US3864910A

US3864910A - Device for supplying fluid under pressure to two reversible load elements

Info

Publication number: US3864910A
Application number: US395445A
Authority: US
Inventors: Gerard H Mechin
Original assignee: Poclain SA
Current assignee: Poclain SA
Priority date: 1972-05-24
Filing date: 1973-09-10
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11

Abstract

This application discloses a device for supplying pressurized fluid to two load elements such as hydraulic motors, comprises two first conduits each connected to one load element and to a source of pressurized fluid, and two second conduits each connected to one load element and to an exhaust reservoir, a first flow divider being disposed in the first conduits, characterized in that the load elements are reversible, the first and second conduits are respectively placed in communication with the fluid source and the exhaust reservoir or vice versa, and a second flow divider is disposed in the second conduits.

Description

O United States Patent 1 [111 3,864,910 Mechin Feb. 11, 1975 DEVICE FOR SUPPLYING FLUID UNDER [56] References Cited PRESSURE T0 TWO REVERSIBLE LOAD UNITED STATES PATENTS ELEMENTS 2,365,095 12/ I944 Miller et al 60/97 E UX [75] Inventor: Gerard II. Mchin,

Nameull'lel'laudoulm France Primary Examiner-Edgar W. Geoghegan 73 Assignee; societe Anonyme podain, Le Attorney, Agent, or Firm-Fitzpatrick. Cella, Harper Plessis-Belleville, France Sumo [22] Filed: Sept. 10, I973 [57] ABSTRACT [2]] App]. No.: 395,445

This application dlscloses a devlce for supplying pres- Rehmd Application Data surized fluid to two load elements such as hydraulic [63] Continuation-impart of Ser. No. 256,324, May 24, motors, comprises two first conduits each connected I972, abandoned. to one load element and to a source of pressurized fluid, and two second conduits each connected to one [30] Foreign Application Priority Data load element and to an exhaust reservoir, a first flow Nov. 17, 1972 France 72.40991 divider being disposed in the first conduits, character ized in that the load elements are reversible, the first [52] U.S. Cl 60/420, 60/468, 60/484, and Second Conduits are respectively placed in com- 60/494 munication with the fluid source and the exhaust res- [51] Int. Cl. F15b 11/22 ervoir or vice versa, and a Second fl divider is [58] Field of Search 60/97 F, 420, 468, 484, p s d in the nd conduits- 13 Claims, 5 Drawing Figures PATENIEDFEBI I I975- SHEET 30F 4 N F N.

Eur

DEVICE FOR SUPPLYING FLUID UNDER PRESSURE TO TWO REVERSIBLE LOAD ELEMENTS This is a continuation-in-part of copending application Ser. No. 256,324, filed May 24, 1972 now abandoned.

The present invention relates to a device for supplying fluid under pressure to two reversible load elements. In the field of load elements supplied with fluid under pressure, and particularly, but not exclusively, in the field of hydraulic jacks and motors, it is known to use circuits in which two load elements or groups of elements are connected in parallel. It is also known how to maintain a given ratio between the supply rates to the elements or groups, by incorporating a flow divider in the respective supply conduits, for example.

Such supply circuits are highly satisfactory for irreversible elements. Until now, however, no satisfactory arrangements have been proposed for reversible elements. A' first aim of the present invention is therefore to fulfill this requirement.

Occasionally it is advantageous to provide a parallel supply to the elements,'either without flow division or with flow division for a selected sense of operation of the load elements. It is thus convenient to be able to render the corresponding flow dividers operative or inoperative at will. Another aim of the invention is to propose an arrangement providing for such selection.

The presence of a flow divider in the supply conduits and another in the exhaust conduits may result not only in supply to the load elements in a given ratio but also of an'unwanted restriction in the exhaust flows. The invention also proposes an arrangement with which this disadvantage can be avoided.

Further, the invention proposes an advantageous construction for the device, more particularly in that it comprises a monobloc valve actuated by the pressurized fluid.

The invention thus has for its object a device for supplying pressurized fluid to two load elements such as hydraulic motors, comprising two first conduits each connected to one load element and to a source of pressurized fluid, and two second conduits each connected to one load element and to an exhaust reservoir, a first flow divider being disposed in the first conduits, characterized in that the load elements are reversible, the first and second conduits are respectively placed in communication with the fluid source and the exhaust reservoir or vice versa, and a second flow divider is disposed in the second conduits.

Advantageously, each first conduit is connected to a third conduit providing a by-pass for the first flow divider associated with that first conduit, each second conduit is connected to a fourth conduit providing a by-pass for the second flow divider associated with that second conduit, the by-passes are provided with position-controlling elements, being those of the two third and two fourth conduits respectively, and which are so coupled that the two corresponding conduits are always in the same position.

Further, in one preferred embodiment of the invention, the control elements of the third conduits and the fourth conduits are respectively actuated by the pressure of the fluid in the second conduits downstream of the second flow divider with respect to the load elements and by the pressure of the fluid in the first conduits downstream of the first flow divider with respect to the load elements, so that the first andsecond conduits are respectively placed in communication with the fluid source, the free communication of the first and second conduits with the exhaust reservoir being assured by by-passing the first and second flow dividers respectively.

According to a further embodiment of the' invention there are provided additional advantages according to which there is obtained with certitude, the bypass of the flow divider disposed in the delivery conduits, whatever the instantaneous mode of use of the device, and, of course, when it is desired to obtain the division of the flows in the supply conduits of the two load elements.

This last mentioned embodiment comprises two reversible load elements, a source of pressurised fluid, an exhaust enclosure, two first conduits, two second conduits, each of said first and second conduits being connected, on the one hand to one of the load elements, on the other hand, selectively, the first conduits to the source of fluid and to the exhaust enclosure and the second conduits to the exhaust enclosure and to the fluid source, respectively. A first flow divider is interposed in the two first conduits, a second flow divider in the two second conduits, and four first connecting conduits are connected on the one hand in shunt to the parts of the first conduits connected on either side of the first flow divider, to the first flow divider, and on the other hand together at a first common point. Two non-return valves are each disposed respectively in one of the connecting conduits which are connected to the parts of the first conduits connecting the two load elements to the first flow divider. These two first nonreturn valves allows the passage of the fluid through said parts of the first conduits towards the first common point, and four second connecting conduits are connected, on the one hand, in shunt to the parts of the second conduits connected on either side of the second flow divider to this second flow divider on the other hand, together at a second common point, and, two second non-return valves are each disposed respectively in one of the connecting conduits which are connected to the parts of the two conduits connecting the two load elements to the second flow divider, these two second non-return valves allowing the passage of the fluid through said parts of said second conduits towards said second common point.

Each of the first conduits is advantageously connected to a third conduit, which constitutes a by-pass to the first flow divider for said corresponding first conduit, each of the second conduits is connected to a fourth conduit, which constitutes a by-pass of the second flow divider of said second corresponding conduit, whilst the by-passes thus constituted are provided with position selecting means.

The selecting members are constituted by a twoway distributor, which is interposed concomitantly in the by-passes of the first and second flow dividers, whilst, in its first position, this distributor ensures the continuity at its level of the said by-passes and, in its second position, said distributor obturates, at its level, said bypasses.

In the above described embodiment, there is provided a variable flow pump connected by two main conduits to the first and second conduits respectively. As a function of the first position of the member adjusting the flow of said pump, one of said main conduits then constitutes the source of pressurised fluid, or the exhaust enclosure, while the other of said conduits constitutes, complementarily, the exhaust enclosure or the source of pressurised fluid.

The invention will be better understood and secondary features and their advantages will emerge from the following description of a number of embodiments of the invention.

The description and the accompanying drawings are given by way of non-limitative example.

Reference will be made to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a supply device according to the invention;

FIG. 2 is a plan view of a valve used in the device of FIG. 1;

FIG. 3 is a view of the valve of FIG. 2 in the direction of the arrow F in that Figure;

FIG. 4 is a section on the line IV-IV of FIG. 3; and

FIG. 5 is a circuit diagram of a supply device forming a further embodiment of the invention.

The device shown in FIG. 1 comprises two reversible hydraulic motors 1 and a source of pressurised fluid comprising a pump 2 connected by a conduit 3 to a fluid reservoir 4 providing an exhaust reservoir. The motors I are connected in parallel by two first conduits 5, each connected to one of the two chambers of a motor and to a single conduit 6, and by two second conduits 7, each connected to the other chamber of the corresponding motor and to another single conduit 8.

A three-position distributor 9 is linked to the conduits 6 and 8, to a conduit of the pump 2, and to a conduit 11 which returns fluid to the reservoir 4 through a biased discharge valve 12. The first position of the distributor 9 connects together

conduits

6 and 10 and conduits 8 and 11. The second position connects together

conduits

6 and 11 and conduits 8 and 10. The third position connects together conduits l0 and 11 and shuts off conduits 6 and 8 at the distributor.

A valve 13 is disposed in

conduits

5 and 7 to connect conduits 6 and 8. It comprises a first flow divider 14 which connects the conduit 6 to the two conduits 5 and a second flow divider 15 which connects the conduit 8 to the two conduits 7. A first position of each flow divider provides a given ratio between the fluid flow rates in the two conduits 5 (or 7). In the second position third conduits l6 and fourth conduits 17 provide bypasses for

conduits

5 and 7 respectively.

The

flow dividers

14, 15 comprise respective control elements coupled to the pistons 18, 19 of jacks whose

cylinders

20, 21 are linked to conduits 8, 6 by

conduits

22, 23. The control elements are also coupled to

pistons

18a, 19a of jacks whose

cylinders

20a, 21a are linked to a common conduit 26 to which is connected a two-position distributor 27.

The distributor 27 is also connected to a conduit 28 connected to the conduit 11 upstream of the valve 12, relative to the reservoir 4, and to a conduit 32 which returns fluid to the reservoir 4. In a first position, the distributor 27 connects

conduits

26 and 32 and closes conduit 28 at the distributor. In its second position it connects

conduits

26 and 28 and closes conduit 32.

In the valve shown in FIGS. 2 to 4 are provided some of the elements already mentioned. The valve comprises a body 36 to which are coupled the

conduits

5,6,7,8, 24 and by means of respective couplings 5a,

6a, 7a, 8a, 24a and 25a. FIG. 4 shows the flowdivider 15 in section. The

identical flow dividers

14, 15, are disposed inYthe valve body 36.

Regarding flow divider 15, the two conduits 7 are connected in parallel to conduit 8 in a manner known per se. A double piston-37 slides freely in a housing 38 formed in the valve body 36 and defines a chamber 7d at each end of this housing. A shaft 39 slides in a housing 40 in the valve body 36 and has two shoulders 41 which can occupy two positions. In a first position the shaft 39 assures communication between the upstream portion 7a and the downstream portion 7b with respect to piston 37 of each conduit 7, through a calibrated orifice 7c and the passage 42 formed between the end of the piston 37 and the valve body 36. In a second position the shaft 39 assures communication of parts 7a and 7b of the conduits 7 by grooves 43 from which the shoulders 41 are in this position disengaged. The shaft 39 is coupled to

pistons

19 and 19a while a spring 44 is located between the shaft 39 and the valve body 36. This spring has an action opposite to those of the fluid contents of

cylinders

21 and 21a. The conduit 22 is formed in the valve body 36 and connects the conduit 8 to cylinder 20 (not visible in FIG. 4 but similar to cylinder 21).

The supply device which has just been described operates as follows, the operation being described by way of example with reference to a vehicle in which one motor 1 drives a left-hand set of wheels while the other motor 1 drives a right-hand set.

With the distributor 9 in its first position,

conduits

6 and 10 and conduit 8 and 11 are in communication. With the distributor 27 in its first position, as shown in FIG. 1, the fluid contained in

cylinders

20a and 21a is returned to the reservoir 4 via

conduits

24, 25, 26 and 32 and is not under pressure. The spring of the flow divider 14 pushes back the corresponding shaft 39, since it exerts a greater force than the fluid in cylinder 20 which is that exhausted into conduit 8 by the motors 1. The spring 44 of flow-divider 15, however, exerts less force than the fluid in cylinder 21 which is the pressurised fluid from

conduits

6 and 23. The divider 15 is thus brought into its second position in which direct communication is established between parts 7a and 7b of conduits 7, without flow division, whereas the divider 14 is in its first position and divides the fluid flows in a known manner, as will be outlined below. The two motors 1 are thus supplied by flows in a given ratio, their exhaust being entirely free with no restriction at the divider 15. The vehicle thus has a blocked differential which allows for either left and right wheels driven at the same speed with equal flows, or for left and right wheels driven at different speeds. The first provides a forwarding driving force and the second a turning mechanism.

When the divider 15 is in its first or flow-dividing position as shown in FIG. 4, the fluid reaching conduit 8 also reaches conduits 7a. The fluid in each conduit 7a pushes back the corresponding end of piston 37, which is thus held in equilibrium, and reaches conduits 7b through the orifices 7c and passages 42 which generally form restrictions. The flow through orifices causes a drop in load and thus a pressure drop between the corresponding conduit 7a and the associated chamber 7d. The resulting pressures on each side of the piston 37, in chambers 7d, cause the admission to conduits 7b of flows in a given ratio determined by the orifices 7c.

With the distributor 9 kept in its first position and the distributor 27 in its second position,

cylinders

20a and 21a are supplied via

conduits

24, 25, 26 and 28 with fluid at the pilot pressure which is that maintained in conduit 11 by biased valve 12. Whatever pressure subsists in

cylinders

20 and 21, the fluid forces on pistons 18a and 190 are greater than the spring forces of the

corresponding flow dividers

14 and 15. Thus each flow divider is in its second position with no flow division. The motors 1 of the left hand and right hand wheels are thus supplied in parallel and exhaust in parallel without any intervention by flow dividers l4 and 15, which in this configuration are by-passed.

If the distributor 9 is now brought into its second position, pressurised fluid is supplied via conduit 8 and exhausted from motors 1 via the conduit 6. The complete operation, already described in relation to the first position of distributor 9, will not be described again, but with the distributor 27 in its first position, flow dividers l4 and are in the second and first positions respectively, with no flow division by divider l4 and division by divider 15. This is evidently the position required, since division of the exhausted fluid is to be avoided in all cases, with the attendant load drop, whether the supply flows are divided in a given ratio or not and whether the reversible motors 1 turn in one sense or the other.

There is thus obtained a hydraulic differential which can be locked but whose operation involves only small load losses. The advantages of using a monobloc for the valve 13 are well known, as are those of adopting hydraulic control for the selection by distributor 27 of the mode of operation of the motors l.

The supply device shown FIG. 5 comprises two reversible hydraulic motors 101 and a variable flow pump 102. The pump 102 is, for example, constituted as a pump with axial pistons and orientable plate, well known per se. It is connected to the rest of the device by two

conduits

102a and 102b which as a function of the position of the rod 102c for controlling the orientation of the swash plate of pump 102, constitute, one, the suction conduit, the other, the delivery conduit, and vice versa, of said pump.

Two

flow dividers

103 and 104 are each shown diagramatically by two restrictions and are in fact similar to the combination described in the first modification, with reference to FIG. 4, of the double acting piston 37 mounted to slide in the housing 38 and making two passages 42, generally forming restrictions themselves.

The motors 101 are connected to pump 102 by two first conduits, each in two parts 105a and 105b, and by two second conduits, each likewise in two parts 106a and l06b. The two parts 105a of the first conduits connect one of the two connections of each motor 101 to the flow divider 103, the two parts 10512 of these first conduits connecting said flow divider 103 to the conduit 102a of the pump 102. Similarly, the two parts 106a of the two conduits connect the other of the two connections of each motor 101 to the flow divider 104, the two parts 10612 of these two conduits connecting said flow divider 104 to the conduit 10211 of the pump 102.

In addition, it is noted that a two-position distributor 107 is interposed in the

conduits

105b and 106b, and that two third conduits 108 connect conduits 105a to this distributor 107, in the same way as fourth conduits 109 connect conduits 106a to said distributor 107. In

its first position, the distributor107 places the third conduits 108 in communication with the second parts b of the first conduits on the one hand, and the fourth conduits 109 with the second parts l06b of the second conduits, on the other hand. On the contrary, in its second position, the distributor 107 obturates at its level the third conduits 108 and fourth conduits 109. In its two positions,-the distributor 107 maintains in communication the two parts of each of the conduits l05b and 10612, which are connected thereto.

Furthermore, it is noted that four connecting conduits 110,111 and 112, 113 are connected in shunt, to each of the first parts 1050 of the first conduits and to each of the second parts 10512 of said first conduits, respectively. These four connecting conduits are in addition connected together by means of another conduit 114 forming a junction and common point. Two nonreturn valves 115 are disposed in the connecting

conduits

110 and 111, so as to permit the passage of the fluid from the first parts 105a of the two first conduits towards the conduit 114 forming common point I In the same way, four other connecting conduits 1'16, 117 and 1 18, 119 are connected in shunt, to each of the first parts 106a of the two conduits and to each of the second parts 106b of said second conduits respectively. These four connecting conduits are in addition connected together by means of another conduit 120 forming a junction and common point. Two non-return valves 121 are disposed in the connecting

conduits

116 and 117 so as to permit the passage of the fluid from the first parts 106a and the two second conduits towards the conduit 120 forming common point.

An auxiliary pump 122 is connected by a suction conduit 123 to a fluid tank 124. To its delivery conduit 125 are connected, in parallel, two

conduits

126, 127 respectively connected, furthermore, to the conduits 102a and 10212 of the pump 102. A first non-return valve 128 is disposed in conduit 126 and a second nonreturn valve 129 is disposed in conduit 127, and each allow passage of the fluid of the delivery conduit 125 towards

conduits

102a and 102b, respectively.

A conduit 130 is branched in shunt in known manner to the delivery conduit 125 and is connected to the fluid reservoir 124. A calibrated discharge valve 131 is disposed in this conduit 130.

Finally, a single acting jack 132 is coupled to the movable member of the distributor 107. The effect of the pressurisedfluid in the jack 132 is antagonistic of that of a spring 133 which tends to return said movable member of the distributor 107 into its first position. A second two-position distributor 134 which is, for example, manually controlled, is provided, to which are connected on the one hand a conduit 135 connected to the delivery conduit 125, on the other hand a conduit 136 connected to jack 132, and a conduit 137 connected to the fluid reservoir 124. In its first position, the distributor 134 obturates at its level the conduit 135 and places the

conduits

136 and 137 in communication, whilst, in its second position, this distributor 134 obturates at its level the conduit 137 and

places conduits

135 and 136 in communication.

Of course, the supply device which has just been described may be completed by additions known per se and with their functions. It is thus possible, for example, and it is often in fact done, to provide an extra supply of pressurized fluid to the motors 101. To this end, it is sufficient to connect in shunt to conduits 105a and low pressure, almost zero, and to dispose in each of these four conduits a non-return valve allowing passage of the fluid of the source under low pressure towards the conduits 105a and 106a.

In addition, the device described comprises several variants among which the following two will be mentioned:

The pump 102, as such is connected to the rest of the device, in fact makes a closed circuit supply. Naturally, an equivalent of this connection, which remains in the domain provided by the present invention, consists in connecting said pump on the one hand to a fluid reservoir and on the other hand to a three-position reversing distributor enabling the delivery conduit of said pump to be placed in communication either with the first conduits 105a and 105b or with the second conduits 106a l06b of the motors 101. This latter connection is said to be open circuit and is moreover known per se.

The other variant consists in coupling the movable member of the distributor 107, not to a power-assisted control device but to an ordinary device for manually controlling its position.

The advantages in adopting the device which has just been described will be better seen on reading the following description of the functioning obtained.

lt is assumed that the control rod 102C of the pump 102 is disposed so that the conduit 102a constitutes the delivery conduit, the conduit 102b consequently constituting the suction conduit. Moreover, it is obvious that the reverse configuration leads only to reversing the direction of rotation of motors 101.

It is noted that disposing the distributor 134 in its first position placed

conduits

136 and 137 in communication, and consequently places jack 132 in communication with the reservoir 124. The action of the spring 133 is therefore preponderant and the distributor 107 is maintained or returned to its first position, too. In this first position of the distributor 107, direct communications are established between the first parts 105a and second parts 10512 of the first conduits by conduits 108, and in the same way between the first parts 106a and second parts 106b of the second conduits by conduits 109. The

flow dividers

103 and 104 are thus bypassed by

conduits

108 and 109.

When, on the contrary, the distributor 134 is disposed in its second position, the fluid delivered by the pump 122 reaches, via

conduits

135 and 136,jack 132 and has a preponderant effect over that of the spring 133. The distributor 107 is then pushed back until it is disposed in its second position. In this position, the only communications which remain are those between the first parts 105a and second parts 105b of the first conduits and between the first parts 106a and second parts l06b of the second conduits by means of the

flow dividers

103 and 104, and possibly in one direction only, by connecting conduits 110, 1 11, 112, 113 and 114 on the one hand, and 116, 117, 118, 119 and 120 on the other hand, since the

conduits

108 and 109 are now obturated. It is then said that the flow dividers are not bypassed, it being understood that they are not done so by

conduits

108 and 109.

Finally, by way of example and to specify the materiality of the application made of the supply device, it is indicated that the motors 101 constitute the motors driving the right and left-hand wheels on the same axle of avehicleysuch as a tractor. On the other hand, these motors which are generally sufficiently fed with pressurised .fluid to effectively drive the vehicle, may sometimes, when said vehicle goes down a slope, no longer be supplied in sufficient volume. Under these conditions, the motors are in fact driven by the vehicle and the pressure in their inlet conduit drops and becomes practically zero.

The following four situations are thenstudied:

First situation: the motors 101 effectively drive the loads to which they are coupled, and the

flow dividers

103 and 104 are by-passed;

Second situation; the motors 101 are driven by the loads to which they are coupled, and the

flow dividers

103 and 104 are by-passed;

Third situation: the motors 101 effectively drive the loads to which they are coupled, and the

flow dividers

103 and 104 are not by-passed;

Fourth situation: the motors 101 are driven by the loads to which they are coupled, and the

flow dividers

103 and 104 are not by-passed.

Concerning the first and second situations, in which the motors 101 drive the vehicle or are driven by the vehicle, the fluid passes freely between the conduits 105a and 105b on the one hand, 106a and l06b on the other hand, by means of

conduits

108 and 109 respectively. Consequently, the supplies of the motors 101 by

conduits

102a, 105b, 108 and 105a are effected in parallel, in the same way as the motor exhausts are also effected in parallel by

conduits

106a, 109, 106b and 102b. This mode of supply and exhaust is commonplace and well known per se.

When the distributor 134 is then disposed in its second position, the

conduits

108 and 109 are closed. The fluid delivered by pump 102 into conduit 102a, then into conduits 10512 must obligatorily pass through the flow divider 103. In fact, the path through

conduits

112, 113 and 114 is obturated at the level of the nonreturn valves 115. There therefore remains only the path passing through the flow divider 103. The flows feeding the two motors 101 are in a fixed ratio, this corresponding to the blocking of the hydraulic differential. This blocking may be advantageous for moving over poor ground.

If one is in the third or fourth situation, the fluid delivered by the motors 101 in the conduits 106a may return directly to the conduit 102b by

conduits

116, 117, the non-return valves 121 and the

conduits

120, 118, 119 and 106b, since the non-return valves 121 effectively allow the fluid to pass in this direction. In fact, it is noticed that the

conduits

116, 117, 118, 119 and 120 and the non-return valves 121 constitute a second bypass path of the flow divider 104, this path being permanently open, but only in the direction permitting the flow of the fluid from motors 101 by conduits 106a towards conduit 102b.

Consequently, even if the pressure of the fluid in the supply conduits l05b 105a drops, the flow divider disposed in the delivery conduits 106a-106b of the motors 101 is efficiently by-passed, contrary to example, to what happened with the device shown in the modification of FIG. 1. Naturally, it is understood that, in view of the symmetry of the dispositions relative to the supplies and exhausts of the motors 101, the functioning is conserved, except for the direction of rotation of said motors, when it is the conduit 10212 which becomes the supply conduit of the pump 102, and when the suc- ,tion conduit of said duit 102a.

It is to be 'noted'in addition that the lack of fluid which may occur in the supply conduit of the pump 102, conduit 102a in the present case, when the motors 101 are driven by the vehicle, may be compensated by the extra supply procured from pump 122, by means of the

conduits

125 and 126, through the non-return valve 128.

What is claimed is:

1. A device for supplying pressurized fluid to two load elements such as hydraulic motors, comprising two first conduits each connected to one load element and to a source of pressurized fluid, and two second conduits each connected to one load element and to an exhaust reservoir, a first flow divider being disposed in the first conduits, characterized in that the load elements are reversible, the first and second conduits are respectively placed in communication with the fluid source and the exhaust reservoir or vice versa, and a second flow divider is disposed in the second conduits, a third conduit connected to each first conduit and providing a by-pass for the first flow divider associated with the first conduits, a fourth conduit connected to each second conduit and providing va by-pass for the second flow divider associated with the second conduits, said by-passes being provided with positioncontrolling elements and so coupled as to maintain the two corresponding conduits in the same position, the control elements of the third and fourth conduits being respectively actuated by the pressure of the fluid in the second conduits downstream of the second flow divider with respect to the load elements and by the pressure of the fluid in the first conduits downstream of the first flow divider with respect to the load elements, so that the first and second conduits are respectively placed in communication with the fluid source, the free communication of the first and second conduits with the exhaust reservoir being assured by by-passing the first and second flow dividers, respectively.

2. A device for supplying pressurized fluid to two load elements such as hydraulic motors, comprising two reversible load elements, a source of pressurized fluid, an exhaust enclosure, two first conduits, two second conduits, each of said first and second conduits being connected, on the one hand to one of the load elements, on the other hand, selectively, the first conduits to the source of fluid and to the exhaust enclosure and the second conduits to the exhaust enclosure and to the fluid source, respectively, a first flow divider interposed in the two first conduits, a second flow divider interposed in the two second conduits, four first connecting conduits which are connected on the one hand in shunt to the parts of the first conduits connected on either side of the first flow divider, to the first flow divider, on the other hand together at a first common point, two first non-return valves which are each disposed respectively in one of the connecting conduits which are connected to the parts of the first conduits connecting the two load elements to the first flow divider, these two first non-return valves allowing the passage of the fluid of said parts of the first conduits towards the first common point, four second connecting conduits which are connected, on the one hand, in shunt to the parts of the second conduits connected on either side of the second flow divider to this second flow divider on the other hand, together at a second pump is then constituted by concommon point, and, two second non-return valves I which are each disposed respectively in one of the con- 'necting conduits which are connected to the parts of the two conduits connecting the two load elements to the second flow divider, these two second non-return valves allowing the passage of the fluid of said parts of said second conduits towards said second common point.

3. A supply device as claimed in claim 2, characterized in that each of the first conduits is connected to a third conduit, which constitutes a by-pass of the first flow divider for said corresponding first conduits, in that each of the second conduits is connected to a fourth conduit, which constitutes a by-pass of the second flow divider for saidsecond corresponding conduits, and in that the by-passes thus constituted are provided with position selecting means.

4. A supply device as claimed in claim 3, characterized in that said selecting members are constituted as a two-way distributor, which is interposed concomitantly in the by-passes of the first and second flow dividers, whilst, in its first position, this distributor ensures the continuity of the said by-passes and, in its second position, said distributor obturates, said by-passes.

5. A supply device as claimed inclaim 2, characterized in that it comprises a variable flow pump connected by two main conduits to the first and second conduits respectively and in that, as a functionof the position of the member adjusting the flow of said pump, one of said main conduits constitutes the source of pressurized fluid, or the exhaust enclosure, the other of said conduits constitutes complementarily the exhaust enclosure or the source of pressurized fluid.

6. A 'device for supplying pressurized hydraulic fluid to two load elements such as hydraulic motors, comprising two first conduits each connected to a different load element and to a first single conduit and two second conduits each connected to a different load element and to a second single conduit, a first flow divider having restrictive flow paths capable of producing a selected appointment of flow from said first single conduit to said first two conduits, said first flow divider being switchable into and out of fluid communication with said first single conduit and said first two conduits, a second flow divider having restrictive flow paths capable of producing a selected apportionment of flow from said second single conduit to said second two conduits, said second flow divider being switchable into and out of fluid communication with said second single conduit and said second two conduits, a distributor arranged for connecting said first and second single conduits to a source of pressure and to a reservoir respectively and vice versa, first control means responsive to application of pressurized fluid to said first single conduit to prevent switching of said second flow divider into communication with said second single conduit and with said second two conduits and second control means responsive to application of pressized fluid to said second single conduit to prevent switching of said first flow divider into communication with said first single conduit and with said first two conduits.

7. A device according to claim 6 wherein said device further includes a second distributor operable subject to the operation of said first and second control means to switch said first and second flow dividers into communication with their respective conduits.

8. A device according to claim 6 wherein said first and second flow divider means include hydraulic valves and wherein said control means comprise pressure operated pilot systems connected to operate said valves in response to changes in pressure in said first and second single conduits.

9. A device according to claim 8 wherein said device includes further pressure operated pilot systems connected to operate said valves, a second distributor and means associated with said second distributor for supplying different fluid pressures to said further pressure operated pilot systems, said pilot systems and said means associated with said second distributor being of a size to provide less valve operating force than said pressure operated pilot systems.

10. A device according to claim 6 wherein said first and second control means comprise bypass lines bypassing said flow dividers and check valves in said bypass lines permitting free fluid flow in a direction away from said load elements.

11. A device according to claim 10 wherein said first and second single conduits are connected respectively to opposite terminals of a reversible hydraulic pump.

12. A device according to claim 11 wherein said first and second single conduits are further connected, via associated check valves, to a reservoir, said check valves allowing free fluid flow in a direction away from said reservoir and toward said hydraulic pump and said load elements.

13. A device according to claim 12 wherein said device includes means for maintaining a continuous circulating flow of hydraulic fluid past a junction at a given pressure, a fluid operated, pressure responsive pilot system for switching said first and second flow divider means and a second distributor switchable to connect said junction and said reservoir alternately to said pilot system.

} UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,864,9l0. Dated February 11, 1975 Inventor(s) Gerard H. Mechin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 35, "allows" should read --allow-;

Column 7, line 15, after "distributor" insert Column 7, line 35, "placed" should read -places;

Column 10, line 42, "appointment" should read --apportionment- Signed and sealed this 22nd day of April 1975.

(SEAL) Attest: I

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks

Claims

1. A device for supplying pressurized fluid to two load elements such as hydraulic motors, comprising two first conduits each connected to one load element and to a source of pressurized fluid, and two second conduits each connected to one load element and to an exhaust reservoir, a first flow divider being disposed in the first conduits, characterized in that the load elements are reversible, the first and second conduits are respectively placed in communication with the fluid source and the exhaust reservoir or vice versa, and a second flow divider is disposed in the second conduits, a third conduit connected to each first conduit and providing a by-pass for the first flow divider associated with the first conduits, a fourth conduit connected to each second conduit and providing a by-pass for the second flow divider associated with the second conduits, said by-passes being provided with position-controlling elements and so coupled as to maintain the two corresponding conduits in the same position, the control elements of the third and fourth conduits being respectively actuated by the pressure of the fluid in the second conduits downstream of the second flow divider with respect to the load elements and by the pressure of the fluid in the first conduits downstream of the first flow divider with respect to the load elements, so that the first and second conduits are respectively placed in communication with the fluid source, the free communication of the first and second conduits with the exhaust reservoir being assured by by-passing the first and second flow dividers, respectively.

2. A device for supplying pressurized fluid to two load elements such as hydraulic motors, comprising two reversible load elements, a source of pressurized fluid, an exhaust enclosure, two first conduits, two second conduits, each of said first and second conduits being connected, on the one hand to one of the load elements, on the other hand, selectively, the first conduits to the source of fluid and to the exhaust enclosure and the second conduits to the exhaust enclosure and to the fluid source, respectively, a first flow divider interposed in the two first conduits, a second flow diviDer interposed in the two second conduits, four first connecting conduits which are connected on the one hand in shunt to the parts of the first conduits connected on either side of the first flow divider, to the first flow divider, on the other hand together at a first common point, two first non-return valves which are each disposed respectively in one of the connecting conduits which are connected to the parts of the first conduits connecting the two load elements to the first flow divider, these two first non-return valves allowing the passage of the fluid of said parts of the first conduits towards the first common point, four second connecting conduits which are connected, on the one hand, in shunt to the parts of the second conduits connected on either side of the second flow divider to this second flow divider on the other hand, together at a second common point, and, two second non-return valves which are each disposed respectively in one of the connecting conduits which are connected to the parts of the two conduits connecting the two load elements to the second flow divider, these two second non-return valves allowing the passage of the fluid of said parts of said second conduits towards said second common point.

3. A supply device as claimed in claim 2, characterized in that each of the first conduits is connected to a third conduit, which constitutes a by-pass of the first flow divider for said corresponding first conduits, in that each of the second conduits is connected to a fourth conduit, which constitutes a by-pass of the second flow divider for said second corresponding conduits, and in that the by-passes thus constituted are provided with position selecting means.

5. A supply device as claimed in claim 2, characterized in that it comprises a variable flow pump connected by two main conduits to the first and second conduits respectively and in that, as a function of the position of the member adjusting the flow of said pump, one of said main conduits constitutes the source of pressurized fluid, or the exhaust enclosure, the other of said conduits constitutes complementarily the exhaust enclosure or the source of pressurized fluid.

6. A device for supplying pressurized hydraulic fluid to two load elements such as hydraulic motors, comprising two first conduits each connected to a different load element and to a first single conduit and two second conduits each connected to a different load element and to a second single conduit, a first flow divider having restrictive flow paths capable of producing a selected appointment of flow from said first single conduit to said first two conduits, said first flow divider being switchable into and out of fluid communication with said first single conduit and said first two conduits, a second flow divider having restrictive flow paths capable of producing a selected apportionment of flow from said second single conduit to said second two conduits, said second flow divider being switchable into and out of fluid communication with said second single conduit and said second two conduits, a distributor arranged for connecting said first and second single conduits to a source of pressure and to a reservoir respectively and vice versa, first control means responsive to application of pressurized fluid to said first single conduit to prevent switching of said second flow divider into communication with said second single conduit and with said second two conduits and second control means responsive to application of pressized fluid to said second single conduit to prevent switching of said first flow divider into communication witH said first single conduit and with said first two conduits.