Patent GB-141136-A (GB)
Title: Improvements in or relating to ordnance sighting apparatus
IPC: F41G5/22
Filed: 1919-01-09
Abstract: 141,136. Damson, Sir A. T., and Buckham, Sir G. T. Jan. 9, 1919. Sights.-Relates to anti-aircraft ordnance mounted on ships, and consists (1) in means whereby the horizontal deflexion is automatically corrected in accordance with the angle through which the ship rolls, the quadrant elevation, and the angle of sight, and (2) in means whereby the vertical deflexion is automatically corrected in accordance with the angle through which the ship rolls, the horizontal deflexion angle, and the angle of sight. Figs. 3 and 4 show the apparatus for correcting the horizontal deflexion. A cam A pivoted to a fixed part of the casing has a cam-groove a so shaped that, when the cam A is rotated from the sight by a shaft A<1> and pinion a<1> through an angle proportional to the angle of sight, a carrier D is slid along straight guides D<x> through a distance proportional to the tangent of the angle of sight. The carrier D is similarly constrained by a cam B mounted on a block C slidable along a shaft B<1>, so that when the cam B is rotated from the gun-elevating gear by the shaft B<1>, worm b<1>, and worm-wheel b<2> through an angle proportional to the quadrant elevation, the carrier is displaced in the reverse direction through a distance proportional to the tangent of the quadrant angle. The block C is therefore slid through a distance proportional to the difference of these tangents, and, through a cam-plate E integral therewith, displaces a block F<x> along fixed guides F‹ through a proportional distance. Pivoted to the block F<x> is a lever F to which are pivoted (i) a rack F' gearing with a pinion f<1> on a shaft f<1>x operated in accordance with the angle of roll of the ship, and (ii) a rack F<5> gearing with a pinion f<5> operating the pointer of the horizontal deflexion dial. Thus since the lever F is raised in accordance with the difference of the tangents of the quadrant angle and the angle of sight, and is rotated by the rack F<1> through an angle proportional to the roll of the ship, the rack F<5> displaces the pointer of the said dial through an angle proportional to the product of these quantities. A spring E<x> is provided for eliminating backlash. Fig. 6 shows the apparatus for correcting the vertical deflection. A block H<1>, sliding in a slotted arm H mounted on a fixed pivot h, is connected through gearing h<1>, H<2>, h<2> to the sight-bracket, so that the position of the block in the slot is dependent on the angle of sight. The arm H is pivotally connected by a link h<5> to a block G<2> slidable in a curved guide G<3> mounted on a fixed pivot and rotatable through gearing from the horizontal deflexion dial K. The block G<2> is displaceable in its guide through links g<2>, g<2x> operated in accordance with the angle of roll of the ship. These controls all operate to displace the block H<1>, which is connected by a link h<4> to an arm G on the pointer of the vertical deflexion dial G<x>. A spring in a casing g<x> is provided for eliminating back-lash. The shaft f<1x> and arm g<2x> may be operated by an electric motor controlled by a gyroscope, or by a shaft operated by hand to maintain the indication of a clinometer constant or to maintain a telescope sighted on the horizon. The apparatus may be designed to operate upon the sight-adjusting gears through differential gearing, instead of upon the pointers of the dials; in this case, the apparatus applies the corrections direct to the sight. Specification 129,384 is referred to.