Patent GB-569372-A (GB)
Title: Improvements relating to pre-payment gas meters
IPC: G07F15/04
Filed: 1943-03-26
Abstract: 569,372. Prepayment mechanism for meters. METROPOLITAN GAS METERS, Ltd., SPARKES, J. G., and NEWTON, L. N. March 26, 1943, No. 4943. [Class 27] Relates to a three-coin, Company's option, prepayment gas meter in which the insertion of a coin opens a valve to release gas for consumption in accordance with the value of the coin, the valve being closed by pre-set screw- and-nut mechanism driven by the gas through change-speed worm gearing, and the main feature of the invention resides in the construction and arrangement of the gearing. Pre-setting mechanism.-The mechanism is set before use so that only one particular denomination of three coins can be used while the mechanism is so set, this being effected by a main, gas-driven shaft 3 which is arranged to drive a gas-controlling screw-and-nut device 1, 8 through one of three sets of worm gears A, B or A, C or A, F, the choice of which is predetermined by the manual setting of a rod 11 secured to a sleeve 2 mounted on a rearward extension 1a of the screw 1 so that the screw is non-rotatable, but axially-movable relatively to the sleeve. The sleeve carries the worm A which, according to the axially-adjusted position of the sleeve 2 relatively to the screw 1 engages either (a) the worm B on the shaft 3, or (b) the worm C on a countershaft 4 carrying a worm 5 meshing with a worm E on the shaft 3, or (c) the worm F on a second countershaft 6 carrying a worm 7 meshing with the worm E. The pitches of the worms B, C, F are such that the rate of rotation of the sleeve 2, and thus of the screw 1 and the quantity of gas released, for a given rotation of the shaft 3, are proportional to the relative values of the three denominations of coins which can be used. The rod 11, disposed parallel to the screw 1, carries at one end a pair of spaced annular flanges 12, 13 which embrace a similar flange 14 on the shaft 2 while, at the other end, the rod is bent at right-angles for selective engagement with any one of three slots 15, 16, 17 in a fixed ward 18, a pivoted latch 19 holding the rod in position. The rod is engaged manually in the required slot before the meter is used, according to the denomination of coin to be used. The screw- and-nut device 1, 8 may be such that the nut 8 is movable axially to control the release of gas, but, as shown, the screw is movable axially through the nut 8, a pinion 35 secured to which meshes with a wheel 34 mounted outside a casing 28 containing mechanism directly actuated by the coin. A thrust block 39 integral with the screw 1 is adapted as the screw moves axially to the left, Fig. 1, to engage eventually a notch 40 in a lever 36 pivoted at 37 and to move the lever to close the valve (not shown) controlling the supply of gas. Coin - operation.-The mechanism directly actuated by the coin, which is similar to that described in Specification 342,254, is shown in Figs. 5, 6, and comprises a coin-holder 20 fast with a rotatable spindle 21 extending through a stationary disc 22 on the front of the meter and carrying a turning knob 23. The coinholder 20, which is a flat, hollow member, normally registers with a coin slot 24 in the disc 22 and when the coin is introduced edge-on into the slot it displaces a sliding plunger 25 in the holder to a position in which a tooth 26 on the holder engages a toothed wheel 27 fast with the wheel 34 which is thus rotated, on rotation of the knob 23, while the coin remains in the holder. The open end of the holder sweeps around and in close proximity to the inner cylindrical surface of the casing 28 until it reaches a position in which the coin passes out through the open end into a collecting box (not shown), when a return spring 29 forces the plunger back to its normal position and assists, if necessary, in the ejection of the coin from the holder. The knob is then turned back to its normal position.. The plunger 25 is in two parts, one part 25a carrying the tooth 26 and the other part 25b carrying the surface of the plunger on which the coin engages when inserted in the holder, the latter part being adjustable into three positions towards and away from the open end of the holder, to accommodate one of the three coins of different diameters, by means of a peg 30 on the part selectively engageable with one of three notches 31, 32, 33 in the part 25a. Indicator.-To indicate to the user the amount of gas due to be delivered after insertion of a coin and the quantity used since the insertion, a finger 42 on the screw 1 is movable past a dial having three sets of markings each corresponding to one of the denominations of coin.