US2678206A

US2678206A - Indicating and printing device

Info

Publication number: US2678206A
Application number: US100652A
Authority: US
Inventors: William J Muldoon; Arthur L Thurston
Original assignee: COX AND STEVENS AIRCRAFT CORP
Current assignee: COX AND STEVENS AIRCRAFT Corp
Priority date: 1949-06-22
Filing date: 1949-06-22
Publication date: 1954-05-11
Anticipated expiration: 1971-05-11

Description

y 1954 w. J. MULDOON EI'AL 2,678,206

INDICATING AND PRINTING DEVICE l4 Sheets-Sheet 1 Filed June 22, 1949 turn DInu-rv Punuc l6 H R K UNION srocK YARDS COMPANY up OHAHA(LTD) OMAMA NIIIAKA owl-1n. Sal-Irv ENTORS.

ILL-[AM MULDOON. BY ARTHUR L.THUESTON- ATTORNEYS.

y 1,, 1954 w. J. MULDQON ETTAL 2,678,206

INDICATING AND PRINTING DEVICE Filed June 22, 1949 14 Sheets-Sheet 4 5 I OSCILLATOR-3,75

Sun: WuuzWmomc I I cl El Cmusw Cmuumz AMm..375-

DEMODULAT'OR.

Lew Pass lt-TILL MODULATOR. Amrurma.

(El J! EGULAYIZO To Szavo M.

INVENTORi WILLIAM J MLJLDOON.

ARTHUR L.THuRs1'oN ATTORNEYJ.

May 11, 1954 w. J. MULDOON ETAL INDICATING AND PRINTING DEVICE 4 Filed June 22, 1949 14 Sheets-Sheet 5 v olluwtrm INVENTORS. WILLIAM J.MUL.DOON.

ARTHUR L THus25ToN ATTOi May 11, 1954 w. J. MULDOON ETAL 2, 7

INDICATING AND PRINTING DEVICE Filed June 22, 1949 14 sheets-she t e INVENTOR5 VVI LL'I AM J. Muuaoou ARTHUR L.THUR STON.

ATTORNEYS.

y 1954 w. J. MULDOON ET'AL 2,678,206

INDICATING AND PRINTING DEVICE Filed June 22, 1949 V 14 Shets-Sheet s 'His i w a:

IN VEN TORS 5x I WILLIAM J MUL.DOON.

By A a'rH'urz L.THUESTON.

y 1954 w. J. MULDQON ETAL 2,678,206

INDICATING AND PRINTING DEVICE Filed June 22, 1949 14 Sheets-Sheet 9 Svucu mu Rnczlvzn. (FAs-r) INVENTORS WILLIAMJ.MUL.DOON- Asa'rHug L.THu|as'r0N.

- -mug 3M ATTORNEYS.

May 11, 1954 w. J. MULDOON TAL 2,678,206

INDICATING AND PRINTING DEVICE l4 Sheets-Sheet 10 Filed June 22, 1949 HEN? y 1954 w. J. MULDOON EI'AL 2,678,206

INDICATING AND PRINTING DEVICE Filed June 22, 1949 14 Sheets-Sheet l1 INVENTORS WI Ll .l AM J. Mu LDOON.

A'RTH UR LJTHUESTON.

URN 5.

May 11, 1954 w. J. MULDQON EI'AL INDICATING AND PRINTING DEVICE 14 Sheets-Sheet 12 Filed June 22, 1949 son VIIIIIIIIIJWIIIIIflWIIIIIIIlIL"III/III! A Y INVENTORS WILLlAM J. MULDOON.

AIZTHUQL-THUESTON.

W,@m-8 2" Q I ATTORNEYS.

May 11, 1954 w. .1. MULDOON ETAL INDICATING AND PRINTING DEVICE Filed June 22, 1949 14 Sheets-Sheet l3 QQO 1 2 25 I A r M m Mfi MMXwZ-J l 4400- W m INVENTORS. XVILLJAM J. MULDOON.

nan-qua L.THurzsToN.

y 11, 1954 w; J. MULDOON ETAL 2, 7 6 I INDICATING AND PRINTING DEVICE Filed June 22, 1949 1 1 Sheet -sheet 14 INV NTOR5. WILLIAM J. ULDOON. ARTHUR L THURSTON- ATTORNEYS.

Patented May 11, 1954 INDICAT-ING AND PRINTING DEVICE William J. Muldo'on, Garden City, and Arthur L. Thurston, Wantagh, N. Y., assignors to Cox and Stevens Aircraft Corporation, Mineola, N. Y., a

corporation of New York ApplicationJune 22, 1949', Serial No. 100,652

14 Claims. 1

This invention relates to an indicating and printing device, and more particularly to an automatic force measuring device wherein forces such as those due to weight are automatically indicated and a printed recording made thereof.

The indicating and printing device comprising this invention is adapted forworking in conjunction with force or weight measuring cells which are described in copending United States patent application Serial :No. 539,658, filed June 1-0, 1944, by Arthur L. Thurston, now United States Patent No. 2,488,349.

In the measuring of. large forces, as .n the weighing of heavy loads, for example, the Weighing of livestock in Stockyards, groups or drafts of individuals are weighed upon a large platform, there being possibly "500 to 600 separate drafts or weighings in a day upon a single scale. The ownership of the livestock in normal practice changes hands when weighing takes place and it is usual procedure for the weight of each draft or group of livestock to be printed on a ticket with one or more carbon copies. Usually the weigh master writes in 'longhand on the ticket the name of the owner, the name of the buyer and then his signature. He also may write in longha-nd the number of livestock or cattle, the species and other data as required by the specific stockyard. This is a time consuming and thus an expensive activity. When the name of the-owner and thename of the buyer are the same for several successive we'ighings or drafts of livestock, the "data above mentioned have in the past been marked on separate tickets or cards and the weigh master has thus been required to write such data and to sign his name several times. It is estimated that one-quarter to one-third of the weigh masters time has in the past been spent in signing his name. This invention provides a means for automatically printing one, two or three successive sets of information including weight on the same ticket, each for a separate draft of livestock, and provision is made also by printing means "for stamping a facsimile signature of the weigh master once upon such ticket, thereby saving considerable time. If desired only one set or line of information need be printed.

Also novel means are provided for automatically printing upon such ticket the weights ofthe indivdual drafts of livestock.

Furthermore, in weighing devices for weighing large loads, such as drafts of livestock, the indicatingdevice-has of necessity been located closely adjacent the weighing platform when in many instances it is desirable to locate it in a remote position. This is also true of the device for printing the indication of the weights of the drafts.

Furthermore, weighing devices for large loads heretofore suggested have usually employed knife edges in conjunction with a platform. Such knife edges very often become dulled due to severe fibre stresses and wear requiring frequent replacement and servicing.

In weighing livestock, it is necessary frequently to balance the scale mechanism when it is empty of the livestock. This in the past has been done manually and is normally referred to as manually adjusting scale zero for tare. The Weight of the platform in a livestock scale changes due to the droppings left by the cattle on the platform and necessitates frequent rebalancing or adjusting scale zero for tare. In making such manual adjustment on scales heretofore proposed, there is a possibility of the weigh master erring so that the scales weigh light and, of course, there is always the possibility of a weigh master making a deliberate error when making such adjustment. On some types of livestock scales, on a busy-day between 700,000 and 900,000 lbs. of livestock may be weighed on a single scale in, for example, 500 to 600 dinerent weighings. It is usual for such livestock to be sold throughcommission merchants by a large number of owners to a relatively small number of buyers. If, through mistake or collusion between the buyers and the weigh master, the latter balances the scale to read, for example, 5 lbs. light at each draft, which is not d-iflicult to do without detection on the usual type of scale, this would make a difference of from 2500 to 3000 lbs. during the day in favor of the buyers. Such error in the scale may result in an underpayment of the sellers to the extent of many hundreds of dollars per day.

Furthermore, no accurate electronic scales has been heretofore suggested which provides a rapid visual indication of weight together with rapidly actuatable weight indicia for the printing of such weight upon a card.

One of the objects of the present invention is to overcome the above difficulties or to reduce same to insignificance.

The invention in one aspect thereof is constituted by a force measuring or weighing device having in combination a force or weight sensitive cell means employing force or stress receivmg column means, the latter carrying electrical resistance type strain gauge means bonded thereto. The latter means are connected in an electrical circuit for measuring a change in an electrical characteristic of such means in response to stress received by said column means, that is, a force or weight signal is produced responsive to such stress. Such change in electrical characteristic is employed for controlling a servomotor in conjunction with a so-called null or balancing circuit wherein the signal from the cells is balanced against a signal controlled by the servomotor. The servomotor is initially under the influence of the above-mentioned change in electrical characteristic, and the motor, by being operatively associated with the balancing circuit, establishes a null condition, thereby arresting the servomotor after a movement thereof which is responsive to the change in such electrical characteristic. The servomotor is operatively associated with a remotely located stress or force indicia including a device having a first portion for coarse indications of the movements of the servomotor, and a second portion for fine indications of such movements. Novel means are provided for operatively interconnecting such servomotor and stress indicia device comprising two separate self-synchronous repeater systems, the transmitters of which are driven by said motor in a preselected speed ratio to provide separate fine and coarse transmitter movements. The receivers of the self-synchronous repeater system are respectively connected to the fine and coarse stress indicia devices whereby the coarse repeater system is capable of driving the coarse stress indicia in tracking or repeating relationship throughout its range of movement, and the fine repeater system actuated in response to fine indications of the force signal, due to the high speed of such latter repeater system, loses synchronization due to its inability to follow the high speed of its transmitter whereby the fine stress or force indicia does not track the high speed, or fine repeater transmitter but moves into step and synchronizes with such transmitter a fraction of a second after the servomotor comes to rest.

Novel means are provided for adjusting a visual indicator controlled by the servomotor in order to account for residual forces or stresses upon the force measuring cells, for example, residual weights which may be upon such cells. Such visual indicator can be separate from said stress indicia above mentioned. Such novel means comprises a second servomotor also referrcd to as a zero adjusting motor which is actuated in response to the departure of the fine transmitter or the fine synchronous repeater system when the main load upon the force measuring cells has been removed. Such Zero adiust ing motor is drivably connected with such fine transmitter for returning same to an initial zero position whereupon the zero adjusting motor is stopped.

The above and further objects and novel features will more fully appear from the detailed description when the latter is read in connection with the accompanying drawings. It is to be expressly understood that the drawings are for purposes of illustration only and are not intended as a definition of the limits of the invention, reference for this latter purpose being had to the appended claims.

In the drawings:

Fig. 1 is a perspective view of a Weight indicator and an automatic printing device used in conjunction with a plurality of weighing cells upon which rests a weighing platform, the combination embodying one aspect of the invention;

Fig. 2 illustrates a so-called scale ticket upon which the printing device records certain information desired in the weighing of livestock as at a stockyard;

Fig. 3 is a schematic wiring diagram showing one plan for electrically interconnecting the weighing cells, the indicator and the printing device, together with certain other parts of the apparatus;

Fig. 4 is another schematic wiring diagram, with certain parts omitted for clarity, illustrating the electrical interconnection between the force measuring cells, a visual indicator and a servomotor, together with certain elements for controlling the electrical signal to such motor in accordance with one form of the invention;

Fig. 5 is a graphic representation of the voltage output of the circuit of the force measuring cells under the influence of a so-called dead load and of a moving load, the latter creating random accelerations;

Fig. 6 is a schematic wiring diagram illustrating in greater detail the electrical circuits shown schematically in Fig. 4;

Fig. '1 is a schematic View in perspective, with certain parts omitted for purposes of clarity, illustrating the operative interconnection between a main servomotor and the visual indicator employed in the present invention, together with the motor for adjusting the scale to zero for tare weight;

Fig. 8 is an enlarged perspective view of a mechanical limit stop device employed with the parts shown in Fig. 7

Fig. 9 is a perspective view of the printing device employed in one embodiment of the present invention with the top portion thereof angularly shifted to an open position, and with a lower front cover thereof removed from its normal position thereby illustrating certain of the elements within the housing of the device;

Fig. 10 is a view similar to Fig. 9, with-certain of the parts eliminated for purposes of clarity, such as a carbon ribbon and a supporting shelf therefor and revealing additional parts of the mechanism;

Fig. 11 is a vertical cross-sectional view, with certain parts omitted, showing portions of the printing device illustrated in Figs. 9 and 10;

Fig. 12 is a front view of a group of co-acting type wheels having. numerals embossed upon the peripheries thereof and employed for printing weights upon the scale ticket shown in Fig. 2;

Fig. 13 is a schematic view in perspective showing the mechanical interconnection between certain of the type wheels shown in Fig. 12 and the motor drive means therefor;

Fig. 14 is also a perspective schematic view of the mechanical interconnection between the remaining type wheels and motor drive means therefor, such remaining type wheels being driven at a speed relatively slower than the type wheels shown in Fig. 13;

Fig. 15 is a View illustrating how the type wheels of Fig. 12 might print upon a scale ticket in the absence of type wheel aligning means;

Fig. 16 is an exploded view in perspective of the type wheels of Fig. 12, together with a wheel aligning mechanism embodying a modification of the present invention;

Fig. 17 is a transverse sectional view of a gear element employed in both of the gear trains, as

shown in Figs. 13 and .14, for facilitating alignment-of the type wheels and also the making of an initial adjustment thereto;

Fig. 18 is a side view partly in section and with parts broken away of the gear element shown in Fig. 17;

Fig. .19 is a transverse sectional view of a type wheel and cam employed in the group of type wheels :of Figs. 12 and 16;

Fig. 20 is-a side elevation of the type wheel and cam of Fig. 19;

Fig. 21 is a side view of .an'inde'xing or aligning finger employed in the aligning mechanism shown in Fig. 16;

Fig. 22 is a plan view of the finger shown in Fig. 21;

Fig. 23 is a transverse sectional view taken through a front portion of theprinting device and illustrating a ticket-holding and indexing mechanism employed in the present invention;

Fig. 23a is a perspective view of a pair of notched disk members employed in the ticketindexing mechanism;

Fig. 24 is a sectional view taken substantially along line i l-24 of Fig. .23.

Fig. 25 is a side view of a cam mechanism viewed along line 25-25 of Fig. 24;;

Fig. 26 is a side'elevationof a platen or hammer device employed in the printing device;

Fig. .27 is a plan view of the parts shown in Fig. 26;

Fig. 28 is a front elevation of a carbon ribbon pulling or operating mechanism; and

Fig. 29 is a side 'view of the mechanism shown in Fig. 28.

In the form of the invention shown in Fig. l, the apparatus is designed for the Weighing of livestock upon a platform or weighbridge which can be rectangular and which is shown supported, for example, upon four weighing cells 5| located beneath the respective corners of the platform. The weighing cells are connected by suitable electrical conduits :as at 52 to a visual weight indicating device 53 :also referred to as an indicator unit and having a housing 154. The latter unit is electrically connected as by conduit 55 to a printer unit 56. A suitable source of electric energy is connected to the apparatus by a power .cable v5'! whichis directed into the indicator unit 53. The source of electric energy can constitute, for example, 110 volts cycle A. C.

The above-mentioned indicator unit 53 is, in the form shown, of a visual character but, of course, within the purview of this invention any other 'typeof signal indicator maybe employed as an alternative, and it isnot-essential to employ any indicatorof the character as at 53. The signal responsive to weight can be sent directly to the'printer 56 for anindication thereof as will be explained more fully herebelow.

The housing '54 for the visual indicator 53, as shown in Fig. l, also provides a housing for certain of the elements of the electrical circuits shown in Fig. 3, also to be explained below. The visual indicator proper comprises a dial 58 on which there are calibrated twoiseparate scales 59 and '60 comprising respectively coarse and fine calibrations. Suitable pointers are provided for cooperating with the scales, such as coarse pointer Gland fine pointer 62. Such pointers are operatively interconnected -to move in a preselected speed .ratio, for example, 50 to 1. That is, when the coarse pointer :moves one revolution, the fine pointer :moves fifty revolutions.

Ascale which'is capable of measuring loads up to 50,000 lbs. is considered suitable for normal use in weighing loads such as drafts of livestock and the two scales upon dial 58 are calibrated to indicate loads from zero up to such a maximum. The coarse or inner scale is graduated in 1,000 lb. increments from 0 to 50 and the outer scale is graduated in, for example, 10 lb. increments from 0 to 1,000 lbs. The pointers and their control mechanism are adjusted so that both will indicate zero, for example, when they are pointed upward in vertical position. Thus the form of the visual indicator herein employed gives an indication of weight in a manner analogous to the hour and minute hands of a clock and can be readily observed by a weigh master.

The scale ticket, which is shown in Fig. 2 as at 63,.has been designed for recording the information desired, for example, in the weighing of livestock, and includes a main column 64 in which on successive lines the weight of a plurality, such as three, of separate successive drafts of livestock can be recorded. The recording of such weights is made in column for a purpose which will appear hereinafter, and the recording of other items of information is also made in column. The printing mechanism for printing the weight is automatically set by means to be explained in detail below. There are provided additional columns, for example, columns 65, '66 and -6l which are respectively for recordings of the time of weighing (year, month, data-a. m. or p. 111., hour and minute); scale number; and livestock draft number. The mechanism for printing :in the last three mentioned columns 6", 66 and t! is automatically set by the printing device without assistanoe by the weigh master. Additional columns are provided as at 68, 6.9, 10 and H wherein information is printed which may be manually set by means of suitable knobs upon the printing device 56. .In these columns (68, 69, 1.0, 'H) there are indicated, for example, respectively (a) species of the livestock, ('b) the number of livestock in the particular draft, (0) the name or symbol of the commission agent, and (d) the price.

Space is provided, as at 72, for the printing of the signature of the weigh master. This is accomplished by a metal slug having embossed thereon the signature of the weigh master which slug is removably positioned in the printing device 56, as will be explained below.

Preferably the means for printing the scale number or scale designation for column '65 .is set in the mechanism at the time of its manufacture so that of the mechanisms for printing in

columns

65, 66 and 6"! only the first and last mechanisms require automatic setting.

While the data recordable upon the ticket 3 are particularly adapted for the weighing of livestock, it is, of course, understood that the invention is not limited thereto and that other data can be printed as desired.

The species of livestock is set manually on the printer .56 by manual adjustment of a knob a68a. The number of individuals is indicated by adjustment of the two handles Etaand ii9b,-one for each digit. Normally drafts of livestock are :less than ninety-nine individuals and consequently it is usually unnecessary to employ more than two digits for columns 69. The symbol-of the commission agent for column '70 is manually :set by adjusting the knobs We and 5073. If desired. :an automatic mechanism, which is operatively connected with the weight indicator, can calculate the .price in response to the weight and indicate same in column .1! but in the particular embodi- '7 ment shown, no provision is made for printing in this column. The mechanism for setting the type for printing in columns Gil- 50, inclusive, is comparable to the mechanism used in a conventional check-writing device.

The scale ticket 63 is inserted into the printer for printing by means of a manually controlled clamping device in the form, for example, of a hinge clamp 13 which is resiliently urged to a closed position by means of a spring 14 wound about a pivot pin of the hinge. A handle for opening such hinge clamp is indicated at Hi and is rigidly secured to the top portion thereof. Suitable fingers are secured to the bottom portion of the hinge and extend down into the housing of the printing device through slots 16 and I1, will be explained more fully hereinafter, whereby the hinge is held in accurate alignment with the printing mechanism and is adapted for being advanced by increments into the printing machine for the printing of the above-described data successively on the horizontal lines 63a, 63b and 630, each line representing a separate draft of livestock. Such lines are also referred to as lines (1), 2) and (3), respectively. Although there may be three separate lines of data printed upon the scale ticket, the signature of the weigh master in space '12 is printed only once, namely, when the information on the first line, 63a, is printed. Thereafter suitable means are provided for rendering inoperative the facsimile signature printing means, as will be explained below.

Printer device control elements (weigh masters controls) The controls which are operable by the weigh master are all preferably located on the printing device 56, as shown in Fig. l, and they consist of manually operable switches as of the push button and toggle type as follows:

(1) An on-off toggle switch it which provides a master control switch for the electrical energy to the entire apparatus, as illustrated, for example, in Fig. 3.

(2) A normally open push button switch 19 marked zero which is actuated in order to adjust the scale 58 zero indication for tare. That is, if the weight of the platform after emptied of livestock changes from zero, as it will due to, for example, the droppings of the livestock, so that the pointers GI, 62 fail to return to 0, a momentary closing of this switch by pressing its button will actuate automatic means to be described in detail hereinafter for causing such pointers to return to on their scales. This being an automatic adjustment, the possibility is eliminated of the weigh master making a mistake in such adjustment inadvertently or by design.

(3) A toggle switch 8% which is marked Fast and Slow, which in the Fast position permits the visual indicator and certain printing indicia associated therewith to move at maximum speed, and in the Slow position slows the response of such indicator and printing indicia, and imposes a predetermined dampening upon the apparatus in order to minimize any oscillations of the pointers GI and 52 and/or the means for controlling same, which oscillations normally are due to the milling or stamping of the cattle- Such oscillations are usually referred to as the result of random accelerations due to random loads upon the weighing platform.

(4) A toggle switch 8| marked Run and Stop which in the former position allows a normal operation of the apparatus wherein the pointers iii, 52 indicate, by means of the novel apparatus, whatever weight is put on the platform 50, and in the Stop position arrests the indicator control apparatus and locks such pointers in whatever position they may be when the switch is closed. In weighing livestock, this is used in order to give the weigh master time to read the scale should he require it. This control allows the Weigh master to stop the indicating pointers when the livestock are weighed, to count the individuals and thereafter manually adjust the knobs 69a, 69b to indicate such count before he actuates the printing mechanism for printing the scale ticket 53. This control is also of advantage when weighing a series of objects or drafts of livestock of about the same weight. For example, after one draft of livestock is weighed, the switch 8| is moved to Stop, the livestock removed from the platform and replaced by a second draft or by a second object, whereupon the stop switch is moved to the Run position and the second draft or object is weighed. Thus it is not necessary for the pointers 6|, 62 to return to 0 in between weighings. This saves time and also minimizes wear on the equipment. A further advantage of this stopping feature is found in connection with a fast moving load which may be on the platform only for a very short time, such time normally not being sufficient to permit the weigh master to observe the indicator 53 and to actuate the printing mechanism.

(5) A control switch 82 is provided for controlling the printing mechanism and in the form shown is of 3, conventional push button variety which is normally in an open condition. The momentary closing of this switch by the pressing of its button starts the printing cycle. Once the switch 82 is closed momentarily, the printing cycle is automatically completed within a very short time interval, for example, about three-quarters of a second, by means to be described below.

(6) A single glow lamp 83 is so connected into the electric circuit of the apparatus that it lights only when a scale ticket 63 is in position to print either line (1), (Z) or (3). The main function of this light is to indicate to the weigh master, when it goes out, that all of the lines of the ticket have been printed and that such ticket must be removed and a new one inserted.

Referring again to Fig. 1, the ticket holder or hinge clamp it is withdrawn from a position for printing, as shown in this figure, manually by grasping the handle "55 and pulling it as far as it will go, whereupon the handle is pressed downwardly to open same. The weigh master thereupon can insert a scale ticket within the open hinge clamp, and in order to position the ticket accurately urges it against a guide member 13a at the left of the hinge. Thereupon the handle '15 can be released. The ticket is thus clamped in the hinge and the weigh master then can push the ticket holder away from him, as

r viewed in Fig. l, as far as it will go, which in sorts the ticket in the printing device in position to print line (1). In this position a reference mark, for example, an extremity of the hinge pin, is positioned opposite a numeralfl), as shown upon an index plate 13?). After a draft of livestock has been moved upon the weighing platform 50, the indicator 53 and the Weight printing indicia of the printing device are actuated. Then they print switch or button 82 is pressed, and the desired data are printed in line (1). Thereafter, the hingeclamp or ticket holder 13 is automatically advanced or indexed into position for the printing of line (2). When the ticket holder is in position for the printing of lines (2) and (3), the hinge pin thereof is opposite the numerals (2) and (3), respectively, upon the plate 53b. After printing line (2), the ticket holder again is automatically advanced for the printing of line (3). After line (3) has been printed, the print switch 82 becomes inoperative. whereby no more printing can be done until the ticket is removed and a new one inserted. The mechanism for accomplishing the above will be described hereinafter. During the time that ticket holder I3 is in printing positions (1), (2) or (3) the lamp 83 is lighted indicating that the power means for the printing mechanism can be actuated by pushing button 82. After line(3) has been printed, lamp 83 is extinguished.

Circuit description--System schematic Referring now to Figs. 3, 4, 5 and 6, there will now be described the electrical interconnections between the various parts of the novel apparatus, and also pertinent portions of the mechanical interconnections therebetween.

In general, the apparatus comprises a force sensitive device which, in the form shown, is designed for sensing weight and is constituted by the above-described weighing cells 5| which when subjected to a stress provide an electrical signal output which is proportional to said stress, the output in the embodiment illustrated being constituted by a, voltage. This voltage controls a signal responsive means such as a servo or control motor 84 through the intermediary of a so-called null system or null control means of which the servomotor is a part. The electrical voltage output of the cells 5! is exceedingly small and. must be highly amplified and controlled in a manner to be described in detail hereinafter by means which are illustrated schematically in Fi 4.

i'he above-mentioned null system employs as its main element a means for introducing a counter or balancing signal for balancing the cell signal, such means comprising, for example, a slide wire resistance indicated generally at 85 which is under the influence of the servomotor 84 by means of a suitable operative interconnec- 5' introduced into such circuit and a null condition f can thereby be produced which will be attained when the servomotor 84 has been actuated to an extent proportional to the signal output of the weighing cells 5|.

A so-called oscillator-amplifier is employed which is schematically indicated at 86 in Fig. 3 andillustrated in greater detail in Figs. 4 and 8. This device provides a voltage of carrier fre quency for the cells and is employed for amplitying the output voltage of such cells.

Means are provided for converting such electrical output into the motion of an indicator which is linearly proportional to weight. Suitable electrical means to be described hereinafter are provided for accomplishing this. In the form shown, the control or servomotor M is cperatively associated with a remote signal responsive means such as a weight digital printer which is a part of the printing device 55. The operative interconnection between such servo motor and the weight digital printer permits a remote indication of the weight for the printing thereof within a negligible or substantially no additional time after the servomotor 84 has stopped after adjusting said slide wire element to a null condition. In the form shown, the apparatus is designed for registering loads up to 50,000 lbs. within a time limit of three seconds. This means that the servomotor 84 and. the pointers BI, 52 move from zero up to 50,000 lbs. on dial 5% within three seconds. The remote indicator, for example, the weight digital printer, is prepared for registering such maximum load substantially simultaneously with the time that such pointers reach this mark.

A portion of such weight digital printer is shown in Fig. 3 as at 8'5, and comprises, for example, a plurality of so-called type wheels having embossed upon their peripheries numerals for indicating the weight which is also registered uponthe dial 58. The type wheels 8'! are divided into two groups 81a and 81b for a purpose to appear more fully hereinafter and each group of type wheels is driven by a separate means,

' that is, there is one operative interconnection between wheels 8141 and the control motor 84 and a separate operative interconnection between group 81b and such motor.

The movement of the servomotor 84 is, as above described, indicated upon the dial 58 by means of coarse and fine pointers SI, 62. The groups of type wheels 81a and 81b respond respectively to such coarse and fine indicators. Due to the extreme speed at which it is necessary for the fine pointer 62 to move, it is not practical to have the fine type wheels 8111 move in step therewith. In fact, in the embodiment herein described, it would be substantially impossible to force the fine type wheels 811) to follow the fine pointer 62. In order to overcome this difiiculty without loss of speed, the operative interconnection between said groups of wheels 87a and 81b with the control motor 84 and the pointers 6i and 62, is constituted by separate selfsynchronous transmitter and receiver systems.

Such systems are generally referred to as synchro systems and each is provided with a transmitter and a receiver. A coarse synchro system is indicated generally at 88 and a fine synchro system is indicated generally at 89. The former system is provided with a transmitter 90 and a receiver 9!. The latter system is provided with a transmitter 92 and a receiver 93. The transmitter 90 is constituted by a rotor 90a and a stator 9%, the latter being electrically connected in a well known manner to a stator 9m of the receiver 9i, which stator is electrically associated with a rotor Slb. The transmitter 92 and receiver 93 of the fine synchro system are similarly connected and have analogously designated rotors and stators.

The servomotor 84, for example, by suitable mechanical means to be described in detail in connection with Fig. '7, is operatively connected to the

transmitters

90 and 92. The rotors 93a and 92a are rotated at speeds which are proportional to the speeds of pointers El and 62, respectively.

The coarse synchro receiver 9| is operatively connected with the coarse type wheels 81a by means of a coarse servomotor 9 having a control coil 96a, an exciting coil 94b and a rotor We. The control coil 94a is electrically connected to the rotor illb through the intermediary of a suitable amplifier 95 and the rotor Me is mechanically interconnected to the rotor 91b of said receiver for driving same. When the rotor Qib gets out of step with the rotor Slla, a voltage will be generated which is amplified by the amplifier 95 and which will actuate the servomotor 94. The latter by means of its operative connection with the rotor 9lb, will move such rotor into step with transmitter rotor 50a. In view of the relatively slow movement of transmitter rotor 90a, it is possible for the repeater system, including rotor Bio of the servomotor SM, to follow or track the rotor 90a throughout its range of movement.

The fine or fast receiver 93 is similarly operatively associated with the fast or fine type wheels 81b through the intermediary of a servomotor. 96 having a control field coil 96a, an exciting coil 95b and a rotor 96c. The control coil 96a is connected to the coil of the receiver rotor 93b by suitable electrical means including an amplifier 91' which is analogous to amplifier 55.

The transmitter rotors 90a, 92a are in geared connection so that when the slow rotor makes one revolution, the fast one makes fifty revolutions, these revolutions corresponding to a traverse of the indicator pointers BI, 52 from zero to 50,000 lbs. It has been determined that, in a weighing device of this character, the abovementioned time limit of three seconds is substantially the maximum that should be required for the visual indicator and its servomotor, together with the type wheels 81, to reach their maximum indications from zero to 50,000 lbs. Of course. the time required will be proportionally less for lighter loads. In accordance with the gear ratios existing in the present apparatus, which will be described below, if the fine receiver 93 were to follow the fine transmitter 92 exactly, it would be necessary for the receiver 93 to make fifty revolutions in three seconds (1,000 R. P. M.). The type wheels 812) would have to make five hundred revolutions in three seconds (10,000 R. P. M.) and the servomotor 96 would be required to make 4,166 revolutions in three seconds (83,333 E. P. M.). Such angular velocities are impossible in this type of mechanism. However, by separating the coarse and fine synchro systems into units which are independent of each other mechanically, with the exception of the geared interconnection between the transmitter rotors 99a, 92a, it is not necessary for the fine or fast stystem to follow the indicator 62 or the rotor 92a exactly. As the rotor 93b of the fine receiver 93 attempts to follow the indicator 62 or the rotor 92a, it cannot do so and consequently oscillates back and forth while the fast pointer 62 is traversing the dial. When such fast pointer slows down, as it does when it approaches the proper weight indication, the fast or fine receiver pulls into step, that is, the fine rotor 93b moves into synchronism with the rotor 92a of the transmitter whereby both the fine pointer 62 and the type wheels 87b arrive at the same weight substantially simultaneously. Such pulling into step, in the embodiment herein described, requires not more than one-half revolution of one of the type wheels 81b and five revolutions of the other of such wheels. The slow or coarse system, operating at one-fiftieth of the speed of the fast system, is able to track or follow exactly with the slow pointer 5i.

When the type wheels 8'! have been moved as above set forth by the servomotors 9 and 96 in response to a load upon the platform 50, such wheels are aligned for printing in a straight line by a so-called sequential indexing device to be deone-hundredth of one per cent.

scribed hereinafter, the above-mentioned print switch 82 is momentarily pressed, whereupon the printing device is actuated, as will be described later, and the weight of the draft is printed upon the scale ticket 63, together with the other de-- sired information.

One manner of interconnecting the strain gauge means of each cell 5| is shown in Fig. 3 and consists of a bridge arrangement of resistors somewhat analogous to a Wheatstone bridge wherein two opposite arms, consisting of the strain gauge means, as at Ma, are subject to change due to loading and the other two arms 5 lb are fixed resistances having associated therewith suitable temperature sensitive means which compensate for so-called zero unbalances due to temperature variations of the cell.

Each of the cells 5| is preferably referred to as a weighing cell and the above arrangement of the resistors thereof is referred to as a cell bridge. It is, of course, possible to arrange the electrical resistance type strain gauge means in other suitable circuits. The invention is not limited to such a cell bridge. In order to compensate for the zero unbalances due to temperature variations of the cell, there may be connected in series with each cell bridge and its voltage source a temperature sensitive resistance with a linear characteristic which adjust the voltage of such bridge to compensate for the linear change in the weight-voltage ratio of the output thereof, which change may occur with temperature change. The present apparatus is accurate within 5 lbs. over the range of 50,000 lbs., an accuracy of one Consequently the compensation for temperature variations in the cell must be accurate and stable.

Such temperature sensitive resistances are shown, for example, as at M0.

The apparatus is connected to a suitable source of electric energy (not shown), the power lines of which are indicated in Figs. 3 and 4 at L1 and L2. This source of energy is connected to the amplifiers, modulators, demodulators, and so forth, as shown in Fig. 3, through the above-mentioned on-oif switch 18 and through a so-called power supply element 98 which provides a high plate supply voltage electronically stabilized, and a stabilized 60 cycle tube heater voltage. The power line L1 is directly connected to the power supply element 98 through a lead 99. A second lead I00 is connectable to the other power line L2 via said switch 18 and an intermediate lead It.

The oscillator-amplifier schematically shown at 86 in Fig. 3 is shown in greater detail in Figs. 4 and 6. With particular reference to Fig. 4, the power supply element 98 is electrically connected to an oscillator I02, the purpose of which is to provide a voltage source for the weighing cells 5!. The portions of the apparatus shown in Figs. 4 and 6 will now be described, certain of such portions also being shown in Fig. 3.

The oscillator I02 is preferably a conventional, feedback, resistance-capacity type with a degenerated stabilized buffer stage and provides a source of carrier voltage of constant amplitude and constant frequency to the cells 5| and to the slide wire 85, the frequency being about 37 5 cycles as above mentioned.

It is desirable for the voltage input to the weighing cells 5! to alternate with a frequency of approximately 375 cycles. The latter is chosen as a compromise and is as low as possible, taking into account the 60 cycle interference of the