US2948193A

US2948193A - Alternating pulse servo system

Info

Publication number: US2948193A
Application number: US378696A
Authority: US
Inventors: Leathers Ward; Frank J Furman; Hugo A Panissidi
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1953-09-08
Filing date: 1953-09-08
Publication date: 1960-08-09
Anticipated expiration: 1977-08-09

Description

9, 1960 w. LEATHERS EI'AL 2,948,193

ALTERNATING PULSE SERVO SYSTEM Filed Sept. 8, 1953 6 Sheets-Sheet 1 ELEvATION sERvO MECHANISM TRAv RsE sERvO MECHANISM 12 6 6 17 r ELEVATION TANK TRAVERSE CTRLHANDLE ENGINE CTRL.HANDLE 7 I O PCK FF PICKOFF ALT. PULSE ALT. PULSE I 1I/ GENERATOR GENERATOR PRI. VALVE PRI. vALvE CONTROL HYDRAULIC CONTROL UNIT POWER UNIT 1 r 1 SUPPLY L8 I 8 SEC. VALVE i sEC. VALVE I l a 5 3 a N0 o MANUAL" BACK I HYDRAULIC g L MOTOR LL sELEcTOR \9 VALVE GEAR BOX T s ELEVATION NO I 3 CYLINDER MANUAL BACK I TURRET 10 10 f GUN b III } INVENTORS WARD LEATHERS FRANK J. FURMAN HUGO A.PANISSIDI ATTORNEY HUGO A. PANISSIDI 7 EA) M ATTORNEY ALTERNATING PULSE SERVO SYSTEM Aug. 9, 1960 Filed Sept. 8, 195a Aug. 9, 1960 Filed Sept. 8, 1953 w. LEATHERS ETAL ALTERNATING PULSE SERVO SYSTEM 6 Sheets-Sheet 3 FIG. 3

RESERVOIR I N I E NTORS WARD LEATHERS FRANK J. FURMAN HUGO A PANISSlD! NMX M ATTORNEY Aug. 9, 1960 w. LEATHERS EIAL 4 ALTERNATING PULSE SERVO SYSTEM Filed Sept. 8, 1953 6 Sheets-Sheet 4 1 NIE N TORS WARD LEATHERS FRANK J. FURMAN HUGO A. PANISSIDI BY VYX M A TTOR NE Y Aug. 9, 1960 I w. LEATHERS ETAL 2,948,193

ALTERNATING PULSE SERVO SYSTEM Filed Sept. 8, 1953 e Sheets-Sheet 5 1N VE N TORS WARD LEATHERS FRANK J. FURMAN 359 HUGO A. PANISSIDI 358 J BYE-# 4) ATTORNEY Aug. 9, 1960 W. LEATHERS ETAL ALTERNATING PULSE SERVO SYSTEM Filed Sept. 8, 1953 6 Sheets-Sheet 6 IN V EN TORS.

WARD LEATHERS FRANK J. FURMAN HUGO A. PANISSIDI ATTORNEY Patented Aug. 9, 1960 2,948,193 ALTERNATIN G PULSE SERVO SYSTEM Ward Leathers, Brooklyn, Frank J. Furman, Endicott, and

Hugo A. Panissidi, Binghamton, N.Y., assignors to International Business Machines Corporation, NewYorlr, N.Y., a corporation of New York- Filed Sept. 8, 1953, Ser. No. 378,696

Claims. (CI. 89-41) This invention deals with an improved gun stabilization and control system of the hydraulic type with automatic electric control of the hydraulic system as well as a manual control system.

More specifically, this application is a continuation in part of application, Ser. No. 284,606, filed April 26, 1952, and assigned to the United States of America.

An object of this invention is to provide an improved gun stabilization and control system for use with a gun mounted on a moving vehicle, such as a tank.

Another object is to provide a control system for a gun, which system has safety features to guard against damage to personnel as well as damage to the mechanism.

A further object of this invention is to provide an electric control circuit which has elements that cooperate with hydraulic elements of the gun stabilization and control system to produce a superior system which is best adapted to control a, turret mounted gun on an armored vehicle such as a tank.

These and other objects will appear more fully in the detailed description which follows, and in the drawings in which:

Fig. 1 is a block diagram of the complete traverse and elevation servo control systems of this invention showing the functional relationship of all the elements involved;

Fig. 2 is a schematic diagram showing the physical relation of the elements, especially the gyroscopes and the gun, to clarify the embodiments of the differential mechanism of each servo system;

Fig. 3 is a schematic diagram of the hydraulic supply system located in the hull of the tank for the improved control system of this invention;

Figs. 4a and 4b together constitute a schematic layout ofthe improved system of this invention located in the turret;

Fig. 5 is an electrical circuit diagram of the electric control system of this invention; and

Fig. 6 is an enlarged detail showing the hydraluic no-back device in proper proportions.

The basic elements of the system of this invention are best explained with reference to a block diagram such as that illustrated in Fig. 1. The system includes three :basic functions, namely; onegun stabilization and tracking by means of two

independent servo mechanisms

1 and 2; two-manual gun control whereby the gun may be positioned in either the elevation or traverse plane by :hand driven mechanisms 3 and 4; threetravel lock "whereby the gun and turret will be automatically locked to the tank hull when the stabilizer or hand driven mechanisms are not in use, such travel lock being accomplished by no-backs 5, used in conjunction with the hand driven mechanisms 3 and 4. r p In order to stabilize the gun in both the elevation and traverse planes with respect to a celestial line of reference, it requires two

independent servo mechanisms

1 and 2 as shown in Fig. 1, each servo system comprising agyroscope 6 to establisha mechanical celestial line of ranged to either reposition the gun at a relatively slow reference, a sensing device 7 for the servo mechanism to detect any angular variations from the gyroscopic line of reference, a controlling unit 8 which controls power to a prime mover as a function of these angular variations, and finally a follow-up 9 from the load 10 of the prime mover to the sensing device 7 through a mechanical differential 11 to complete the servo loop. The other input to the mechanical diiferential 11 is from the gunners or commanders tracking handles, 12.

The purpose of the stabilizer and tracking systems is to keep the gun stabilized with respect to the gyroscopic line of reference regardless of vehicle motion over reasonably rough terrain and at the same time allow the gunner or commander to vary the position-of the sensing mechanism 7 with respect to the gyroscopic line of reference in order to track the gun with a moving target or correct for parallax or position the gun to a new target ly in traverse, it becomes impossible to maintain any good accuracy of fire while the tank is in motion. This is true of a target which is stationary and doubly true when a target is also in motion.

, Stabilization of a gun in a moving vehicle is possible only when the system employs a celestial line of reference, i.e., maintains the orientation of the gun constant with respect to space.

When a tank is traveling in some line other than directly toward the target then parallax will be introduced, therefore, some provision must be made for manually operating the power control to track the gun in both elevation and traverse to effect correction for deviation introduced by parallax. Another reason for being able to reposition the gun by tracking is that often the target itself may also be moving. Also, it may be desired to change from one target to another which may be at a considerably different elevation or angle of traverse from the initial target. These various conditions dictate that supplemental manual power controls be provided to enable the gunner to rapidly reposition (or track) the either in elevation orv traverse or both. Such tracking controls are also aror at relatively more rapid rate depending upon the extent of manual adjustment. As will appear in the detailed description of the system, such tracking control is intro duced by manual control handles in conjunction with electric motors, for repositioning the pick-off mechanism of the gyroscopes which are maintaining the gun stabilized about the two axes mentioned, i.e., in traverse or azimuth and in elevation.

There are two separate servomechanisms involved, one of which controls the position of a gun in elevation and the other controls a turret which positions the gun in traverse. Generally, each servomechanism comprises a pick-01f mechanism providing alternate timed pulses, the timed duration of which is determined in accordance with the deviation of the position of the gun from the gyroscopic line of reference. The alternating pulses vary in time duration and are complementary to one another, i.e., as one pulse increases in time duration, the opposite and next succeeding pulse decreases proportionately in time duration.

These pulses are directed to a controlling unit which generally comprises an electrodynamically actuated primary valve converting the electrical pulses into correspond ing hydraulic pulses. These hydraulic pulses arein turn The result is that,.if the gun. which is carried by the tank is not well stabilized, especialamplified by a secondary valve structure which is actuated by the hydraulic pulses from the primary valve.

The amplified hydraulic pulses, which are alternating in character and variable in time-duration as a function of angular error of the gun with respect to the gyroscopic line of reference, are. applied to a hydraulic prime mover which serves to actuate or stabilize the or turret.

A follow-up device is provided to link the gun with the pick-off mechanism through a differential. The other input to the differential is provided from the control handles. Consequently, aiming of the may be cornpletely controlled in both elevation and traverse. Since the gun may be mounted in abalaneed state, itselev ation position may be controlledby asingle hyd aulic cylinder and piston, whereasflto control the turret in traverse involves the moving of the turret itself and also the gun which is mountedon the turret. Naturally, the turret will be mounted in' good anti-friction bearings,'but the great mass involved in these very heavy parts means that a heavy duty drive mechanismis necessary to control the turret in traverse. i

Fig, 2 shows schematically the relationsof the various elements of the two servo systems involved. An important feature in the understanding of the operation of these servo systems is the differential, which in fact is the means by which tracking is superimposed upon mere stabilization control. Any suitable mechanical differential means might be employed but a very simple and reliable one has been used, which eliminates any need for a remote connection between the gun and the pick-off mechanisms elements. This means used is simply that of mounting each of the two gyroscopes directly on the gun with its stable axis properly aligned for stabilizing about the elevation and traverse axes. For example, note the elevation gyroscope unit 370-which is mounted on the side of the gun 44. The gym unit 370 has a turntable 265 which has the gyroscope and its related pick-off elements mounted thereon. The details of these elements have been described with more particularity in application, Serial No. 284,606, previously referred to. It is suificient to point out here that the gyroscope acts to hold a pickoff contact (not shown) in a constant position relative to space. Therefore, if the turntable 265 is rotated about its axis (which is parallel to the trunnion axis of the gun) an error signal will be introduced into the elevation servo system and correction for this error will be made by the elevation cylinder 43. Now attention is directed to the fact that turntable 265 may be rotated in two ways; oneby rotation of the gun aboutits trunnions which carries the whole gyro unit 370 and turntable 265 contained therein withit; and two-by rotation of-the turntable alone by means of a turntable motor 137 which is mounted on the gun with gyro unit 370. It is these wo ways of rotatin. the turntable which constitute the two inputs of a differential, the output of which is the rotation or non-rotation of turntable 265. By way of illustration of the differential action, suppose turntable motor 137 is energized and so the turntable 265 is rotated. An error signal will be set up by the pick-off elements in a known manner such as that described in the aforementioned application, Ser. No. 284,606, and so the gun will be rotated about its trunnion axis by the cylinder 43. This rotation of the gun will be in the opposite direction from that taken by the turntable 265 and will tend to return the turntable to its original position or at least stop its initial rotation so that the gun will continue to rotate as long as the turntable 265 is being driven by its motor 137. This is the situation when tracking is being introduced. When stabilization alone is being effected, rotation-of th gun about its trunnion axis will rotate the turntable 265 with it, and this will cause an error signal to be set up as before. In this case, the error signal will cause the servo systern (by-nieans of the cylinder 43) to return the gun to its original stabilized position as determined by the gyro maintained position of the turntable 265.

The same action takes place about the traverse axis 373 anda pair. of pinions 374 to an internal ring gear 47 located on the hull of the tank. In this manner.

360 of rotation in traverse, may behadl.

In Figs. 3, 4a and 41 there is shown the system according to this invention whieh emhodies some 1mproved elements but which employs the same basic alternate timed pulse stabilization and control system, as that disclosed in application Ser. No. 284,606 mentioned above, but which is not per se involved in this invention. To describe this system we may begin with a description of the hydraulic pressure supplysystem as illustrated in Fig. 3. An engine 280; is the main engine for driving the tank. It has a take-off to a hydraulic fluid pump 281 by means of a clutch 282. This clutch may be any desired type which is adapted to be operated hydraulically. Apreferred type of clutch is that shown which consists of the ordinary disc type Clutch. Ithas a drum member 233 which is driven by a shaft 284 taken from the tank engine 280. The drum member 283 is carried in bearings as shown and carries with it two discs 285 and 286. These discs are splined to drum member ZSS for positive rotation therewith. A third disc member 287 is splined to an output shaft 288 of the clutch. The shaft 283 is carried in appropriate bearings as shown and is coupled to the hydraulic pump in an appropriate manner. The clutch 282 is actuated by means of an annular ring type piston 289 which is carried in an annulus 290 and may slide laterally therein. The ring 289 carries appropriate seals as illustrated and is actuated to slide laterally by means of hydraulic fluid introduced through hydraulic pipe 305. When hydraulic pressure is introduced into the annulus 290 from hydraulic pipe 305, ring 289 is forced to the right as shown in Fig. 3 and, therefore, applies lateral pressure by means of bearings 306 to the

discs

286, 287 and 285. Such lateral pressure on the discs forces them into frictional engagement since they may slide laterally on their splines, and such frictional engagement produces a direct coupling from engine shaft 28,4 to clutch output shaft 288 in the ordinary manner of a disc type clutch.

Operation of the clutch is controlled by means of an electrically actuated hydraulic valve 307. This valve consists of a ball 308 which is spring biased into the position shown by means of a rod 309 and a spring 325. There is a guide (not shown) to keep the ball in line with the rod. When the ball is held in the position shown, it closes hydraulic input pipe 326 which is connected to the main pressure line 338 of the hydraulic system. Under such conditions, no hydraulic pressure is applied via pipe 305 to annulus 290 for operation of the clutch and therefore the clutch is allowed to remain disengaged, In order to engage the clutch, there is a solenoid 327 which actuates an armature 328 carried by the rod 300. When the solenoid 327' is energized, it draws armature 328 to the right against the spring pressure of spring 325, and at the same time draws rod 309 to the right allowing ball 308 to be unseated and seated again on the aperture 329 to cause the fluid pressure to be applied directly to hydraulic pipe 305. and thence to annulus 290 and so actuate the clutch. Solenoid 327 is actuated by means to be laterdescribed so that the, clutch may be actuated at appropriate times. The main purpose for having the clutch is to allow starting of the engine without the extra load of the hydraulic pump. Furthermore, this arrangement avoids driving the pump when dry (because no hydraulic pressure would then be available to actuate the clutch 282) which would be very injurious-to the pump. There is a hydraulic pipe 330 which is connected to the inside of valve 307 asshown in order to bleed ofl hydraulic pressure from the clutch whenever ball 308 is seated against the inlet from pressure pipe 326. The remainder of the hydraulic system shown is conventional. Pump 281 receives hydraulic fluid from a reservoir 331 by means of hydraulic pipe 332 and forces hydraulic fluid under pressure out through hydraulic pipe 333 and a filter shown to a check valve 334 and then to a pressure regulator 335. The pressure regulator has connections in the conventional manner to pressure and return by means of

hydraulic pipes

336 and 337 respectively. Pressure pipe 338 leading from the pressure regulator joins pipe 339 which is connected to a hydraulic slip ring device 271, the lower portion of which is here illustrated. There is an accumulator 363 which is connected to the pressure side of the system in conventional manner. There is a relief valve 364 connected across from pressure to return as illustrated. Hydraulic fluid return comes from slip ring device 271 to hydraulic pipe 365, which leads to the reservoir 331 as illustrated. There is an oil-level-temperature switch 376 located in the reservoir 331; The function of this oil-level-temperature switch in the system is as the name implies and will be explained more fully in connection with the electrical circuit diagram of Fig. 5.

The remaining portion of the hydraulic system is shown in Figs. 4a and 4b. Fluid under pressure is 'introduced from pressure pipe 339 (Fig; 3) to hydraulic slip ring device 271 (Fig. 4a). Fluid is then carried through and sent to hydraulic pipe 272 under pressure as deter-- mined by the system pump 281 (Fig. 3) which is located in the hull. Pipe 272 leads to a shut-off valve 273 which energizes the whole control system when it is open.

Shut-01f valve 273 is controlled electrically from control box 274 by means of a solenoid 275. It may be observed that main valve core 276 is controlled by a differential of hydraulic forces. Its operation will be clear upon inspection of the drawing when it is pointed out that when the solenoid 275 is energized, the combination armature and rod 277 will push the ball 279 from a'return valve seat 279a (as shown) to a pressure seat 27%. This then cuts off system pressure from the backor large area piston integral with valve core 276, so that systempressure opens the valve and holds it open. If, however, the solenoid 275 is deenergized, the ball 279 is allowed to rise off its pressure seat 27% and to seat itself on the return seat 2790:, as shown, with the aid of a spring 275a; and then system pressure will be introduced into the auxiliary passage so that the large area piston shown will force the valve core to the left, as shown, and close the valve shutting olf the system pressure at this point.

With shut-off valve 273 energized, hydraulic fluid under pressure is introduced in pipe 291 and so carried to pipe 292. This pipe 292 has a filter 293 for the traverse control system which is illustrated in Fig. 4a. On the other side of filter 293, hydraulic pipe 294 leads to a control unit 295 which contains a primary valve 296, a secondary valve 297, and an output bypass valve 298. Primary valve 296 is electrically operated by the coils 378 to reciprocate horizontally (as viewed in Fig. 4a) in a square wave mechanical motion, as was generally described above and was described in detail in previously mentioned application, Serial No. 284,606. The bypass valve 298 is pressure operated such that, if system pressure falls below a predetermined value, the valve will open, while pressure above the value determined by a spring 300 will keep the valve closed and allow fluid to be transmitted .to a hydraulic motor 299 for operation of the same. The operation of this bypass valve will beclear upon inspection. A rod 301 is snugly fitted in a passage shown which .is directly connected to system pressure. This rod 301 is integral with a valve core 302 which seats on a passage 303 in order to isolate the two pressure lines shown which lead to hydraulic motor 299; If pressure falls below the predetermined level, spring 300 will act against a piston 3tl4which is attached to the valve core 302 and will open the valve and create a bypass. The purpose of this bypass valve is to provide conditions such that when manual operation is eflfected, fluid circulated by the motor 299 (acting as a pump) can freely flow and the resistance to manual operation will be low. Hydraulic motor 299 drives the turret in traverse through a gear box 311, the details of which form no part of the present invention per se.

Traverse gyroscope unit 312 can be a conventional gyroscope and pick-ofl so long as the pick-off is a type which produces alternate timed pulses as generally described above, in order to gain the benefits of an alternate pulse servo system such as the basic servo system disclosed and claimed in the application, Serial No. 284,606. The gyroscope unit is electrically connected to the rest of the system as is indicated in Fig. 4a, the electric circuit being shown in Fig. 5. There is a commanders handle and control box 313 which is arranged to take over manual control from the gunners control station 314 (Fig. 4b) by electrical means which will be fully described in connection with Fig. 5. I

The elevation control system is shown in Fig.'4b where its operation may be traced by following first the hydraulic pressure pipe 292 which leads to a filter 315. From this filter 315, we may follow pressure pipe 316 via flexible connector 317 and hydraulic pipe 318, to an elevation control unit 319. This unit contains a primary'valve 320, and a secondary valve 321, like those of the traverse unit 295. This unit also contains a selector or changeover valve 322 which operates automatically by means of system pressure to selectively connect either the automatically controlled primary and

secondary valves

320 and 321 or to connect a manual hydraulic pump 323, to the gun elevating cylinder 340. The details of this selector or changeover valve 322 are evident upon inspection'of Fig. 4b and are as follows: inner poppet valves 380 and outer poppet valves 381 are actuated by means of a piston operated cam member 383. All four

poppets

380 and 381 are biased against the cam member 383 by springs 384. Cam member 383 has a compression spring 385, which biases the cam member to the left (as viewed in Fig. 4b), but which is overcome by system hydraulic pressure whenever it is at or above a working pressure which may be predetermined by the stiffness of spring 385. Now it will become apparent that the selector or changeover valve 322 operates when system hydraulic pressure falls below a given working level to reverse the positions of inner and

outer poppet valves

380 and 381. This reversal takes place by the cam action when cam member 383 'is moved to the other end of the cylindrical chamber in which it is located, under the force of compression spring 385. So that, so long as system hydraulic pressure is maintained, selector or changeover valve 322 will remain in the position illustrated in Fig. 4b with cam member 383 at the right end of its travel and with inner poppet valves 380 open. This makes a hydraulic connection between gun elevating cylinder 340 and secondary control valve 321 so that the elevation system is on automatic stabilization or tracking control. On the other hand, if system hydraulic pressure should fall below the predetermined working level, cam member 383 would be moved over'to the left (as viewed in Fig. 4b) under the force of compression spring 385, and so inner poppet valves 380 would be closed and outer poppet valves 381 would be opened which would disconnect the primary and

secondary control valves

320, 321 and would connect hydraulic pipes 358 and 359 (of the manual elevation control system to be described below) to the gun elevating cylinder 340 for manual control of the gun elevation. Hydraulic passages of the elevation control unit 319 will not be traced-in detail; it is suflicient to note that there is'a piston 387 at the left end of cam member 383 (as viewed in Fig. 4b) which pistonhas the necessary rings or other type of seal to maintain the pressure of the hydraulic fluid which 7 is introduced into a chamber 388 directly from pressure hydraulic pipe 318.

Gun elevating cylinder 3401s an improved type. The details of this cylinder form no part of the present inv'ention per se, but are the subject matter of a separate application in the name of Lawrence Bruehl Serial No. 340,451, filed March 5, '1953. Hydrauliciluid is intro duced to either side of a piston 341, which has a piston rod 342 extending full length of the cylinder above and below the piston 341 -in order to equalize the effective pressure areas. There is a bleed passage 3d?) which operates to vent the space between a pair of hydraulic seals 341a and 341k encircling the piston 341; thereby preventing a pressure lock from developing between the seals rendering them useless, and at the same time permitting the hydraulic seals 341a and 34% to be preloaded when pressure is applied to both sides of the piston as in the case of manual operation. The cylinder 340 is fastened securely to the. gun by means of a gimbal arrangement, only part of which is shown, for clarity. Lugs 344 are securely fastened so as to be integral with the top of the cylinder 340. These lugs 344 are in turn carried .by a gimbal ring 345 which has lugs on it (not shown) at right angles to lugs 344. The lugs (not shown) on gim'bal ring 345 are in turn carried by brackets (not shown) which are fastend to the gun. At the lower end, piston rod 342 has an eye bracket 346, which maybe used to fasten the piston rod to the turret framework by any convenient bracket means. Hydraulic fluid-is introduced toeither side of the piston 341 by means of hydraulic pipes 347, which carry fluid to the gimbal ring 345, and then via sealed swivel joints as shown to a chamber 348 above the piston 341 and to a hydraulic piper349 which leads to a like chamber 353 at the bottom of the cylinder 340.

If hydraulic pressure is removed, there is -a system provided to manually control the gun in elevation. This system is amanually operated separate'hydraulic system. It has a manual pressure pump 54, connected to the return side of the hydraulic system to pick up fluid; also a check value 52 and accumulator 55, all to supply manual pump 323 with fluid to be circulated thereby. Added to this is a hydraulic no-back device 351 which is to keep fluid from flowing back from the elevating cylinder 340 to the manual pump, while allowing fluid to be forced into the elevating cylinder in either direction at any time (while the selector valve 322 is over in its manual position) by the manual pump 323. This noback device 351 is in effect a dual check valve in which either check valve upon opening holds the other valve open at the same time. The drawing in Fig. 4b shows the parts in a hypothetical position in which fluid is being forced through the left-hand hydraulic pipe 352 and returned to the pump through right-hand pipe 353. The pressurein pipe 352 has pushed back a ball 354 which is normally urged against its valve seat by a spring 355 and so acts as an ordinary check valve. The same pres sure inpipe 352 has forced a piston 356 over to its righthand position as illustrated and as viewed in Fig. 4b. Thispiston 356 has two pins or rods which are attached as integral parts with the piston and all of which (piston 356 and the pins) move together. The result is that a right-hand ball 357, which is likewise spring biased against its valve seat to act as a check valve, is lifted from its seat and held open. It is to be explained that piston 356 and its pins are so made as to allow both check valves (right and left-hand, having

balls

357 and 354, respectively) to remain closed when there is equal I pressure on both sides of each. The result is that any back pressure developed in the elevation cylinder 340, e.g. due to vehicle traveling over rough terrain, will not motor the hand elevation pump 323. In other words, any back pressure on the separate manually operated hydraulic system, which may develop in either

hydraulic pipe

358 or 359 will *be checked at the hydraulic noback device 351, while any time pressure is applied by means of the manual pump 323, it will be allowed to circulate fluid freely (whenever selector valve 322 is in its manual positionnot shown).

Elevation gyroscope unit 362 may be the same type of gyro unit as traverse gyro unit'312. The physical location determines its datum line or line of reference so that otherwise both elevation and traverse gyros are identical. The gyro unit 362 is connected electrically to the control system by electrical lines 362a and 362k as indicated generally in Fig. 4b of the drawings. The electrical circuit diagram is shown in Fig. 5. The setting of a gunners control switch 365 to its on position initiates an electrical action whereby the gyroscopes are brought into operation. After a specified time delay to enable the gyro rotor -to obtain operating speed, the entire system becomes operative.

A loaders safety switch 360 permits the loader to render the stabilizing system inactive in order to retrieve ammunition from the hull storage compartment. The opening of switch 360 causes the deenergization of the solenoid 275 of 'shut-ofi' valve 273 (Fig. 4a), and deenergization of solenoid 327 of clutch control valve 307 (Fig. 3), thereby removing pressure from the gun control system and placing the control in an automatic travel lock condition.

A pressure gauge 361 which has a snubber (not shown) integral therewith, is located opposite the accumulator 55 in the manual hydraulic system to show this systems pressure.

Fig. 5 is an electrical circuit diagram which shows the inter-relation of the various electrically actuated elements in the system. The electrical circuit, being that of a tank, is a DC. one wire type of system in which the positive D'.C supply is connected to a single wire 390 which directly supplies two branch circuits. There is a fuse 391 in each of these branches. These fuses may be an appropriate rating mechanical type of circuit breaker if desired. A wire 392 is connected to the positive wire 390 via one of the fuses 391 and leads to one side of the control switch 365 which is located in the gunners control tmit adjacent to his control handles 314 (Fig. 4b). When this control switch is closed, a common circuit wir'e 393 is energized. Branching from this common circuit wire 393 are a number of circuits for electrical devices among which is a pilot or signal light 394 which will be energized to indicate that the control system has been turned on. Also connected to common circuit wire 393 is an elevation gyro rotor motor 395, the field winding of which is indicated at 396. Since the gyro rotor motor 395 is directly connected to wire 393, and to the common ground circuit, it will be energized as soon as the control switch 365 is closed and the gyro rotor will begin to be rotated up to its operating speed. Traverse gyro rotor motor 397--which has its field winding 398 shown connected in series in the same manner as with elevation gyro motor-As also connected directly to wire 393 and to ground as illustrated, and will likewise be energized upon closing of control switch 365. Elevation pick-off motor 399 and traverse pick-off motor 400 are similarly directly connected to wire 393 and will be energized as soon as control switch 365 is closed. The completion of each circuit for the elements just recited is made by a common ground circuit in the usual manner for a DC. system of this sort and such ground connection is illustrated in a functional manner by a ground connection symbol.

There is a thermal 'delay switch 405 which is of a type having a pair of contacts that are closed after a predetermined time delay from the time that a heating element 406 is energized. This time delay switch405 has two

resistors

407 and 408 connected in series with its heating element 496. These resistors are shown asvariable merely for the purpose of adjustment. Arela'y 409 is connected toone of the contracts of thermal delay 9 switch 405 for -actuation thereby'when its contacts are closed. This relay controls three circuits as shown which are as follows:

One circuit is that of the control coils 404 and 378 for elevation and traverse

primary control valves

320 and 296 respectively (Figs. 4b and 4a), which includes wire 410 connected to the right-hand fuse 391 (as viewed in Fig. 5) and to a normally open pair of contacts 411 of relay 409. The remainder of this circuit will be discussed in more detail below.

The second circuit is that of the various control solenoids and includes a wire 412 which is directly connected to common circuit wire 393 and to normally open contacts 413 of the above relay 409.

' The third circuit includes normally closed contacts 414 of relay 409. The purpose of this circuit is to insert resistor 407 into a series circuit including heating element 406 of thermal delay switch 405. So, when relay 409 has been actuated, contacts 414 will be opened and resistor 407 will act to reduce the current flow through the heating element 406 to a lowerlevel which will be sufficient to maintain actuation of thermal delay switch 405 without overheating, and thereby permitting quicker deactuation. The purpose of delay switch 405 is to give a sufficient time delay before energization of the first and second circuits mentioned above in order to allow the gyro rotor motors to reach approximately 60% of their final speed.

The first circuit controlled by relay 409 includes wire 417, which is connected to contacts 413 and leads to the loaders safety switch 360. Then the circuit continues via wire 418, which is part of a common circuit for the solenoid 327 of hydraulic clutch valve 307, solenoid 275 of the system shut-off valve 273, a traverse gyro caging solenoid 419, an elevation gyro caging solenoid 420, and a traverse tracking motor 421 which has two

series fields

422 and 423 for reversible operation. A separate circuit for each of these elements is completed by a ground connection as clearly shown in the drawing.

The oil level and temperature responsive switch 376 is connected in a circuit common to both

solenoids

275 and 327.. The purpose is to obviate any damage to the hydraulic system if there is insuflicient hydraulic fluid or if its temperature is too high for proper circulation. 'It (switch 376) may be any suitable type of switch which will be responsive to both temperature and to the level of the hydraulic fluid. The responses are set to open the circuits of clutch valve solenoid 327 and system shut-off valve solenoid 275 if the hydraulic fluid level falls too low for safe operation or if the temperature of this fluid is too high for safe operation of the system.

There are resistors 426 which are connected in series with each of the elevation and traverse

gyro caging solenoids

420 and 419 respectively. These resistors 426 however have short circuiting contacts 425 connected across each resistor 426. The caging

solenoids

419, 420 and the resistors 426, as well as the contacts 425 are all elements of the known gyro systems 312 and 362 (Figs. 4a and 4b) which are well known types of gyro and pickoif units such as the type described in US. Patents Nos. 2,521,379 and 2,464,592 to Leathers et a1. and assigned "to International Business Machines. As described in these patents just mentioned the operation of the caging mechanism is such that, when the solenoid is energized, the gyro will be uncaged. It is to be noted therefore that the gyros will not be uncaged until after their rotors have had time to get up to at least 60% of full speed as pointed out above. The action of contacts 425 and resistors 426 is an auxiliary one which serves to reduce the current flow through the

solenoids

420 and 419 after the uncaging actionhas been completed. This allows a positive and rapid uncaging action to be had without overheating the uncaging solenoid windings during standby uncaged condition.

The elevation and the traverse tracking motors 137 .10 ar'1d4421 are normally connected to the circuits leading to the gunners control handles 314 (Fig. 4b) which determines the positions of sliding contactors 427 and 428. These sliding contactors may be the usual type found intracking motor control circuits such as the type fully described in the application, Serial No. 284,606, filed April 26, 1952, and act to determine the direction and speedof their

respective tracking motors

137 and 421. There is a commanders over-ride switch 431 which is conveniently located on the commanders control unit 313 (Fig. 4a) and which is shown directly connected to the commonly energized wire 393 by wire 432. When the tank commander desires to take tracking control of the gun away from the gunner, he closes thisswitch 431 which energizes a relay 433 as well as a motor 434 in the commanders tracking motor control unit. Actuation of the relay 433 shifts control of the tracking

motors

137 and 421 from the gunner to the commander so that the gunners tracking control is no longer efiective. This shift is eflected by the action of multiple contacts 436 of relay 433, which contacts are mechanically actuated by an armature 437, also of relay 433. The contacts are spring biased into the position illustrated and will assume the opposite position when relay 433 is energized. Therefore, when relay 433 is energized, the circuits for tracking

motors

137 and 421 will be connected to

commanders sliding contactors

438 and 439 respectively which are physically positioned by the commanders control handles 313 (Fig. 4a) in generally the same manner as the

gunners sliding contactors

427 and 423 are positioned by the gunners control handles 314 .(Fig. 4b). .The, commanderscontactors 438 and 439 .and break commutator drum 440 which is the speed controlling element for both tracking

motors

137 and 421. A motor 441 is directly connected to common wire 393 so that the gunners control unit has its commutator drum 440 constantly driven whenever the system is energized by the gunners control switch 365. The motor 434 on the other hand is only energized whenever the commanders over-ride switch 431 is closed.

It will be observed that there is a safety circuit for the benefit of the loader so that whenever he must make a trip between the turret and the hull of the tank, he can be sure that no relative motion is going to take place while he is in danger of being seriously injured by such relative motion. This safety circuit is controlled by loaders switch 360 which shuts off the hydraulic system and declutches the main hydraulic pump.

There are limit switches 442 in circuit with the elevation tracking motor 137. One switch 442 is in the circult of each of the two field windings 443 of the motor 137. The purpose of these limit switches 442 is-to avoid tracking the gun in elevation positions higher or lower than the structural limitations of the gun mount will allow. Thephysical location of the switches 442 may be any convenient mounting which will accomplish the desired results.

Operation The operation of the system of our invention may be summarized with primary reference to Figs. 3, 4a and 4b. Beginning with stabilization, it will be noted that the gun 44 (Fig. 2) is to be maintained in a given position which will remain fixed with respect to the earth regardless 'of the changes in attitude which the body of the tank may assume. Any tendency for the gun 44 to change its position relative to the earth will be sensed by 'one of the two gyroscopes 370 and 371 (Fig. 2) or gyros 312 and 362 (Figs. 4a and 4b), and the hydraulic control system will be actuated by these gyroscopes in order to cause the relative position between gun 44 and the hull of the tank upon which it is mounted, to change in such a way as to maintain the position of gun 44 (relative to the earth) fixed. The operation will be described with reference only to the system for maintaining gun 44 in a constant elevation position since both the elevation and the traverse control systems are similar and a description of the operation of either one will apply to the other.

When the hydraulic system is in operation following the electric control system having been turned on at the switch 365 (Fig. 4b) on the gunners control panel, and following the delay period for run up of the gyro rotors to speed, the solenoid 327 (Fig. 3) will be energized and "hence the valve 3ii7 will be actuated to cause fluid under pressure, due to the accumulator 363, to cause the clutch 282 to be engaged so that the main hydraulic system pump-281 will be driven by the tanks engine 280. At the same time, solenoid 275 (Fig. 4a) of the cut off valve 273 will be energized and so the valve 273 will be opened to allow the hydraulic system to be energized. Therefore hydraulic pressure will be applied over pipe 318 (Fig. 4b) to the central chambers of secondary control valve 321 and primary control valve 320, as well as to the piston for actuating automatic-manual selectro valve 322.

As described in detail above, there is a continuous alternate, cyclic energization of the solenoids which position hydraulic valve 320 (Fig. 4b) at a predetermined constant frequency in such a manner that the valve 320 is being driven against first one of its stops and then the other for equal periods of time. Therefore, the secondary valve 321 is being correspondingly driven from one extreme position to the other at the same frequency, and consequently hydraulic pressure is being admitted first to one side of the elevation piston 341 and then to the other side thereof at a given frequency. This series of hydraulic energy pulses which are applied to the elevation cyllinder 340 to reversibly drive its piston 341 in opposite directions, will obviously tend to cause the gun ai to be driven up and down in elevation at the same frequency as these pulses of hydraulic energy. The frequency of the pulses of hydraulic energy is so chosen that the gun will not be substantially displaced so long as the two pulses which make up any given cycle, are equal and opposite in their duration. The result will merely be that of holding the gun 44 in a vibratory condition having a neutral or medium position which corresponds to the desired aiming point of the gun44.

So long as the tank hull is in such a position that gun 44 has the desired elevation, the gyroscope 362 (Fig. 4b) will control the switching mechanism for the solenoids so that energization of the solenoids that control valve 32th will be had in equal duration pulses, alternately, as was clearly described above. Therefore the vibratory motion without any displacement, as just described, will be produced in gun 44.

However, should the hull of the tank change position due to rough terrain such as hills, or the like, the gyroscope 362 (Fig. 412) will sense this change of position and will correspondingly vary the duration of the energization of the coils which actuate the valve 320, by increasing the length of time that one coil is energized and decreasing the length of time the other coil is energized in any given cycle. Therefore, a difierential in the duration of the hydraulic pulses which are produced in the elevation cylinder 340 will be set up and this differential will cause a displacement of the piston 341 Within the cylinder 34?; in-the required manner to change the elevation of the gun 44 relative to the hull of the tank upon which it is'niounted, so that the gun elevation will not change relative to the earth. This is theusual operation of a stabilization system as controlled by a gyroscope; however, it will be noted that our system enables 'the inertia .of =the gun 4410 work with the stabilization failure of hydraulic pressure.

eflfect rather than against the same. This is due to the fioating action which was described above.

error signal, so that the hydraulic system will act to reposition gun M in a manner as just described with regard to stabilization.

There is also a manual hydraulic system for controlling the position of the gun 44 in case the stabilization or automatic control system is not in operation due to a This manual system is simply comprised of a mechanical hydraulic pump 323 which may be manually operated in one direction or the other to circulate hydraulic fluid in such a way as to reposition the piston 34 1 Within its cylinder 340'. This may be accomplished when the automatic system is not operating because the change-over valve 322 will bepositioned (by its spring) to the left, as viewed in Fig. 4b, and therefore the

hydraulic lines

359 and 358 from the manual pump 323 will be connected to the lines 347 which lead to the elevation cylinder 3'40.

While we have described a specific embodiment of our invention, it is to be taken as illustrative only and in no way as limiting our invention.

We claim:

1. In a hydraulic control system for positioning a body in traverse including a primary control valve for determining the flow of hydraulic fluid from a source of fluid under pressure to a plurality of control channels, a secondary control valve for receiving the flow of fluid in said control channels and amplifying the same, a reversible hydraulic motor having two pressure lines fed by said secondary control valve, a manual pump having a pair of normally closed hydraulic lines connecting the same with said motor, and hydraulic pressure operated means for by-pa'ssing fluid between said pressure lines and for opening said normally closed hydraulic lines between said manual pump and said motor when the system pressure falls below a predetermined minimum.

2. In combination with a hydraulic cylinder and piston arranged to be connected to a gun and its supporting body for variably elevating the gun by varying the volume of liquid in the cylinder from one side of the piston to the other, said piston having equal areas on both sides subject to pressure; an hydraulically controlled valve for varying the volume of liquid in said cylinder, pressure lines connecting said valve and said cylinder, an electrically controlled valve for controlling the actuation of said hydraulically controlled valve, manual pump means having a pair of normally closed hydraulic lines connecting the same with said cylinder, gyroscopic means including an electric circuit for controlling said electrically controlled valve in order to automatically control said cylinder and piston, and hydraulic pressure operated means for bypassing fiuid between said pressure lines and for opening said normally closed hydraulic lines between said-manual pump and said motor when the system pressure falls below a predetermined minimum.

3. In a hydraulic control system for positioning a body in traverse including a primary control valve for determining the flow of hydraulic fluid from-a source of fluid under pressure to a plurality of control channels, a secondary control valve for receiving the flow of fluid in said control channels and amplifying the same, a reversible hydraulic motor having two pressure lines fed by said secondary control valve, a manual pump having a pair of normally closed hydraulic lines connecting the same with said motor, an hydraulic pressure operated valve means, a spring means adapted to bias said valve means to open or by-pass position for by-passing fluid between said pressure lines and for opening said normally closed hy- 13 draulic lines between said manual pump and said motor when the system pressure falls below a predetermined minimum, and a valve means face subject to system pressure whereby said valve means is held closed against the pressure of said spring means so long as system pressure exceeds the pressure of said spring means.

4. In a hydraulic control ystem for positioning a body in traverse including a primary control valve for determining the flow of hydraulic fluid from a source of fluid under pressure to a plurality of control channels, a secondary control valve for receiving the flow of fluid in said control channels and amplifying the same, a re versible hydraulic motor having two pressure lines fed by said secondary control valve, a manual pump having a pair of normally closed hydraulic lines connecting the same with said motor, a plurality of hydraulic pressure operated valves, spring means adapted to bias said valves to open or by-pass position for by-passing fluid between said pressure lines and for opening said normally closed hydraulic lines between said manual pump and said motor when the system pressure falls below a predetermined minimum, and a hydraulic pressure responsive piston having a face subject to system pressure associated with said valves to hold the same closed against the pressure of said spring means so long as system pressure exceeds the pressure of said spring means.

5. In combination with a hydraulic cylinder and piston arranged to be connected to a gun and its supporting body for variably elevating the gun by varying the volume of liquid in the cylinder from one side of the piston to the other, said piston having equal areas on both sides subject to pressure; an hydraulically controlled valve for varying the volume of liquid in said cylinder, pressure lines connecting said valve and said cylinder, an electrically controlled valve for controlling the actuation of said hydraulically controlled valve, manual pump means having a pair of normally closed hydraulic lines connecting the same with said cylinder, gyroscopic means including an electric circuit for controlling said electrically controlled valve in order to automatically control said cylinder and piston, hydraulic pressure operated changeover valve means for by-passing fluid between said pressure lines and for opening said normally'closed hy- References Cited in the file of this patent UNITED STATES PATENTS 2,311,964 Parsons Feb. 23, 1943 2,388,010 Pohl Oct. 30, 1945 2,425,433 Linderoth Aug; 12, 1947 2,445,765 Dawson et al July 27, 1948 2,457,242. Knowlton Dec. 28, 1948 2,532,334 -Rhyne et a1 Dec. 5, 1950 2,569,571 Newell et a1 Oct. 2, 1951 2,591,800 Gardiner Apr. 8, 1952 2,614,390 Poitras et a1 Oct. 21, 1952 2,655,838 'Ernst et a1. Oct. 20, 1953 2,660,793. Holschuh et a1 Dec. 1, 1953 2,663,995 Price et al Dec. 29, 1953 2,679,138 Kane May 25, 1954 2,681,116 Treseder June 15, 1954 2,735,405 Hipple Feb. 21, 1956 2,766,587 Newell et al. Oct. 16, 1956 2,766,731 Brandes et al Oct. 16, 1956 UNITED STATES PATENT OFFICE CERTIFICATE or CoRRRCTIoN Patent No., 23 18 193 August 9, 1960 Ward Leathers et al6 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column l line 52 for "hydraluic" read hydraulic column 3 line 54, for "inputs" read inputs column 7 line 41, for "value" read valve column 8. line 75,, for

"contracts" read contacts column 13, line 7 for "ystem" read system column 14, line 21 list of reference cited for the patent number "2,311,964" read 2 311 864 =--i ERNEST W. SWIDER mxxx 1 Attesting Oflicer V v ARTHUR -W. CROCKER Acting Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo 2,948,,193 August 9 1960 Ward Leathers et al It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent Should read as corrected below.

Column 1 line 52,, for "hydraluic read hydraulic column 3 line 54 for "inputs" read inputs column 7 line 41, for "value" read valve column 8 line 75 for "contracts" read contacts column 13 line 7 for ."ystem" read system column 14 line 21 list of reference cited for the patent. number "2,311,964" read 2 3l1 864 Signed and sealed this 4th day of April 1961.

(SEAL) Attest: ERNEST W. SWIDER XXXXQQQQX X ARTHUR w. CROCKER Attesting Oflicer Acting Commissioner of Patents