Patent GB-534233-A (GB)
Title: Improvements relating to prepayment mechanisms suitable for electricity, gas and other meters
IPC: G07F15/02
Filed: 1939-08-30
Abstract: 534,233. Prepayment mechanism for meters. BRITISH INSULATED CABLES. Ltd.. and THORPE, C. H. M. Aug. 30, 1939, No. 24928. [Class 27] In prepayment meter mechanism having a cam 25 driven in one direction by the coin device and in the opposite direction by the meter to cut off the supply, the cam having "supply" and "no-supply" surfaces 27, 28 joined by a steeply-inclined edge 58 and the surfaces being engaged by a cut-off lever 31, the cam is connected to the coin side of the mechanism by a spring or yielding member which (1) permits movement of the cam-operating mechanism when the cam is held by the engagement of the lever with the steeply-inclined edge and (2) returns the cam to its normal position relatively to its operating mechanism when the lever is disengaged from the inclined edge. In the construction shown applied to an electricity meter rotation of the handle 1, when a coin has been inserted, rotates a shaft 4 having a cam 5 which moves the supply switch 17 to a closed position shown in Fig. 1. At the same time the shaft 4 rotates or tends to rotate the cam 25 clockwise through gearing 6, 8, shaft 9, gearing 15, 16, and a spring 49, Fig. 5. If there is no fixed charge to be collected the pin 30 on the lever 31 would be lying on the " no-supply " surface close to the inclined edge 58. When the switch 17 is moved to the closed position a projection 69 on the switch arm strikes a spring 70 carried by a link 35 and moves this link to the left thereby rocking the lever 31 and lifting the pin 30 clear of the edge 58, so that the spring 49 can rotate the cam and bring the outer or "supply" surface under the pin 30. The link 35 is pivoted to the lever 31 and also to a pivoted stop 62 which is moved by the link into a position in which it engages over a catch 63 on the switch arm 17 and holds the switch closed against the action of an opening spring 22. The gear 16 does not drive the cam 25 directly but through a sleeve 43 and a differential gear 40, 41, the other sleeve 46 of the differential being driven from the meter motor (not shown) which rotates the cam in the opposite direction to the coin mechanism. When the commodity paid for has been consumed the pin 30 on lever 31 moves down the edge 58 of the cam, the lever 36 is rocked by a spring, the link 35 is moved to the right and the stop 62 is rocked to release the switch arm 17 and open the switch. If a basic charge is to be collected the cam 25 is still rotated in the counterclockwise direction by a motor and consequently this basic charge must be prepaid before the cam is brought back by the coin mechanism to the position in which the pin 30 can be lifted from the " no-supply " surface to the "supply" surface. In the modification shown in Fig. 8 the cam is of helical form having a "supply" surface 127 of large diameter and a " no-supply " surface 128 of small diameter connected together by an incline 158. Much longer surfaces can be provided in this form of cam which is engaged by a pin 130 and is connected to its shaft by a spring 149. The cam slides axially on its shaft and the helical surface is kept under the pin by a guide 159, 160.