GB129386A - Improvements in or relating to Ordnance Sighting Apparatus. - Google Patents

Abstract

129,386. Dawson, Sir A. T., and Buckham, Sir G. T. Nov. 16, 1917. Sights.-Relates to independent line of sight mechanism having means for correcting for the inclination of the trunnion axis. According to the invention, the sighting-apparatus comprises a plate moving with the gun during elevation, a second p.ate, supporting the sight-carrier, mounted on the first plate and capable of being adjusted about an axis parallel to the axis of the gun, and transverse guides and blocks or rollers co-operating between the sight-carrier and a part moving with the gun during pointing only, the guide on the sight-carrier being maintained horizontal by the adjustment of the second plate, and the guide on the part moving during pointing only being parallel to the trunnion axis. In the construction shown, the sight-arm A moves with the gun during pointing only and carries a plate B, Figs. 3 and 4, which is displaced through the same angle as the gun during elevation for range by a parallel-motion link. Mounted on the plate B on a pin C parallel to the axis of the gun is a second plate D which can be set into the vertical plane by a screw E to correct for the error in the horizontal plane. The sight-carrier D' is mounted on a boss on the plate D by a slot d<1x>, Fig. 3, so as to be capable of a slight vertical movement as well as a turning movement. The carrier is provided with a transverse guide d<1>, Fig. 4, engaging a roller a<1>, Figs. 1 and 4, carried by the sightarm A, and with a roller d<2> engaging a transverse guide a<2> on the sight-arm A. The guide d<1> on the sight-carrier is maintained horizontal by the adjustment of the plate D, and the guide a<2> is inclined at an angle corresponding to the inclination of the trunnions. The interaction of the guides and rollers on the eight-carrier and sightarm corrects for the error in the vertical plane.