US1484274A - Level-correction device for ordnance - Google Patents

Description

- 4 Sheets-Sheet 1 A. L. PERHAM LEVEL CORRECTION DEVICE FOR ORDNANCE Flled June 8. 1923 Feb. 19 1924:

c O A. 2 3 3 INST?? UMENTKL A. L. PERHM i LEVEL CORRECTION DEVICE FOR ORDHANCE Feb. 19, 1924 Filed. June 8, 1923 4 Sheets-Sheet z \\l rv A v .O HU Al? feb. 19, 1924. v1,484,1@344 A. l.. PERHAM I 4:Jg-:vlan CORRECTION DEVICE fon onnNANcE Fild-'June 8. 1923 A4 sheets-snee; :y

'mum Hl Ylmlmumh I Febr 199 1,454,274 A. L. PERI-AM LEVEL COIRRECTION DEVICE FOR QRDNANGE 'l Filed, June 8; 1923 4 Sheets-Sheet L Patented Feb. 19, 1924.

UNITED STATES 1,484,274 PATENT OFFICE;

ARTHUR LEONARD PERHAM, OF EAST MOSELEY, ENGLAND, ASSIGNOR T0 VICKERS LIMITED, 0F WESTMINSTER, LONDON, ENGLAND.

LEVEL-CORRECTION DEVICE FOR ORDNANCE.

Application filed .Tune 8,

To all w hom it may concern.

Be it known that I, ARTHUR LEONARD PERHAM, a subject of the King of Great Britain, residing at The New House, Matham Road, East Moseley, in the county of Worcester, England, have invented certain new and useful Improvements in or Relating to Level-Correction Devices for Ordnance, of which the following is a speciiication.

This invention relates to level correction devices for ordnance, particularly guns for anti-aircraft or coast defence mounted on portable or automobile carriages. Such gun carriages are often required to be placed on ground that does not afford a level or constantly rigid support, and it is necessary for accurate shooting to provide means for levelling the gun mounting itself so as to bring the training axis into a truly vertical position, or for adjusting the sighting apparatus to compensate for the inclination of the training axis of the gun from the vertical. If the gun is other than a very light one it is not practicable, owing to the weight of the parts, to provide means for maintaining its training axis vertical, and the object of the present invention is to provide an improved correction device by which errors in the aiming of the gun due to the lack of level of the gun carriage can be neutralized or compensated for without the gun mounting itself requiring to be levelled.

In gun mountings to which the invention is particularly applicable, the gun is usually laid in elevation and training by means of pointers or other members set to scales of elevation (or range) and of angles o training; alternatively the said pointers are arranged to turn on axes concentric with other pointers under the control of a distant sighting apparatus on the well known followthe-pointer77 system, or a pointer (one for elevation and one for training) under the conjoint influence of the distant sighting apparatus and the gun may be employed, the pointer being maintained opposite a fixed mark as is well understood.

According to the invention the pointer or other member by which the gun is laid either in elevation or in training is connected to a spirit level or its equivalent in such a manner that when the level is brought horizont-al an adjustment will be given to the pointer so as to compensate for the er- 1923. Serial No. 644,118.

ror due to the tilt of the training axis. For example, in the case of elevation the gun elevat-ion dial might be arranged to rotate once for G0o of gun elevation. In this case the level would be coupled to the gun ele.- vation pointer so that each degree of angular movement of the level would eli'ect 6 of angular movement of the said pointer. In the case of the gun training pointer, the level correction is applied through a variable-ratio device the ratio of which is adjusted in accordance with the gun elevation. This is necessary because the lateral error due to the inclination of the gun trunnions varies with the angle of gun elevation. At 45" of gun elevation the inclination of the trunnions requires a training correction of an amount equal to this inclination and at higher or lower elevations the correction is increased or reduced in proportion to the tangent of the angle of gun elevation.

By the use of the invention as hereinbefore described guns may be laid in accordance with angles transmitted from a distant or separate sighting station without the lack of level oi" the mountings introducing inaccuracy in the shooting, but it is necessary that at every angle of gun training the levels appertaining to the gun elevation pointer and the gun training pointer should be readjusted, because the effect of a tilted training axis varies with the training angle of the gun as measured from the direction in which the axis is tilted. To obviate the necessity for such continual adjustment of the levels, the levels may be connected to crossheads free to slide in directions at right angles to each other, in which crossheads a crank pin engages. If this crank pin is adjusted in radius to correspond with the angle of inclination of the training axis and if it is adjusted relatively to the angle of gun training so that the rotation of the member carrying it is in phase with the angles of the gun training in relation to that angle of training in which the training axis is tilted, then at all angles of training the levels will be adjusted automatically by the crank pin to gun training the two levels are adjusted to a horizontal position the two crossheads Will cause the crank pin to take up a position on the said rotatable member corresponding to the amount and direction of the tilt ot the gun trainingaxis. If the crank pin is now locked to the rotatable member, then at all training angles it Will keep the tivo levels horizontal.

The invention is also applicable to gun sighting apparatus that is combined with the gun mounting, its mode ot application varying with the type of sighting apparatus in use. As applied to gun sighting apparatus combined with the mounting it is generally only the training that requires correction and the invention Would then be applied to the lateral deflection dial.

A common type of levelling arrangement is that in which the sighting apparatus is pivoted about an axis parallel to the axis of the gun and is levelled about this axis. Such a levelling arrangement is open to the objection that relevelling is necessary with every change in gun training and to avoid this necessity the automatic levelling teature of the invention can be applied to such devices. For example a crank pin can be positioned by the two levels and erossheads as hereinbetore described and be so connected to the sighting apparatus that during the training of the gun the said crank will automatically level the sighting ap paratus about its axis parallel to the axis ot' the gun.

In order that the said invention may be clearly understood and readily carried into effect, the same Will now be described more fully with reference to the accompanying drawings, in Whichz Figure l is a side elevation shewing diagrammatically a simple lorm of the cor rection device applied to the elevation pointer of a gun,

Figure 2 is a section taken approximately on the line 2, 2 of Figure 1,

Figure 3 is a side elevation shewing diagrammatically a form of the correction device applied to the elevation and train ing pointers of a gun, in conjunction with an arrangement by which the corrections are effected automatically at all angles of elevation and training so long as the tilt of the training axis remains the same,

Figure 4 is a section taken approximately on the line 4f, 4 of Figure 3,

Figure 5 is a front elevation of part of Figure 3,

Figure 6 is a view similar to Figure 3 shewing the correction device employed for automatically levelling a gun sight, and

Figure 7 is a rear elevation of Figure 6.

Referring first to Figures 1 and 2, A represents the elevation dial connected to a pinion a meshing With the elevating rack a' of the gun, B represents the reader or pointer associated With this dial and C represents the level the support C ot which is pivoted at c to a bracket c on the gun carriage and has a toothed segment C2 meshing with a pinion b connected to the pointer B. It is essential that the same gear ratio shall exist between the support C and the pointer B as exists between the gun and the dial A. It Will therefore be seen that if the training axis of the gun is inclined to the vertical in a direction affect-ing the correct elevation of the gun, the bringing of the level C to the horizontal will vary the position ot' the pointer B by an amount suiiicient to compensate for the elevation error caused by the tilt of the training axis at the particular angle ot' training existing at the moment. It the angle of tilt remains constant and the angle of training is altered, the level C will require readjustment to maintain it horizontal in this particular construction. A similar arrangement may be employed in conjunction with the training pointer (the level being situated at right angles horizontally to the level C) but in this ease the correction is applied from the level carrier to the training pointer through a variable-ratio device, such as is hereinafter described, the ratio of which is adjusted in accordance with the gun elevation for the reason hereinbefore referred to.

In the construction shewn by Figures 3, 4 and 5 the elevation dial A and the pointer B are geared to the elevating rack a of the gun and to the level support C respectively in substantially the manner described with reternce to Figures l and 2. The level sup port C is adjusted about its pivot c by a bar D which is free to slide vertically in guides and carries at its lower end a crosshead (Z. This crosshead can be adjusted vertically by means of a haudwheel D and pinion rl, the latter gearing with rack teeth ou the bar D. Another level E (Figure 5) at right angles to the level C in the horizontal plane, is carried by a support E pivoted at c on the gun carriage. This level adjusted about it pivot by abar F through a bell crank lever Fx and a link f". The said bar is free to slide horizontally in guides and carries at one end a erosshead f which can be adjusted horizontally in a similar manner to the crosshead Z by means of a handwheel F and pinon f. The said crossheads engage with a pin g in the centre of a disc G (Figure 4). This pin passes through the disc and en ages 0n the other side With triction discs The discs G and G are assembled in alternate layers with friction Washers g. The Whole thus assembled is contained in a casing G2 by means of a cover g2 which exerts sutiicient pressure between the various contacting faces to frictionally grip the crank pin disc G in any Wart-ffl uw:

desired position to which it is set by means of the handwheels D and F. The casing G2` is suitably geared to the training rack of the| gun mounting so that it rotates with, and at the same angular velocity as, the mounting. The pin g thus conveys motion, by reason of its eccentricity, through the crosshead d and the bar D to the pointer B of the elevation dial A, and through the crosshead f and the bar F to the bar H of a variable-ratio device and thence to a differential gear z, which operates the pointers H of a training receiver.

The aforesaid variable-ratio device through which the corrections are made to the pointers H of the training receiver is necessary on account of the fact that the lateral error due to the inclination of the gun trunnions varies With the angle of the gun elevation. Therefore, the amount of correction applied must be variable accordingly. This is lobtained as follows The bar H is supported by a pin h2 in the extension o-f a rack H2 operating upon the differential gear L and has a movable fulcrum h3 which is capable of being set to a scale Ha of gun elevations. The lower end of the said bar is forked and engages with al pin f2 on the bar F. The latter bar in its backward and forward move-ments oscillates the bar H about its fulcrum f1.3 and transmits movement to the rack H2 varied in magnitude according to the gun elevation, i. e., according to the position of the fulcrum h3 relatively to the pins h2 and f2. It will be seen that by the operation of the two handwheels D', F each level is brought to the horizontal, the resistance of the friction plates G', g overcome, and the crank pin g by this operation correctly positioned according to the amount and direction of the tilt of the training axis so that the correct compensation will be given to the pointers B and H at all angles of training. Should the operator notice that the levels are no longer maintaining the horizontal position during change of the angle of training, then he knows that the inclinationA of the training axis has changed and he again adjusts the levels to the horizontal by the handwheels D and F thereby impressing a new setting upon the crank pin g to suit the changed conditions of tilt. The duty of the operator is merely one of supervison of the levels and re-adjustment of them as necessary. The fact that the levels and the operator move with the gun in training is an advantage that the invention possesses over mountings in which the axis of training is itself adjusted to the vertical position.

When the invention is used in conjunction with an elevation receiver adjustable from a distant station in accordance with the angles of elevation to be given to the gun, the bar D of Figures 3 to 5 and the level support C of Figures 1 and 2 would be connected to the equivalent of the pointer B through a differential gear.

In Figures 6 and 7 K is the gun sight the bracket L' of which is connected to a shaft K rotatably supported in bearings 7c', lc on the gun cradle so that the said shaft lies parallel to the axis of the gun at all angles of elevation. In employing the automatic arrangement shewn in Figures 3 to 5 for rocking the shaft K the following modifications are made, the same reference letters as are used in Figures 3 to 5 being also used for similar parts in Figures 6 and 7. The level support C has a slotted end with which a pin d* on the bar D engages, the level support E also has a slotted end with which a pin f* on the bar F engages and the casing G2 (together with the parts contained therein) is arranged horizontally instead of vertically as in Figures. 3 to 5. The elevation dial A and pointer B are dispensed with, the bar D being merely employed for the purpose of assisting in the correct positioning of the crank pin g. The pivot pin e of the level support E is rigid with the latter and extends forwardly through a bearing E2 on lthe gun trunnion. This extension of the pivot pin is made to form one half of a Hookes joint E3 the other half of which forms part of the aforesaid shaft K. The axis of the pivotal connection e3 of this universal joint is arranged to be in alignment with the axis of the gun trunnions. In operation, the two levels having been adjusted by their respective handwheels and the crank pin g set to its correct position relative to the angle of training in which the vertical axis of the mounting is tilted and to the magnitude of such tilt` the pivot pin e is always kept cross levelled by the movement of the bar D and this correction is transmitted through the Hookes joint E3 to the gun sight. So long as the gun is kept horizontal and the sight and the shaft K therefore parallel to the pivot pin e, both halves of the Hookes joint will move together and through the same angle, but as the gun is elevated the shaft K moves with it whilst leaving the pivot pin e in its original position. The movementimparted to the gun sight through the Hookes joint is therefore increased in the inverse proportion of the cosine of the angle of elevation. In this manner the Hookes joint functions as a variable-ratio device and with the added correction derived from the range setting of the sight replaces the variable-ratio device described in connection with Figures 3 to 5.

What I claim and desire to secure bv Letters Patent of the United States is l. A level correction device for ordnance, comprising in combina-tion a member by which the gun is laid, a levelling element and a connection between said member and said elementoperating to adjust said member to compensate for the error due to the tilt of the training axis of the gun.

2. A level correction device for ordnance, comprising in combination a member by which the gun is laid in elevation, a levelling element and a connection between said member and said element operating to adjust said men'iber to compensate for the elevation error due to the tilt of the training axis of the gun.

3. A level correction device for ordance, comprising in combination a member by which the gun is laid in training, a levelling element and a connection between said member and said element operating to adjust said member to compensate for the training error due to the tilt of the training axis of the gun.

4. A level correction device for ordnance, comprising in combination a member by which the gun is laid in elevation, a member by which the gun is laid in training, a levelling element, a connection between said levelling element and the first mentioned member, a second levelling element, and a connection between the latter levelling clement and the second mentioned member.

5. A level correction device for ardnance, comprising in combination an elevation indicator composed of two movable members, mechanism for operating one of said members in accordance with the elevating movements of the gun, a levelling element and mechanism interposed between said element and the other member of the indicator, the last mentioned mechanism having the same gear ratio as that of the rst mentioned mechanism.

G. A level correction device for ordnance, comprising` in combination a member by which the gun is laid in training, a levelling element.l connections between said member and said element and a variable ratio device forming part of said connections.

7. A level correction device for ordnance, comprising in combina-tion a member by which the gun is laid in training, a levellingr element, connections between said member and said element, a fulcrnmed lever forming part of said connections and means for adjusting said fulcrum to agree with the gun elevation.

8. A level correction device for ordnance, comprising in combination a member by which the gun is laid in elevation, a member by which the gun is laid in training, a levellingr element, a connection between said levelling element and the first mentionel member, a second levelling element, a connection between the latter levelling element and the second mentioned member, and means for automatically maintaining said elements in their levelled position during the training of the gun so long as the tilt of the training axis of the gun remains unaltered.

9. A level correction device for ordnance, comprising in combination a member by which the gun is laid in elevation, a meniber by which the gun is laid in training, a levelling element, a connection between said levelling element and the first mentioned member, a second levelling element, a connection between the latter levelling element and the second mentioned member, an adjustable member, means for connecting said adjustable member to said levelling elements and means for rotating said member in synchronism with the training of the gun.

l0. A level correction device for ordnance, comprising 'in combination a member by which the gun is laid in elevation, a member by which the gun is laid in training, a levellingwelement, a connection between said l=`levelling@eleinenti/ and the first mentioned imem'ber, a second levelling clement, a connection between the latter levelling element and the second mentioned member, a crank pin, a member carrying said crank pin, guided bars connected to said levelling elements, said crank pin engaging in slots formed in said bars at right angles to the paths of movement of the latter, and means for rotating said member in synchronism with the training of the gun.

l1. A level correction device for ordnance, comprising in combination a member by which the gun is laid in elevation, a member by which the gun is laid in training, a levelling element, a connection between said levelling element and the first mentioned member, a second levelling element, a connection between the latter levelling element and the second mentioned member, a crank pin, a member carrying said crank pin, guided bars connected to said levelling ele ments, said crank pin engaging in slots formed in said bars at right angles to the paths of movement of the latter, a further member, means for rotating the latter member in synchronism with the training olf the gun and means for frictionally holding the last two mentioned members in operative connection with each other.

l2. A level correction device for ordnance, comprising in combination with the gun sight, two levelling elements arranged to move in vertical planes at right angles to each other, means for automatically maintaining said elements in their levelled position during the training of the gun so long as the tilt of the training axis of the gun remains unaltered and means operated by the first mentioned means for rocking the sight about a longitudinal axis parallel to the axis of the gun barrel.

13. A level correction device for ordnance,

comprising in combination with the gun sight, tWo levelling elements arranged to move in vertical planes at right angles to each other7 an adjustable member, means for connecting said member to said levelling elements, means for rotating said member in synchronism with the training of the gun and means whereby the rotation of Said member automatically rocks the sight about a longitudinal axis parallel to the axis of 10 the gun barrel.

ARTHUR LEONARD PERHAM.

Witnesses BAsIL MARSH, S. MAnsH.

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