Patent GB-886877-A (GB)
Title: Weighing scales
IPC: G01G23/36
Filed: 1958-02-03
Abstract: 886,877. Weighing-machines. HOBART MANUFACTURING CO. Feb. 3, 1958 [Feb. 1, 1957], No. 3459/58. Class 40 (1). [Also in Group XXXVII] A weighing-machine in which a lever, deflected proportionally to the weight, actuates a register through a motor-driven follow-up system. The motor is driven at high, medium or low speed according to the magnitude of the deviation of the follow-up member, excepting that when an article is removed from the scale the high speed is disabled so that the follow-up member returns to zero position at medium or low speed, depending on the deviation of the member from zero. The high speed is available immediately a new load is placed on the scale should the deviation of the member be sufficient to require it. Weighing operation.-On deflection of a lever system 11, 37, 35 when an article is placed on the weighing-platform 10, relay 65 is disconnected at 43 and falls sluggishly, releasing relay 66 and energizing relay 64, and relay 61 and then relays 67 and 68 are energized at 51, 53. Under these conditions, motor 20, 21 driving follow-up member 25 runs at high speed as a series motor driven from A.C. source L1, L2. When the normal relative position of the lever 35 and the follow-up member is nearly reached, relays 67, 68 are released at 53, the A.C. source is disconnected and the motor runs slowly as a shunt motor energized by the D.C. source L3, L2. At a still closer approach 61 is released at 51 and the motor runs still more slowly with its field winding excited as before by the D.C. source L3, L2 and its armature excited from an interrupted D.C. source L4, L2. When agreement is exact, 65 is operated at 43 and opens the driving circuit. Registering weight.-The motor also drives apparatus in a machine 30 which registers the weight and may compute the price and print a ticket as described in Specification 886,876. The operation of 65 releases 64 to signal the completion of the weighing operation to the register and the latter makes a momentary circuit for relay 63 which locks and lights a lamp 70 to signal that a new weighing operation may begin. At the same time the register holds 65 to suspend any follow-up action until its operation has been completed. Restoration of weighing system; further weighing operation.-When the article is removed from the weighing platform, relay 62 is energized at 60 and unlocks 63 but maintains a circuit for lamp 70. Movement of lever 35 upwardly releases 65 (but not 66) and energizes 61 and 67 as in the case of downward motion but not 68 because 62 is energized. As a result, the fast drive circuit is not made at all and field excitation is reversed so that the drive at slow and very slow speeds takes place in the opposite direction. If, however, a new weighing operation is begun before the apparatus has been restored to normal, 62 is released at 60 (64 having been reoperated) extinguishing lamp 70 and restoring conditions pertaining when the first weighing operation took place except that if the new article is lighter than the old, 66 will not be released and the follow-up action may proceed in the upward direction.