Patent GB-476388-A (GB)
Title: Improvements in and relating to weighing machines
IPC: G01G13/00
Filed: 1936-06-08
Abstract: 476,388. Automatic feed weighers. SIMON, W. G., and SIMON, F. R. June 8, 1936, No. 15940. [Class 143] An automatic weighing - machine comprises means for biassing the feed gate towards the open position, a catch for holding the feed gate shut whilst the discharge valve of the weigh pan is open, means for closing the discharge valve upon completion of discharge, a connection between the catch and the discharge valve for releasing the catch to permit the feed gate to open under the bias upon closure of the discharge valve, a detent for holding the discharge valve closed, . a connection between the detent and feed gate for releasing the detent when the feed gate closes completely, and means for closing the feed gate upon descent of the weigh pan. Assuming that the feed gate 11., Fig. 2, has just opened, material from the supply hopper falls into the weigh pan 13 which eventually descends followed by a three-armed lever 20, one arm 20a of the lever bearing against an abutment 18 on the pan, and a second arm 20b being connected by a spring 22 to the feed gate. As the three-armed lever turns, the tension of the spring 22 is relaxed sufficiently to allow the feed gate to descend by gravity to the dribble feed position, a toggle-joint 39, 40 at the same time straightening out and allowing a vertical link 37 to descend and raise the outer end of a trip lever 35. In the dribble position of the feed gate a pin 41 on the link 37 rests on a roller 42 carried on one arm 42a of a two-armed lever pivoted on the frame. As the pan continues to descend a roller 43 on the pan trips the two-armed lever and allows the link 37 and feed gate to fall into the closed position. At the same time, the outer end of the trip lever 35 displaces a locking catch 30, Fig. 3, from a quadrant lever 26 and permits the discharge valve 16 to open under the weight of material in the pan. A counterweight 17 closes the discharge valve. The trip lever 35 is retained by one arm 33b of a two-armed lever 33a, 33b. As the discharge valve closes, the quadrant lever 26 is rotated until the locking catch 30 drops into locking position behind a face 60. A second face 32 at the same time rocks the two-armed lever 33a, 33b and liberates the lever 35, thereby permitting the link 37 to rise and break the toggle-joint, and allowing the spring 22 to re-open the feed gate, the cycle of operations then being repeated. If the feed gate fails to close (for example owing to wedging by a foreign body) the lever 35 fails to displace the locking catch 30, and the discharge valve 16 remains closed thus preventing running through. If the discharge valve fails to close, the two-armed lever 33a, 33b continues to hold the trip lever 35 and the feed gate remains closed. If the supply hopper contains insufficient material for a further weighing, a pivoted plate within the supply hopper swings into a vertical position and causes a depending arm to hold down the trip lever 35 and prevent the weigh pan from discharging. For testing the accuracy of the machine, the trip lever 35 may be held down by a small lever to prevent the discharge, and adjustments may then be made by means of a small beam pressing on the main beam. Specification 476,389 is referred to.