Patent GB-577908-A (GB)
Title: Improvements in or relating to gun mountings
IPC: F41G5/04
Filed: 1943-11-02
Abstract: 577,908. Aircraft gun turrets; sights. RICE, E. A. B., ROSE, A. G., NICHOLLS, K. H., and ROSE BROS. (GAINSBOROUGH), Ltd. Nov. 2,1943, No. 18110. [Classes 92 (i) and 92 (ii)] Relates to gun mountings of the type in which pivotal movement of the gun or guns is controlled by a sighting arm, movement of which brings into operation follow-up mechanism which causes the gun or guns to move substantially as one with the sighting arm. According to the invention, the sight is pivotally mounted on the sighting arm about an axis coincident with or parallel to the pivotal axis of the gun or guns, and means are provided for imparting to the sight an angular movement in a direction opposite to the movement of the arm, to compensate any movement that the arm may make before the guns commence their pivotal movement. As applied to the gun mounting described in Specification 577,904 in which the sight 26 is mounted on an arm 24 pivoted in bearings 23 on an operating member 22 in an aircraft turret, the sight, as shown in plan in Fig. 3 and in side elevation in Fig. 2, is movable on the arm about axes 27 and 28. When the arm pivots about the bearings 23, a valve 17 is actuated as in Specification 577,904 to operate an oil motor which moves the guns 11 in elevation. On the axis 27 of the sight is mounted an arm 29 which, when moved, produces a vertical movement of a link 32 which in turn produces a rotation of a shaft 43 via ball crank lever 34, rod 37, ball crank 38, link 41, and arm 42. Shaft 43 passes through arm 24 and carries at its opposite end a segmental gear 44 meshing with a similar gear 46 rotatably mounted on the arm 24 about an axis 47 coincident with the axis of bearings 23. To the gear 46 is riveted an arm 49 connected by rods and links, as shown in Fig. 2, to a part 61 which moves with the guns in elevation. The arrangement is such that if the guns remain stationary during the slight initial movement of the arm about bearings 23, the gear 46 is held stationary due to its connection with the part 61, and the gear 44 meshing with gear 46 causes shaft 43 to rotate about its axis thereby causing the sight to perform its compensating movement about its axis 27. As soon as the guns move in elevation the lug 61 causes gear 46 to move, and no further relative motion takes place between the gears 44, 46. In the training operation, wherein movement of the member 22 about an axis coincident with the axis about which the turret rotates actuates a valve 16 associated with a training motor, the sight is given its compensating movement about axis 28 by mechanism incorporating a link 71 connected to a bearing ring 69 on which the sight is mounted. The link is connected also to bell crank 72 carrying a link 73 formed with a slot 76. In this slot is housed a roller mounted on the arm 77 of a two-armed lever, pivoted on member 22 and having its other arm 78 slotted to engage a roller 79 mounted on the turret framework 18. During the period of valve lag the roller produces a pivoted movement of the arms 77, 79, and thus effects the required movement of the sight. Specifications 576,621 and 577,919 also are referred to'. ' The Provisional Specification describes a modification in which flexible shafts are employed to impart the required angular movements to the sight.