GB745350A - Improvements in or relating to weighing mechanism - Google Patents

Abstract

745,350. Weighing apparatus. BEST, C.. and MOLINS MACHINE CO., Ltd. July 2, 1953 [April 7, 1952], No. 8846/52. Class 143 A reflector is angularly movable with the balance beam and reflects the image of a straight filament of an electric lamp on to a screen. The balance beam is pivoted at 2. Fig. 1, and has rpivoted on it at 5 a depending arm 8 which carries a goods pan 11 on a column 10, and is constrained to vertical movement by being pivoted at 13 on a beam 14 pivoted at 15. The column '10 moves within a casing 110, and portions 111, 109 act as stops to prevent excess movement of the arm 8. Pivots. All pivots are constituted by torsion wires 2, Fig. 4, attached to the beams and led over pulleys 3. attached either to the frame or, for pivots 5, 13, to the arm 8. The torsion wires 2 are tensioned as desired by rotation and subsequent clamping of a differential pulley 28. Damping. The oscillations of the balance beam 1, Fig. 1, are damped by copper loop 18 on the beam and embracing one limb of a magnet 21. Sensitivity. The sensitivity of the balance beam is adjusted by screwing a weight 23, Fig. 1, up or down to vary the centre of gravity of the system. Counterpoise. A weight 25, Fig. 2 can be screwed along the balance beam to adjust the counterpoise. Indicating. A linear source of light 32, Figs. 1 and 2 is imaged by lens system 34 on screen 31, via a mirror 36 on the balance beam, and fixed mirrors 37 and 38, 39, Fig. 3, so as to produce a line of light moving up and down on the screen 31 as the balance beam oscillates. Screen. The screen comprises a ground glass plate 50, Fig. 5, behind which are two plates 51 of one colour transparent material known under the Registered Trade Mark "Perspex", and a plate 52 of the same material but of contrasting colour. Some light from the source 32 is allowed to reach the back of the screen so as to faintly illuminate it. and the plate 52 has its lower edge chamfered and polished to cause light from the rear of the screen to be totally reflected at that point and thus produce a dark area on the screen. In front of the plate 50 is a "Perspex" plate 53 suitably engraved, e.g. with the words "correct weight" located at the lower edge of plate 52 and lit by a light guide 54 from the source 33. Slotted masks 55, 56 as shown in Fig. 6, and a glass cover plate 57 are provided. A prismatic plate 152 causes the light beam from the mirror 39 to be deflected to the direction in which a viewer looks at the screen. Casing. A casing 58, Fig. 1, encloses the whole of the apparatus, the screen lying in a cavity 59 Specification 647,029 and 745,419 [Group XXXIV], are referred to.