Patent GB-520338-A (GB)
Title: Improvements in or relating to prepayment mechanism for electric supply meters
IPC: G07F15/00
Filed: 1938-10-17
Abstract: 520,338. Prepayment electric supply meters. ENGLISH ELECTRIC CO., Ltd., TILSTONE, G., and DONELLY, J. F. Oct. 17, 1938, No. 30027. [Class 27] Comprises a meter including a rotary device for controlling the switch for cutting off the supply and lost-motion coupling means for driving the device in a credit-registering direction against the action of a returning spring, and a stop which arrests the device in the switch-tipping position, but allows debt for fixed rent to go on accumulating and provides for its repayment before further supplies can be obtained. Repayment of arrears by instalments by temporary delivery of less per coin also is provided for. The member 2 of the differential gear is driven by the combined action of the meter which registers the amount used, and a clock device comprising a continuously-running motor which debits the fixed rent of the apparatus. A second member 3 of the differential is moved to register credit on insertion of coins. These two members affect the third member 4 in opposite senses so that a projecting tappet 5 thereon gradually moves backward as credit is exhausted, thus allowing the pin 6 on the disc 7 to follow up under the influence of spring 12 and rotate the disc until the switch arm 8 eventually falls 'into the notch on the disc 7 and cuts off the supply. In the present construction the disc 7 is geared to a second notched disc 11 and the switch arm only falls when the notches in both discs are in line. This gives a longer range of movement of the disc 7. Similarly the range of action of the pin 5 can be increased by fitting an additional disc with two pins between the pin 5 and the member 4. One complete revolution of the latter can then be made before the pin 5 is engaged by one of the pins on this second disc. When the supply is cut off, the pin 6 on the disc 7 is held by the stop 10, but the pin 5 continues to recede to register rent against the user. Sufficient coins must be inserted to pay off this arrear before the pin 5 re-engages the pin 6 to allow a further supply to be obtained. To enable arrears to be paid by instalments, the arm 10 can be temporarily advanced beyond its stop position to deliver a supply, notwithstanding the fact that the pin 5 has receded from the pin 6 owing to arrears, but in such a case arrangements are made to cut off the supply when only a proportion of the full-money rate has been delivered. Thus in Fig. 2 the arm 10 is mounted on an axis 13 and in the normal position, corresponding to that of the fixed arm 10 of Fig. 1, is held against the stop 14 by a spring 15. The pin 6 bears against this arm and cuts off the supply so long as the consumer is in debt. The insertion of the first coin, however, rotates a one - toothed disc 17. thereby rotating the wheel 16 one tooth and advancing the lever 10, thus also moving pin 6 into a crediting position and releasing a supply. The lever 10 is held in the advanced position by a pawl 18. The rotation of the member 4. as consumption proceeds, causes the wheel 20 to release the pawl 18 at intervals and restore the lever 10 to normal position, at the same time allowing the spring 12 to move pin 6 backwards to the original position in which the supply is cut off. In practice this cut - off would be arranged to occur when about half the normal quantity had been consumed. As an alternative, the disc 17 may make only half a revolution per inserted coin and thus only alternate coins permit a supply to be obtained when the customer is in arrear. In this case the pawl 18 need not be released until full value for the alternate coin has been supplied.