US3530883A - Fluid flow control apparatus - Google Patents

Description

United States Patent Inventor Manfred Kramer I Fellbaeh-Llndle, Germany Appl. No. 804,473

Filed March 5, 1969 Patented Sept. 29, I970 Assignee Robert Bosch Gmbl-I,

Stuttgart, Germany Priority March 8, 1968, Dec. 7,1968

Germany FLUID FLOW CONTROL APPARATUS 22 Claims, 8 Drawing Figs.

U.S. (l w I 137/596, 137/567, 137162548, 137/6254, 137162569, 91/6, 137/608 Int. (I ..Fl6k 11/07, Fl6k l l/ 10 Field of Search 137/596,

[56] References Cited UNITED STATES PATENTS 2,800,798 7/1957 Korsmo 137/625.4X 3,204,662 9/1965 Williams 137/596 FOREIGN PATENTS 941,041 3/1956 (ie rrnany my 1,253,539 1 H1967 Germany;

Primary Examiner-Henry T. Klinksiek Attorney-Michael S. Striker ABSTRACT: A control apparatus wherein a battery of sliding spool directional control valves controls the flow of hydraulic fluidfrom two sources to single-acting or double-acting loads. The valves form two groups but may be inrandom distribution and their bodies are formed with channels defining two fluid circulating and two connecting passages. One of the connecting passages can be sealed by the spools of valves of one group and the other connecting passage can be sealed by the spools of valves in the other group when the spools are moved from neutral to working positions. Analogously, the spools of one group of valves can seal the first fluid circulating passage and the spools of the other group can seal the second fluid circulating passage in working positions of such spools.

Patented Sept. 29, 1970 3,530,883

Shoot 1 014 FIG] 75 76 77 79 7s INVENTOR Manfred KRAMER his ATTORNEY Patented Sept. 29, 1970 Shoat g of 4 INVENTOR Manfred KRAMER 0m flu/9,

his AT TOR N EY Patented Sept. 29, 1910 3,530,883

sheet 3 of4 Wag)!!! INVENTOR Manfred KRAMER By ml/dl/ 'vj his A TORNEY Patented Sept. 29, 1970' 3,530,883

Sheet 4 01'4 INVENTOR Manfred KRAMER his ATTORNEY FLUID FLOW CONTROL APPARATUS BACKGROUND OF THE INVENTION apparatus wherein the bodies of several sliding spool directional control valves are installed between a connector block and an end block. A selector unit is installed between the bodies of two adjoining directional control valves. The selector unit serves to connect those valves which are located between the connector block and the selector unit with a first source of pressurized fluid which is admitted by way of the connector block. At the same time, the selector unit connects the remaining valves (namely, those valves which are located between the selector unit and the end block) with 'a second source of pressurized fluid. A drawback of such apparatus is that the valves which are connectable with the first source must be grouped together, and that the remaining valves which receive fluid from the second source must also form a group. Thus, it is not possible to randomly distribute the valves of one group between the ,valves of the other group, or vice versa. Such random distribution of valves which control the flow of fluid from two separate sources to different loads is often desired in industrial installations or other establishments.

German DAS No. 1,253,539 discloses a similar fluid flow control apparatus wherein a multi-way valve discharges two separate streams of pressurized hydraulic fluid. The apparatus further comprises a connector block, an end block and a battery of sliding spool directional control valves between the two blocks. An intermediate plate is installed between two adjoining directional control valves to accommodate the aforementioned multi-way valve as well as a fluid admitting valve. The directional control valves at one side of the intermediate plate receive fluid from one of the two separate streams and the directional control valves at the other side of such plate receive fluid from the other stream. The just described apparatus exhibits the same drawbacks as the apparatus of German Pat. No. 1,222,753, namely, it is not possible to arrange the directional control valves which receive fluid from different streams in random distribution.

SUMMARY OF THE INVENTION An object of my invention is to provide a fluid flow control apparatus which is simpler, more versatile and more compact than presently known apparatus.

Another object of the invention is to provide an apparatus which can regulate the flow of hydraulic fluid from two separate sources to several single-acting or double-acting loads and wherein the valves which regulate the flow of fluid from one source can be arranged in random distribution with valves which regulate the flow of fluid from the other source, or vice versa.

A further object of the invention is to provide novel and improved sliding spool directional control valves which can be utilized in the just outlined apparatus.

An additional object of the invention is to provide novel blocks which can be used in the improved apparatus to deliver fluid to and to receive fluid from the valves. 7

Still another object of the invention is to provide a fluid flow control apparatus wherein the number of valves can be varied at will and wherein the positions of valves can be interchanged. Y

A concomitant object of the invention is to provide an apparatus which can be assembled or taken apart with little loss two separate sources to several single-acting or double-acting loads. The apparatus preferably comprises two channeled blocks flanking a battery of sliding spool directional control valves having bodies provided with supply chambers each of which is connectable with one of the loads in the working position of the corresponding sliding spool. Each sliding spool is movable between a neutral position andat least one working position.

In accordance with a feature of my invention, the bodies of the directional control valves are provided with first and second fluid circulating passages each of which is connected or connectable with one of the sources. The valves form two groups each of which includes at least one valve and the valves of the two groups can be arranged in random distribution between the two blocks. Each passage includes first sections which are provided in the bodies of the first group of valves and second sections provided in the bodies of the second group of valves. The first sections of the first passage can be sealed by spools of the first group of valves and the second sections of the second passage can be sealed by spools of the second group of valves. The first sections of the first passage preferably include enlarged portions or chambers of bores in the bodies of the first group of valves and the second sections of the second passage preferably include enlarged portions or chambers of bores in the bodies of the second group of valves. Such bores are provided in the valve bodies for reciprocatory movements of the respective spools.

The ends of sections in the ,bodies of directional control valves are preferably disposed in mirror symmetry with reference to the axes of the respective spools. This reduces the space requirements of the valve bodies. It was found that the bodies of my directional control valves need not belarger than the bodies of conventional valves.

The sources of pressurized fluid may include two discrete pumps or a single pump and a regulating valve with two outlets, one for a main fluid stream and the other for a remaining or residual fluid stream.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic sectional view of a first fluid flow control apparatus with five sliding. spool directional contro valves; Y

FIG. 2 is an enlarged partly elevational and partly sectional view of one of the valves, the section being taken along the line Il-Il of FIG. 1;

FIG. 3 is a fragmentary partly elevational and partly sectional view of a second valve, the section being taken along the line llI-lll of FIG. 1;

FIG. 4 is a fragmentary transverse sectional view as seen in the direction of arrows from the line lV-IV of FIG. 3;

FIG. 5 is an enlarged transverse sectional view as seen in the direction of arrows from the line V-V of FIG. 1; a

FIG. 6 is a sectional view as seen in the direction of arrows from the line VI-VI of FIG. 5;

FIG. 7 is a schematic sectional view of a second apparatus; and

FIG. 8 is a schematic sectional view of a modified valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a fluid flow control apparatus which comprises a battery of five sliding spool directional control valves 10, ll, l2, l3, 14 whose bodies 10a-l4a are arranged side by side and together form a composite valve housing. The two outermost bodies 10a, 14a are respectively in abutment with a channelled connector block 15 and a channelled end block 16. The bodies la-l4a are connected to each other and to the blocks 15, 16 by bolts and nuts or like fasteners, not shown (see the holes A in the body 10a of FIG. 2), so that the side face 33 of the body 100 abuts against the adjoining side face 26 of the connector block 15, that the side face 34 of the body 140 abuts against the side face 26a of the end block 16 and that the side faces 34 of the bodies l0a-13a respectively abut against the side faces 33 of bodies Ila-14a.

The connector block 15 is formed with a first main pressure line or channel 17 which is connected to the outlet of a first source of pressurized fluid here shown as a hydraulic pump 18 which draws fluid from a reservoir R. A second main pressure line or channel 19 of the connector block 15 is connected to the outlet of a second source or pump 21 which draws fluid from the reservoir R. The main pressure lines 17, 19 respectively communicate with two parallel branch pressure lines or channels 22, 23 and 24, 25 all of which extend to the side face 26 of the connector block 15. A main return line or channel 29 which discharges fluid into the reservoir R is connected with a pair of branch return lines or conduits 27, 28 which also extend to the side face 26 of the block 15. Two pressure relief valves 31, 32 are respectively installed between the branch pressure lines 22, 25 and main return line 29.

Each of the valve bodies 100-141: is formed with an elongated bore 35 whose axis is parallel to the side faces 33, 34, and each bore 35 accommodates an axially reciprocable sliding valve member or spool 36. Each bore 35 is further provided with annular enlarged portions or chambers 37, 38, 39, 40, 41, 42 and 43. The two leftmost enlarged portions or chambers 37, 38 which are adjacent to the operating sides of the valves 10-14 serve to permit flow of pressurized fluid in neutral positions of the respective spools 36. Of the remaining enlarged portions or chambers 39-43, the central chamber 41 is a supply chamber, the chambers 40, 42 which flank the supply chamber 41 communicate with the corresponding double-acting load A, B, and the two remaining chambers 39, 43 serve to convey returning fluid.

Each spool 36 is movable between a central or neutral position and two end positions or working positions. The neutral positions of spools 36 are shown in FIG. 1. The two leftmost chambers 37-38 of each bore 35 are then in communication with each other by way of a circumferential groove 44 between the pistons or lands 45, 46 of the respective spool 36. The pistons 45, 46 then seal the respective chambers 37, 38 from the remainder of the respective bore 35. The remaining chambers 39-43 are sealed from each other by the pistons 47, 48, 49 of the corresponding spools 36. The pistons 46-47, 47-48, 48-49 respectively flank three circumferential grooves 50 of the corresponding spools 36.

Each of the valves 10-14 further includes a double-acting resetting unit 51 at the righbhand end of the respective spool 36. The left-hand ends ofthe spools 36 can be moved between the aforementioned neutral and working positions in which the spools are yieldably held by customary detents, not shown.

Each of the valve bodies 10a-14a is provided with two return channels 52, 53 which extend between the corresponding side faces 33, 34. The channels 52, 53 of the body 100 communicate with the branch return lines 28, 27 of the connector block 15. The channels 52, 53 respectively communicate with corresponding chambers 39, 43.

The spools 36 of a first group of valves including the valves 10, 12, 13 control the flow of pressurized fluid which is delivered by the first pump 18. The spools 36 of a second group of valves including the valves I1 and 14 control the flow of pressurized fluid which is delivered by the second pump 19. The arrangement of channels in the bodies 10a, 12a, 13a is the same but is different from the arrangement of channels in the bodies 11a, 14a. It will be seen that the valves of the first and second groups are in random distribution. However, it is clear that the valves of each group can be placed immediately adjacent to each other.

41 to the compartment 56. The channel 54 serves to convey pressurized fluid from the branch pressure line 22 (see FIG. 1) to the supply chamber 41 of the body in a working position of the corresponding spool 36, and the channel 55 serves to convey pressurized fluid from the branch pressure line 24 through the body 10a of the valve 10 (without delivering it to the supply chamber 41 of bore35 in body 10a) and to a channel 70 in the body 11a. The channel 70 delivers fluid to the supply chamber 41 of the bore 35 in the body 11a by way ofa one-way valve 72 shown in FIG. 1. The channel 54 in the body 10a communicates with a channel 69 in the valve body 11a. The channel 69 bypasses the bore 35 in the body 11a; it delivers fluid to the channel 54 in the body 12a. Thus, the channel 54 of the body 10a, 124 or 13a corresponds to the channel 70 of the body 11a or 14a, and the channel 55 of the body 10a, 12a or 13a corresponds to the channel 69 of the body 11a or 14a. The arrangement of channels in the body 10a is the same as that in the body 12a or 13a, and the arrangement of channels in the body 11a is the same as that in the body 14a. This is clearly shown in FIG. 1.

As shown in FIGS. 1, 5 and 6, the body 10a is formed with a further channel 59 (indicated in FIG. 5 by broken lines) which communicates with the chamber 37 of the bore 35 and with the branch pressure line 23 in the connector block 15. Still another channel 61 connects the chamber 38 of body 100 with the side face 34. The chambers 37, 38 and the channels 59, 61 together form a section 62 ofa first fluid circulating passage. A first section or channel 63 of a second fluid circulating passage is provided in the body 100 between the side faces 33, 34 and is of arcuate shape (see FIG. 5). The inlet ends 64, 66 and outlet ends 65, 67 of the sections 62, 63 are mirror symmetrical with reference to the axis of the bore 35 and spool 36 in the body 100. The just described arrangement of first sections 62, 63 takes up very little space and their channels and enlarged portions or chambers offer low resistance to the flow of fluid. It will be noted that the axes of the ends 64-67 of the sections 62, 63 in the valve body 10a and the axes of ends 64- 67 of the sections 74, 73 in the valve body Ila are normal to the axis of the respective bore 35 and spool 36. The arcuate section or channel 63 of the body 10a is adjacent to the corresponding enlarged portions or chambers 37, 38.

FIGS. 1 and 3-6 show details of the body 11a in the valve 11. The channel 54 of the body accommodates a tube 68 which is a tight fit therein and defines the aforementioned channel 69. This channel 69 bypasses the bore 35 of the body 11a. The channel 70 of the body 110 communicates with the supply chamber 41 by way of the compartment 56 and a bore or channel 71 which accommodates the aforementioned oneway valve 72. FIG. 5 shows that the second section 73 of the second fluid circulating passage communicates with the outlet end 67 of the first section 63 and includes the enlarged portions or chambers 37, 38 of the body 11a. The arcuate second channel or section 74 of the first fluid circulating passage communicates with the outlet end 65 of the first section 62 in body 100 and bypasses the bore 35 in the body 11a. The second sections 73, 74 extend between the side faces 33, 34 of the body 11a and the arcuate section 74 is adjacent to the enlarged portions or chambers 37, 38 in the body 110.

The first fluid circulating passage extends through the entire composite housing including the bodies 10a-14a and comprises three first sections 62 and two arcuate second sections or channels 74. The second fluid circulating passage includes three arcuate first sections or channels 63 and two second sections 73.

As shown in FIG. 1, the channelled end block 16 has four branch lines 75, 76, 77, 78 which extend inwardly from its side face 26a and communicate with a collecting'line 79. The lines 76, 77 respectively communicate with the sections 73, 74 in the body 14a. The line 77 communicates with the channel 52 and the line 78 communicates with the channel 53 of the body 14a.

The conduits 54, 69 in the valve bodies a-14a form sections of a first connecting passage of the fluid flow control apparatus; this first connecting passage communicates with the first pump 18 by way of the connector block and with the first fluid circulating passage which includes the sections 62 and 74. The second connecting passage includes the channels or sections 55, 70 and communicates with the second pump 21 as well as with the second fluid circulating passage including the sections 63, 73. The two fluid circulating passages are connected with the return line 29 means by way of the end block 16 so that they together form a dual neutral fluid circulating means.

THE OPERATION When the valve members or spools 36 of valves 10-14 are held in the neutral positions shown in FIG. 1, the pumps 18, 21 deliver oil or another suitable pressurized hydraulic fluid through the first fluid circulating passage including the sections 62, 74 and the second fluid circulating passage including the sections 63, 73 back to the main return line 29 which discharges into the reservoir R. For example, and as shown in FIG. 1, the output of the pump 18 flows from the first main pressure line 17 into the branch pressure line 23, through the' section 62 of valve body 10a, through the section 74 of the valve body 11a, through the sections 62 of bodies 12a, 13a, through the section 74 of the body 14a, lines 76, 79, 77, channels 52, 53 of the bodies 14a.-10a and into the return line 29. if the spool 36 in the bore 35 of the valve body 10a is moved to first working position, the spool seals the channel 59 from the channel 61' in the section 62 of the body 10a. Fluid delivered by the pump 18 then flows through the channel 54, supply chamber 41 and one of consumer chambers 40, 42 to the load part or B. The returning fluid flows from the part B or A of the load by way of the chamber 42 or 40 and channel 53 or 52 to the lines 27, 29 and back to the reservoir R.

lfthe spool 36 in the body 110 of the valve 11 is moved to one of its working positions, fluid delivered by the pump 21 is supplied by conduit 55 and valve 72 to the part A or B of the load which is connected with the valve 11. It will be seen that the spool 36 of each of the valves 10-14 can be moved to either working position or back to neutral position independently of the other spool or spools even though the valves of the first and second groups are in random distribution. Two or more spools 36 can be moved to working positions at the same time or one after the other. The pressure of fluid which is circulated by the pump 18 can be higher or lower than the pressure of fluid which is circulated by the pump 21, depending on the setting of relief valves 31 and 32. The same holds true for the rate offiuid flow from the pumps 18, 21 to the reservoir R.

FIG. 7 illustrates a second fluid flow control apparatus wherein the valves 1014 are identical with the valves 'of the apparatus shown in FIG. 1. The main difference is that the apparatus of FIG. 7 comprises a single pump 101 which cooperates with a flow regulating valve 104. The latter divides the output of the pump 101 into amain stream which flows at a constant rate and a residual stream. Thus, the valve 104 can be said to constitute two separate sources of pressurized hydraulic fluid. The apparatus of FIG. 7 includes a somewhat different connector block 100 and a modified end block 102. The outlet of the pump 101 is connected with a main pressure line 103 in the connector block 100 which delivers the output of the pump to the regulating valve 104. The residual stream leaves the valve 104 by way of a pressure line 105 (first outlet of valve 104) which communicates with the channel 54 of the valve body 10a. The main fluid stream flows from the valve 104 by way of a pressure line 106 (second outlet of valve 104) and into the channel 55 of the body 10a. The side face 33 of this body abuts against the side face 107 of the connector block 100. A line 108 in the connector block is in parallel with the regulating valve 104 and connects the main pressure line 103 with the section 63 in the body 10a. The main return line 109 in the connector block 100 communicates with three branch return lines 111, 112, 113 which extend to the side face 107. The line 111 communicates with the section 62 in the body 10u,and the lines 112,113 respectively communicate with the return channels 52, 53 of the body 10a. Pressure relief valves 114, 115 are respectively installed between the lines 108, 106 and the main return line 109.

The end block 102 has a side face 116 which abuts against the side face 34 of the valve body 14a. Lines 117, 118, 119, 120, 121 extend inwardly from the side face 116. The lines 117, 118, l20.are.connected to each other by a collecting line 122. The open ends of the lines 117, 118, respectively communicate with the sections 73, 74 and channel 69 in the valve body 14a. The lines 119, 121 are connected to each other by a second connecting line 123. The lines 119, 121 respectively communicate with the return channels 52, 53 in the valve body 140.

THE OPERATION if all of the spools 36 are held in neutral position, the entire output of the pump 101 flows through the line 108 ofthe connector block 100, through the sections 63, 73 of the first fluid circulating passage in valve bodies 10a-14a, the lines 117, 122, 118 of the end block 102, and sections 62, 74 of the second fluid circulating passage in the valve bodies 14a-10a back to the reservoir R by way of the main return line 109. If a spool 36 in the body 10a is moved to one working position, it seals the channel 59 from the channel 61 of the section 62 in the valve body 10a so that the fluid flows from the lines 103, 108, through the second fluid circulating passage 63, 73, through the lines 117, 122, 120 of the end block 102 and into the channels 54, 69 to enter the supply chamber 41 and chamber 40 or 42 of the body 100 prior to flowing to the corresponding part A or B of the load. i

If one of the spools 36 in the valve body 11a or 14a (e.g., in the body 11a) is moved to one of its working positions, the spool seals the section 73 of the second fluid circulating passage. The mainstream of fluid flows from the regulating valve 104 through the line 106 and the channels 55, 70 to the flows from the regulating valve 104 through the channels 54,

69, the lines 120, 122, 118 of the end block 102 and the sections 62, 74 and return line 109 back to the reservoir R.

If the operator decides to move two spools 36 (for example, in valve bodies 10a, 12a or 11a, 14a) to working positions, the residual stream cannot flow back by way of the end block 102 and sections 62, 74. Such residual stream then flows to the part A or B of the corresponding load.

The setting of both pressure relief valves 114, 115 is the same. The valve 115 insures that the directional control valve 10, 12 or 13 is not sealed from the pump 101 on sealing of the sections 70 (main stream) when the spools 36 of valves 11, 14 are in neutral positions and while the residual stream flows to one or more loads. Thus, the valve 115 prevents closing or blocking of the regulating valve 104.-

lt is clear that the improved fluid flow control apparatus can employ other types of directional control valves. For example, instead of being connected in parallel, the directional control valves can be connected in series. Also, one can resort to a socalled blocking arrangement or to a mixed arrangement of valves. FIG. 8 shows a blocking sliding spool directional con valve 180 (replacing the valve 11 of FIG. 1) is in one of its working positions.

It is further clear that the improved apparatus need not necessarily control the flow of fluid to and from double-acting loads. Thus, it is possible to employ the apparatus in connection with the control of fluid flow to and from single-acting loads. It is equally possible to employ composite valves wherein the spools of two or more valves are movable in a common housing. The apparatus of FIG. 7 can employ a further directional control valve. Still further, the connector block 15 or 100 can accommodate a multi-way valve of the type disclosed, for example, in German DAS No. 1,253,539.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. In a hydraulic fluid flow control apparatus for delivery of fluid to at least two loads, a combination comprising first and second sources of pressurized fluid; a reservoir, valve housing means; and first and second valve members each movable with reference to said housing means between a neutral position and at least one working position, said housing means having first and second supply chambers each communicating with one of the loads in the working position and each sealed from the corresponding load in the neutral position of the respective valve member, said housing means further having first and second fluid circulating passages connected with the respective sources and return channel means connected with said reservoir and communicating with at least one of said passages in the neutral positions of said valve members, said first fluid circulating passage having a first section sealed from said return channel means in the working position of said first valve member and a second section bypassing said second valve member, said second fluid circulating passage having a first section bypassing said first valve member and a second section sealed from said return channel means in the working position of said second valve member.

2. A combination as defined in claim 1, wherein said housing means is further provided with first and second connecting passages, said first connecting passage including first channel means connecting the first source with said first supply chamber in the working position of said first valve member and second channel means bypassing said second valve member, said second connecting passage including first channel means bypassing said first valve member and second channel means connecting said second source with said second supply chamber in the working position of said second valve member. I

3. A combination as defined in claim 2, further comprising a channelled connector block connecting said first and second fluid circulating passages with said first and second sources and a channelled end block connecting said first and second fluid circulating passages with said return channel means.

4. A combination as defined in claim 3, wherein said housing means comprises first and second channelled valve bodies disposed side-by-side between said blocks, each of said bodies having a bore reciprocably accommodating the respective valve member.

5. A combination as defined in clalm 4, wherein the first and other with reference to the axes of the respective valve members.

8. A combination as defined in claim 5, wherein each of said bores includes a first enlarged portion constituting the respective supply chamber and two additional enlarged portions, the additional enlarged portions of the bore in said first body forming part of the first section of said first fluid circulating passage and the additional enlarged portions of the bore in said second body forming part of the second section of said second fluid circulating passage.

9. A combination as defined in claim 8, wherein the first section of said second fluid circulating passage includes an arcuate channel extending transversely across said first body and the second section of said first fluid circulating passage includes a second arcuate channel extending transversely across said second body. I;

10. A combination as defined in claim 9, wherein said arcuate channels are adjacent to said additional enlarged portions of bores in the respective bodies.

11. A combination as defined in claim 5, wherein the channel means of said connecting passages include channels extending transversely of the respective bodies, the first channel means of said first connecting passage further including a first bore connecting the respective channel with said first supply chamber and the second channel means of said second connecting passage further comprising a bore connecting the respective channel with said second supply chamber, and further comprising one-way valve means provided in said bores to prevent return flow of fluid from said supply chambers to the respective channels.

12. A combination as defined in claim 11, wherein said second channel means of said first connecting passage is defined by a tube which is inserted into said second body.

13. A combination as defined in claim 5, wherein said connector block is provided with a first main pressure line connecting said first source with said first passages and a second main pressure line connecting said second source with said second passages.

14. A combination as defined in claim 13, wherein said end block is provided with a line communicating with said fluid circulating passages and with said return channel means.

15. A combination as defined in claim 14, wherein said connector block is further provided with a return line connecting said reservoir with the line of said end block by way of said return channel means, and further comprising a pair of pressure relief valves each connected between said return line and one of said main pressure lines.

16. A combination as defined in claim 1, further comprising a channelled connector block and a channelled end block, said blocks flanking said housing means and said first passage communicating with said second passage by way of said end block.

17. A combination as defined in claim 16, wherein said sources include a regulating valve in said connector block and a pump for delivering pressurized fluid to said regulating valve, said regulating valve having a first outlet for a main fluid stream and a second outlet for a residual fluid stream.

18. A combination as defined in claim 17, wherein said housing means is further provided with a first connecting passage communicating with one of said outlets and a second connecting passage communicating with the other outlet, said first connecting passage having first channel means communicating with said first supply chamber in the working-position of said first valve member and second channel means bypassing said second valve member, said second connecting passage having first channel means bypassing said first valve member and second channel means communicating with said second supply chamber in the working position of said second valve member.

19. A combination as defined in claim 18, wherein said end block is provided with a line connecting one of said connecting passages'with said fluid circulating passages.

control valve.

22. A combination as defined in claim 21, wherein one of said sections is connected with the respective supply cham her by a channel provided in said housing means.

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