Patent GB-487432-A (GB)
Title: Improvements in or relating to prepayment mechanism for electric supply meters
IPC: G07F15/00
Filed: 1937-02-12
Abstract: 487,432. Prepayment mechanism for electricity meters. ENGLISH ELECTRIC CO., Ltd., TILSTONE, G., and DONELLY, J. F. Feb. 12, 1937, No. 4261. [Class 27] Relates to a prepayment mechanism for a two-part tariff electric supply meter having rotary locking members advanced by the insertion of coins and moved back again under the joint action of the meter and a clock mechanism for the fixed charge, the locking members being adapted to hold the switch latch in the latching position until the prepaid credit is exhausted. According to the invention, two locking members 1, 2, Fig. 1, rotating at different speeds, so that they release the latch only when they are simultaneously in the releasing position, are combined with a third rotary locking member 10 which, on continued backward movement under the action of the clock mechanism after the tripping of the switch, releases the latch independently of the action of the other two members 1, 2, thereby preventing the switch from being latched in closed position until the arrears of fixed charge are paid off. The switch latching and operating means are as described in Specifications 449,556, 449,673, 449,674, 449,675, and 450,106, and comprise a pivoted carrier 6 biassed to the switch releasing position and having pivoted to it on a latch piece 7 spring-biassed relatively thereto to the latching position, the piece 7, when the prepaid credit is exhausted, releasing a pin 8 on a switch operating arm 9 which moves in the direction of the arrow to open the switch. The arm 9 in this movement hits the part 6a of the carrier and restores the carrier 6 and piece 7 to latching position. The carrier 6 has pivoted thereto at 5, a lever 4 having a projecting end 4a which rests on the peripheries of the discs 1, 2 and enters notches 1a, 2a therein to trip the switch. The lever 4 can rock to one side or other of an intermediate position to which it is biassed by a light spring 12. The lever 4 is extended and provided with a projection 4b resting on the periphery of the disc 10 which is geared to the discs 1, 2 to rotate at a still slower speed. If no further coins are inserted after the credit is exhausted, the discs 1, 2, 10 rotate backwards under the action of the clock mechanism and the end 4b slips off the disc 10. This causes the lever 4 to be in such a position that the switch cannot be relatched until the arrears are paid off and the end 4b re-engaged with the disc 10. A device for allowing a diminished supply per coin, when arrears are owing so that the arrears can be paid off by instalments, comprises a sector 13 frictionally driven by the disc 10, Fig. 3, and engaging a fixed stop 14 on backward rotation of the disc 10. Forward movement of the sector 13 to more than half the value of a coin is prevented by a stop 15 carried by a lever 16, so that this stop is withdrawn if the full amount of the arrears is paid off. The rocking of the lever 16 to withdraw the stop 15 is effected by a cam 10a on the disc 10. Payment of arrears by instalments may be effected by the provision of a sector 17 geared to the disc 10 to rotate at a higher speed than the disc, the projection 4b engaging with the disc 10 and the sector 17.