US2657535A - Hydraulic remote control system, including transmitter and receiver stations and means for automatically resynchronizing the receiver - Google Patents

Description

Nov. 3, 1953 LEVY 2,657,535

HYDRAULIC REMOTE CONTROL SYSTEM, INCLUDING TRANSMITTER AND RECEIVER STATIONS AND MEANS FOR AUTOMATICALLY RESYNCHRONIZING THE RECEIVER Filed May 5, 1947 4 Sheets-Sheet l NOV. 3, 1953 LEVY 2,657,535

HYDRAULIC REMOTE CONTROL SYSTEM, INCLUDING TRANSMITTER AND RECEIVER STATIONS AND MEANS FOR AUTOMATICALLY RESYNCHRONIZING THE RECEIVER Filed May 5, 1947 4 Sheets-Sheet 2 Nov. 3, 1953 LEVY 2,657,535

HYDRAULIC REMOTE CONTROL SYSTEM, INCLUDING TRANSMITTER AND RECEIVER sTATIoNs AND MEANS FOR AUTOMATICALLY RESYNCHRONIZING THE RECEIVER Filed May 5, 1947 4 Sheets-Sheet 5 1953 R. LEVY 57,535

HYDRAULIC REMOTE CONTROL SYSTEM, INCLUDING TRANSMITTER AND RECEIVER STATIONS AND MEANS FOR AUTOMATICALLY RESYNCHRONIZING THE RECEIVER Filed May 5, 1947 4 Sheets-Sheet 4 Patented Nov. 3, 1953 UNITED STATES PATENT OFFICE RECEIVER Ren Lucien Levy, Paris, France, assignor to Societe dInventions Aeronautiques et Mecaniques S. I. A. M., Geneva, Switzerland, a corporation of Switzerland Application May 5, 1947, Serial No. 746,029 In France January 9, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires January 9, 1961 11 Claims.

,The present invention relates to a hydraulic remote control system providing for automatic setting from the mid position.

The prior art is replete with hydraulic systems for reproducing remotely by means of a receiver the movement of a transmitter in such fashion that for a particular position of the transmitter a similar position of the receiver is obtained.

Ingeneral such systems are provided with auxiliary devices or controls providing for resynchronizing of the transmitter and receiver at the conclusion of their travel. In some instances, particularly in telemotor systems, the normal position of the apparatus is the mid position of the total travel. Therefore it is necessary to provide means for synchronizing the receiver with respect to the transmitter when the transmitter is in the mid position; inother words, it is necessary to positively move the receiver into the mid position in the event it has for any reason drifted out of this position. I 7

.Accordingly it is one object of the present invention to provide in a hydraulic remote control system an arrangement which will automatically move the receiver to its mid position when the transmitter has been brought to mid position and one in which the restoring torque eifecting this movement will cease as soon as the transmitter is moved away from the mid position.

A more specific object of the present invention is to provide a hydraulic remote control system in which the receiver and transmitter each include a pair of hydraulic cylinders and pistons constituting hydraulic groups and each pair of cylinders and pistons are respectively pivoted to a base and to an oscillating cross beamin turn pivoted to a post by a pivot which lies outside of the line connecting the pivoting axes of the hydraulic groups with the cross beam.

It is a further objectto provide in an arrangement of this character, conduits connecting the transmitter hydraulic groups to the receiver hydraulic groups and'means automatically connecting these conduits with a hydropneumatic accumulator or the like when the transmitter is in its mid position. r I

A further object is to provide an arrangement in which either the pistons or the cylinders of the hydraulic groups are bodily pivoted to the cross beam.

Another object is to provide, in a system of this character, rods carried by the pistons of, the hydraulic groups pivoted to the .cross beam at the opposite ends thereof and above the axis of pivotation of the cross beam with respect to the post and pivoting the cylinders with which the pistons are associated to the base of a post and extending the piston rods beyond the pistons so that they pass through the base of the respective cylinders.

It is a further object to provide in a system of this character a particular disposition of the conduits interconnecting the cylinders of the hydraulic groups respectively associated with the receiver and transmitter so that the liquid in the cylinders are on opposite sides of the pistons in the respective groups. 7

It is a further'and more specific object to provide an arrangement in which the piston rods are each provided with a duct through which the liquid in the cylinders pass to and from the conduits connecting the respective transmitter and receiver groups and in which construction the rods are pivoted to the base of the post thereby providing that the cylinders which are pivoted to the cross beam constitute the movable members.

It is another object to provide an arrangement for use in installations where the receiver must overcome a comparatively high resistance such as'in moving rudders of heavy aircraft and in which event, the movement of the receiver corresponding to that of the transmitter may be initiated by an external source of energy independent of the transmitter and which energy may constitute the pressure existing in another hydropneumatic accumulator operative as a servomotor.

Further and more specific objects will be apparent from the accompanying drawings in which:

Figure 1 is a view partly in section illustrating a first example of the remote control system;

Figure 2 is a cross sectional view on an enlarged scale through a valve chest providing automatic communication between the hydropneumatic accumulator and the connection pipes or conduits when the transmitter is in its mid position;

Figure 3 is a view partly in section illustrating a modification of the system shown in Figure l in which the cylinders of the hydraulic groups constitute the movable members;

Figure 4 is a diagrammatic view of a third embodiment;

, enlarged scale of a distributor device embodied in the modification shown in Figure 4; and

Figure 6 is a partial view of the embodiment of Figure 3;n1odifled toiprovide for automanere storing of the transmitter to mid position.

In the modification of Figure 1, the system includes a transmitter and dagger-respectively provided with hydraulic grou .cOIIiprisin cylinders I, 2 and 3 and 4. ' gonduitsorfpiping 5 and 6 connect the upper portions oi the cylin i ders l and 2 with the lower portions of the cylinders 3 and 4 respectively. I

Pistons 1, 8, 9 and 10 are associated withthe respective cylinders l to 4 "an ody piston; rods ll, I2, [3 and [4.

the piston rods IS-and l-ll are'pivoted at st nd} 31" to a' :crossbe'anr l 5- "which :in turn 1 is pivoted at 3D to the post and the cylinders 3 and 4-are'further .iprovi ded with extensions Blfldbarihgs l9 and-1 0: by which =-they are 'pivotally connected to thezbase 22in amanner similar to the-arrangementof the transmitterr 1i It isnoted t-at the-piston at the receiver the chambers25 and 26 containing the liquid are 'below thepistonst and In, that is they are on} the side of the piston'opposite to'the'location of the cross beam whereas in the constructional arrangement "of the transmitter,

As indicated i I rods H'to Mpass through liquid chambers-23 24, 25 arid'ifi and plane, as illustrated, thus providing for the ex istence of unequal effective lever arm distances. A hydropneumatic accumulator 35, consisting of a cylinder closed at its upper end, containing a p ston caboiie is provided a compr aincushion"; 3 'lg"isiconnected by a pipe or conduit tion 3.3C'to" valve1 chests 39 and 43, respectively which insure that; the control wheel 21 is in the mid position ef-its total movement the conduits 5, andare automatically placed in communicahthe accumul r As indicated. in Eigure 2 the valve chests 39 and 40.?are' each provided with a valve 4| urged by, a spring, lg to closed position. The valves are died with stems t3 and 44 respectively passing-urrougli the casings 39 and 4B and engageable bycam surfaces '45 and 46 formed on a ring 41. Aslshowni-nthis figure, the cam surfaces 45 and 46 ;arev in alignment with one another and have their axes horizontal when the control wheel occupies its mid position. The valve chests are so disposedj"thattheaxes ofthe valves are horizofiitalii. .i y l H Preferably the ring A l; is iast with the control shaft 29-wh-ich' also constitutes the pivot of the cross beam-ls: This shaft is driven by a pinion the- -liquidichambers-23" 2 4 "are arra'nged be-' twentl e pistons 'l-and'B and the crosslzvearn I 5. 'i'lihedriv-ing member at the transmitter is constitutedlhy-a control wheel 2 and the member to be iilove'd in conformity therewith constitutes a lever 28 actuated by the controlling memberor e lvrllj i t v i V The arrangement just described will providean exact reproduction-oi thefmOvements of the transmitter at" the l receiver if the transmitter and j receivef are equal: However, it will not provid 'forompensation' for positive ornnegative se'tting onrest ring of the receiver to the mid-positio'rir' Kcord-ig to the main characteristics of thel present invention the cross beams 15 and IB'osiIEW bWt i ffifend fl, p i e w ich asiriri-iate;a; are positioned "outside of the line joining the axes 3I -3 2 and 33 -3 4 which con"- stitiit'jthe "pivoting axes ofthe piston rods with respect-w th:cross beams; The importance of this physical disposition of the various pivot points" will bdbio'ught *out hereinafter. 7 Suffice it to say, that in accordance with well knownme chani'c'alprinciples such'ia'n arrangemenr rev s for theexiste'nce of-unecnial effective lever arms:

with respect tdthe vertical planepassin'g through the pivot points 29 and 30 and bisecting the bases Zlaa'nd fi respectively between the pivot connections -of 'the cylinders to the-bases." In this; arrangement it is :clear that when the cross beam 16 is oscillated theoylin'ders 3' and 4 can respec-" may move through different angular distances and thereby provide that the pivot pointtaap-i preaches .the; aforementioned vertical plane while the pivot-point '34 moves-further away from this "oi-thevolume of the working fluid 0';-

48,l' 'iey:e'cl "to the-shaft of the whee1 2-'l, and which pin-ion is in mesh with a gear 49=fixed to shaft 29.

The operation of this arrangement is such'that" when the transmitter wheel 21 is held by the pilot in" the "mid positibn, the volumes of liquid COfitained i'n cylinders land 2 are equal'to'oneanother',' owing tetlie particular design ofthe systerri,- further, these cylinders, as well as the cylinders Sfand- 410i" the receiver, are connected in parallel with the'accumulator 35,the valves dlfofchests 39 and debeing in the open position under the actioir ofethecarn surfaces or shoul ders 45, 49,1 r

7 erefor'e, if atthis instant'the cross beam l6 oi the'receiver should, for any particular reason, be'ili a positioll bliliertha nthe mid-position, with the axis 33 for instance disposedat 33' and thus means 35' att l fi the moment of the force exertedby piston ill on thecross beam I5; with respect to 'the jpivot axis 30;,- will be "greater" than thern'omenti of theforce exerted, byp'iston 9- on ai r s am. livine e a e en h f eti h ev a ilftransmi tine t e x rc i x- Consequently, and, owing solely to theaction 'im iils'e provided by the accumulator, th re r will be automatically reset into thiiniid sit n.

auo'ma c resetting of the remote hy -v to,itsmid-position there;

nt, inwhich a notch ember in the midposition frel a ns t sieg t e wo s enci eri esyn hre ism.

f; d l sciati ahe; ilot.- m e theimhs: i itte aw ame 'i n m l m ql-nqsie ni the;

; va. m i cal m.

Ifq h iorainsta ce acteillupcn in such that the volume of *l,iquid; in hambervzl lso cy inder 1 dec ea es inithe di ectionyindicated; by thegarrow -.-'-j' the pressure.

in; pipe 5min increase, thereby increasing the.

closing force exerted upon valve 4! in. chest;;39-. At fthe sameg;time, the-cylinder 3i will receive liquid deliveredlfrorh cylinder l; causing the pis.-. ton 9iltoi-moveiin direction of arrow -41? and swing the cross beam it into the corresponding direction indicated by arrow f2.

At the same time, the combined action of cross beam I6 and the suction established in pipe 6 .by the downward movement of piston 8, while leaving the valve 4| in chest 40 closed, will cause the piston I8 to move downward as indicated by arrow f3.

The controlled lever 28 will consequently occupy, at any instant, a position corresponding to that given by the pilot to the control wheel 21.

It will be observed that the pistons 9, I8 of the receiver work constantly in compression in their action upon the cross beam I6, so that the cross beam is constantly in a state of stable equilibrium, while the transmitter cross beam I5 is in unstable equilibrium. These equilibrium characteristics are a direct result of the arrangement of the liquid chambers with respect to the pistons and cross beams. With respect to the equilibrium characteristics, by the particular structure embodiedit is apparent that pistons 9 and I8 always exert a positive compression action on the cross beam I6 since when these pistons are stationary they are submitted to the action of the accumulator 35 and in operationthey are submitted to the pressure exerted by either one or the other of the transmitter pistons 1 and 6. Therefore there can never exist an empty space between either of the pistons 9 and I8 and the liquid in the compartments 25 and 26 below these pistons. On the contrary, with respect to the transmitter arrangement an empty space maybe produced above whicheverof pistons I or 8 moves downward in its associated cylinder.

For this reason cross beam I6 is in stable equilibrium and cross beam I is in unstable equilibrium. When the wheel is brought back into the midposition, the two valves 4| will open and permit fluid under pressure to return, if necessary, the lever 28 to its mid-position.

Figure 3 shows an alternative embodiment in which the pistons 1, 8, 9 and I8 are provided with simple rods instead of the double rods of the preceding embodiment. Ducts 58, 5| and 52, 53 provided in these rods and in the pistons 9 and I8 respectively connect the cylinder chambers 54, 55 and 56, 51' respectively to pipes 5 and 6. In this embodiment the cylinders constitute the movable parts of the system with respect to movement toWard'or away from the bases 2| and 22. Apertures 59 to 62 connect with the atmosphere the other cylinder chambers, that is, those chambers containing no liquid.

The resynchronization is obtained, in case of V misadjustment, by the presence of accumulator 35, as before.

For permitting the receiver to exactly follow the movements of the transmitter, it is merely necessary that when the apparatus is at rest, in its mid-position, the volumes of chambers 54 and ,55 be equal to those of chambers 56 and 51 and 92 151 1 316 relation 1. be verified, where 1?. is the radius of cylinders I and 2, I I

,t the radius of the corresponding piston rods, and P the radius of cylinders 3 and 4.

uid in the accumulator 35 and the pipe 38, this action being also controlled by the operation of the valve chests.

In case it should be desired, for convenience or by habit, that the transmitter be reset automatically to the mid-position when or if the pilot releases wheel 21, then the arrangement shown in Figure 6 is employed. In this modification the apertures 59 and 58, that communicate with atmosphere in the zone shown in Figure 3, are in communication 'with a branched conduit 38 so that fluid under pressure constantly flows into the upper cylinder chambers above pistons 1 and 8. Under these conditions, when the transmitter occupies a position other than the mid-position, the pressure from the accumulator will exert upon the cross beam I5 a restoring torque similar to that exerted upon the cross beam I6, as previously described, when the transmitter is in its mid-position.

In the alternative embodiment of Figures- 4 and 5, the transmitter T comprises two hydraulic groups 63 and 84. Group 63 is constituted by a cylinder 65 in which is arranged a liquid-tight piston 85 dividing the cylinder into two chambers 5'! and 88. The piston rod 59, extends from both faces of piston 65, passes through the upper and lower end plates 18 and II of cylinder 65. The cylinder has embodied therewith an upper cap 12 pivoted at E3 to the endof the arm 14 of a beam in turn pivoted on the pin 16. The end of piston rod 89, opposite the beam 15, is

ivoted at H to a fixed support or base.

The construction of the hydraulic group 64 is similar to that of group 63. It is constituted by a cylinder I8 in which is arranged a liquid-tight piston 19 dividing the same into two chambers 88 and 8|. The piston rod 82 extends from both faces of piston 19 and passes through the upper and lower end plates 83 and 84 of cylinder 78. The latter also has embodied therewith an upper cap 85 pivoted at'88 to the end of an arm 81, of length equal to the length of arm 14, of beam "I5. The end of the piston rod 82, opposite the beam 15, is pivoted at 88 to a fixed support. On two other arms 89 and 98 of beam 15 is mounted the hand-wheel 9| 'of the transmitter.

The construction of the receiver R is similar, as concerns'its hydraulic groups 92 and 93, to that of the transmitter T. Group 92 is constituted by a cylinder 94 in which is arranged a liquid-tight piston 95 dividing the cylinder into two chambers 95 and 91. The piston rod 98 extends from both faces of piston 95 and passes through upper andlower end plates 99 and H38 of cylinder 94. The latter has embodied therewith an upper cap I8I pivoted at I82 to the end of an arm I93 of a beam I88 pivoted on pin I85. The end of piStOIlTOd 98, opposite the beam Hid, is pivoted at I88 to a fixed support. V

The hydraulic group 83 is constituted by a cylinder I8? in which is arranged a liquid-tight piston I83 dividing the cylinder into two chambers 589 and H8. The piston rod III extends from both faces of 'p-istoniI88 and passes through the upper and lowerend plates H2 and H3 ofv cylinder I81. The latter" has embodied therewith an upper cap H4 pivoted to the end II5'of an arm N6 of the beam I84, and the length of arm H6 is equal to the length of arm I83. The end .of the piston rod III, opposite the beam I8 5, is pivoted at I I! to a fixed support. A lever H8, integral with beam,|84;is1connected to the controlled member i amass The: transmitter cylinder chambersv 5.8: and 81 and, the receiver cylinder chambers 96: and W9 are filled with liquid. Chamber 68, is hydraulie cally connected to chamber 96. through a-pipeor conduit M9,. and chamber al is connected to. chamber. I09 through pipe or conduit I20.

The transmitter T includes a hydrop-neumatic accumulator I21 from which branch pipes I22 and. I2'3- lead to the valve chests I24 and I251 The valves I25 and I.2 1 of these chests are con.- trolled by a shouldered disc or cam. I28,- the spindle. I29. of which is fast with a lever I3II'pivotedto a rod- I3I pivoted in turn. to an arm I32 otbeam 15. Pipes I-3'3 and I34 lead respectively from the valve chests. I24 and I25. to the pipes H9 and I20.

The operation ofthe. described remote control system is quite similar to that of the various embodiments of this system, set forth above. ensures the reproduction, at a distance, by h receiver.,,of the movement given the transmitter, while. the receiver is automatically restored into its mid-position when the transmitter is itself set. in this position and the' resetting torqueceases. to be effective as soon as the transmitter is swung out of the mid -position;

According to the present embodiment, the

chambers 91- and I10 of receiver Bi, are utilized for receiving the pressure from a hydropneumatic accumulator I35, which in effect constitutes a. servo-motor. The latter is supplied by. a

pump I35 drawing liquid through a pipe I31 from a tank I38 and delivering it under pressure into a. pipe .I 39. leading to the lower side of the hvdropneumatic accumulator I35. A check valve. I411 prevents back flow through pipe I391 The pipe I411, extending from the hydropneumatic accumulator I35, is branched into'two pipes I42 and. I43 leading respectively to two distributors I44 and I45". Such a. distributor is shown on a larger scale in Figure 5.

This distributor, for instance I 44, comprisesa casing I46 divided. by a transverse partition or wall I41 into alower chamber I4'81and' an upper chamber I49. The wall I41 is provided with an aperture I58, the opening. and closing of which is controlledby thehead. I.5I of'a valve I52. A spring I53 arranged in chamber I48 urges the valve I52 towardsclosed position. Thevalve I54 slides in a sleeve I5.5fembodied within casing I45 andprovided with bearings I58 and I51'pr'ovided with stuiiing rings I59 and I59. The stem I55 of valve I52 is provided with a channel IEO in permanent communication with the threeicham bers limited by the sleeve I55, namely, by means of an aperture IBI with the lower chamber I52, by an aperture I63 with the middle chamber IE4 and directly with the upper chamber I;

The sleeve I55 and casing I46 areprovidedwith two aligned apertures I56 and I61, from which a pipe I58 leads to chamber III) of the hydraulic group 93. an aperture I59 in communication with chamber I and from which abr'anch pipe I10 extends which after merging with a corresponding branch'pip-e I11 extending, from distributor I45, continues as return pipe I12 leading fluid back to the tank I38; The" distributor I communicates viaa pipe I13; similar to pipe I68, with chamber 91 of.the hydraulic group 92.

In chamber I65'is arranged a valve head I14 which may cooperate with the endportioni I15 of the hollow stem I54 so as to .closethe channel I60. The stem. I11, on which is moun ed the head I14; passes through the bottom I19 of ranged next. to casing I-46- and integral with thelatter. The stem I11 constitutes. the rod of a piston I82 arranged in liquid-tight relationship within cylinder I-BI and forming' in the latter a lower chamber I83' and an upper chamber I84. Inthe lower chamber I83 is arranged a. calibrated spring. bearing on the one hand against the cylinder bottom I80 and on the other handagainst under side of piston I32. From the upper chamber L84; a pipe I86 extends and communicates with pipe I19 A, corresponding pipe I81, extends from distributor I45 and com municates. with pipe I20.

The operation of this remote control system, fitted with an effective servo -mot'or, is as'follows:

When. the pilot moves the hand-wheel 9I, for instance, in the. direction shown by arrow I88, thus setting up in chamber 68, and" consequently in. the piping I19, a pressure above a predetermined value, depending upon the force exerted by the. spring 1195, the piston I82 of distributor I4Y4' will be depressed under the action of this pressure and overcome the force of spring I85. In the first phase of its downward motion, the valve head I14 closes fluid fiow through the channel I55; thus interrupting the communication between chamber I I'IIanjd tank I 38; During the subsequent descending movement of piston I82, the valve. 152 is moved and its head I5I is moved clear from its seat. The chamber I48, subjected to. the pressure .of the hydropneumatic accumulator I35, is thus connected; through the aperture 156,. apertures i'iil', channel I69; apertures I53 and pipe I53, with chamber I I9} The pressure set up in this chamber causes the hydraulic group 93 to move downward, thus'rotating. the beam ,Ill'gfin the 'direction'of arrow. I89. When the force-exerted by the pilot falls below the said predeterminedivalue, the distributor will operate in the opposite direction, disconnecting-chamber I iil' from the hydropneumatic' accumulator I35 andficonne'cting it to'the tank.

The receiver, connected to lever' III}, is thus brought .to a position corresponding to' that of the handwhefel 8110fthetransmitterwithout it being necessary for the force exerted bythe pilot to exce'edat any .rhcrnejnt, a predeterminedvalue. When the resistance encountered by thecontrolledirnember becomes such that it requires that..anIeXcessiVe,fbrceibe exerted by the pilot, thi resistance will be'overccme' by the pressure of accumulator I3'5flactirig asjth je servo-motor applied accordingt'o the invention.

when. the pilotlnioves the'wheel'SI inthe' direction opposite t'o'arrow18'8; it is the distributor 5.615. which. will now connect, whenthe' force exceeds a predetermined value, chamber $1 of" the hydraulic-group 9.2"w t t e hyd uma umula cr 1.3.52.

Th'e: chambers. 51. and" ,80 of" transmitter. T may be used, "if' desired} for obtaining the. auto matic resetting of the transmittento its midposition when the pilot releases the wheel BI, as set forth at the beginning 01 .thespecification with reference to the embodimentof Figure 6, by connecting chambers;.Iiv1=and 8.0 to .hydrohheumaticaccumulator I21I.

In allcases whereithe pilot vexert'sia force which is less than the predetermined value, the remote control system"operates as described further What I claim is l. A hydraulic remote control system; includ- -ing a transmitter and a receiving station each including two similar cylinders, stationary pivots for securing same at their outer ends, pistons adapted to reciprocate therein, piston rods therefor, a cross-beam the ends of which are Divotally secured to said piston rods and a pivot for said cross-beam located at equal distances from and outside the line connecting the connection points of said cross-beams with the piston rods, pipes fconnecting each cylinder of the transmitter with the corresponding cylinder of the receiver, said pipes opening inside the transmitter cylinder compartment on one side of the piston with reference to the cross-beam and inside the receiver cylinder compartment on the other side of the piston with reference to the cross-beam of the receiver, a mass of liquid filling said pipes and the cylinder compartment communicating therewith, a hydraulic accumulator, a valve box including valves for connecting said accumulator with each of said two pipes respectively at a point in proximity with the corresponding transmitter cylinders and control means for the valve boxes responsive to the movement of the transmitter cross beam and operative upon the rocking of the transmitter cross-beam round its pivot to its medial position of symmetry for opening the valves to automatically restore the receiver into its medial corresponding position through the balancing action of the pressure impulse from the accumulator on the fluid in the pipes.

2. A hydraulic remote control system, including a transmitter and a receiving station each including a system. embodying two similar cylinders, pistons adapted to reciprocate therein, piston rods for said pistons pivotally secured to a stationary point, a cross beam havin opposite ends pivotally secured to the cylinders of each system and a pivot for said cross-beam located at equal distances from and outside the line connecting the connection points of each said crossbeam with the cylinders, pipes connecting each cylinder of the transmitter with the corresponding cylinder of the receiver and including conduit means passing at least through the piston rods and opening into the compartment defined by the cylinder and the piston lying to one side of said piston with reference to the cross-beam at the transmitter station and to the other side thereof for the receiver station; a hydro-pneumatic accumulator, a valve box including valves for connecting said accumulator with each of said two pipes respectively at a point in proximity with the corresponding transmitter cylinders and control means for the valve boxes responsive to the movement of the transmitter cross beam and operative upon the rockin of the transmitter crossbeam round its pivot to its medial position of symmetry for opening the valves to automatically restore the receiver into its medial corresponding position through the balancing action of the pressure impulse from the accumulator on the fluid in the pipes.

3. A hydraulic remote control system, including a transmitter and a receiving station each including a system embodying two similar cylinders and pistons slidable therein, a cross beam pivotally connected to each said cylinder and piston system and a pivot for each said cross-beam located at equal distances from and outside the line connecting the connection points of said cross-beam with the cylinder and piston systems, pipes connecting each cylinder of the transmi 10 ter with the corresponding cylinder of the receiver, a hydraulic accumulator, a double valve box including valves for connecting said accumulator with said two pipes respectively at a point in proximity with the corresponding transmitter cylinder and means whereby the rocking of the transmitter cross-beam round its pivot opens both valves when in its medial position of symmetry for restoring the receiver to its medial corresponding position through the balancing action of the accumulator on the fluid in the pipes, a second hydro-pneumatic accumulator at the receiver station, ducts adapted to provide for selective communication of the side of the receiver cylinders which does not communicate with the pipes from the transmitter, with the atmosphere and with said second accumulator, a distributing system including distributors controlling said ducts, branch pipes communicating with the said first mentioned pipes and controlling the distributors for closing at increasing pressures the communication between the ducts and the atmosphere and then connecting the ducts with the second accumulator for thereby furthering the movement of the receiver piston.

4. A hydraulic remote control system, including a transmitter and a receiving station each including a system embodying two similar cylinders and pistons slidable therein, a cross beam pivotally connected to each said two cylinder and piston systems and a pivot for said cross-beam located at equal distances from and outside the line connecting the connection points of said cross-beam with the cylinder and piston systems, pipes connecting each cylinder of the transmitter with the corresponding cylinder of the receiver, a hydraulic accumulator, a double valve box including valves for connecting said accumulator with said two pipes respectively at a point in proximity with the corresponding transmitter cylinder, means whereby the rocking of the transmitter cross-beam round its pivot opens both valves when in its medial position of symmetry for restoring the receiver into its medial corresponding position through the balancing action of the accumulator on the fluid in the pipes, a second hydropneumatic accumulator at the receiver station, branch pipes communicating with each receiver cylinder on the side thereof which is not fed by the pipe from the transmitter, a distributor for each receiver cylinder adapted to make the corresponding branch pipe communicate selectively with the atmosphere and with the second accumulator, and means whereby said distributors are submitted to the action of the transmitter station for controlling the connections of said branch pipes and amplifying thereby the efiort transmitted by the main pipes.

5. A hydraulic remote control system, including a transmitter and a receiving station each including a system embodying two similar cylinders and pistons slidable therein, a cross beam pivotally connected to said two cylinder and piston systems and a pivot for said cross-beam located at equal distances from and outside the line connecting the connection points of said cross-beam with the cylinder and piston systems, pipes connecting each cylinder of the transmitter with the corresponding cylinder of the receiver, a hydraulic accumulator, a double valve box including valves for connecting said accumulator with said two pipes respectively at a point in proximity with the corresponding transmitter cylinder, means whereby the rocking of the transmitter cross-beam round its pivot opens both valves when in its medial position of symmetry for restoring the receiver into its medial corresponding position through the balancing action of the accumulator on the fluid in the pipes, a second hydro-pneumatic accumulator at the receiver station, branch pipes communicating with each receiver cylinder on the side thereof which is not fed by the pipe from the transmitter, a distributor for each receiver cylinder, adapted to make the corresponding branch pipe communicate selectively with the atmosphere and with the sec ond accumulator, and-a further branch pipe connecting the main pipe communicating with one cylinder at the receiver station with the distributor corresponding to the-other for urging same in the direction closing communication between its first mentioned branch pipe and the atmosphere and opening it into the second accumulator.

6. A hydraulic remote control system including a transmitter station and a receiving station, each station including hydraulic groups respectively comprising cylinders and pistons associated therewith, a cross beam at each station, means pivotally connecting the hydraulic groups at each station to the respective endsof the cross beam and means pivotally supporting the cross beams about an axis outside the line intersecting the axes of pivotation of the groups with respect to the ends of the beams, conduits connecting the cylinders of the respective groups, a hydropneumatic accumulator, valve controlled conduits providing for controlled communication between the accumulator and the hydraulic groups, valves in said conduits, and valve control means movable in response to the movement of the transmitter cross beam for opening the valves to permit fluid to pass from said accumulator to said hydraulic groups when the transmitter cross beam is in its median position thereby automatically restoring the receiver cross beam .to a corresponding median position.

*1 A hydraulic remote control system including a transmitter station and a receiver station, each station including a pair of associated cylinders and pistons and a cross beam, the pistons and cylinders being bodily pivoted to opposite ends of the cross beams at one end of the associated cylinders and pistons and means .at the opposite ends of the associated cylinders and pistons fixedly pivotally supporting the same, means fixedly pivotally supporting each cross beam for oscillation about an axis equidistant from and outside a line intersecting the pivotal connections between the respective associated pistons and cylinders and the said opposite ends of the cross beams, the cross beams having a neutral position where the opposite ends thereof lie in a horizontal plane and the disposition of the axes of pivotation between the cross beam ends and the associated pistons and cylinders and the axis of pivotation of the cross beams being such that when the cross beam is oscillated in either direction with respect to its neutral position an unbalanced eiiective lever arm length exists as between the opposite ends of the cross beam and the axis of pivotation or the cross beam, conduits connecting the cylinders of the respective groups, said conduits communicating with the cylinders at the transmitter station between the pistons and the cross beam and with the cylinders at the receiver station on the side of the piston remote from the cross beam, a hydropneumatic accumulator, additional conduits providing communication between said accumulator and said first- 12 mentioned conduits, valves controlling fiuid flow through said second-mentioned conduits, means urging said valves to closed position and means movable in response to the movement of said transmitter cross beam for opening said valves to provide fluid fiow'from said accumulator to said first-mentioned conduits, said last-mentioned means being operable when said cross beam is in its neutral position to permit the fluid flow from said accumulator into said first-menopening said valves includes a cam ring having oppositely arranged cam surfaces thereon disposed in alignment With one another and in parallelism with the line intersecting the axes of pivotation oi the associated pistons and cylinders of the transmitter station with respect to the cross beam ends and in which said valves includestems fixedly supported for sliding movement along a line parallel to said first mentioned line when the cross beam is in its neutral position, and said cam ring being movable with said cross beam and operative to open said valves only when said cross beam is in its neutral position.

9. A hydraulic remote control system as defined in and by claim 6 in which said valve control means includes a cam ring having oppositely arranged cam surfaces thereon disposed in alignment with one another and in parallelism with the line intersecting the axes of pivotation of the associated pistons and cylinders of the transmitter station with respect to the cross beam ends and in which said valves include stems fixedly supported for sliding movement along a line parallel to said first mentioned line when the cross beam is in its .eutral position, and said cam ring being movable with said cross beam and operative to open said valves only when said cross beam is in its neutral position.

10. A hydraulic remote control system as defined in and by claim 9 and additional conduits providing communication between said accumulator and the cylinders at said transmitter station on the side of said pistons opposite to the side communicating with said first-mentionecl conduits whereby fluid now from said accumulator automatically resets said transmitter cross beam to neutral position.

11. A hydraulic remote control system as de" fined in and by claim 6 in which said cylind are pivotally connected to the opposite ends of the cross beams and in which each piston of the respective groups includes a rod projecting through said cylinders, means fixedly pivotally supporting the projecting end of said rods, a second hydropneumatic accumulator, ranch conduits extending from said firstunentioned conduits, a distributor device in respective communication with each cylinder of the receiver group and said second accumulator, said branch conduits communicating with said distributor device, movable valve means in each distributor d said second accumulator whereby movement of 5 said transmitter cross beam applies a fluid impulse through the hydraulic groups at the transmitter station to the distributor devices to move the valves therein to provide fluid flow from said second accumulator to the cylinders of the groups at the receiver station in dependence upon the direction of oscillation of the transmitter cross beam whereby fluid flow from said second accumulator effects movement of said receiver cross beam corresponding to the movement of said transmitter cross beam.

RENE LUCIEN LEVY.

References Cited in the file of'this patent UNITED STATES PATENTS Number Number Name Date Greene Dec. 27, 1887 Paidassy May 23, 1897 Schoen Aug. 9, 1910 Williamson Jan. 23, 1917 McLeod Feb. 20, 1923 Sperry June 21, 1927 Ballard June 30, 1942 Ellinwood Aug. 21, 1945 FOREIGN PATENTS Country Date Great Britain June 10, 1940 Great Britain May 11, 1944

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