US3727639A

US3727639A - Control device

Info

Publication number: US3727639A
Application number: US00204556A
Authority: US
Inventors: J Gratzmuller
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-12-10
Filing date: 1971-12-03
Publication date: 1973-04-17
Anticipated expiration: 1990-04-17
Also published as: DE2161503A1; IT943800B; GB1362042A; CA947617A; DE2161503C3; CH547959A; DE2161503B2; FR2116863A5; JPS534197B1

Abstract

This invention relates to a two-line hydraulic drive, especially for the control of driving member such as a double-acting hydraulic jack. A valve adapted both to feed and to drain is mounted on each of the two lines, the valve being hydraulically controlled. One of two control electro-valves, in response to a transient electrical impulse, puts one feed/drainage valve in the feed position and the other feed/drainage valve in the drainage position. The other of the two control electro-valves puts said other feed/drainage valve in the feed position and the first-mentioned feed/drainage valve in the drainage position. The two-line hydraulic control is applicable to the hydraulic control of electrical circuit breakers.

Description

[451 Apr. 17, 1973 537,372 6/1941 Great Britain...................l37/S96.l6 1,202,440 7/1958 France............................l37/596.I6

Primary Examiner-Henry T. Klinksiek Assistant Examinen-Robert J. Miller Attorney-Holman & Stern [57] ABSTRACT This invention relates to a two-line hydraulic drive, especially for the control of driving member such as a 7()4446] double-acting hydraulic jack.

A valve adapted both to feed and to drain is mounted Inventor: Jean Louis Gratzmuller, 66, Boulevard Maurice Barres, Neuillysur-Seine, France Dec. 3, 1971 [21] Appl.No.: 204,556

Foreign Application Priority Data Dec. 10,1970

United States Patent [191 Gratzmuller CONTROL DEVICE [22] Filed:

-valves, in

puts one the other -valves puts said other 18 Claims, 5 Drawing Figures on each of the two lines, the valve being hydraulicall controlled. One of two control electro response to a transient electrical impulse,

feed/drainage valve in the feed position and feed/drainage valve in the drainage position. The other of the two control electro feed/drainage valve in the feed position and the firstmentioned feed/drainage valve in the drainage posi- The two-line hydraulic control is applicable to the hydraulic control of electrical circuit breakers.

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PATENTEDAPR 1 7.1975

'SHEET 1 OF 3 PATENTED APR 1 7 I973 SHEET 2 [IF 3 PATENTEU APR 1 71975 SHEET 3 BF 3 CONTROL DEVICE The invention is applicable to pneumatic controls just as it is to hydraulic controls, but will hereinafter be described especially when applied to installations wherein the fluid under pressure is a liquid, such as oil, without however implying any limitation to the latter within the scope of the invention.

The invention is concerned with hydraulic control devices with two lines ensuring the selective setting-up either of a first hydraulic arrangement wherein the first hydraulic line is put into communication with a highpressure source (feeding) while the second hydraulic line is simultaneously put into communication with a low-pressure tank (drainage), or a second hydraulic arrangement in which the first line is connnected to the drainage and the second line is simultaneously connected to feed. In the following description, these controls will be referred to by the term two-line hydraulic control of the type stated.

There have, of course, heretofore been proposed control systems with two lines, especially those for example comprising slide-valve deviceswhich are used to control double-acting jacks.

These heretofore proposed systems, however, are difficult to make perfectly fluid-tight and there are risks of leakage, particularly with the slide-valve motions. On the other hand, for certain applications, and especially for the control of electrical circuit-breakers to which the invention more particularly applies, it is required that the operational commands be solely nonsustained transient commands, in general transient commands in the form of an electrical impulse. The known systems cannot be well adapted to work in response to very brief transient commands, as the activated change-over members can not have the time to be completely displaced from one position to the other. It is necessary, on the contrary in response to a transient command, that each operation which is started must be completely carried out, as, if not, it should not even be begun. The system according to the invention enables this condition to be fulfilled and, moreover, enables that which is advantageous in certain applications, for example certain particular types of circuit-breaker, namely the maintenance of the pressure in the fed line after cessation of the operational command and up to the advent of the reverse command.

The control according to the invention obviates or mitigates these disadvantages and enables operation of the circuit-breakers from a transient command whose duration is smaller than the time of operation.

The invention is applicable to a control device fed from a source of fluid under pressure to operate a double-acting jack whose two working spaces are connected, respectively, to said device by a first and a second line, comprising a first and a second distributorvalve with two positions and three orifices whose obturating members are controlled, respectively, by two auxiliary jacks, and each including a first orifice connected to said source, a second orifice connected to one of said spaces, and a third orifice communicating with a low-pressure tank, whilst the obturating member which is permanently urged in the direction of closure of said first orifice, enables said second orifice to be put into communication selectively with said first and third orifices. It is characterised in that the working space of the auxiliary jack of each distributor-valve communicates through a non-return clack-valve preventing the outflow of fluid from said space and past a first obturating valve controlled with said source; through a conduit with the second orifice and through a second obturating valve controlled with said low-pressure tank, while, on the one hand, the control of the first valve communicating with the space of the auxiliary jack of the first distributor-valve and, on the other hand, the control of the second valve communicating with the space of the auxiliary jack of the second distributor-valve, are associated with the aid of first synchronisation means for a simultaneous operation of transient effect, and that, on the one hand, the control of the first valve communicating with the space of the auxiliary jack of the second distributor-valve and, on the other hand, the control of the second valve communicating with the space of the auxiliary jack of the first distributor-valve, are likewise associated with the aid of second synchronization means for a simultaneous operation of transient effect.

As a result, and according to the invention, a two line hydraulic control of the type stated includes, mounted in each of the two lines, a distributor-valve with three orifices each controlled by the auxiliaryjack, said distributor-valve being taken in itself towards a first position, or position of rest, where it puts the pertaining line into communication with the low-pressure tank (drainage). The auxiliary jack, when it is put under pressure, takes the distributor-valve into a second position where it puts the pertaining line into communication with the high-pressure source (feeding). Each of the said distributor-valves includes an hydraulic guard circuit, or self'maintaining circuit, fed by the corresponding line and capable of keeping the corresponding distributor-valve in the. second position (feeding) as soon as it has been taken there by an aux iliary jack. A first set of manually-controlled, transientaction valves controls at the same time the putting under pressure of an auxiliary jack of the triple-apertured distributor-valve of the first line and the putting to drainage of the guard circuit of the triple-apertured distributor-valve of the second line, whilst a second set of manually-controlled, transient-action valves controls at the same time the putting under pressure of an' auxiliary jack of the triple-apertured distributor-valve of the second line and the putting to drainage of the guard the detailed description which follows and examining the accompanying drawings, given by way of non'limiting example, and which represent one embodiment the invention.

In the drawings:

FIG. 1 is a diagrammatic view of a two-line hydraulic control device according to the invention;

FIG. 2 is a more detailed representation of the same device; and

FIGS. 3, 4 and 5 are different electro-mechanical, mechanical and electrical variations of the actuating device for the obturating valves controlled according to the invention.

Referring firstly to FIGS. 1 and 2, the hydraulic control device 2 according to the invention includes a first line 4 and a second line 4, which are connected to a double-acting hydraulic jack 6 whose stem 8 actuates the member, not shown, to be operated. This member is, for example, the moving contact of the circuitbreaker.

The equipment is fed or supplied by a pipe-line 9 connected to a source of oil under pressure which has been diagrammatically represented by a hydro-pneumatic accumulator 10.

There is interposed on the first line 4, between this line and the feed pipe-line 9, a first distributor-valve l2 with three orifices or apertures, hydraulically guided,

of the open-centre type.

An identical distributor-valve 12' is interposed on the second line 4, between this line and the pipe-line 9. It is, therefore, only necessary hereinafter to describe the distributor-valve 12, the parts of the distributorvalve 12 being denoted by the same reference numerals with the prime notation applied thereto.

The distributor-valve 12 includes two opposed and

integral valves

14 and 16 constituting a double clackvalve selectively establishing communication of the line 4 with the pipe-line 9 (feeding) or with a low-pressure tank connected to the outlet orifice l8 (drainage). On FIG. 1, the distributor-valve 12 is shown in the drainage position and the distributor-valve 12' in the feeding position.

When at rest, the clack-

valve

14, 16 of the distributor-valve is brought into the drainage position, for example, by a spring 20. The clack-

valve

14, 16 is guided hydraulically by the position 22 of an auxiliary jack whose space 24 may be selectively put into communication with the high-pressure source (feed of the auxiliary jack) or with the low pressure tank (drainage of the auxiliary jack).

Feed of the auxiliary jack is controlled by an electrovalve 26 interposed between a pipe-line 28 connected to the pipe-line 9'and a pipe 30 joined to the space 24 of the auxiliary jack.

In the preferred embodiment of the invention shown in FIGS. 1 and 2, the electro-valves 26, 26', when they are not excited, put the pipe-line 30 to drainage and a now-return clack-valve 32, the function of which will be described hereinafter, is interposed on the pipe-line 30. Likewise preferably, calibrated orifices 29-29, the function of which will be described hereinafter, are interposed on the pipe-lines 28-28.

When the electromagnet 34 of the electro-valve 26 is excited, for example, by manual closure of a switch 35, the clack-valve of the electro-valve 26 opens and transmits an hydraulic command which puts under pressure the auxiliary jack including the piston 22, as a result of which the distributor-valve 12 is brought to the feeding position (the position taken by the distributor-valve 12' in FIGS. 1 and 2). Each distributor-

valve

12 and 12 is provided with a hydraulic guard circuit (self-maintaining circuit) maintaining the valve in the feeding position, even after the aforesaid hydraulic command has disappeared. This guard circuit is constituted by a pipeline 36 putting into communication the space 24 of the auxiliary jack and the circuit being used, that is the line 4. A calibrated orifice 38 is provided in this pipe-line 36. Such a hydraulic guard circuit has already been described in French Pat. No. 1,098,565 and it is sufficient to point out only that as soon as the distributorvalve 12 or 12' has been brought into the feeding position, the line 4 or 4 is put under pressure and that at the same time the pressure remains unchanged in the space 24 of the auxiliary jack including the piston 22.

As a result such a mechanism may be controlled by a transient electrical command (transient excitation of the electromagnet 34 or 34'), a condition which is generally imposed for control of electrical circuitbreakers.

The method of feeding and maintaining fed the auxiliary jack have just been described. There will now be described the method of putting to drainage this same jack, or, which comes to the same thing, the guard circuit. The space 24 of the auxiliary jack (or any part whatsoever of the guard circuit) is provided with a drainage clack-valve 40 which, when it is opened, puts the space 24 into communication with an outlet 42 connected to the low-pressure tank.

The drainage clock-valve 40 is controlled, on opening, by the electro-valve 26' controlling (in the same way as the electro-valve 26 for the distributor-valve 12) the putting under pressure of the space 24 of the auxiliary jack of the distributor-valve 12'.

Transmission between the electro-valve 26 and the clack-valve 40 may be effected mechanically, electrically, or hydraulically, or by a combination of these different means.

In FIGS. 1 and 2 there is shown, by way of example, an hydraulic transmission which will now be described.

The drainage clack-valve 40 is actuated by a guide jack 44 connected to the pipe 30' of the electro-valve 26' by a pipe 46. As a result, the electro-valve 26', when it is excited, takes the distributor-valve 12' into the feeding position and the distributor-valve 12 into.

the drainage position, which the electro-valve 26, when it is excited, controls the reverse movements.

The system operates as follows, taking as a starting point the condition represented in FIGS. 1 and 2. In this position, neither of the electromagnets 34 or 34' is excited. The distributor-valve is in the feeding position, that is to say that the opened valve 14 puts the highpressure pipe-line 9 into communication with the second line 41 which supplies the space 48 of the double-acting jack 6.

The member to be actuated by the stem 8, for example the movable contact of a circuit-breaker which is not shown, is thus maintained in one of its extreme positions, for example the position closing the contactbreaker. It should be noted that the high pressure continues to be maintained in the jack 6, which is advantageous for certain applications, especially circuitbreakers when the pressure between the stationary and movable contacts is necessary to ensure good conductivity.

The high pressure in the line 4 is transmitted by the pipe-line 36' of the guard circuit to the jack space 24 which thus maintains the distributorvalve in the feeding and supply positions, without requiring any lasting electrical command.

In this position, the line 4 is on drainage through the outlet 18, the valve 16 being raised from its seat, especially by the spring since there is no pressure in the space 24 of the auxiliary jack nor in the pipe-line 36 of the guard-circuit.

If the switch 35 is then closed, even transiently, excitation is effected of the electromagnet 34 of the electro-valve 26 which supplies simultaneously with fluid under pressure the space 24 of the auxiliary jack of the distributor-valve 12, through the non-return clackvalve 32, and directly the guide jack 44' of the distributor-valve 12.

Simultaneously, the following activities take place: on the distributor-valve 12', the drainage clack-valve 40, repelled by the guide jack 44', opens and puts in the drainage condition through the outlet 42', the jack 24 and the pipe-line 36' of the guard circuit. Because of the presence of the calibrated orifice 38' in the guard circuit, the high-pressure oil contained in the line 4 and the space 48 of the jack 6 is not able to compensate for the drainage through the outlet 42. In these conditions, the pressure falls in the space of the jack 24', and the spring 20' aided by the hydraulic pressure causes the double clack-valve 14', 16 to go up, which connects to drainage through the outlet 18 the line 4' and the space 48 of the jack 6. This situation remains unchanged after the transient electrical signal has vanished.

At the same time, on the distributor-valve 12, the following activities take place: as the space of the auxiliary jack 24' is put under pressure, the drainage clackvalve 40 is closed (this being permitted because its jack 44 is connected to drainage by the pipe-lines 46, and the valve 26 which is in the drainage condition when being again fed or supplied through the guard circuit 26' of the distributor-valve 12' is intercepted by the non-return clack-valve 32'), and the piston 22 of the auxiliary jack is repulsed downwardly (FIGS. 1 and 2). The valve 16 is closed, the valve 14 opens which results in communication being established between the line 4 and the high-pressure pipe-line 9. At the same time the pipe-line of the guard-circuit 36 is put under pressure and maintains the pressure in the space of the jack 24, even after the transient electrical command has vanished.

As the chamber or space 50 of the jack 6 is put under pressure by the line 4, while the chamber or space 48 is connected to drainage through the line 4, the piston 52 of the jack 6 is repulsed towards the left (FIGS. 1 and 2) and the stem 8 takes the member to be operated into its second position (for example, the opened position of a circuit-breaker) where it remains until a new com- I mand is sent by means of the switch of the electro- Such a control device enables the achievement of a rapidity of response much superior to systems hitherto known, especially thanks to the use of clack-valves without preliminary stroke.

However, this system also obtains a very high reliadoes not result in the carrying out of any operation whatsoever.

Indeed, on being opened, the electro-valve 26' puts the chamber or space of the auxiliary jack 24' under pressure, but the latter was in that condition already thanks to the self-maintaining circuit, which changes nothing in the condition of the distributor-valve 12. At the same time, the opened electno-valve 26' puts under pressure the guide jack 44 of the distributor-valve 12 and maintains open the clack-valve 40 which was already opened.

For its part the electromagnet 34 of the other electro-valve 26, which was excited at the same time, enables this valve to feed or supply the chamber or space of the jack 24 with oil under pressure coming from the pipe-lines 9, 28and 30. The calibrated orifice 29 interposed in the circuit (for example, in the pipe-line 28) has such a section that its flow of oil is less than that which may flow on the auxiliary jack (chamber or space 24) of the distrubibutor-valve 12 getting into the drainage condition, that is to say by the opened clackvalve 40 and by its outlet 42. As a result, the pressure does not rise in the space of the jack 24 and the

clackvalves

14, 16 of the distributor-valve 12 remain in the position which they occupied at the time. On the other hand, as the pressure may not increase downstream of 4 the electro-valve 26, the pipe-line 46' is not put undera pressure sufficient to actuate the quick jack 44' whose drainage clock-valve remains closed.

It will thus be clearly apparent that not one of the contradictory commands is carried out and that the system remains in the initial condition t In actual fact, it is practically impossible for two contradictory. commands to be given exactly simultaneously, due to the transience of these commands. If the contradictory commands are given, not exactly simultaneously, but with a certain lag, which is the only situation which can occur in practice, the command which is first sent is carried out and maintained, the sending of the reverse command being rendered impossible by the opening of the appropriate drainage clack-valve 40 or 40'.

It is impossible for the two sides of the double-acting jack 6 to be put under pressure simultaneously.

It will also be noted that his advantageous to provide an orifice 54 and 54' of calibrated section in each of the lines 4 and 4', respectively. The function of this orifice is to establish immediately the pressure in the pipeline of the guard circuit 36 and 36' as soon as the distributor-valve l2 and 12' occupies the feeding position and, thus, before the circuit being used is put under pressure completely. There is thus obtained with certainty an hydraulic self-maintenance following a command itself very transient and whatever may be the characteristics of the circuit being used. Such a device has been described in French Pat. No. 1,181,089.

There has been represented in FIG. 1 a diagrammatic case where the lines 4 and 4' directly supply or feed the jack to be operated.

In practice, just as at present, hydraulic relays may be used instead of a direct feed, that is to say that the lines 4 and 4' supply the guide jacks of the hydraulic relays which, themselves, control the feed or the drainage of the receiving prime mover. Such hydraulic relays have been described in French Pat. No.

It is preferable, in order to avoid any delay in putting the driving jack, to provide in the lines 4 and 4' (whether they feed or supply the jack 6 directly or through the intermediary of hydraulic relays) an automatic air-purging device in accordance with French Pat. No. 1,230,514.

On the other hand, it is generally preferred to regulate the speed of operation of the two-stroke driving apparatus, such as the double-acting jack'6, by means of a calibrated orifice, such as has been described in French Pat. No. 1,135,122.

In the preferred odiment shown in FIGS. 1, and 2, I

control of drainage of the distributor-valve 12' (clackvalve 40') from the electro-valve 26 is effected by a The embodiment represented in FIG. 2 corresponds exactly to the lay-out in FIG. 1. It may be noted in FIG. 2 that the assembled device is disposed in a fluid-tight chamber 62 which forms a low-pressure tank to receive drainage oil delivered through the outlets 'such as 18, 18, 42 and 42' of the distributor-valves. It may also be noted that certain obturators of clack-valves and valves, such as 32, 32, 40 and 40 are constituted by balls and are free of return springs in the closed position.

These small-diameter balls are very light in the oil and the slightest discharge of oil suffices to bring them back towards their seats and close the valve.

As a result, in spite of the fact that the calibrated

orifices

29 and 29 are of smaller section than the

outlets

42 and 42 and the passages co-operating with the clack-

valves

40 and 40, the latter are closed immediately on opening of the first valves 26 and 26', respectively. i

' There will now finally be described in FIG. 2, referring to the valve 26, the particular construction of the hydraulic transmission (pipe-line 41' and guide

jack valves

26 and 26. The ball 64' may be pushed clear of its seat, against the return spring 66', by a stem 68' on which comes to act an extension 70' of the armature of the electromagnet 34.

The stem 68' has a central part 72' of larger diameter forming a'slide-valve which is guided in the axial bore of a member 74providing the clack-valve seat. The central part 72 of the stem obturates, when at rest, a boring 76' which communicates with the low-pressure tank through an orifice 78'.

When the electromagnet 34 is excited, the extension 70' moves downwards and drives the stem 68 which displaces the ball 64' from its seat. The pipe-lines 30' and 46 are thus put under pressure.

When the transient signal of excitation of the electromagnet 34 vanishes, the ball 64 returns to its seat and the pressure in the pipe-line 30' (upstream of the non-return clack-valve 32') as well as in the pipe-line 46 raises the stem 68' whose central part 72' plays the and the clack-valve of the valve 26' by single manual closure of the switch 35'.

A purely mechanical link-up may justjas readily be provided, as is shown in FIG. 4. In this'case, it is sufficient to press manually and transiently on one of the push-buttons 58 and 58' to lower one or the other of the arms 56 and 56' controlling the operation of the valves.

Finally, as shown in FIG. 5, an electrical set-up may be selected. In this case, the valve 26 is controlled at operated valves open or, if the command is too brief,

neither opens.

role of a piston. The stem is raised until its narrower lower part gets to be opposite the orifice 76, so that the pipe-lines 30' and 46 are subject to drainage. Of course, the non-return clock-valve 32 prevents the fall of pressure in the space orchamber of the auxiliary jack 24'. H

This particular arrangement of the electro-valves 26 and 26' provides the advantage that in case the clackvalve 64' wereto glide away when at rest, the high pressure in the pipe-line 28 would raise the stem 68' and would escape through the orifices 76, 78 without causing the pressure to rise in the pipe-

lines

30', 46' or 30, 46. Thus any risk of untimely operation in the event of movement away on the base of the clack-valve 64 is avoided.

In a preferred arrangement, especially as regards hydraulic control of circuit breakers, there is provided in one of the lines, and preferably in both, a rapiddischarge device, or rapid drainer such as that which has been described in French Pat. No. 1,099,949 and it cation in view and without thereby departing from the scope of the invention.

1 claim:

1. A control device fed from a source of fluid under pressure to operate a double-acting jack whose two working spaces are connected, respectively, to said device by a first and a second line, comprising a first and a second distributor-valve with two positions and three orifices whose obturating members are controlled, respectively, by two auxiliary jacks, and each including a first orifice connected to said source, a second orifice connected to one. of said spaces, and a third orifice communicating with a low-pressure tank, whilst the obturating member which is permanently urged in the direction of closure of said first orifice, enables said second orifice to be put into communication selectively with said first and third orifices, the working space of the auxiliary jack of each distributorvalve communicating through a non-return clack-valve preventing the outflow of fluid from said space and past a first obturating valve controlled with said source; through a conduit with the second orifice and through a secondobturating valve controlled with said low-pressure tank, whilst, on the one hand, the control of the first valve communicating with the space of the auxiliary jack of the first distributor-valve and, on the other hand, the control of the second valve communicating with the space of the auxiliary jack of the second dis tributor-valve, are associated with the aid of first synchronisation means for a simultaneous operation of transient effect, and that, on the other hand, the control of the first valve communicating with the space of the auxiliary jack of the second distributor-valve and, on the other hand, the control of the second valve communicating with the space of the auxiliary jack of the first distributor-valve, are likewise associated with the aid of second synchronisation means for a simultaneous operation of transient effect.

2. A control device according to claim 1, in which the fluid is an hydraulic fluid.

3. A control device according to claim 2, in which the first and second hydraulic lines are connected respectively, to hydraulic relays controlling supply to and drainage from the double-acting hydraulic jack.

4. A control device according to claim 3, in which the two triple-apertured distributor-valves are of the double clack-valve type with open centre, the obturating member being constituted by two opposed and integral valves forming the double clack-valve.

5. A control device according to claim 4, in which said synchronisation means are constituted by mechanical linkages.

6. A control device according to claim 5, in which the mechanical linkages are actuated by-means of electromagnets in each of the feed circuits in which is intercalated a transient-action switch.

7. A control device according to claim 6, in which the transient action is exerted on the mechanical linkages by means of push-buttons.

8. A control device according to claim 7, in which the valves are electro-valves, each synchronisation means being constituted by an electrical control circuit common to two electro-valves and in which is intercalated a transient-action switch.

9. A control device according to claim 8, in which each of said synchronisation means is constituted by a hydraulic connection between the valves.

10. A control device according to claim 9, in which the two first valves are electro-valves each actuated by means of a transient-action switch, the two second valves being controlled each by a guide hydraulic jack, the synchronisation means being constituted each by a conduit connecting the working space of said guide hydraulic jack of the second valve communicating with the auxiliary-jack space of a distributor-valve at the outlet of the first valve communicating with the auxiliary-jack space of the other distributor-valve.

11. A control device according to claim 10, in which each of the said electro-valves is a feed and drainage electro-valve which, when it is not excited, effects drainage of the pipe-lines connecting the said electrovalve to the auxiliary-jack space of the first triple-aper tured distributor-valve and/or guide jack of the second triple-apertured distributor-valve and in which a nonreturn clack-valve is interposed in the pipe-line connecting the said electro-valve to the auxiliary jack of the first triple-apertured distributor-valve.

- 12. A control device according to claim 11, in which a calibrated orifice restricts the outflow of fluid through each first valve, the section of said orifice being smaller than that of the second valve connected to the same space of the auxiliary jack of the said first valve.

13. A-control device according to claim 12, in which a calibrated throat is intercalated in the said conduit connecting the said auxiliary-jack space to the said second orifice of the distributor-valve.

14. A control device according to claim 13, in which at least one of the conduits connecting therebetween the valves and/or distributor valves is fitted with an automatic air-purging device.

15. A control device according toclaim 14, in which a calibrated throat is intercalarted between the said second orifice of the distributor-valve and one of the working spaces of the double-acting jack.

16. A control device according to claim 15,in which the distributor-valves, their auxiliary jacks, the valves and the non-return clack-valves are located in a liquidtight casing forming a drainage reservoir and constituting the said low-pressure tank.

17. A control device according to claim 16, in which at least one of said lines is provided with a rapid-

Claims

1. A control device fed from a source of fluid under pressure to operate a double-acting jack whose two working spaces are connected, respectively, to said device by a first and a second line, comprising a first and a second distributor-valve with two positions and three orifices whose obturating members are controlled, respectively, by two auxiliary jacks, and each including a first orifice connected to said source, a second orifice connected to one of said spaces, and a third orifice communicating with a low-pressure tank, whilst the obturating member which is permanently urged in the direction of closure of said first orifice, enables said second orifice to be put into communication selectively with said first and third orifices, the working space of the auxiliary jack of each distributor-valve communicating through a non-return clack-valve preventing the outflow of fluid from said space and past a first obturating valve controlled with said source; through a conduit with the second orifice and through a second obturating valve controlled with said low-pressure tank, whilst, on the one hand, the control of the first valve communicating with the space of the auxiliary jack of the first distributor-valve and, on the other hand, the control of the second valve communicating with the space of the auxiliary jack of the second distributor-valve, are associated with the aid of first synchronisation means for a simultaneous operation of transient effect, and that, on the other hand, the control of the first valve communicating with the space of the auxiliary jack of the second distributor-valve and, on the other hand, the control of the second valve communicating with the space of the auxiliary jack of the first distributor-valve, are likewise associated with the aid of second synchronisation means for a simultaneous operation of transient effect.

6. A control device according to claim 5, in which the mechanical linkages are actuated by means of electromagnets in each of the feed circuits in which is intercalated a transient-action switch.

11. A control device according to claim 10, in which each of the said electro-valves is a feed and drainage electro-valve which, when it is not excited, effects drainage of the pipe-lines connecting the said electro-valve to the auxiliary-jack space of the first triple-apertured distributor-valve and/or guide jack of the second triple-apertured distributor-valve and in which a non-return clack-valve is interposed in the pipe-line connecting the said electro-valve to the auxiliary jack of the first triple-apertured distributor-valve.

12. A control device according to claim 11, in which a calibrated orifice restricts the outflow of fluid through each first valve, the section of said orifice being smaller than that of the second valve connected to the same space of the auxiliary jack of the said first valve.

13. A control device according to claim 12, in which a calibrated throat is intercalated in the said conduit connecting the said auxiliary-jack space to the said second orifice of the distributor-valve.

15. A control device according to claim 14, in which a calibrated throat is intercalated between the said second orifice of the distributor-valve and one of the working spaces of the double-acting jack.

16. A control device according to claim 15, in which the distributor-valves, their auxiliary jacks, the valves and the non-return clack-valves are located in a liquid-tight casing forming a drainage reservoir and constituting the said low-pressure tank.

17. A control device according to claim 16, in which at least one of said lines is provided with a rapid-drainage means.

18. A control device according to claim 17, in which said double-acting jack includes a movable element connected to the movable contact of an electric circuit-breaker.