Patent GB-190914749-A (GB)
Title: Improvements in Weighing Apparatus.
Inventor: MELING JONAS
Filed: 1909-06-23
Granted: 1910-01-06
Abstract: 14,749. Meling, J. June 29, '1908, [Convention date]. Loose and sliding weight apparatus.-Relates to a weighbridge steelyard having the poise automatically adjusted by means of an electric motor, and consists in the employment of relays actuated by a very weak current, whereby injurious sparking at the contacts is avoided. The steelyard poise 2 is connected by a coupling-rod 3 to a sliding nut 4, which is traversed along a screw 6 by an electric motor 7. The screw is mounted in stationary bearings alongside the steelyard and operates a counter 9, which indicates the weight. The ends of the coupling-rod are joined to the poise and nut by a system of co-linear knife-edges, Fig. 9, so that longitudinal and lateral play are prevented without interfering with the oscillation of the steelyard. The free end of the steelyard may be locked by means of a stopping-bar 11 connected to a toothed segment 13 gearing with a segment 15. By turning a hand-lever 18, the segment 15 is rocked by a bar 17 and the steelyard unlocked. A spring 20 returns the segment and locks the steelyard. Pivoted arms 29,30 carrying switches 48, 49 are similarly operated by the movement of the hand-lever 18. The steelyard carries switches 31, 32 placed opposite contacts 37, 38 fixed to a pivoted contact lever 33. The contacts are connected with electro-magnets 44, 45, 46 and a battery 47. The armature 24 and the field magnets 26 of the motor 7 receive current from the terminals 22. When the load is placed on the bridge, the machine is set in operation by moving the handle 18, Fig. 2, to the left, thus unlocking the steelyard and bringing the segments 15 and arms 29, 30 against electromagnets 46, 45, 44. The steelyard rises and strikes the switch 31, thus completing. the circuit of the battery 47, as shown by full lines in Fig. 2, and at the same time tilts the contact lever 33, thereby causing a bead of mercury 41 to open a shunt circuit through the motor armature. The handle 18 is next brought back to its initial position, the arm 29 following under the action of a spring 50 but the arm 30 and segment 15 being retained by the electro-magnets. The movement of the arm 29 places the motor armature in circuit with the terminals 22, and the poise is moved rapidly along the steelyard. As equilibrium is approached, the steelyard sinks, and the contact lever 33 follows under the action of a weighted arm 35 until, a little before equilibrium, the mercury 41 closes the shunt circuit of the armature and consequently reduces the speed of the motor. Finally, the beam leaves the switch 31, and thereupon the electro-magnets 44, 46 release the arms 30, 15, and the various levers and connexions assume the original position shown in Fig. 1. In this position, the armature current is cut off and the armature placed in a circuit of low resistance through the switches 48, 49, thus stopping the motor immediately. The weight can then be read off from the counter 9. If a lighter load is now placed on the bridge, the beam sinks when unlocked and the electro-magnets 45, 46 are energized, the arm 30 returning with the bar 17. The action is then similar to that already described, except that the current through the motor is in the reverse direction, and the poise is driven towards the fulcrum of the steelyard until balance is obtained.