Patent GB-191202058-A (GB)
Title: Improvements in or relating to Sighting Apparatus for Ordnance.
Inventor: DAWSON ARTHUR TREVOR
IPC: F41G1/393
Filed: 1912-01-25
Granted: 1913-04-25
Abstract: 2058. Dawson, Sir A. T., and Buckham, G. T. Jan. 25. Sights. -Relates to sighting-apparatus for high-angle fire guns, of the kind having a solid cam-device for automatically correcting the line of sight for the range and altitude of the target during the ranging and pointing operations, and without any previous setting of the sight. According to the invention, the cam is so arranged in relation to the ranging and pointing gears that it receives an angular displacement during ranging, to correct the sight for range, and an axial displacement during pointing, to correct the sight for altitude. A drift cam is combined with the apparatus, and is laterally displaceable, in known manner, to correct for lack of level of the carriage wheels. The cam B, shown in side elevation in Fig. 1, and in sectional plan in Fig. 4, is supported by a bracket B<Î>, which is pivoted upon a sleeve C<1> arranged co-axial with the gun trunnion B‹. The bracket is connected by a link b<Î> with an arm a<Î> on the sight carrier A', which is trunnioned in a fixed bracket. The sleeve C' moves during the pointing operation only, and has keyed to it an arm C one end of which bears upon the cam B by means of a ball c. The other end of the arm C is conneetd to the bracket B<Î> by a spring c<Î>. The cam B is slidably mounted, by means of an end plate having an hexagonal sleeve b, upon a spindle B<1>, which spindle is rotatably mounted in the bracket B<Î> and is formed with a pinion b<2> gearing with a toothed quadrant B<2> pivoted co-axial with and keyed to the trunnion B‹. The cam B rotates freely upon a sleeve EX, which is keyed to a sleeve B<3> formed integral with the bracket B<Î> and has two radial arms extending into cam-grooves e in a drum E rotatably mounted on the bracket B<Î>. The drum is connected by a link e<2> with a fixed part of the mounting. When the gun is elevated for range, the sleeve C' and arm C remain stationary, while the quadrant B<2> moves with the gun. Consequently, the cam B is rotated by the pinion b<2>, and the bracket B<Î> moves relatively to the arm C and imparts the correction for range to the sight. When pointing, the sleeve C<1> and arm C, and consequently the bracket B<Î>, rotate with the quadrant B<2>, but the link e<2> rotates the drum E, and the cam-grooves e effect a lateral displacement of the cam B, upon the spindle B<1>, relatively to the ball c on the arm C. The bracket B<Î> is thus displaced relatively to the arm C to effect the altitude correction. The quadrant B<2> has a rearwardly-extending arm which is connected by a link d to an arm D‹ pivoted concentrically to the sight carrier A<1>. The arm D<0> carries the drift cam D which guides the end of a forwardly-extending arm a on the sight carrier. The cam D is inclined in accordance with the mean drift curve, and may be adjusted by a worm gear d<Î> for inclination of wheels. When therefore the gun is elevated for range, the cam D moves relatively to the arm a and deflects the sight carrier A<1> about a vertical axis to make the drift correction.