Patent GB-742255-A (GB)
Title: Improvements in apparatus for calculating the volume, weight, density and/or transitcharge of an object or package
IPC: G01F17/00
Filed: 1952-09-26
Abstract: 742,255. Electric analogue calculating systems; ohmic resistors. CONTINENTAL SILVER CO., Inc. Sept. 26, 1952 [Nov. 17, 1951], No. 24169/52. Addition to 742,051. Class 37. [Also in Group XXXVIII] In apparatus for determining the volume, weight, density, and transit charge for a package, of the kind described in the parent Specification, the deflection of the spring balance under the weight of the package rotates a contact over a logarithmically wound circular resistance element to derive a resistance value proportional to the logarithm of the weight, and the adjustable sliders determining the linear dimensions traverse contacts over logarithmically-wound lineal resistance elements to derive resistance values respectively proportional to the logarithms of the several dimensions so that the combined series value of such dimensional resistances represent the volume of the package while in the several bridges the rebalancing resistances are connected in series with and in the same arm as the measuring resistances, adjustably to restore the resistance of such arm to the value for bridge balance while the several bridges and their associated rebalancing servomotors are arranged for A.C. operation. Modified selfbalancing bridge circuits for determining the combined length and girth of a package, and for multiplying, dividing, adding and subtracting input quantities are also set forth. The spring balance platform 66 (Fig. 1) is movable vertically under the weight of the package to rotate through a rack and pinion linkage 33, 34 (Figs. 5, 6) a drum 42 carrying a rotary slider 48 and roller contact 49 engaging a fixed circular wound resistance comprising an insulating plate 53 wound toroidally with a wire 51 in parallel equally spaced runs 251, of predetermined resistance to give a logarithmic progression, the slider width spanning the distance between adjacent runs, and the surplus wire in each run being disposed round pegs 253 in the back of the plate 53. Slider 48 is connected over conductor 55 to slip-ring 56 on the end of drum 42 engaged by fixed contact 61. The measuring sliders 73, 74, 75 of the linear dimension resistances RB1, RB2, RB3 which may be set to engage the limits of the package each comprise blocks 82, 83 (Fig. 8), screwed together through a guide slot in a plate 71, forming part of the balance platform, block 83 having a rib 85 which engages the slot to define the movement of the blocks. An insulating strip secured to block 83 by the central screw 84 carries a wiper arm engaging an associated contact rail at one end and fitted at the other with a roller contact movable over an insulating strip 60 (Fig. 9), wound with a continuous resistance wire 111 in a plurality of equally spaced parallel runs 112, the wiper roller successively engaging the runs whose predetermined resistance values are proportioned to give a logarithmic progression of resistance; the surplus wire in each run .being disposed round pegs 113 in the back of the strip 60. The three linear dimension resistances RB1, RB2, RB3 (Fig. 13), are connected in series so that their total resistance represents the logarithm of the volume of the package. In operation, the sliders are set to the package limits, the ratio and zone switches 104, 105 are set to neutral, and start switch 228 is closed to energize motor 208 from the A.C. mains 135, 142 and rotate shaft 207 and the cyclically operative peripherally slotted timing discs 202 to 206 carried thereon. Disc 202 initially engages wiper 211 to hold motor 208 energized from the A.C. mains, for one complete cycle until disc 202 again disengages wiper 207 after one revolution, irrespective of the opening of switch 221. Then disc 203 engages wiper 212 which operates volume relay 117 and weight relay 223 to respectively close contacts 186, 192; 116, 143; and 296, 301; 222, 257, and thus to set up a volume and a weight measuring bridge energized from the A.C. mains. The volume bridge arms comprise fixed resistances 168, 179, fixed resistance 171, and resistances RB1, RB2, RB3 in series with a volume rebalancing resistance 151, and the weight bridge arms comprise fixed resistances 279, 289, fixed resistance 291, and the weight variable resistance 51 in series with a weight rebalancing resistance 267. The rebalancing resistances 51, 151 each comprise a rotary insulating disc 149 (Figs. 3, 4) having a slip-ring 152 engaging a fixed arm carrying a roller contact 175, and toroidally wound through grooves and notches with a continuous resistance wire 151 so that a roller contact 153 on a fixed contact arm 145 engages successive parallel spaced runs of the wire 151 over the face of the drum, which are wound to give a logarithmic resistance progression, surplus wire being disposed round pegs 154 in the back of the drum. The unbalance voltages from the volume and weight bridges respectively energize the inputs of known servo-amplifiers 163 and 283 across input matching resistances 181, 280 to energize the servomotors 162, 282 which adjust the rebalancing resistances 151, 267 to a value at which the bridges are rebalanced and rotate the indicating drums 101, 102, displayed through slots in the panel 99 to show the package volume and weight. Further cyclic rotation of the disc shaft 207 disengages disc 203 from wiper 212 to release relays 117, 223, and arrest the rebalancing resistances and indicating drums at the measured volume and weight values. Simultaneously disc 204 engages wiper 213 to operate discriminator relay 121, thus closing contacts 119, 315; 261, 318; and 337, 338 to connect the series connected resistances RB1, RB2, RB3, and the weight resistance 51 with fixed resistances 322, 326 in an A.C. energized discriminator bridge which is normally balanced for a package of standard density, e.g. 1 lb. per 8 cu. in. Any unbalance voltage energizes servo-amplifier 324 across input resistance 328 to drive servomotor 335 to rotate operating arm 340 clockwise for package densities greater than standard to retain contacts 341, 363 open and anticlockwise for densities less than standard to close contacts 341, 363. Continued rotation of the disc shaft 207 disengages disc 204 from wiper 213 to release the discriminator relay 121 and engages disc 205 with wiper 214 to energize the weight cost relay 264 and light indicator lamp 197 across its coil. Contacts 198, 378; 263, 387; are then closed to connect weight resistance 51 in series with cost rebalancing resistance 392 (constructed similarly to the volume and weight rebalancing resistances 151, 267) in an A.C. energized cost bridge with fixed resistances 402, 406 and cost rebalancing resistance 408, the unbalance voltage of which is applied across the input resistance of a servoamplifier 404 controlling a servomotor 381 which adjusts resistance 392 to rebalance the bridge and also drives a cost indicating drum 97 displaying the transmit cost for a package of standard density through a slot in the panel 99. Further rotation of disc shaft 207 disengages disc 205 from wiper 214 to release the weight cost relay and disable the weight cost bridge, while after a complete revolution disc 202 is disengaged from wiper 211 to arrest the apparatus with drums 101, 102, 97 indicating the volume, weight and transit cost of the package. However, if the latter has a lower density than standard, the above-mentioned operation of the discriminator relay 121 and unbalance of the discriminator bridge energizes servomotor 335 to drive arm 340 clockwise and close contacts 341, 363 to operate relay 346 and close contacts 350, 344; 356, 345. The latter contacts operate volume cost relay 124 and light indicator lamp 362 across its coil. Contacts 367, 368 are opened to disable the weight cost relay operating circuit and contacts 358, 351; 372, 373; 382, 123; are closed to connect volume resistances RB1, RB2, RB3, cost rebalancing resistance 392, balancing resistance 408, and fixed resistance 402, 406 in a cost bridge circuit as before, which is rebalanced by servo-amplifier 404 and servomotor 381 driving drum 97 to indicate a package transit charge based on volume. Once operated, the volume cost relay 124 holds over contacts 351, 358 until the measuring cycle is completed and disc 202 is disengaged from wiper 211 regardless of de-energization of the discriminator relay 121 or the slave relay 346. Holding of relay 346 after disengagement of disc 204 and wiper 213 due to the contacts 341, 363 remaining closed, and the consequential undesired operation of volume cost relay 124 over contacts 345, 356 during the succeeding measuring cycle is prevented by further contacts 344, 350 of relay 346, which when operated by the closure of contacts 341, 363 maintains the discriminator relay 121 energized even after disengagement of disc 204 and wiper 213 so that the servomotor 335 will then drive contacts 341, 363 into disengagement interrupting the operating circuits of the discriminator relay 121 and the volume cost relay 124. The density of the package is determined by closing switch 127, connecting the volume resistances RB1, RB2, RB3 and the weight resistance 51 and fixed resistances 131, 136 in a density bridge circuit which is normally balanced at, e.g. a density of 1 lb. per 8 cu. ft. as unity. The unbalance currents of the bridge are indicated by meter 103 calibrated in density referred to the standard value. Ratio switch 104 connects predetermined resistances RAW 2  or RAW 3  in series with the weight resistance 51 in the discriminator bridge when for a given weight and transit charge an increased volume is allowed, and resistances R a V 2  or R a V 3  are similarly inserted in series with the combined volume resistances RB1, RB2, RB3, when for a given volume and transit charge an increased weight is allowed. Zoning switch 105 enables a graduated series of resistances Z2, Z3, Z4 to be selectively inserted in series with the weight resistan