Patent GB-1058598-A (GB)
Title: Improvements in and relating to automatic weighing machines
IPC: G01G21/00
Filed: 1963-08-15
Abstract: 1,058,598. Automatic feed weighers. PELZ & NAGEL G.m.b.H. Aug. 15, 1963 [Aug. 16, 1962], No.32232/63. Heading G1W. An automatic weigher has a means to prevent oscillation of its lever system due to impact of material on a scale pan which would be transmitted as apparent weight to an indicator, and has means controlled by the indicator to provide main and dribble feeds. GENERAL - To prevent oscillation the lever system 3, 6 (Fig. 1), is engageable with two stops one of which (a spring-loaded bell crank lever 8) is operative to support the levers 6, 3 in a position approximately corresponding to that when the required amount of material has been supplied in the main feed, thereby preventing movement of the lever system in the direction of load relief, and the other stop (an electromagnet 11 operating a locking lever 12) is operative to prevent the lever system moving in the direction due to the load and is releasable when the feed is reduced to a dribble feed. A damping device 15 is also provided and is arranged to provide a powerful damping effect at the beginning of the lever system movement and only a slight damping effect in the region of the final position of an indicating pointer 5'. OPERATION - An electrical contact 10 is positioned on a calibrated scale 5" at a predetermined value, below the target weight, so that when the material fed to a scale pan (not shown) attains that value the pointer 5' co-operates with the contact 10 and the main feed is switched off and the dribble feed commences. The switch simultaneously energizes the electromagnet 11 which moves the locking lever 12 so as to prevent movement of the lever 6 in the direction due to the load. As the lever 6 moves up toward the locking lever 12 and its equilibrium position, a spring 8' rotates the bell crank lever 8 against a permanent magnet 13 which holds it and prevents the lever system swinging back to its old position. (The strength of the magnet is such that it will release the locking lever 8 when the lever 6 moves downward against it as the scale pan is being emptied). After the lever system has been locked the locking of its upward movement by the magnet 11 is released, following an interval determined by a time switch (not shown); since the impact loading due to the main feed has now ceased. The dribble feed is switched off when the pointer 5' reaches a contact 14 on the scale 5". The scale pan is then emptied by means not described. LEVER SYSTEM - The lever system includes a tare lever 3, with an adjustable counter-weight 9, and connected to a lever, supporting a scale pan, by a pull rod 2. The lever 3 is rigidly connected through links to bolts 3', 3" which support a load counter-balancing lever 6 having a slidable counter-weight 7. When adjusting the zero of the indicator to allow for tare the lever 6 can be lifted off the bolts by an electromagnet 22. After a preselected number of weighings the tare can be adjusted automatically by a motor (19) Fig. 2 (not shown), co-operative with a chain (20). The indicator pointer is coupled to the lever system by a steel tape 4.