Patent GB-989758-A (GB)
Title: Improvements in or relating to balances provided with approximate weighing devices
Inventor: CHAPPELL FRANK ARTHUR
IPC: G01G1/00
Filed: 1963-01-21
Abstract: 989,758. Weighing apparatus. L. OERTLING Ltd. Jan. 21, 1964 [Jan. 21, 1963], No. 2527/63. Heading G1W. Relates to a balance with an approximate weighing arrangement and with a preselection system of weight loading, wherein a stop arm 48 (Fig. 2) displaced during approximate weighing in proportion to the out of balance load determines by its position after such displacement the movement of a weight selection shaft 33 so as to effect a selection of weights such that the balance beam 10 is substantially balanced when released for fine weighing. BEAM CONSTRUCTION AND ARRESTMENT MECHANISM. The balance beam 10 (Figs 1, 2) pivots on a knife edge 11 and carries a scale pan suspended by a member 15 and a counterweight 18 also a damping piston 19 movable in a cylinder 21. A loose weight carrier 23 is mounted on the suspension member 15 and normally supports a group of weights acting in opposition to the counterweight 18, the weights being removable by arms 24 whereby the remaining weights plus the sample to be weighed 25 just balance the counterweight 18. An arrestment frame 26 is provided to support the beam 10 and separate off the knife edge 11 from a stationary pad 12 and lift the suspension member when the balance is not in use. The arrestment frame is carried by a vertically slidable stem 27 moved up and down by a cam (not shown) on an arrestment shaft 29. A blade spring 43<SP>1</SP> is arranged to bear upwardly on the beam when approximate weighing. PRE-SELECTION OF WEIGHTS. During approximate weighing all the loose weights are supported on the carrier and with a sample on the scale pan the spring 43 is deflected since there is an excess of weight on that end of the beam. Fixed to the free end of the spring is the stop arm 48 the position of which is determined by the deflection and a clamp 49 (detailed in Fig. 4 not shown) clamps it in this position while the beam is returned to the arrested position. On the return movement a driving arm 61 is driven by its cam 56 on the arrestment shaft 29 to apply torque to a driving gear wheel 36 on the shaft 34, rotating it until a pin 64 thereon engages the stop arm 48 the distance moved depending on the position of the stop arm and determining the weights to be removed. Gearing 36, 37, 39, 41 multiplies the movement of the arrestment shaft 29 and shaft 34 so that the weight selection shaft 33 can make a complete revolution for a small movement of shaft 29. As the shaft 29 approaches the arrested position a detent 81 engages a toothed wheel 77 (the number of teeth on which corresponds to the number of removable weights) on the selector shaft 33 and holds the wheel in any one of a plurality of predetermined positions and if the shaft stops between two specific weight positions rotates it to the next lower weight position. The arrestment shaft 29 is next turned to the fine weighing position causing selected weights to be lifted off the carrier 23, the beam to be released and the spring 43 disengaged from the beam. A graticule 22 indicates the unbalance and the weight of the article can be read directly. The actual mechanism for selecting and manipulating the weights and the arrestment mechanism may be of any known type however.