US1723623A

US1723623A - Self-centered, nonsighted, second-of-time gun

Info

Publication number: US1723623A
Application number: US101367A
Authority: US
Inventors: William Q Kennedy
Original assignee: Individual
Current assignee: Individual
Priority date: 1926-04-14
Filing date: 1926-04-14
Publication date: 1929-08-06
Anticipated expiration: 1946-08-06

Description

Aug. 6, 1929. w. Q. KENNEDY 1,723,623

SELF CENTERED, NONSIGHTED, SECOND-OF-TIMEGUN 3 Sheets-Sheet Filed April 14, 1926 47/47/17 V wI/lI/ g- 1929- w. Q. KENNEDY SELF CENTERED, NONSIGHTED SECOND-OF-TIME' GUN Filed April 14, 1926 3 Sheets-Sheet m h A Nu W W W ATTORNEY Aug. 6, 1929.

w. Q. KENNED Y SELF CENTERED, NONSIGHTED, SECOND-OF-TIME GUN 3 Sheets-Sheet Filed April 14, 1926 Patented Aug. 6 "1929.

WILLIAM e. KENNEDY, on NEW 1033,; E

snnr-cmnann, NoNsIeHrEii,; sEconn-or-Tmn eon;

A noanon niean ru 14, 1326'. [serial No. 101,867.

The invention relates to ordnance and more particularly to guns and controlling mechanism therefor.

Among the objects of this invention is to 6 provide a gun that is self-centered and which will move automatically so as to maintain the axis of its barrel in the same vertical plane when elevating the gun regardless of the fact that the platform whereon the gun is mounted may be in non-horizontal position, due to irregularity of the ground or for other like causes.

Another object of this invention is to provide a gun which is so designed that after i the gun has been adjusted to fire at a target,

it will automatically retain its aim after a shot has been fired and the gun has recoiled, so that the time ordinarily consumed in resetting the gun to fire again at the samev target is saved.

jectile and the novel co-operatin Another object of this invention is to pro- I vide for a gun novel controlling mechanism cO-Operating therewith which co-ordinated with the known muzzle velocity of the profinder, all calibrated in seconds of time, will constitute this piece of ordnance a second of time gun.

Another object of this invention is to provide a novel method of finding and following a moving object so that the gun can be fired thereat with a minimum of time and labor and yet with peculiar accuracy.

Still another'object of this invention is to provide novel elevating gear for a gun to 'perntilit the gun to be elevated at a maximum s ee It will be recognized by a study of this invention that the primary underlying motive of my invention has been to reduce to a minimum the time necessary -to manipulate the gun, while at the same time rendering the operation thereof in various ways automatic, thus reducing the total number of errors possible in the manipulation of the gun. The mechanism has been retained as of a comparatively simple nature. and various features have been rendered less intricate. In certain respects, devices provided herein will be recognized as being applicable, by reason of their character or principle of operation, to machines of Widely varying types.

With the foregoing and other objects in view the invention consists in the arrangement and combination of parts hereinafter range 7 described and claimed, and While the invention is not restricted to theexact details of construction disclosed or suggested herein, still for the purpose of illustrating a practical embodiment thereof reference is had to the accompanying drawings in which like reference characters designate the same parts a in the several views, and in .Which Figure 1 is a side elevation of the invention with certain others insection.

Fig. 2 1s an elevation ofthe gun in the diparts broken away and rection of arrows 22 of ig. 1, parts being broken away. i

Fig. 3 is a sectional view on the line 3-3 ofFig.1. I Fig. 4 is an enlarged fragmentary sectional vlewof a part of the elevating gear.

Fig. 5 is a sectionalview on the line 5-5 of14F1g.g. f 4 1 1s a ra menta I view showin a a i g '5 I g Fig. 7 is a fragmentary view in plan showing a detail of the elevating gear-in collapsed.

position. 1 r

Fig. 8 is an enlarged sectional view in elevatlon of the range finder.

' Fig. 9 is a sectional view approximately on the line 9-9 of Fig 8..

Fig. 10 is a reduced sectional view approximately on the line 10-10 of Fig. 9.

Figs 11 and 12 are diagrams illustrating a the method of operation of the instrument.

Fig. 13 is a fragmentary view of the bottom of the derrick.

Referring now more, specifically to the draw1ngs,,I show my invention as mounted upon any supporting means whether movable or stationary, and including generally a plurality of steel beams 15 or the like cooperating to form a strong unitary structure. A revolving platform'is supported on said structure, and means are provided operative between said structure'and the platform to cause rotation thereof to any predetermined degree. More specifically, an annular or bevel gear 16 is provided on the casting or form 17, a top plate 18 servin to unite the parts and afford a floor. he revolving platform and the supporting structure with its gear thus have a single axis at shaft 19. The revolving platform includes a top plate 20 strengthened by a radial T-bar 21 or the like underneath the plate, and a strong peripheral re-enforcement member or casting 22 of annular form which -moves in radially spaced relation to the gear 16. Anti-fric- Lition means in the form of a race and balls 23 are provided to permit of easy rotation of the platform. For this purpose the member 22 is arranged with an annular groove to cooperate with a similar groove in a member 24 on a beam 15. The specific details of the construction thus far described can be varied to suit.

Actuating means is provided for rotating I i the platform which is novel in its applicaworm 29 movable bodily in a lane at right angles to. the shaft 26 as by epressing the wormshaft 30 to cause a rapid rotation of the worm wheel, and therefore of the bevel pinion 25, and cause consequently a more rapid rotation of the platform when the gun is to be moved through a relatively large horizontal angle.

Fixed rigidly to the platform are inner and

outer bearings

34 and 35 which support a continuous shaft 36 which may be somewhat enlarged at its central portions 37.

A bearing 34 and a bearing 35 co-operate to form a unit and are positioned to receive therebetween' a hub 38 of a gun carriage 39. The carriage or derrick may assume any specific form but for purposes of illustration will be seen to comprise a plurality of longitudinally extending beams 40 connected by

transverse members

41, 42. In any event the gun carriage can be elevated in the usual manner upon the shaft 36.

' This invention includes novel elevating or trail mechanism and gear. More specificaL iv, a plurality of

screws

43 and 44 are provided-which are operative singly or together, a rapid vertical movement of the gun being obtained in the latter instance. These schews are supported by means which permit of vertical movement of the gun from 0 to However, these screws do not bear more than a comparatively small portion of the weight. of the gun and carriage, since I provide novel counterbalancing means. of suitable mechanical form, which for the sake of simplicity may as- -sume the form of a resilient member such as a spring 45. This spring 45 is coiled about,the square member 37 between the inner bearings 34 to which it may be fixed as shown at 46, the shaft 36 being for, this purpose secured against rotation. The-other end of the spring is secured to the gun' carriage at 47, so as to tend to take up the preponderant Weight of the gun and carriage, exerting a force thereon in a counterclockwise direction. The form of the spring shown is to be considered as illustrative only.

When the gun is elevated to an angle of 90, its" weight and the weight of the carriage will be borne directly by the shaft 36, the spring'being then unwound and generally idle, the hubs 38 abutting against stop means 48, thus. preventing further counterclockwise movement of the gun. lVhen the gun is lowered,.the center of gravity thereof shifts from the verticalplane of the shaft 36, but the spring is then wound up, and when the gun is substantially horizontal, the spring bears'substantially the entire Weight of the gun and carriage. position of elevation the gun may be, the

screws

43, 44 bear but a small portion of the load.

The screw-.44 is pivotally connected to the gun carriage'as by means of a bar 44, the screw being retained against movement longitudinally of the bar. A gear box 49 is arranged to receive screw 44 so as to permit of longitudinal movement of the screw. For this purpose'abevel gear 50 is internally threaded to receive the screw 44, said gear being likewise arranged to mesh with bevel gear 51 mounted fixedly in the gear box, and rotatable by a'crunk 52. A bracket 53 may be provided in the gear box. The gear 50- has bearing relation with'an end Wall of the gear box whereby-the gears 50, 51 are retained. in constant meshing engagement. \Vhen crank arm 52 is rotated the non-rotatable screw 44 will travel up or down through the gearbox. A gear box 49 is mounted on screw 43, a bevel gear 50 being internally threaded to receive screw 43, and arranged to mesh constantly with the bevel gear 51, a crank" 52 being provided for ro-- Thus in whatever tation of the gear 51, and consequent relative movement longitudinally as between gear box 49 and screw 43. A bracket 53 may alsov beprovided. The screw 43 is retained against movement whether of rota tion or translation, being retained fixedly in a bracket structure 54. The gear box 49 has dovetail connection with bracket 54 as by means of flanges 55 moving in guides 54". Thus the gear box 49 is held against rotation about the screw 43.

Gear boxes

49 and 49 are suitably connectcd'to each other so as to move upward or downward as a unit. However, it will be understoodat this point that cranks 52 and 52 can beopcrated singly or together. If it is desired to elevate the gun from the 45 position shown in Fig. 1, crank 52 may be manipulated alone. The result will be that gear box 49* will move upward carrying gear box 49 along with it, thus moving screw 44 which thus raises the carriage and elevates the gun. Should it be desired to elevate the gun very rapidly or through a large angle, both

cranks

52 and 52 are turned at the same time in the proper direct-ion as determined by the direction of the threads, the result being now that screw 44 moves upward through gear box 49 at the same speed that this gear box itself is moving upward, thus causing a lifting of the gun carriage at double speed. Similar results are obtainable if the gun is to be depressed. One man may operate both cranks conveniently, as both are turned in the same direction for double speed upward or downward movement. The co-operation of spring 45 as described hereinbefore renders this easy.

\Vhen, however, the gun is to be depressed below 45 and toward horizontal, ifi'becomes desirable to so manipulate the screws 43, 4-4 as to provide sufiicient room for such movement of the gun carriage. With the gun at 45, I prefer that the gearboxes be arranged as shown in Fig. 1, that is gear box 49 is at the base of the screw 43, and gear box 49 is near the lower end of screw 44. The bracket 54 can then be partially tilted and partially swung out of the way of the gun carriage, and when this is done, crank 52 will be operated to move screw 44 downward through gear box 49 and lower the gun. An opening 56 is provided in the platform to receive the lower end of screw 44 as the gun is being lowered toward the horizontal. To permit of the aforesaid movement of bracket 54, it willfirst of all be observed that

gear boxes

49 and 49 are pivot-ally connected together in the manner of a universal joint. Thus a yoke 57 has pivotal connection with gear box 49 at 58, and pivotaI connection with gear box 49 at 59. Bracket 54 is hingedly connected with a movable member or trail 60 at 61. The trail is mounted for movement about a vertical axis at 62. A stop 63 may be provided on the revolving platform to limit the movement of the trail about its axis. The direction of movement. of the bracket 53 with respect to the trail when the lifting gear is tobe collapsed is always in the direction of arrow a as shown in Fig. 6. The bracket may be moved about its hinge either by manual force or by suitable mechanism. In any event, when such movement occurs gear box 49 will turn at an angle with respect to gear box 49, screw 43 moving correspondingly and into a horizontal. plane, and trail 60 tilting about-s its vertical axis to such degree as may be necessary. This collapse of the elevating mechanism will be especially easy in view of the number of pivotal connections provided. \Vhen the elevating mechanism is collapsed, screw 44 will continue in its usual position and may then be operated as aforesaid to permit the gun to be lowered. When the elevating mechanism is collapsed, it is in a balanced condition and stop 63 is not relied on for this purpose. A supporting member 63 may be provided on the platform to limit the depression of the gun. The screw 44 may be called the derrick screw, and the screw 43 the trail screw.

Supported on the carriage or derrick is a cradle 64 which is pivotally mounted on the derrick as by means of a trunnion 65. Within the cradle is a gun 66 movable lengthwise to permit of the proper recoil. A gun circle or race 67 is provided having balls 68 on the derrick to support the cradle with minimum frictional resistance to movement thereof. The breech 69 of the gun is generally lowermost. Consequently the effect will be that the superior weight of the breech will tendalways to swing the gun about trunnion 65 so that the axis of the gun will lie in a vertical plane. This is particularly valuable especially as if the land or ground be uneven, the platform of the gun may not be in a horizontalplane. By this invention, however, the muzzle of the gun will always move through the operation of gravity, as described, in a vertical plane as the gun is being elevated or depressed. This object can be obtained with great accuracy especially by suitable geometrical proportioning of the various parts, including the distances between shaft 36, trunnion 65, and the muzzle of the gun. A hood 70 may be mounted on the cradle to retain the gun securely therein, as when a shot is being fired, and a level 71 of any suitable kind fixed to the hood to indicate whether the gun is in true position. The top plate 39 of the der? rick is provided with an .opening 39 along which clutches 39 that are fixed to the gun carriage engage the plate 89 to hold the carriage securely when the gun is fired.

The recoil of the gun is taken up by means of coil spring buffers 72 acting on the trunnions 73 of the gun, within the slots or guides 74 of the cradle. The springs 72 are retained on suitable telescopic means 75,'76.

I come now to'the main feature of my invention, and one which I believe will work a virtual revolution in ordnance practice. This resides in providing means by which a gun obtains its true vertical center before being aimed at a target, and if necessary to center the gun ancw after each tiring, allowing at the same time for the recoil of the gun as usual. More specifically, a guide member or keel 77 is provided which cooperates slidably with another member which is fixed with respect to the gun, so that the gun is retained in a fixed position for continuous firing at a particular target. The mechanism used for this purpose cooperates in such manner that the gun may be moved about the trunnion 65 when sightas-a oresaid. Thus one of the'members 77, 78 'may have an opening to receive its oooperating member. After proper adjust ment, the gun may be positioned at an angle.

to the longitudinalvertical plane of the derrick,qand yet the recoil will occur with greatest ease, the gun being always returned to its initial or aimed greatest precision. 1

By way of illustration of the broad aspect of this feature of the invention, I show the member 77 as assuming the form of a bar or the like, while member 78 has a plurality ,of radial slots 79. These slots are position with the very close together and they are arranged to receive the bar or keel 77.- The slot plate 78 is mountedin a frame 80 so as to be movable only lengthwise of the derrick. A rod 81, journaled in the derrick,- and offset at its central portion 82, acts in the nature of a lever to throw the slot plate forward into locking position when the rod is rotated by a crank 83; Slotted bearings 84 receive the part 82 ofthe rod. Thus theplate 78 is I movable in a fixed lane. When it is thrown forward toward t e gun, the pointed end of the keel 77 is received within the opening of one of the various slots 79. The slots 79 now have their common center or point of convergence at the center of the trunnion 65. In this position, the gun cannot be moved about the trunnion 65, but is locked.

When a shot is fired, and the gun recoils, the keel 77 passes down .a slot 79 wherein it is locked. After recoil has occurred, and the buffer springs have returned the gun, the gun will be in its previous aimed position, and another shot may be fired forthwith.

Since the keel is fixed to the gun, it is clear that the horizontal angle of the gun has not changed. If another target is to be struck, the slot plate is thrown back into the position shown in Fi 2 and out of enga ement with the'keel. fter'being aimed, t e slot plate is locked and the gun can be operated again as before. It is clear that, within the scope of the princi le disclosed, the co-operation as between t e keel and the slot plate can be varied or rendered adjustable in such manner as to permit the slot plate engaging the keel at any angle of the gun and with absolute accuracy.

A range finder '85 is secured to the trunnion so as tomovetherewith directly. It is positioned beneath the gun and in front of the same and mounted for longitudinal movement by ide means 86. The range finder is sighte on the target and the range is obtained by bringing the image to a focus.

By suitable calibration of the instrument,

the elevation of i the gun is obtainable di rectly from the range. Means are likewise provided'to' allow for the movement of the target while the projectile is traveling through the air to strike it.

The range finder includes. a casing 87 within which is slidably fitted a telescopic chamber or tube 88 which contains various focusing lenses. Guide means 89 are pro vided to insure of absolutely uniform movement of the focusin tube. A plurality of racks 90 are mounte on a side of the focusing tube to mesh with inions 91 on shaft 92 which is rotated by thimble 93, whereby the focal len justed.

a plate of bufi'ed glass 94 which is disposed across the instrument in perpendicular relation to the axis of the instrument, and the movement of the focusin tube is toward or away from the plate. I accurately calibrated, as at a dial 95 adjacent to thumb piece 93, so that when the target is pro erly focused on the plate 94 by. movement 0 the thimble and corresponding movement of the dial and focusing tube,'the

80. h of the instrument. can be adhe image is brought to a focus on he instrument is 1, I

range may be directly read u onthe dial.

However, since the muzzle ve ocity of the gun is known, that being always ascertained projectile to reach the target can be easily obtained. This time is marked on the dial opposite to the figures for different distances or ranges. Thus, if the muzzle velocity of the gun is 2500 feet per second, and the range found by focusing 17,500 feet, then clearly the time isseven seconds.

A mirror 96 is mounted at the base of the instrument pivot about an axis at 97. Props 98- are fixedto a shaft 99 to be rotatable therewith as by manipulation of a thumbpiece 100. Upward or downward movement of the props causes a similar movement of the mirror, the mirror being retained in en agement with the'props by brackets 96. cans are provided operative between the thumbpiece 100 and the body of the instrument to lock the thumbpiece after adjustment. As a simple illustration of conventional locking means, I show the thimble 100 as being of hollow form, and connected to shaft 99 by a spline 101. A locking pin 102 engages said body through the reaction of a spring 103 which continually forces the thumbpiece toward the body. A window 104 is provided in the line of sight, so that when the mirror is'moved in clockwise direction away from the axis of the instrument, a view may be obtained through window 104 directly through the instrument. A window "105 is likewise provided through which the operation of the instrument is observed continuously and 95 v by proper tests beforehand, the time in num- I ber of seconds that it would require for the i readings are taken. On'the focusing plate 94: are various permanent markings, including a central line of sight 106, and a plurality of transverse lines 107 at right angles thereto beginning with a zero line at point 108 which is the axial line of sight, the other transverse lines being marked 10,000, 20,000, and 30,000. An image ofthese lilies and the markings appears on the mirror 90 as shown at 106*, 107 F and 108.

The elevation of the gun that is necessary to hit a particular target is obtained by means of the lines and markings on the focusing plate and their images on the mirror. It is assumed that the range has been determined at 17,500 feet as stated hereinbefore. Bearing in mind that the mirror is retained always at a fixed predetermined angle of say 45 with the axis of the instrument, the gun is elevated until the image appears on the mirror as near to a value of 17,500 as may be obtained. Further focusmg may or may not be resorted to as desired. Lines 107-being properly calibrated, the gun is at the right elevation for firing at the target which is 17,500 feet distant.

As a preliminary step, however, to placng the gun at the elevation for firing readrugs are made to determine the necessary allowance for the movement of the target while the projectile travels toward it. For this purpose a screw 109 is provided, threaded right hand at one side of the axial plane of the instrument and left hand and of the same pitch at the other side thereof. The screw is rotated by thumbpiece 110. Point ers 111 are provided, one for each side of the instrument with respect to said axial plane, the pointers having hubs 112 threaded on corresponding portions of the screw. The pointers include the extending or indicating members 113 which are pivotally connected to the shanks of the pointers at 114. A spring 115 tends to move member 113 in counterclockwise direction. A sleeve 116 is mounted coaxially with screw 109 and is rotatable independently of the screw, by thumbpiece 116". Member 110 may have suitable marks along its edge whereby the deflection of the pointers from the central longitudinal plane of the instrument can be noted. The sleeve is slotted longitudinally at.116 to permit of sliding movement of the pointers therealong, but the sleeve retains the pointer at a fixed inclination with respect to the focusing plate, the spring 115 co-operating to keep t e pointer in snug contact with the focusing plate. This feature is a mere detail of convenience, and is intended merely to permit the end of the pointer to be adjusted or moved in a direction transverse to screw 109 according as the image is nearer or further from said screw. A second-of-time clock 117 is provided in conjunction with which the pointers are operated. The instrument is in every case so manipulated as to cause the image to move across the mirror horizontally. If the gun is being aimed upon a flying machine, for instance, the flying machine will sooner or later move in such relation to the gun that the image produced will move horizontally on the mirror. It is preferable to take observations and make adjustments at such time. The pointers will be understood to cast shadows on the mirror which follow the image as the pointers are moved in accordance with the movement of the image. The movement of the pointers from the central longitudinal plane of the instrument is exactly equal.

Let us assume that the axis of the gun is represented by line A X, T being a target, L a lens in the range finder, and I an image of the target. The range of the target is now obtained as described hereinbefore, and likewise the time corresponding to the range. The target'travels to the position at T and the image moves correspondingly to P. A period of time corresponding to the range of the target is allowed to elapse while the image moves from X to I, the target moving correspondingly from A to T and the deflection is noted. The gun is now traversed so that the image moves back to the opposite side of the line A X, i. e., it will appear again at I, or at such other point as corresponds with the pointer at this side of the instrument. If the gun is now fired, the target will travel from T to A, in the time that the projectile moves from the gun to A. The gun will, of course, have been properly elevated as described hereinbefore.

I claim:

1. In ordnance, the combination of a gun, a carriage, means to elevate the carriage, a cradle supporting the gun, said cradle being pivotally mounted on the carriage to permit the gun to be traversed, and means on the carriage fixed relative to the cradle and co-operating with the gun to retain the same after recoil thereof in predetermined centered position.

2-. In ordnance, the combination of a gun, a cradle in which the gun is mounted for recoil, a carriage and a trunnion for supporting the cradle and permitting the same to be tilted right or left whereby the gun can be centered for proper deflection, said trur.- nion being perpendicular to the cradle and forming an axis for, the gun, and guide means on the carriage fixed with respect to the cradle to retain the gun in predetermined centered positiop after recoil.

3. The combination as in claim .2, wherein the guide means includes a plurality of relatively slidable members, one on the gun and one on the means supporting the cradle.

4. The combination as in claim 2, wherein the guide means includes a plurality of' relatively slidable members, one on the gun and one on the carriage, one of said members being provided with a plurality of slots radial to the trunnions, the other member being slidable along one of said slots when the gun recoils, the members being arranged for disengagement when the gun is to be centered, and being engaged at one of said slots after the gun has been centered.

The combination as in claim 2 wherein the guide means includes a keel on the gun, and a plate on the carriage, said plate being movable along a fixed path to engage said keel, said plate having a plurality of slots within any one of which the keel is slidable, the slots being radial toward the center of the trunnion when the slot plate is moved into engagement with the keel, a recoil of the un causing the keel to move along a slot wherein the end of the keel has ,been received according to the centering of the gun, thus retaining the gun' in fixed centered position.

6. In ordnance, the combination of a gun, a cradle for the gun, a derrick supporting the cradle, a trunnion connecting the derrick and cradle for centering the gun right or left for proper deflection in a plane, a platform to tiltably support the derrick at the breech of the gun, and means on the platform to elevate or depress the derrick, the center of gravity of the gun being belowthe pivotal center of the cradle trunnion thus causing the gun to swing by gravity into a vertical plane even though a non-horizontal position of the platform throws the derrick out of a vertical plane.

7. In ordnance, the combination of a gun, means including a rotable platform to support the gun, a supporting structure for the platform, and means for rotating the platform including a gear train operating between the platform and the supporting structure, the gear train comprising an annular gear onone of the parts, means ineluding a worm wheel on the other part engaging the annular gear, a worm meshing with the worm wheel, means supporting the worm in bodily revoluble position about the axis of the worm wheel, and means to rotate the worm for normal slow adjustment of the platform and to cause a bodily movement of the worm as aforesaid for a rapid rotation of the platform.

8; In ordnance, the combination of a gun, means including a carriage supporting the gun, and means to elevate the carriage including a fixed screw, a gear box to travel along the screw, and means pivotally connecting the gear box and the carriage.

9. In ordnance, the combination of a gun, means including a carriage supporting said gun, and means to elevate the gun and carriage including a screw fixed against rotation, means traveling along the screw, and a member engaging the carriage and said means to elevate or lower the carriage as desired according as said means travels up or down on the screw.

10. In ordnance apparatus, the combination of a gun, means including a derrick supporting said gun, and means to elevate the gun and derrick including a plurality of screws, swivel means connecting said screws together and including means having threaded engagement with the screws,

whereby one or both of the screws can be made effective for elevating the gun accord mg as a slow or rapid elevation of the gun is desired, and means co-operating with said swivel means and supporting one of said screws and permitting the screw to be swung at an angle to the other screw and out of the way of the derrick to permit the same to be depressed by manipulation of the other screw alone.

11. In ordnance apparatus, the combination of a gun, means including a derrick to support said gun, supporting means pivotally supporting the derrick atthe breech of the gun, counterbalancing means to take up most of the weight of the gun and derrick when the un is elevated at an inclination, and elevating gear for the gun and derrick including a plurality of screws, one or both .of which can be made effective to cause a slow or rapid elevation of the gun as desired, one of said screws being supported on a trail, a gear box being mounted on the trail screw and having means to render the gear box movable therealong, the other screw having connection with the derrick and-having a gear box having connection with the ,first-mentioned gear box whereb. it is supported, the derrick screw gear ox having means to cause the derrick screw to move up or down through said gear box according as the gun is to be elevated or depressed, themeans supporting the trail screw being collapsible to permlt the gun to be depressed practically to the horizontalv In tesimonv whereof I affix my signature.

WILLIAM Q. KENNEDY.