Patent GB-601392-A (GB)
Title: Improvements in and relating to weighing apparatus
IPC: G01G13/00
Filed: 1945-07-03
Abstract: 601,392. Automatic-feed weighers. BRECKNELL, MUNRO, & ROGERS, Ltd., and LAWSON, C. W. July 3, 1945, No. 16937. [Class 143] Weighing-apparatus has a scale counterbalanced so that it has the same equilibrium position whether loaded with a weight equal to a predetermined standard or with a weight whose excess above said standard is not greater than a prearranged tolerance, but is not in equilibrium in saidposition when loaded with a weight that is not within these limits. The weigh beam during part only of its permissible movement carries with it an auxiliary counterbalance so that, for the single predetermined position at which it starts to carry, it is in equilibrium for any load within a predetermined range. Movements of the scale from the equilibrium position may effect corrective adjustment of apportioning mechanism delivering articles such as butter pats thereto in succession. The scale unit comprises a beam 1, Figs. 2 and 5, supported on knife edges 2 and carrying a pan 10 which is maintained horizontal by a parallel motion device comprising a bar 13 and rod 20. An adjustable counterbalance weight 22, and a pair of weights 26 on rod 27 permit exact balancing of a pat of standard weight. A bent lever 28 pivoted at one end and carrying riders 31 is supported by a stop 35 and normally does not affect the weigh beam but an overweight pat will tend to depress the pan 10 when the auxiliary weight of lever and riders comes into effect and opposes the depression. Any overweight beyond the predetermined tolerance imparts a movement to the beam. An overweight pat produces a lift at the pan end. The scale is maintained steady during loading and removal of the pats by providing on the beam 1 a blade 37, Fig. 2, whose top 39 enters a guide track formed in a rotatable disc 38 by means of fences 40, 41. The entrance end of the track is provided with three separate passages formed by barriers 42, 43 so that the tip 39 passes through the central passage when a pat of correct weight or overweight within the permissible tolerance is on the scale, and through one of the side passages when a pat is over or below this weight. Levers 44, 45 extend into the side passages and are rocked by the tip 39 to actuate underweight or overweight switches 56, 57 and operate warning lights or means for automatically regulating the means for apportioning the butter as described in Specification 601,393. The barriers 42, 43 are yieldingly mounted and shaped to facilitate clean engagement with the tip 39. Vibration of the beam during resetting is prevented by providing on each side a pair of damper pads which are urged inwards to grip the ends of floating pins 88, Fig. 5, carried by the beam by means of toggles comprising links 75, 77, and rockers 79, 82, the pressure being relieved cyclically by rocking the spindle 80 by moving an arm 87. The dampers operate before the resetting commences when the barriers 42, 43 have been carried past the blade tip 39. During resetting, pressure is also applied to the knife edges 2 by sliding plungers 89 which are lifted during the weighing period and preceding steadying period by means of rockers 92 on a spindle 93 rockable by an arm 94. The arms 87, 94 are moved synchronously with the rotation of the disc 38 by means of cams 95, 96, Fig. 2, on a shaft 97 driven from a main shaft 102 whose rotation is also transmitted to the disc shaft 53 by bevel gear 107. Reject mechanism comprises a shaft 109 driven from shaft 97 and carrying a disc cam 111, Fig. 1, which actuates through a pivoted arm 113, a rejector bar 116. Closing of the underweight or overweight switches 56 or 57 may be made to energise a solenoid 122 which results in disengagement of a pawl 127 from a notch 126 in the bar. As the switch is closed, a fresh pat is being loaded and the weighed pat to be rejected pushed off on to table 121. Continued rotation of cam 111, as the switch opens, allows the bar to move inwards to displace the rejected pat and then resets it to the rest position. The check weigher may be held with the scale stationary, and dampers and knife edge plungers operating, the scale forming part of a guideway for the packeted articles.