control valve 24 and the working ports A, B of the section 12 in the direction of the plunger cylinders 18, 20 in order to extend this. For retracting the plunger cylinders 18, 20, the valve spool 48 according to FIG. 5 top off his in FIG. 4 shown center position by applying the left control chamber 4 with a control pressure to the right position (b) shifted so that via the control edge 96 a flow cross section from the working control chamber 54 to the tank control chamber 52 and the control edge 100 of the piston collar 108 a flow cross section of the other working control chamber 58 to the tank control chamber 102 is opened. The connection between the pressure control chamber 56 and the two adjacent control chambers 54, 56 is shut off. At the in FIG. 5 In the variant shown, the LS control chamber 62 is not connected to the tank control chamber 102 via the LS connection chamber 64. In principle, the end collar 70 could also be designed such that in the positions of the directional valve spool 24 into which the pressure medium from the plunger cylinders 18, 20 runs, the LS control chamber 62 is connected to the tank. In the in FIG. 5 The position shown above the valve spool 48, the pressure medium flows from the two cylinder chambers 40, 42 of the plunger cylinder 18, 20 from the tank T of the hydraulic system, wherein the pressure medium flow is determined by the controlled flow cross-sections, in which in FIGS. 4 and 5 illustrated embodiment, only three piston necks 78, 112 and 114 are required, so that the production of in FIG. 4 illustrated embodiment is somewhat simpler than the embodiment described above.

In principle, one could also form the two control edges 96, 98 on a single piston collar 110 with a greater axial length and then correspondingly provide the control edges 99 and 100 on two separate piston collars. In this case, however, suitable LS channels or grooves, bores would have to be provided in order to be able to be connected to the tank connection T in the middle position and, if necessary, in the drainage position (working connections A, B of the directional control valve). to connect the LS control chamber 62 or at least the LS communication chamber 64 to the tank T.

In the above-described embodiments, a single-acting consumer (plunger cylinder 18, 20) is controlled via the control block section 12. In principle, the control of double-acting consumer is possible, in which case each pressure chamber of the consumer is assigned a control block section 12 with the above-described structure.

Disclosed are a control block for supplying pressure medium to at least one consumer with a large pressure medium requirement and at least one smaller consumer and a control block section suitable for such a control block, via which the larger consumer can be supplied with pressure medium. This control block section has two working ports, both of which are connectable to the pressure space, so that pressure fluid flows through two parallel pressure fluid flow paths toward the consumer.

LIST OF REFERENCE NUMBERS

1

control block

2

tank line

4

pump line

6

variable

8th

pump regulator

10

input element

12

Control block section

14

Control block section

16

end element

18

plunger

20

plunger

22

tilter

24

way valve

26

Individual pressure compensator

28

Compensator spring

30

inlet channel

32

drain channel

34

forward channel

36

forward channel

38

supply line

40

cylinder space

42

cylinder space

44

Supply measuring orifice

46

Supply measuring orifice

48

valve slide

50

valve bore

52

Tank control chamber

54

Work control chamber

56

Pressure control chamber

58

Work control chamber

60

Tank control chamber

62

LS-control chamber

64

LS-connecting chamber

66

LS-connecting chamber

68

end union

70

end union

72

middle piston collar

74

second piston collar

76

third piston collar

78

tang

80

tang

82

tang

84

tang

86

ring groove

88

housing web

90

channel mouth

92

channel mouth

94

housing web

96

control edge

98

control edge

99

control edge

100

control edge

102

control edge

104

control room

106

control room

108

piston collar

110

further piston collar

111

housing web

Claims (12)

1. Control block for the supply of pressure medium to at least one consumer (18, 20) with a high demand for pressure medium and to at least one relatively small consumer (22), wherein each consumer (18, 20; 22) is assigned at least one control block section (12, 14, N) with in each case one continuously adjustable directional valve (24), by means of which a pressure chamber (42, 44) of the consumer (18, 20) can be connected to a pressure medium source (B) or pressure medium sink (T), characterized in that the control block section (12) assigned to the relatively large consumer (18, 20) has a continuously adjustable hydraulic directional valve (24) with two working ports (A, B) which are both connected to the pressure chamber (40, 42), and wherein the control block section (12) has a pressure port (P) and a discharge port (T), wherein, by means of a valve slide (48) of the directional valve (24) of the control block section (12) assigned to the relatively large consumer (18, 20), both working ports (A, B) can be connected jointly to the pressure port (P) or to the discharge port (T).
2. Control block according to Patent Claim 1, wherein the relatively large consumer has two pressure chambers to which in each case one dedicated control block section (12) is assigned.
3. Control block according to Patent Claim 1 or 2, wherein said control block is in the form of an LS or LUDV control block.
4. Control block section for a control block according to one of the preceding patent claims, having a pressure port (P), having a discharge port (T) and two working ports (A, B) and having a continuously adjustable hydraulic directional valve (24), by means of the valve slide (48) of which both working ports (A, B) can be connected jointly to the pressure port (P) or to the discharge port (T).
5. Control block section according to Patent Claim 4, wherein a valve slide (48) of the directional valve (24) has three piston collars (72, 74, 76), by means of the control edges (96, 98, 99, 100) of which the connection between the two working ports (A, B) and the pressure port (P) and also the discharge port (T) can be opened and closed in a controlled manner, wherein a piston collar (72, 110) by means of which the connection between the pressure port and at least one working port (A, B) can be opened and closed in a controlled manner is, in a central position, substantially completely covered by a housing web (88, 111) between a working control chamber (58, 54), which is assigned to the working port (A), and a pressure control chamber (56), which is assigned to the pressure port (P).
6. Control block section according to Patent Claim 5, wherein the piston collar (72, 110) is covered by the housing web (88, 111) and has a control edge (99, 98) by means of which the connection between the working control chamber (54, 58) and the pressure control chamber (56) can be opened or closed in a controlled manner.
7. Control block section according to Patent Claim 5 or 6, having a second piston collar (74) with two control edges (96, 98) by means of which, respectively, a connection between a working control chamber (54) and a tank control chamber (52) connected to the tank port (T) and between the pressure control chamber (56) and the working control chamber (54) can be opened and closed in a controlled manner, wherein the third piston collar (76) has a control edge (100) for opening and closing in a controlled manner the connection between the first working control chamber (58) and a second, adjacent tank control chamber (60).
8. Control block section according to Patent Claim 5 or 6, having a further piston collar (108) which has two control edges (99, 100), of which one opens and closes in a controlled manner the connection between the pressure control chamber (56) and the working control chamber (58) and the other opens and closes in a controlled manner the connection between the working control chamber (58) and a tank control chamber (60) connected to the tank port, wherein the third piston collar (68) is formed with a control edge (96) by means of which the connection between the working control chamber (54) and a further tank control chamber (52) can be adjusted.
9. Control block section according to Patent Claim 8, wherein the valve slide (48) is formed with three piston necks (78, 112, 114).
10. Control block section according to one of Patent Claims 4 to 9, having an LS control chamber (62) which can be charged with the load pressure in one of the working control chambers (54, 58) via a duct (90, 92) which extends through the valve slide (48).
11. Control block section according to Patent Claim 10, wherein the duct opens out at one side in an annular groove (86) of the valve slide (48) and at the other side on the outer circumference of a piston collar section (74, 108) which is movable into a working control chamber (54, 58).
12. Control block section according to Patent Claim 10 or 11, having an LS control edge (102) which is formed on an end collar (70) and by means of which an LS connecting chamber (64) which adjoins the LS control chamber (62) can be connected to the adjacent tank control chamber (60).

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