Patent GB-449365-A (GB)
Title: Improvements in or relating to prepayment meters
IPC: G07F15/06
Filed: 1935-07-02
Abstract: 449,365. Prepayment mechanism for meters. WRIGHT, N., 15, Woodheys Drive, Sale, Cheshire, and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd., 1, Kingsway, London. July 2, 1935, Nos. 18921 and 26802. [Class 27] Mechanism, for prepaying basic charges; price-changing mechanism.-In a prepayment meter or apparatus, in which a quantity mechanism is set back wholly or in part under the action of a constant speed basic charge motor, a main operating shaft is driven intermittently under the control of the basic charge motor at a constant average speed taken over a long period, and is connected with the quantity mechanism through a second intermittent driving mechanism whereby the proportion of the movement of the shaft which is transmitted can be adjusted for price-changing purposes. In the construction shown in Fig. 1 (18921/35), the constant speed motor drives continuously through gearing 1, 2, and 31 a wheel 32, loosely carried on the main shaft 33, and connected through a spring 35 with a ratchet wheel 34 secured to the shaft 33. The ratchet wheel 34 is normally held against rotation by a pawl 36 mounted on a fixed pin 37, so that the action of the constant speed motor winds up the spring. After approximately one revolution of the wheel 32, a rod 39 carried thereby trips the pawl 36, releasing the ratchet wheel 34 so that the spring 35 unwinds and drives the main shaft 33, after which the action is repeated. The shaft 33 is connected through the adjustable intermittent driving mechanism described in Specification 423,438 with the commodity side of the quantity mechanism whereby the proportion of the rotation of the shaft 33 which is transmitted can be adjusted for price-changing purposes. In the modification shown in Fig. 1 (26802/35), the gear 32 driven continuously by the basic charge motor carries a pawl 36 engaging a ratchet 34 loose on the main shaft 33 but connected therewith by a ratchet and pawl one-way drive 41, 42. The continuous rotation of the wheel 32 is transmitted to the ratchet wheel 34, the pawl 42 travelling idly back over the ratchet wheel 41 which remains stationary. At the same time, a spring 35 connected to the ratchet 34 is wound up. After one revolution of the wheel 32, the pawl 36 is tripped by a fixed stop 39 to release the ratchet 34, which is then driven rapidly through one revolution in the opposite direction by the spring 35, this motion being transmitted to the shaft 33 through the drive 41, 42, and thence, in part, to the quantity mechanism through the price-adjusting mechanism described in Specification 423,438. In Fig. 2 (26802/35), a spring 11, which operates under the control of the basic charge motor to effect a debit charge, is wound up by operation of the coin mechanism 17 to which it is connected by gearing 13, 14, 15, and 16, a suitable friction clutch being interposed to prevent over-winding. The basic charge motor is thus freed from the load of winding the spring. This spring 11 drives a shaft 2 which is normally held from rotation by engagement of an escapement pin 20 with a notched escapement disc 22 which is connected through gearing 24, 25, 26, 27, 28 with a shaft 36 driven continuously by the basic charge motor. Periodically, the wheel 22 releases the pin 20, so that the shaft 2 is turned rapidly by the spring 11 through a revolution, this movement being in part transmitted through a priceadjusting intermittent ratchet and pawl drive 3, 6, constructed similarly to that described in Specification 423,438, and through gearing 8, 35, 34, 33, and 32 to a sun-wheel 30 of a differential mechanism D. This differential summates a continuous drive of the basic charge motor which is directly connected with the second sun-wheel 29, and the adjustable intermittent drive applied to the sun-wheel 30, the two drives, which may be in the same or opposite directions, being conveyed from the planet carrier 31 to the commodity side 41 of the quantity mechanism. If there is a commodity metering element in addition to the basic charge meter, a second summating differential is provided to apply further movement to the quantity mechanism in respect of commodity consumption. In a further modification, the driving spring of the main shaft is wound up by an auxiliary shaded pole or other motor provided solely for this purpose, a slipping clutch being included to prevent overwinding.