Patent GB-712893-A (GB)
Title: Apparatus for controlling the weight of material conveyed by a conveyor belt
IPC: G01G11/00
Filed: 1949-06-07
Abstract: 712,893. Automatic feed weighers. BROWN, S. C. May 22, 1950 [June 7, 1949], No. 15196/49. Class 143 [Also in Group XXXV] Apparatus for controlling the feed rate of material conveyed by a conveyer belt 1, Figs. 1 and 2, comprises a weigh beam system including a weigher 23 responsive to the weight of a predetermined loaded length 24-24 of the belt and a beam 26 movable about a fulcrum 27 in conjunction with movements of the weigher, and electronic or mechanical control mechanism adapted in response to departures of the weigh beam system in either direction from the position of equipoise, to impart step by step changes in the rate of delivery of the material by the belt until the condition of equipoise is restored. Over an end of the belt 1 is mounted a delivery hopper 5 the outlet 6 of which is bounded at the lower side by the belt 1, at the upper side by the lower edge of a door in the form of a plate 7 capable of being raised and lowered by racks 8 and pinions 9, operatable through a shaft and handwheel 10, and at the lateral sides by the edges of two vertical doors 11 and 12 movable horizontally towards and away from one another by a spindle 18 operated by spindle 20 under the action of the control mechanism. Mechanical control mechanism, Figs. 5 and 6. A body 47 including spaced movable levers 48, 49 is mounted for rocking movement about the axis of spindle 20 by a pivoted linkage 50. A plate 53 mounted on pins 54<SP>1</SP> rigid with the body 47 is capable of being rocked in its own plane relative to the body 47 and carries a pin 55 which projects, normally with clearance, between a pair of pins 56, 57 carried at the upper ends of the levers 48, 49. A block 59 is suspended at the lower end of bars 58 and is arranged to move to and fro by means of a cam 60 and spring 62. A blade 63, co-operating with a lever 72 actuated by the end of the beam 26, is mounted at the end of the block 59 for rocking movement with a pin 64 and is connected by a link 65 with bar 66 supported by bars 67, 68. Movement of the block 59 also actuates a lever system 77 for moving a cone 74 between spaced contacts 75 to position the contacts 56, 57 nearer or farther from one another. A connecting link 69 is provided between one of the bars 58 and' bar 68. With the belt 1 running and material being delivered from the hopper the body 47 including levers 48, 49 is rocked to and fro by connecting rod 51 and the body 59 is rocked to and fro with bars 58 by the cam 60 and spring 62. If the weight of material delivered varies from that required the lever 72 contacts the blade 63 during rocking in a position other than the mid-point and rocks blade 63, the movement being transmitted by link 65 to bars 66, 68, 69, 70 and rollers 71 to rock the plate 53 about one or other of pins 54' so that one or other of a pair of pawls 44 or 45 connected tc the plate is brought into engagement with its related ratchet wheel 32, 33 mounted on the spindle 20. The pin 55 is also brought nearer to one of pins 56, 57 the arrangement being such that upon the next movement of the body 47 pin 56 or 57 engages pin 55 so that the plate 53 is taken with the body 47 and the appropriate ratchet wheel rotated through a given angle thereby imparting step by step control to the spindle 20 and doors 11, 12 in a sense to correct the deviation. The extent to which blade 63 is moved also determines the movement of the cone 74 through link 77 so that for a large deviation and large movement of the blade 63 the cone is moved so as to position the contacts 56, 57 nearer one another more movement then being imparted to the appropriate ratchet wheels. Greater correction is thereby provided for large deviations. The cone is withdrawn and repositioned upon each stroke of the body 59. An electrical control system (see Group XXXV), may alternatively be employed. The hopper doors may be modified for use with a troughed belt, Figs. 7, 8, 9 (not shown). In this arrangement two doors are provided both being movable vertically and one being controlled automatically. The manually movable door is operated by one hand wheel, and a second hand wheel is provided which can operate both doors in unison for initial setting or quick changes in the weight to be delivered to the belt. After setting the auto-controlled door is operated by the above electric or mechanical control mechanism. Specifications 587,765 and 712,968, [Group XXXV], are referred to.