US2559588A - Tracking system and valve therefor - Google Patents

Description

E. A. BLUMENTHAL' TRACKING SYSTEM AND VALVE 'IHEREFOR July 10, 1951 2 Sheets-Sheet 1 Filed July 13, 1946 3 rworvtm', Emunuel Ablumenihn] y 10, 1951 E. A. .BLUMENTHAL I 2,559,588

TRACKING SYSTEM AND VALVE THEREFOR Filed July 13, 1946 I V 2 Sheets-Sheet 2 Patented July 10, 1951 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 20 Claims.

The invention described herein may be manuiactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

. In firing upon moving targets, it is customary to employ a computer or director into which a number of variables are introduced and from which the director computes and supplies output data including the angles. measured in vertical and horizontal planes, by which the gun should be in advance of, or lead, the line of sight to the target, in order to compensate for the travel of the target during the time the projectile is traveling from gun to target. This correction or lead. is of especially great importance in firing at high speed aircraft and tanks which may travel appreciable distances during the time of .fiight of the projectile.

Correct operation of the director requires the continuous determination of a line from director to target. This line may be determined by radar, direct sighting or sound locators. In a conventional director using direct sighting, two telescopes are employed. The telescopes are mounted with their optical axes parallel and at right angles to a normally horizontal axis about which they are rotatable as a unit. This axis is carried by the director housing which, in turn, is mounted for training about a normally vertical axis. The trainer's telescope has a hair extending vertically while the pointer's telescope has a horizontally-extending hair. A handwheel is located conveniently for operation by the trainer while looking through his telescope. This handfwheel is connected to rotate the director and telescopes as a unit about the vertical axis. Likewise a second handwheel is located convenient to the pointer while looking through his telescope. This second handwheel is connected to elevate the telescopes together about their common horizontal axis. Thus, in operation, the trainer operates his handwheel to maintain his vertical line of sight intersecting the target by rotation of the entire director and sights while the pointer keeps his horizontal hair line intersecting the target by operation of his handwheel. The two movements are thus introduced into the director where they are combined with other input values. such as range, to produce computed angular values of the elevation and azimuth of the gun necessary to hit the target at that particular instant. th'lthc foregoing procedure involves difficulties in i. It requires two men to do a job that should 2. In event one man becomes a casualty the weapon might become useless unless a substitute were available.

3. The accuracy of the angular values introduced will depend upon the skill of the leasttrained and least-able of the two trackers.

4. It is difiicult to get two trackers to operate in coordination at all times.

5. The necessity for two trackers increases the cost of equipment and the cost of training and maintaining each gun crew.

It is therefore an object of my invention to provide a tracking system in which one man may do the work requiring two persons in former systems, such as the one just described.

A further object is to provide a system wherein one man determines the relative values of the two mutually-normal components of motion of the line of sight to the target by an adjustment effected with one hand, determining the rates or absolute values of the motions by an adjustment or motion effected with the other hand.

A still further object is to provide a trackin system in which the relative values of the two, mutually-normal components of motion are determined by adjustment of a retlcle in the line of sight.

Another object is to provide a special type of distributing valve in which the flow of pressure fluid to two or more fluid motors or prime movers, may be positively and inversely controlled irrespective of the ratio of power required to be exerted by the respective motors.

A further object is to provide a distributing valve suitable for numerous industrial uses.

Another object is to provide a method of effecting resultant movement of an object in a desired direction and at a desired rate, from two angularly-reiated component movements, by operating two motors, each connected to effect a respective one of the aforesaid component movements, supplying pulses of fluid flow of varying ratio to vary the ratio of the rates of operation of the motors and, hence, the direction of said resultant movement, and varying the average pressure of said pulses and thus the volume of fluid conveyed by each pulse. to vary the rates of operation of the motors and the absolute value of the resultant movement.

Other objects and advantages will. become apparent as the description proceeds.

In the drawings,

Figure 1 is a diagrammatic view showing a sight. valve, pump, elevation and traversing I i l I the mechanical and hydraulic connections between the elements.

Figure 2 is a cross section of the valve, taken upon the line 2-2, Figure 3.

Figure 3 is a section upon the line 3-3, Figure 2; showing the principle upon which the valve optrated, this driving element is shown as a simple wheel having a handle 4 by which shaft 2 and the pump rotor may be turned manually. However, it is within the purview of my invention to drive shaft 2 by a variable-speed motor or other power means where the object to be controlled is of such a size as to require more power for moving the same than can be exerted by an operator. In such a case, the means for varying the speed of the motor, might be a rheostat, manually adjusted to thereby selectively control the motor speed and, hence, the maximum hydraulic pressure effective upon the motor or motors during a pulse.

Rotor shaft 2 extends from the other side of pump I, as indicated at 2', where it has a gear 5 fixed thereon. This gear meshes with a pinion 6 secured to the shaft 1 of a control sleeve 8 of a special valve, indicated generally at 9. This valve of the face adjacent cap II, as indicated at 4|, Figure 2. The end of rotor I5 adjacent cap I2, has a circular plate 42 secured thereto as by means of screws 43, only one of which is shown. This plate has circular ridges on one face adapted to fit within channels 24 and 25, respectively, to form fluid-tight passageways. A passageway 45 is formed in aligned openings in rotor I5 and plate 42, to place channel 24 in continuous communication with port 30. A second passageway 68 extends through plate 42 to place channel 25 in continuous communication with port 3|.

It will be noted from Figure 2, that the bottom surfaces of the cavities in caps II and I2 are provided with circular raceways which coact with opposed raceways in the end faces of sleeve 8, to form bearing surfaces for balls 32 and 33 journaling the sleeve for free and accurate rotation within casing I and about rotor I5. Spokes 2| connect shaft I and sleeve 8 for rotation as a unit. As more clearly shown at Figure 3, the sleeve has four diametrically opposite openings 46, 41, 48 and 49, through its wall which, in the position of the parts there shown, act to afford communication between ports 3| and 39 on the one hand, and 30 and 31 on the other. In the model illustrated openings 46 to 49, inc., each 'subtend an angle of about 30 at the center of rotor I and are equally spaced. These dimensions may be varied somewhat without mate-- rially affecting the principle upon which the valve operates. Assuming that sleeve 8 is rotating, it will be noted that it acts four times in each revolution to place ports 30 and 3| in communication with ports 31 and 39 and that, by rotation of rotor or distributor I5, the sleeve is effective to place port 30 selectively into communication with any consecutive pair of ports comprises a casing I0 having a generalcyllndrical chamber 36, Figure 3, having four equally spaced wall portions cut away to form ports 31,

38, 39 and 40, respectively. In the model shown, each port extends for about 60 about the inner face of chamber 36 and extends axially through the two end faces of the casing.

One end face of casing I0 is closed by a cap II secured thereto. This cap has a cavity to receive an antifriction bearing I3 journaling shaft I and a second and larger cylindrical cavity 22, concentric of shaft I. The reduced end 20 of shaft I'acts through an antifriction bearing I9 to journal the adjacent end of valve rotor I5 whose construction and function will be subsequently described.

The other end face of easing I0 is closed by a cap I2 bolted or otherwise secured thereto. This cap is provided On its inner face with a cylindrical cavity having a pair of channels 24 and 25, concentric of the axis 44 of shaft I. Channel 24 communicates with a passageway 26 in cap I2 and having an external nipple for connection with a pressure line 21. Channel 25 communicates with a passageway 28 in cap I2, and having an external nipple for connection with a suction line 29. Cap I2 also has a central bore adapted to journal an extension stud I6, integral with rotor l5. The outer end of this bore is enlarged to accommodate a packing gland II.

As best shown at Figure 3, rotor I5 has an outer, generally cylindrical surface provided with a pair of diametrically opposite chambers or ports 30 and 3I. Each port has about the same angular extent as the ports 31 to 49, inclusive. These ports extend through the face of the rotor adjacent cap I2 but stop short 31 to 40, inclusive, while at the same time, placing theremaining pair of ports 3! to 40, inclusive, into communication with selector port 3I. A knob 54' and gear 55 are fixed to the outer end of extension I6 for rotation for effecting adjustment of distributor I5.

At 50, Figure 1, I have shown a hydraulic elevating motor of any suitable type, and having a rotor shaft 5| with an emergency handwheel 52 secured to one end, and a pinion 53 attached to the other end. It will be understood that this pinion is intended to mesh with the elevating gear of a gun, not shown. For example, it may mesh directly with an elevating gear sector concentric of the trunnion axis of the gun so that, when motor is driven in one direction or the other, a corresponding change in elevation of the gun is effected. A hydraulicline 55' is in communication with port 40 and extends therefrom to one port of motor 50. In a likemannena line 56 is in communication with port '38 and ex'tends therefrom to a second port of motor 50. In a known manner, motor 50 rotates in onedirection when fluid under pressure is supplied over line 1 55 and exhausted over line 56, and-in theoppo I site direction when fluid under pressureis sup- 1; plied over line 56 and exhausted through 55'. A traversing motor 5'I.-has a. -s'haft1 58 to one end of which is' fixed a'n emergencyhandwheel 59. A pinion 59' i fixed-toitlie other end of sh aft 58 and is adapted to meshflwith andldrive thetraversing gear train of the gun. For example, motor 51 may be mounted upon the-ripper-car riage of the gun in a position such that pinion 59 meshes with a fixed rin gear so that, as the motor rotatcs,-the gunis traversed. A pressure line I 60 communicates with port 31 and "extends to one port of motor 51 siinilarly anotherfline 6| places port .39 incom'munication with other portof motor 1';- A sighting .device'ln the io'rmof a elcscope is shown at 62, mounted in a sleeve 64 for rotation about an axis 63 coincident with its optical axis. Sleeve 64 is shown as carried by a support 65 rigidly connected with valve 9. A gear 66 is fixed to telescope 62, concentric of axis 63. Gears 55 and 66 have equal pitch diameters and both mesh with an idler gear 61 journaled upon sup port 65. Gears 55 and 66 are thus connected for synchronous rotation in the same direction. Telescope 52 ha a reticle, in the form of an arrow 59 extending diametrically across the field of view. This reticle, of course, rotates with the telescope as the latter turns in sleeve 64. In the explanation of the operation following, it will be assumed that lines 55, 56, 60 and SI are flexible and that the pump, valve, and telescope are connected for movement with the gun, as, for example, by being mounted upon or carried by the gun cradle.

' Operation In use; the operator grasps knob 54 with one .hand, and handle 4 with the other, while lookthrough telescope 52. Turning of handle 4 drives pump I and simultaneously rotates sleeve 8 at a much higher speed because of the geared connection 5, 6. The pump then supplies fluid under pressure to port 30 by way of line 21, passageway 26, channel 24 and passageway 45, while acting to exhaust fluid from port 3| by way of passageway 68, channel 25, passageway 28 and line 29.

For convenience and clarity of explanation, the connection effected by gears 55, 66 and 61, between distributor I5 and telescope reticle 69 is shown as operating to maintain a median line through ports 30 and 3I parallel to-reticle 69. This median line is indicated at 10, Figure 4 so that as rotor I5 is turned it reciprocally varies the rates of fluid flow to the two motors 50 and 51 and hence the relative rates at which these motors rotate. Theoretically the rotor I5 alone might be sufficient to thus vary the rates of operation of the two motors. However, it must be remembered that there may be large differences in the work which the two motors may have to perform and that the torque which the two will have to exert are almost never equal. For example, it might require a great deal more work to elevate a gun through a given angle than to traverse it through an equal angle. sure port 30 were in simultaneous communication with, say, ports 31 and 40, substantially all of the fluid would flow to the motor required to exert the least torque while little or none would flow to the other motor.

The rotating sleeve 8 solves the problem discussed in the foregoing paragraph because, in the preferred form shown the openings 46 to 49 through the wall of sleeve-8 have substantially the same angular extent as the solid portions or lands of casing I between ports 31 to 40, e. g.,

30. Thus, no matter what angular position distributor I may have within and relativelyto casing III, pressure port '30 is never in communication with more than one of the ports 31 to 40, at the same time. As a result the'rotating sleeve is rapidly connected in succession with any two adjacent ports 3! to 40, and the pressure flows thereto in rapid pulses. to rotate the two motors in exact proportion to the areas of the two consecutive ports 31 to 40, covered by port Figures 4 to 8, inclusive, are presented to show and explain the function of the invention with distributor I5 In various positions of rotation rel- Thus, if pres- I atively to casing I0. Sleeve 8 is assumed to be rotating clockwise in all figures. In Figure 4 pressure port 30 is so adjusted as to embrace substantially equal areas of ports 31 to 48, while exhaust port 3I is similarly positioned with respect to ports 38 and 39. Sleeve 8 has just begun to connect ports 30 and, and ports 3| and 38. Fluid now flows through line 55' to motor 50 and returns by way of line 56, ports 38 and 3f to the suction side of the pump. Distributor I5 is assumed to be motionless at this time. As sleeve 8 continues to rotate the effective area of the passageway between ports 30 and 40 at first increases and then decreases to zero as the trailing edge of the opening in sleeve 8 passes the leading edge of port 40. A definite pulse or flow of fluid to motor 50 is thus produced t operate the same by a definite increment. At this time all flow to port 31 is cut ofi so that motor 51 is at rest.

At the instant that sleeve 8 cuts off flow between ports 30 and 49, and 3I and 38, it also acts to establish communication between ports 30 and 31 and 3| and 39. Motor 50 now stops and motor 51 starts and continues until the trailing edge of the opening in sleeve 8 passes the leading edge of port 30. Under this condition motor 51 is given an increment of motion equal to the motion just previously imparted to motor 50. These alternate pulses are repeated in an obvious manner, four times for each rotation of sleeve 8. Since the sleeve itself is being rotated relatively rapidly, the pulses follow each other in such rapid succession that the operation of the motors is substantially smooth and continuous. Nevertheless the pulses or increments of flow to the two motors are completely separate and distinct and, in the position of distributor I5 shown at Figure 4, the sum of the increments flow to the two motors, will be equal over any given period of time. Hence the rotations-of the two motors will be equal irrespective of possible differences in the torque which each is called upon to exert. In the position of the distributor shown at Figure 4, the hydraulic and mechanical connections are such that motor 50 will cause the gun to elevate, while motor 5'! will traverse it to the right. Thus the gun moves upwardly and to the right as viewed from the breech. In short, its resultant movement is substantially parallel to reticle 69.

The operation of the motors under the conditions depicted in Figures 5 to 8, inclusive, will now be clear. In Figure 5, distributor I5 is so adjusted that pressure port 30 is in exact agreement with port 31, while exhaust port 3I is in agreement with port 39. Under this adjustment, elevation motor 50 is completely cut off from pressure fluid and remains at rest, while traversing motor 51 operates to drive the gun to the right, as indicated by reticle 69.

In Figure 6, distributor I5 has been turned clockwise so that pressure port 30 subtends equal areas over ports. 31 and 38. Thus while meter 51 is still operating to traverse the gun to the right, fluid is now conveyed to motor over line 56, thereby causing it to rotate in a direction the reverse of that effected in Figure 4. As a result, the gun muzzle moves downwardly and to the right in accordance with the corresponding position of reticle 69.

' In Figure '7, rotor I5 has been moved clockwise from the position shown at Figure 6, so that.

while motor 50 continues to depress the gun, motor 51 has now been reversed and is traversing the gun to the left, so that the resultant angular 7. motion of the gun is substantially in the direccause the gun to traverse to the left and to move upwardly in correspondence with the direction indicated by telescope reticle 59.

The gun will be angularly moved at all times In accordance with the resultant of the component motions imparted by the two motors, and this resultant may have any direction, as determined by the rotational adjustment of rotor i and telescope reticle 69. Furthermore, the speed of rotation of the gun will, in each instance, be determined by the speed of rotation of the rotor of pump I. Thus, once the telescope isdirccted upon a target, it may be tracked merely by adjustment of knob 54 until reticle G9 is parallel to the apparent path of the target, while handle I is turned at the rate necessary to maintain the optical axis directed upon the target. Furthermore. for each steady state of tracking, the rates of actuation of motors 50 and 51 will be proportional to the corresponding vertical and horizontal components of motion of the craft and may be used to determine the proper angles by which the gun should lead the line of sight to compensate for the travel of the target during the time of flight of the projectile, as by introduction 0! said rates into a standard gun fire director.

While I have shown and described my invention in connection with the tracking of a moving target, it will be understood that this is by way of example only and that the system is of wide utility where the rates of rotations of two power sources or motors is to be varied to cause an element to traverse a predetermined path in an exact and precise manner and irrespective of the relative sizes of the load which the two motors must overcome. Examples of possible uses are i a) a sine-cosine integrators in calculating and navigational instruments, (b) a motion regulator for various types of machine tools, such as milling machines, (0) high torque variable speed drives, (d) torque amplifiers, (e) gyroscopically controlled stabilizers for use on air and water craft; and many others. In fact, the invention may find use whenever two component motions.

angular or translational, are to be combined in a precise and accurate relation, to afi'ord a resultant motion having a desired direction and absolute value. While I have shown pump i as hand operated, it will be obvious that it may be power driven. Sleeve 8 may also be power driven in such a construction, the operator might then control knob 54 with one hand, and a throttling valve with the other, connected in pressure line 21 to vary the pressure within chamber 33 as desired.

The foregoing disclosure is to be taken in an 51- lustrative rather than a limiting sense and it is my desre to rescrve all such modifications and substitutions of equivalents, as fall within the Scope of the subjoined claims.

Having now fully disclosed the invention, what i claim and desire to secure by Letters Patent is:

l. The herein described method of controlling it pair of hydraulic motors operable to move an object in two angularly-related directions respecp i g, applying discrete pulses of mild p dly and successively to said motors to operate the same, inversely varying the time period or alternate pulses to vary the ratio of the i l i p eds of said motors, and varying the applied fluid pressure to correspondingly vary the absolute values of said speeds.

2. That method of controlling the direction and rate of resultant movement of an object connected to be driven in two angularly-related component directions by respective first and second fluid pressure actuated motors, comprising, consecutively. and in rapid succession sup plying discrete pulses of fluid flow to said motors from a common source of fluid under pressure, to simultaneously drive said motors, varying the ratio of the times of consecutive pulses to inversely vary the ratio of the speeds of said motors and the direction of said resultant movement, and varying the pressure applied to said motors by said pulses to correspondingly vary the absolute rates of operation of said motors and the rate of said resultant movement.

3. That method of eflecting resultant movement of an object as a result of two component movements in angularly-related directions each component being effected by respective ones of a pair of hydraulic motors, comprising, supplying discrete pulses of flow of fluid from a source of fluid under pressure to said motors to thereby drive the same, varying the ratio of the times of flow of the increments to the respective motors to thereby correspondingly vary the ratio of the integrated movements of said motors and the direction of said resultant movement, and varying the average pressure of said pulses to thereby correspondingly vary the absolute values of said integrated movements and said resultant movement.

4. The method of controlling the direction and rate of resultant movement of an object connected to be driven in two mutually-normal 'component directions by respective first and second fluid pressure operated motors, comprising, supplying first discrete pulses of fluid flow to said first motor, supplying second discrete pulses of fluid flow to said second motor alternating with said first pulses, each two consecutive pulses forming a pair, varying the ratio of the times of the pulses forming a pair to thereby correspondingly vary the ratio of the rates of operation of said motors, and the direction of said resultant movement, and varying the average pressure of said pulses to correspondingly vary the absolute rates of operation of said motors and the absolute rate of said resultant movement.

5. The method recited by claim 4, all said pulses being supplied from a common source of fluid under pressure.

6. That method of efl'ecting resultant movement of an object from two angularly-related component movements, each said component being effected by a respective one of a pair of fluid pressure operated motors, comprising, supplying discrete increments of flow of fiuid from a source of fluid under pressure to said motors to thereby drive the same, varying the ratio of the duration of flow of the increments to the respective motors to thereby correspondingly vary the ratio of the integrated movements of said motors and the direction of said resultant movement, and varying the pressure applied by said source to thereby correspondingly vary the absolute values of said integrated movements and said resultant movement.

7. In a system for controlling the direction and rate of motion of an object movable in two angularly related directions, first and second variable speed motors each connected to so move said object in a respective direction,- a single source of fluid under variable pressure, and valve means operable to alternatively and successively connect and disconnect said source with said motors to drive said motors by a series of equally timed discrete impulses of pressure fluid.

8. In a system for controlling the direction and rate of motion of an object mounted for movement in two angularly-related directions, first and second fluid pressure variable speed power means connected to move said object in said directions, respectively, a source of fluid under pressure, connections between said source and 'motors and including a single valve having a continuously movable element adapted to connect and disconnect said source with each said motor alternatively and in succession.

9. In a system for controlably moving an object in two angularly-related directions, first and second motors connected to move said object in said directions, respectively, a valve having first and second out et ports and a single inlet port, said valve including a rotatable element adapted to connect said inlet port with said outlet ports in succession, whereby to alternatively drive said motors in alternative increments, pump means connected to supply fluid under pressure to said inlet port, and a single means connected to drive said pump means and simultaneously rapidly rotate said rotatable valve element.

10. A valve for controlling an object connected for movement in two mutually-normal directions by first and second motor means, respectively, a casing having a pair of outlet ports, a distributor rotatable in said casing and having a pressure port rotatable into agreement with either or both said outlet ports, and a sleeve rotatable within said casing between said outlet ports on the one hand and said pressure port on the other hand and having an opening adapted successively to connect said pressure port with either of said outlet ports, rapidly and in succession.

11. In a valve, a casing having first and second pairs of internal ports all said ports being equally spaced about the wall of said casing, the ports of each pair being diametrically disposed, said casing forming solid wall portions between said ports, a distributor rotatable within said casing and having diametrically opposed pressure and exhaust chambers, each of said chambers having a passageway adapted to communicate with a region of high pressure and a region of low pressure, each said chamber being constructed and arranged as to be brought into radial agreement with any one of said ports or any successive pair of said ports by adjustment of said distributor, a sleeve rotatably interposed in fluid-tight relation between said distributor and the wall portions of. said casing, there being four equallyspuced openings in said sleeve, each opening havlllH nnnngular extent not greater than said solid wall portions whereby on rotation of said sleeve, two consecutive ports may be successively connected with said pressure chamber while the remaining ports are simultaneously connected with said exhaust chamber and means to continuou ly eilect rotation of said sleeve.

ill. in a valve, a casing having a surface provided with two pairs of ports cireumferentiallyr, urml about an axis, the ports of each pair being- (iinu'u-trleally opposite, a distributor mounted for loiuilen about said axis and having a pair of diumcirical y-opposite chambers, each adapted. 011 i t'ltlillllil adjustment of said distributor, to exl ud over any one of said ports, or to subtend fl hrocallywnrying areas of consecutive ports. ouch oi said chambers having a passageway re-- spectively adapted to communicate with a region of high pressure and a region of low pressure, an element positioned between said ports and chambers and rotatable to periodically place each chamber successively in communication with the port or ports subtended thereby and means to continuously rotate said element.

13. In a valve, a casing having a cylindrical cavity, there being a pair of peripherally-spaced pressure ports opening through the interior wall of said cavity, a sleeve rotatably fitting said cavity and having an opening through its wall with a circumferential extent not greater than the space between said ports, and a distributor rotatably fitting said sleeve and having a fluid supply port constructed and arranged to progressively cover one said port and simultaneously progressively uncover the other said port "in response to rotational adjustment of said distributor, whereby, on continuous rotation of said sleeve, said supply port is successively connected with said pressure ports to supply increments of fluid flow thereto having reciprocally varying time integrals in accordance with the rotationally adjusted position of said distributor.

14. A valve comprising a casing having a chamber with a generally cylindrical wall and two pairs of circumferentially-spaced ports in said wall, the ports of each pair being diametrically opposite, a sleeve rotatably fitting said chamber and having at least one opening adapt ed to communicate in succession with each said port on rotation of said sleeve, the peripheral extent of said opening being substantially equal to the lands between successive ports, a distributor fitting said sleeve and having a pair of diametrically opposite chambers, positioned for rotational adjustment and constructed and arranged to progressively cover one said port and simultaneously to progressively uncover the next adjacent port, means for conducting fluid under pressure to one chamber, means for conducting fluid from the opposite chamber, means for continuously rotating said sleeve, and means for rotatably adjusting said distributor, whereby rapidly succeeding pulses of pressure may be applied to any one port or, in varying time duration, to any two consecutive ports, a pair of motor means, and respective fluid pressure connections each including a motor means and a pair of ports, in series.

15. In a system for tracking a moving target, means adapted to establish a line between said means and target and including a reticljjxtending transversely of and rotatable about said line as an axis into parallelism with the apparent course of a target being tracked, a pair of reversible motors, each motor being operable to rotate said means about a respective one of a pair of mutually-normal axes, a valve having two pairs of pressure ports, theports of each pair being connected to supply fluid under pressure to drive a respective motor in a respective one of two opposite directions of rotation, said valve including a distributor rotatable to direct pressure fluid from a source to any two ports in succession, and to exhaust fluid from the two remaining ports. and means connecting said reticle and distributor for synchronous rotational adjustment.

16. In a control system for an object to be moved in two angularly-related directions to traverse a desired path, a pair of motors each adapted to move said object in a respective one of said directions, a pump, and pressure fluid connections between said pump and motors in- 11 eluding a valve selectively operable to supply discrete pressure pulses from said pump to said motors in rapid succession and to reciprocably vary the duration of successive pulses to said motors.

17. The combination recited in claim 16, and means for varying the maximum pressure of said pulses.

18. A valve comprising a first surface having first and second spaced discharge ports therein. a distributor having a second surface in parallel with said first surface and provided with a supply port, said distributor being movable relatively to said first surface, said supply port being constructed and arranged to progressively uncover one said discharge port and simultaneously to progressively cover the other discharge port, a control element movably interposed between said first and second surfaces, said element having a passageway which, in response to movement of said element, periodically places said supply port in communication with one or both of said discharge ports, in accordance with the adjusted position of said distributor, means adapted to connect said supply port with a source of pressure fluid, and means operable to continuously mov said control element.

19. In a valve, casing means forming a cylindrical surface provided with two discharge ports spaced about the axis of said surface, a distribu' tor rotatable about said axis relatively to said casing means and having a supply port constructed and arranged to progressively uncover one said discharge port and simultaneously progressively cover the other said discharge port, in response to relative rotational adjustment between said casing means and distributor, means adapted to connect said supply port with a source of fluid pressure, a sleeve rotatably interposed between said cylindrical surface and said distributor, said sleeve having an opening through its wall not greater in angular extent than the angular spacing between said discharge ports, relative rotation between said casing means and distributor, on the one hand, and said sleeve on the other hand, acting to supply increments of fluid flow from said supply port to said discharge ports having reciprocably-varying integrals with respect to time.

20. In a system for tracking a moving target, a sight-line device having a reticle extending transversely of the line of sight and rotatable about said line as an axis, into parallelism with the apparent path of a target, a pair of reversible fluid motors, each motor being operable to rotate said sight-line device about a respective one of a pair of mutually-normal axes, a valve casing forming a cylindrical chamber, there being four valve ports equally angularly spaced about the axis of said chamber opening through the wall of said chamber, each two diametrically opposite ports forming a pair, fluid connections between the ports of each said pair and a respective motor, a distributor rotatable in said chamber and having two diametrically opposite outwardly directed openings, each opening having an angular extent about said axis, greater than the angular spacing between adjacent edges of said ports, and a sleeve rotatable in said chamber about said axis, between said ports and openings, said sleeve having a passageway operable, on rotation of said sleeve, to provide for passage of fluid from an opening to any two consecutive ports, and pressure and exhaust connections to said openings, respectively, from a source external of said casing.

EMANUEL A. BLUMENTHAL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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