Patent GB-449970-A (GB)
Title: Improvements in or relating to prepayment meters
IPC: G07F15/06
Filed: 1935-03-11
Abstract: 449,970. Prepayment mechanism for meters. ELECTRICAL APPARATUS CO., Ltd., and BARBOUR, R. H., Vauxhall Works, South Lambeth Road, London, and WELSH, G. G., The Bungalow, New Barnes Avenue, St. Albans, Hertfordshire. March 11, 1935, No. 7526. [Class 27] Mechanism for prepaying basic charges ; price-changing mechanism; indicators.-In a prepayment meter incorporating a constant speed motor operating on the differential quantity mechanism for collecting a basic charge, and a primary price - adjusting mechanism connected between the coin mechanism and the quantity mechanism to vary the amount by which the quantity mechanism is set forward for a given coin, a compensating price-adjusting mechanism is provided between the basic charge motor and the quantity mechanism so that the basic charge rate is unaffected by adjustment of the primary priceadjusting mechanism. The invention is described as applied to the prepayment meter of Specification 443,599 which is adapted to receive pennies or shillings, and in which rotation of a hand shaft during prepayment is conveyed through the primary price-adjusting mechanism 20 to either sun-wheel of a differential mechanism 28 according to the coin inserted. The movement of the planet-carrier shaft of this differential 28, instead of being transmitted directly to the coin side of the quantity mechanism as in the above Specification, is conveyed to a second differential mechanism 34 which also receives opposite movement from the basic charge motor 35 as determined by the compensating price-adjusting mechanism, the resultant movement being conveyed to the coin-side of the quantity mechanism. The detailed construction is as follows : the planetcarrier shaft of the coin-operated differential 28 is connected through gearing 29, 30, 32, and 33 with one sun-wheel of the second differential 34. The basic charge motor 35 drives, through worm gearing 39, 40 and 41, 36, the compensating price-adjusting mechanism 45, which is of the adjustable intermittently engaging ratchet and pawl type, and is constructed in the same manner as the primary price-adjusting mechanism described in detail in Specification 443,599. The compensated movement of the basic charge motor is then conveyed through gearing 46, 50, and 51 to a basic charge adjusting mechanism 53, constructed similarly to the primary and compensating price-adjusting mechanisms, and thence to a shaft 56 on which is secured, by means of a screw 58, an axially adjustable set of gears 59, 60, and 61 any one of which can be brought into mesh with a corresponding gear 62, 63, 64 connected with the other sun-wheel of the second differential 34, the alternative gear ratios afforded by the adjustable gear enabling the basic charge to be further varied. The dial 54 of the basic charge adjuster is removable and interchangeable for others, the appropriate one being inserted by the inspector according to his setting of the gears 59, 60, 61. The movement of the planet-carrier shaft 66 of the second differential 34 is finally conveyed to the appropriate sun-wheel of the quantity mechanism (not shown), through gears 67, 68, 70 and 72. The dials of the price-adjusting and compensating mechanisms can be rotated for adjustment by means of screw-driver slots, as shown at 48, after the removal of sealed covers. The dials 21, 47 of the primary and compensating price adjusting mechanisms are located adjacently so that they can be readily set to corresponding values : in the modification of Fig. 8, they are geared together to avoid the necessity of setting both. The switch tripping mechanism comprises a square shaft 88 carrying a threaded sleeve 89 working into a fixed threaded boss 90, and connected by bevel gears 86, 87 with the planet shaft of the quantity mechanism. When prepayment is exhausted, the downward travel of the sleeve 89 causes a ratchet wheel 91, secured thereto, to engage a stop 102 on a shaft 93 which is consequently given a slight rotation. This shaft 93 is connected with a second shaft 94 by parts 98, 99 held in engagement by a spring 100, so that this second shaft 94 is also rotated to cause an arm 101 to trip the switch. As the threaded sleeve 89 continues to descend under the action of the basic charge motor, the ratchet 91 clicks over the stop 102, movement being ultimately stopped by engagement of a pin 92 with a stop 104 on the shaft 94, a slipping clutch being provided to take up the drive of the basic charge motor, or its circuit being broken at contacts operated by the stop 104. If, when the switch is tripped, further coins are inserted which are insufficient to pay off the accumulated arrears of basic charge, the ratchet 91 still engages the stop 102, but its backward rotation displaces the stop 102 to move the switch tripping arm to permit the switch to be reset. After a small return rotation of the ratchet 91, however, the switch is tripped again. In this way a limited supply is given to the consumer corresponding to a fraction of the prepayment made, the full supply being available only when the arrears have been paid off. Other details of the complete mechanism are as described in Specification 443,599.