Patent GB-507480-A (GB)
Title: Improvements in or relating to prepayment mechanisms
IPC: G07F15/06
Filed: 1937-11-11
Abstract: 507,480. Prepayment mechanism for meters ; gearing. BRITISH SANGAMO CO., Ltd., and WESTON, G. E. Nov., 11, 1937, Nos. 31048/37 and 3920/38. [Class 27] [Also in Group XXIV] Prepaying basic charges, In a gear-changing device, more particularly for use in basic charge collectorsfor prepayment meters, in order that the gear ratio between the driving and driven shafts may be varia;ble in 'a large number of small steps, the gear ratio is controlled by variation of the extent of travel of a member 23, Fig. 1, along a screw 10 between two stops 18, 20 which determine the limits of travel in either direction by directly arresting the rotary movement of the member 23, the stop 18 being connected to a setting indicator 12, 13 and being adjustable in helical path towards or away from the stop 20. At the beginning of an operative cycle in the drive between a constantly operating motor 49 and a driven shaft 31, which is connected, for example, to the credit registering means of a prepayment meter, the wheel nut 23 is at'one end of its travel with a pin 21 thereon engaging the stop 19. The motor 49 drives one sun wheel 47 of an epicyclic mechanism, rotating the shaft 45 carrying the planet wheels 46 and through gearing 52, 53, 55 rotating a wheel 43 eccentrically and rotatably mounted on a wheel 44 which is loose on the shaft 45 and is held stationary by a worm 36 and so holds stationary the other sun wheel 50 of the epicyclic mechanism. A pin 42 on the wheel 43 engages and drives an arm 41 on a shaft 39 in alignment with the shaft 45, the shaft 39 being geared to a long pinion 38 mashing with the wheel 23. The wheel 23 travels along the screw 10 winding up a spring 24 until a pin 22 thereon engages the stop 20, which is on an arm 19 fixed to the shaft 10, whereupon further rotation of the wheel 23 rotates the shaft 10, the drive being transmitted through gearing 25 . . . 30 to the shaft 31. This effective rotation of the shaft 10 winds up a spring 34 connected by gears 35, 37 to the worm 36. At the end of the operative cycle, the pin 42 leaves the arm 41, and the spring 24 then returns the wheel 23 to its initial position, the arm 41 being also returned part of the way towards its original position. The disengagement of the pin and arm 42, 41, also frees the wheel 44 which is rotated from the spring 34 to bring the axis of the wheel 43 into its original position relative to the arm 41. Rotation of the wheel 44 through gearing 51 rotates the sun wheel 50 and therefore the shaft 45 to bring the'pin 42 into engagement with the arm 41. The cycle now recommences but with the arm 41 and pin 42 angularly displaced from the position at the beginning of the previous cycle. The effective portion of the forward stroke of the arm 41 is varied by.moving the stop 18 towards or away from the stop 20. The stop 18 is on an arm 1 rigid with a disc 15 in screw-threaded engagement with the screw 10. The setting is accomplished by rotating the dial 13 which through rods 14 rotates the disc 15. Since the dial can be rotated through several revolutions, the particular revolution that the pointer 12 is indicating on, isshown by a pointer 62 moved by a cam which is rotated through gearing 59, 60 by rotation of the dial 13. In another construction, Fig. 2, a constantly rotating driving shaft 86 through gearing 87, 85 rotates a sleeve 81 mounted on a normally fixed threaded shaft 70. At the beginning of an operative cycle, a wheel nut 76 having a pawl 77 carrying oppositely projecting abutment members 79, 80 is at one end of the screw 70 and the abutment 80 engages a fixed stop 75 so that the pawl 77 is raised into engagement with an arm 83 on the sleeve 81. The wheel 76 is thus rotated and travels along the screw until the abutment 79 meets a second stop 72 projecting from an arm 71 carried by the screw, whereupon the pawl 77 is disengaged from the arm 83 which rotates idly for the ,rest of the cycle. The wheel 76 meshes with a long pinion 89 on a sleeve on a shaft 94. This sleeve drives the shaft 94 through a pawl and ratchet drive 91, 92 and also has a pinion 90 meshing with a wheel 105 on a shaft 106. The shaft 94 through gears 95, 97, 99, 100 drives a shaft 101 which is the driven shaft. It has a motion storing device in the form of a spring drum 102 from which the motion is conveyed to the credit registering mechanism of a prepayment meter. During the drive, a pawl 118 is held by a spring 118a in engagement with the wheel 105 to prevent rotation of this wheel in the direction of the dotted arrow. The pawl is released by a pin 114 on a shaft 113 engaging an arm 115 on the pawl shaft 116 so that the wheel 105 is rotated in the reverse direction through gearing 85, 108, slipping clutch 107 and shaft 106. This returns the wheel 76 to its initial position to restart the cycle. The shaft 113 is rotated through one revolution per cycle by the sleeve 81 through gearing 84, 112. The position of the stop 72 is adjusted by rotating the screw 70 which passes through a threaded hole in the casing plate x and carries a dial plate 74, the adjustment being effected by rotating a shaft 120 by a screw driver. The shaft 120 is geared to the screw 70 by a pinion 127, a toothed disc 128, and a pinion 129. The disc 128 indicates the particular range section being dealtwith by the dial 74.