Patent GB-118045-A (GB)
IPC: G01G1/38
Abstract: 118,045. White, A. E., (Toledo Scale Co.). Dec. 14. 1917. Sliding-weight apparatus.-In a weighing-scale of the kind in which a self-propelled poise for counterbalancing the load moves along a scale beam at different speeds according to its position with respect to the counterbalancing and normal or zero positions until equilibrium is established, the poise is moved by magnetic influence first in a continuous and then in an intermittent manner. As shown, the poise 25, Figs. 1 and 3, comprises wheels 71, 71<a>, mounted in brackets 72, 72<a>, and travelling along an upper conducting bar 23 of the scale beam 10, and solenoids 40, 40<a> each surrounding a beam side-bar built up from upper and lower strips 26 of non-magnetic material and central bars 13, 13<a> of magnetic material and of varying cross-section; the crosssection of the bar 13 decreasing and that of the bar 13<a> increasing towards the free end of the beam. The beam has insulating end-plates 16, 21, lower side-bars 22, 22<a> of conducting material, and a central bottom bar 14 having an extension 15 carrying the knife-edge bearings 17 by which the beam is pivoted on a bracket 18 of the stand 6, 7, 8. The load placed on a platform 9 acts on the beam through connexions 11, 12, and an adjustable balancing-weight 20 is provided. An insulated bracket 42 is secured to the cross-bar 8 of the stand and supports a pivoted contact-member 41, preferably provided with a pendulum weight 41a. A multiple switch is secured by a bracket 27 to the free end of the bar 14 and comprises an insulating-block 28, Fig. 5, contact-plates 37, 38 electrically connected by wires d, c to the bars 13, 13<a>, and contact-members 33, 34 pivoted to plates 35, 36 electrically connected by wires b, a to the bare 22, 22<a>, the inner ends of the members 33, 34 being normally in contact with adjusting-screws 31, 32 on insulated plates 29, 30. When a load is placed on the platform 9, the free end of the beam is tilted upwards and the member 41 tilts the member 34 so that it leaves the screw 32 and contacts with the plate 38. An electric current passes from a plug P, or a battery Z in the base 6 of the stand, by a wire 60, screw 61, bracket 42, and member 41 to the member 34, whence it passes by the plate 38 and wire c to the bar 13<a>; a brush contact 47<a> conveys the current from the strip 26 of the bar 13<a> to the solenoid 40<a>, which is energized, the current returning by a wire 45, the bracket 72<a>, wheel 71a, bar 23, a connector therefrom to the bar 14, the bracket 18, a screw 63, and a wire 65. When the solenoid 40<a> is energized, it tends to move towards the centre of mass of the bar 13a adjacent the free end of the bar, and the poise is therefore moved continuously towards the balancing position, the free end of the beam being moved downwards. When the member 34 leaves the plate 38, the current passes along the plate 36 and the wire a to the bar 22<a>, whence it is led by a brush contact 54a, bracket 53<a>, wire 52a, bracket 51a, screw 49a, and spring contact 48<a> to the solenoid 40<a>. When the solenoid is thus energized, a floating armature 55<a> on the spring contact 48<a> is drawn downwards and the contact 48<a> is drawn away from the screw 49<a>, thus interrupting the current, so that the further movement of the poise is intermittent until it reaches the balancing position when the member 34 leaves the member 41. The weight is indicated by a pointer 58 on the poise and a scale on the bar 13<a> or other part ot the beam. The return of the poise to the zero position is effected when the load is removed by energizing the solenoid 40 through the member 33 and connexions similar to those described, the solenoid being first continuously and then intermittingly energized as the poise nears the zero position. Buffers 64 for the poise are provided at the ends of the beam.