US2655311A - Automatic clear sign printing - Google Patents

Description

Oct. 13, 1953 4 H. L. PITMAN AUTOMATIC CLEAR SIGN PRINTING MECHANISM 5 Sheets$heet 1 Filed Aug. 20, 1948 INVENTOR. HENRY L.P/TMAN ATTORNEY Oct. 13, 1953 H. L. PITMAN AUTOMATIC CLEAR SIGN PRINTING MECHANISM 5 Sheets-Sheet 2 Filed Aug. 20, 1948 s. Q L

1953 H. L. PITMAN AUTOMATIC CLEAR SIGN PRINTING MECHANISM 5 Sheets-Sheet 3 Filed Aug. 20, 1948 \EECEC CEE Oct. 13, 1953 H. L. PITMAN AUTOMATIC CLEAR SIGN PRINTING MECHANISM 5 Sheets-Sheet 4 Filed Aug. 20, 1948 INVENTOR HENRY L. P/TMA/V BY 4 7% g wmmy 0d. 13, 1953 4 P|TMAN 2,655,311

AUTOMATIC CLEAR SIGN PRINTING MECHANISM Filed Aug. 20, 1948 5 Sheets-Sheet 5 INVENTOR. HENRY L. P/TMAN Patented Oct. 13, 1953 AUTOMATIC CLEAR SIGN PRINTING MECHANISM Henry L. Pitman, Melbourne, Fla., assignor to Underwood Corporation, New York, N. Y., a

corporation of Delaware Application August 20, 1948, Serial No. 45,372

12 Claims. I

This invention relates to combined typewriting and computing machines and more particularly to machines wherein a single keyboard is employed, such as found on ordinary typewriters.

Machines of the type with which this invention is particularly concerned comprise a computing base surmounted by a typewriter cooperating therewith. Within the base are normally contained a plurality of registers located in lateral alignment across the front thereof. For running amounts into the wheels of the registers, there is provided a set of differential operator bars for each register.

The typewriter carriage is provided with a plurality of column units extending horizontally from the rear thereof, and as the carriage moves into a computing zone corresponding to a column on the work sheet, one of the column units, which may carry a plurality of dogs, depresses a vertically extending plate, thereby selecting one of the registers for operation. If the column unit carries more than one register selecting dog, then, of course, more than one register will be selected for operation.

The differential operator bars which actuate the wheels of the registers are provided with indexing pins which are set in accordance with the depression of numeral keys of the typewriter. When a numeral key is depressed, the digit represented by said key is printed and the digit value is also indexed in one of the differential operator bars. Machines of the character with which this invention is concerned are normally provided with a continuously operating power source and a one-revolution clutch which, when engaged, connects a cycling general operator to the constantly rotating power source. After all of the digits of an amount have been selected, the one-revolution clutch is engaged, thereby cycling the machine and running the selected and indexed amounts into the wheels of the selected register or registers.

With machines of the type with which this invention is concerned, it is possible to automatically print totals. That is to say, after one or more amounts have been entered into a register, the amount then standing in the wheels of the register may be automatically read out and printed. For accomplishing this purpose, a set of total reading feelers is provided for each registe and each register wheel is provided with a spiral arrangement of stops. When it is desired to print a total, the set of feelers is released and the individual feelers of the set move forward into engagement with the stops, the amount of for- 2 ward movement being determined by the particular digits standing in the wheels. These different forward positions of the feelers are then employed in selecting the amount to be printed.

The machine is also provided with a fugitiveone mechanism, making it capable of recording and printing true overdrafts as well as true positive amounts.

When a total is automatically read out of a register and printed, the amount standing in the register is indexed in the differential operator bars for said register, and during the subsequent cycle of the machine, which always follows a total printing operation, the register moves to its subtractive position and the indexed amount is subtracted out of the register thereby leaving the register clear.

The general form of the machine, as set forth above, is well known and is more particularly described in my prior Patent No. 2,372,681. Also described and shown in said patent is a mechanism whereby a star or other indicating symbol is automatically printed following a total taking operation if the register is properly cleared. In said patent, a star is only printed when a register is cleared as a result of a total taking operation.

It has been found desirable to print a star or other clear sign in certain columns wherein a register is cleared by an operation other than a total taking operation. For example, in certain bookkeeping setups, a Proof column is provided, and when an amount is typed in the usual Old Balance column, said amount is run into at least two registers one of which is a proof register. After the operator has entered the appropriate Debits and Credits and the machine has automatically printed the new balance, the carriage is tabulated to the Proof column where the operator again copies the old balance. At this carriage position, the proof register is again selected, but this time it is selected subtractively so that during the cycle following the typing of the old balance, the amount is run into the register subtractively thereby clearing the register provided the operator has copied the old balance in the same way in both the Old Balance column and the Proof column. In order that the operator may be made aware of the fact that the old balance has been correctly copied, it is desirable to automatically print a clear sign in the Proof column, and this cannot be accomplished with a machine constructed in accordance with my prior Patent No. 2,372,681 referred to above.

It is, therefore, a primary ob'ect of this invention to provide, in a combined typewriting and computing machine, an improved arrangement whereby a star or other clear sign may be automatically printed in any desired columns of a work sheet without the necessity of taking an automatic total in such columns.

It is a further object of this invention to pro vide a reliably operable arrangement whereby a clear sign will be printed at only certain definite preselected letter space positions.

It is a still further object of this invention to provide an improved means whereby a clear sign will be printed only when the particular register selected for operation in a certain column is clear.

It is another object of the invention to provide a means for printing a clear sign which is operable early in the second half cycle of a cyclically operating computing machine.

These and other objects, features and advantages of the present invention will become more readily apparent as the description of a preferred embodiment of the invention proceeds.

Referring now to the-drawings:

Fig. 1 is a perspective view of a portion of a combined typewriting and computing machine showing the details of the present invention,

Fig. 2 is a side elevation of the general operator mechanism and shows a portion of the means for rocking the registers into their adding or subtracting positions,

Fig. 3 is a View similar to Fig 2 but shows the relation of the parts after a cycle has progressed to approximately the one fourth point,

Fig. 4. is a view similar to Fig. 2 but shows the relation of the parts at the time a cycle has reached the halfway mark,

Fig. 5 is a side elevation of the tens carry-over mechanism and shows the means for restoring the clear sensing feelers to their normal position,

Fig. 6 is a perspective view showing part of the mechanism for releasing a state control slide for forward movement to an addition or subtraction determinative position,

Fig. 7 is a front elevational view of a portion of the mechanism shown in Fig. 6,

Fig. 8 is a plan view of a modification of one of the features of the invention,

Fig. 9 is a plan view of a further modification of one of the features of the invention, and.

Fig. 10 is a perspective view showing the mechanism whereby various functions of the machine are controlled by the carriage.

Describing first the cycling mechanism and referring primarily to Figs. 2, 3 and 4, it will beobe served that the usual general operator bar it has been provided. During a cycle of operation of the machine, general operator bar it is moved from its Fig. 2 position to the position shown in Fig. 4 and then back to the Fig. 2 position by means consisting in general of a bar it to which said general operator bar is operatively con.- nected. The bar H is moved toward. the front of the machine and back to the Fig. 2 position by means of a crank arm i2 fixed to a shaft i3 and provided with a roller l4 fitting within a groove in a plate IS'secured to said bar through the intermediary of a stiffening: member ll. The shaft i3 is connected for one-revolution operation to a continuously rotating power source through the usual one-revolution clutch, as described in my prior Patent No. 2,178,702.

The forward end of bar I! is provided with rack teeth i8, which are constantly meshed with a pinion l9 rotatable upon a fixed stud 2% Fixed to a cross shaft 2!, which corresponds to shaft 7 65 of Patent No. 2,178,702, mentioned above, is

a gear segment 22 which is meshed with pinion 19. By referring to my above mentioned patent, it will be seen that the other end of shaft 2| carries a gear segment similar to segment 22, which, through a pinion similar to pinion I9, is drivingly connected to a rack bar similar to bar ii for moving the opposite end of general operator bar Iii, thus assuring'that the two ends of the general operator bar will move in unison.

As seen in Figs. 2, 3 and 4, a generally V -shaped member 23 isfixed to the cross shaft 2 I, and upon one arm of said V-shaped member is pivoted at as a pawl 25. A spring 26 extends between a pin 21 on a tail portion of said pawl and a pin 28 on the other arm of said V-shaped member and urgessa'id'pawlin a clockwise direction, as viewed in Fig. 2, about its pivot 24. Pawl 25 has an extended end portion 29 providing a pair of shoulders rtil-and 3! between said end portion and the main body of the pawl for a purpose which will presently appear.

Slidably mounted upon a. square stud32, fixed to the framework, is anarm 33', one end: ofwhich' is pivotally connected at 31% to'an arm 35: fixed-.to' across shaft 3%. Crossshaftiitis similar to shaft We of my prior Patent No. 2,192,365; and serves when rocked to move a selected register or reg.- isters from a. normally neutral to; an adding, or subtracting position, as fully explained in. said patent. Shaft 38 is rockedv from its Fig. 2: positionto its Fig. 3 position, by rearward movement. of the arm 33, andfor. moving saidarm the fol.- lowing mechanism is provided.

A cam plate. 3.7 having a cam slot 381s pivotally mounted upon a, shaft fixed in the frame of; the machine andis held upon said shaft by means. of. a screw 32. A. pair of. push pins 82, and 4:! are mounted in. the. cam plate. 3.7, the push pin 2H. co.-, operating with shoulder 39, of the pawl 25'and the pin 25 cooperating with. shoulder 3! of said pawl. A cam follower. G2 is fixed to the arm 33 and rides in the cam slot 28.

As previously pointed out, the bar II is moved toward the front of the machine, that is to say from the Fig. 2 position to the Fig. l-positionduring the first half of the cycle. As will. read ly be understood, the forward movement of. bar I I- will result. in counterclockwise rotation of segmentZZ and V-shaped member 23. During approximately the first quarter of the cycle, the pawl 25- will be held up in the position shownin Figs.,2 and} so that extension 29 and shoulder 30 thereon will be resiliently held in engagement with push. pin 40 by the spring 28. As the V-shaped member 23 begins its counterclockwise. movement, the shoulder 30 on pawl 25 will push the pin 46- from the Fig. 2 position to the Fig. 3 position thereby rotating the cam plate 3'! counterclockwise about its axis. Since the follower 42 on arm 33'stays in the cam slot 38, counterclockwise rotation of cam plate 3'11 from its Fig. 2 position will result in. a rearward movement of arm 33 to the Fig. 3 position, as will readily be understood.

As the arm 33 moves rearwardly, the previously selected registers will be moved into an adding or subtracting position by the resultant rotation of shaft 25, as explained in my prior. Patent No. 2,192,365, referred to above. The registers are, of course, moved to their operative positions before the general operator bar Hi has moved far enough to pick up any of the usual differential operator bars. 7

As the cycle progresses from the Fig. 3 position I to the Fig. 4 position, the pawl 25'is movedby the pin and into engagement with push pin 4| and held resiliently engaged therewith by spring 28, as shown in Fig. 4.

During the second half of the cycle, the crank arm [2, by continuing its clockwise rotation, draws the rack bar I I toward the rear of the machine to return the parts from the position shown in Fig. 4 to their normal position shown in Fig. 2. This rearward movement of bar II will, of course, result in clockwise rotation of gear segment 22 and V-shaped member 23. As V-shaped member 23 rotates clockwise, the shoulder 31 on pawl 25 pushes against pin 41 on the cam plate 3! thereby rotating said cam plate in a clockwise direction and causing the cam follower 42 and consequently the arm 33 to move toward the front of the machine. Forward movement of arm 33 causes counterclockwise rotation of shaft 36 and consequently rocks whichever register or registers have been moved to an adding or subtracting position during the first part of the cycle back to a neutral position, as explained in my prior Patent No. 2,192,365, referred to above.

For resiliently holding the cam plate 31 in its two operated positions, a detent is provided. Said detent may conveniently consist of a member 43 provided with notches 44 and constrained to rotate with said cam plate and having in cooperation therewith a pawl 45 pivotally mounted at 46 upon a stationary part of the machine and carrying a roller 41 which is urged by a spring 48 into engagement with member 43.

As explained in my Patent No. 2,192,365, referred to above, a mere cycling of the machine will not result in the rocking of a register into its adding or subtracting position. In order that a register may be moved into an operative position during a cycle, it is necessary first to select one or more registers. In the type of machine with which the present invention is particularly concerned, register selection is predetermined and is accomplished by the carriage of the machine depressing one or more register selecting cam plates. Depression of a register selecting cam plate causes, among other things, the withdrawal of an add latch 49 (see particularly Fig. 1) from a notch in a state control slide 50, thereby allowing said slide to be moved toward the front of the machine by a spring 5! until its forward movement is arrested by a second or subtract latch 52.

The state control slide is provided at its front end with a cam slot 53 into which slot extends a follower fixed to a slidable bail. As explained in my prior Patent No. 2,192,365, forward movement of state control slide 50 to the point where it is arrested by the subtract latch 52 serves to position the slidable bail at a location wherein subsequent clockwise rotation of shaft 36 will rock the register, controlled by the selected state control slide, into its adding position.

Since the particular construction of the slidable bail and its connection with the register are not within the confines of this invention, the same have not been illustrated in the drawing and reference is to be had to my Patent No. 2,192,365 for the details thereof.

As likewise explained in my PatentNo. 2,192,- 365, the depression of a second cam plate by the carriage will withdraw the subtract latch 52 and allow state control slide 50 to move forward to its fullest extent, provided the add latch 49 has first been withdrawn, to thereby position the above mentioned slidable bail in a location such 6. that subsequent clockwise rotation of' shaft 36 will rock the register into its subtraction position.

In my prior Patent No. 2,160,487, an arrangement is described whereby a single register may be made to perform the function of two registers by the expedient of operatively connecting only half of the differential operator bars at a time for that register to the usual denominational jacks which are depressed seriatim by the carriage during its travel across a column. In the machine constructed in accordance with the present invention, a good part of the register selecting mechanism has been preserved and while, as described below, the machine in its present form is not provided with mechanism enabling one register to serve as two registers, it lends itself to comparatively simple change-over to a split register machine if such is desired.

Referring now to Figs. 6 and 7, it will be seen that the machine of the present invention is provided with a pair of coupler section shifters 54 and 55 similar to coupler section shifters III of my above mentioned Patent No. 2,160,487. Each of the coupler section shifters is guided for vertical sliding movement by a plurality of guide studs 56 fixed in a stationary register bar guiding plate 51'. When the coupler section shifters are raised from the Fig. 6 position to the Fig. 7 position, the couplers 53, only partially shown in Fig. 7, are raised to a position to operatively connect the differential operator bars with the above mentioned denominational jacks, as will readily be understood.

The coupler section shifters 54 and 55 are operated by the depression by the carriage of a cam plate 355. As may readily be seen in Fig. 10, there is a cam plate 335 corresponding to each of the registers of the machine; in the present instance three have been shown. The rearmost cam plate 330 rests upon a tab 33! of an intermediate plate 302. Through a push rod 353, the plate 352 is operatively connected to one end of a lever 55 pivotally mounted upon a shaft 55. It is to be understood that there is an intermediate plate 332, a push rod 353 and a lever 59 corresponding to each of the other register selecting cam plates 3%, but that for clearness of illustration, they have not been shown.

Operation of lever 53 causes rotation of a lever 50, Fig. 6, pivotally mounted upon a part of the framework 6| of the machine by a stud shaft 62. There is a pin-and-slot connection 53 between one end of lever 53 and an arm 35 fixed to one end of a rock shaft 65 mounted in a pair of ears 5%; oi the framework 5!, so that rotation of lever es causes shaft 54 to be rocked clockwise, as viewed in Figs. 6 and 7. An arm 3? is fixed to the opposite end of rock shaft 55 and carries a stud 53 which extends into an opening 59 in the coupler section shifter It will, therefore, be understood that when the end of lever 53 is raised from the position shown in Fig. 6, such movement will result in raising the coupler section shifter 5 Since it is not desired to use the register controlled by a single state control means 55 as two registers, it is necessary to raise the coupler section shifter 55 at the same time that shifter 54 is raised, and for that purpose, the following mechanism is provided.

An intermediate lever it, having one end ii overlying the stud 83, is pivotally mounted upon the guide plate 57 by means of a stud i2. The opposite end of lever 15 overlies one end of a lever i3, which lever is also pivotally mounted upon the guide plate 5'! by a stud 14. The lever i3 is simi- 7 lar to latch rod retracting lever. 268 of my Patent No. 2,160,487, but unlike said lever 256, the lever 13 is provided with a stud 15 extending into an opening it in the coupler section shifter55 so that when the shifter-54 is raised bythe stud 5,8,

the levers l9 and 13 are rocked in such manner as to cause the stud 15 on lever 13 to raise the shifter 55, as will readily be understood. Lever 13 is normally held in its inactive position by a spring '23.

As in the construction .explainedin my Patent No. 2,160,487, the add latch 49 is provided with a notch ll fitted against the edges of lever 13. Thus it will be understood that the depression of a particular cam plate 300 by the carriage of the machine will serve to .completely condition a given register for-addition, inasmuch as the depression of the cam plate will allow the state control slide to move forwardto its add position and will also operatively connect all of the differential actuators for said register with the universal set of denominational jacks. The upper ends of the denominational jacks are indicated generally at 35 in Fig.10.

In the machine in which the present invention has been embodied, the subtract latches 52- are all withdrawn from engagement with their respective state control slides 50 at the same'time. Each subtract latch 52 is pivotally connected as at '53, Fig. 6, to an arm 79 fixed to a universal cross shaft to. When the cross shaft 80 is rocked counterclockwise from its 'Fig. 6 position, all of the subtract latches 52 are raised.

For a description of a preferred means of operating the shaft to, reference is to be had to Fig. 10. A subtraction determining cam plate 305 is operatively connected through an intermediate plate 363 and a push rod'3fll to one end of an L-shaped lever 308. The L-shaped lever 388 is mounted upon a rock shaft 309 and is connected by a bail 3 i ii to one end of a lever 3 H also mounted upon the shaft 3&9. The lever 3| l is urged in a clockwise direction, as viewed in Fig. 10, by a spring 3 i 2 and is pivotally connected by a pin 3 I 3 to one end of a link 3 l t. The opposite end of link 3 i t is pivotally connected to one end of a lever 3 I mounted upon a'rock shaft 3H6. The opposite end of lever 35 5 is connected by a bail 3H to one end of a latch member 318 also mounted upon the shaft 3 I B.

The spring 3i2 serves to hold the cam plate 335 in an elevated position and :also serves'to position a tongue 31% or" the latch member 358 underneath one arm of a generally T-shaped member 326. The member 320 is pivotally connected at 152i to a stationary part of the machine and is urged by a spring 322 in aclockwise direction, as viewed in Fig. 10. One arm of the mem- 32ii is pivotally connected by a pin 32] to a link 322. The link 322' is provided with a slot 323 into which is fitted a pin 324 mounted upon an arm 325 fixed to the aforementioned shaft 80. A spring 32% connects the pin 324 to an ofiset portion 327 of the link 322.

If a register is to be selected for subtraction in a particular column, a column unit 144 which will control the operation of the machine in that column is provided with a tappet 328 fordepressing one of the cams see to select the register for addition and to raise the couplers 58, as previously described, and is also provided with a tappet 329 for depressing the subtraction cam plate 3335. Through the linkage system above described, depression of cam plate 305 serves to withdraw the tongue 319 from beneath the arm of Tshapedmember 320, whereupon the spring 322 rocks the member 320 clockwise until said member abuts a stationary pin 330. When the member 320 is in abutment with the pin 330, the arm of said member lies in front of the tongue 3E9 so that even though the tappet 329 should leave'the cam plate 395, said plate will not at that'time move upward because the tongue 3l9 cannot move to the right as viewed in Fig. 10.

When the member are is rocked clockwise, the link 322' pulls the pin 324 on arm 325 toward the rear of the machine to thereby rock the cross shaft in a counterclockwise direction as viewed in Fig. 10 and thereby withdraw all of the subtract latches 52, as previously explained.

If a register is to be selectable in a. given column alternately for ordinary computing and for automatic total-taking, the column unit will be provided with two tappets 32B and two tappets 329. One of the tappets 328'and 329 will cooperate withthe cam plates 3% and 395 when said camplates are in theirforward, or ordinary computing, positions and one of the tappets .323 and 329 will cooperate with the cam plates 3Mand 355 when saidcamplates are in their rearward, or automatic total taking, positions. It is well known that in-machines of the type with which thisinvention is particularly concerned, the cam plates which control the functioning of the machine may be rocked from a non-total-takin position toa total-taking position, and one mannor of rocking such plates is explained in my prior Patent No. 2,372,681.

Onearm of the T-shaped member 320 is provided witha camportion 33! and a dwell 332 for cooperating witha pin 333 .carriedby a bar 334. The bar33i is part of the means for moving the general operator bar It and earlyin the .cycle the pin 333 contacts the cam portion 331 to thereby rock the'member 323 in a counterclockwisedirection. As the membersze moves counterclockwise, the offset portion 327 of link 322', through thespring 326, pulls upon :thetarm 325 to attempt to rock the cross shaft '89 in .a clockwise direction. If a register has been selected for subtraction the shaft 8d cannotat'this time move clockwise because thetend of .the fsubtract'flatch will be resting upon the state control slide. Spring 826 will, therefore, yield until later inithe cycle when the state control slide has been returned to its normal position, in a manner to be later described, whereupon the springtzfi will snap the subtract latches down into theirrespectivenotches in thestate control slides.

Thecolumn units l lare adjustably mounted uponvthe carriage, partially indicated at 335, and may be placed in any desired positions in accordance with the work-sheet columns.

Referring now to Figs. 1 and 5, a portion of the base of a combined typewriting and computing machine, of the type to which the present invention is particularly adapted, is shown. Since the present machine has three single registers, or'three interspersed registers, as disclosed in'my recently issued'Patent'No. 2,436,055, three fore-and-aft movable state control slides 50 are at least partially shown. Since the operation'of all of the registers and all of'the state control slides is identical, only one state'control slide has been shown in its entirety.

Extending parallel to the state control slide 59 for'each register is a fore-and-aft movable slide 8|. Each slide BI is provided-with an elongated s1ot-82 at its forward end and is mounted I01 guided'movement upona-pin 83 fixed to the framework of the machine. Each slide has an elongated slot 84 in its rear end guidably slidable upon a headed stud 85 fixed in a state control restorer bar 86, the operation of which will be presently described. Each slide 8| is constantly urged toward the rear of the machine by a spring 81. In its forward end, each of the slides 8| is provided with a slot 33 for receiving one arm of a bell crank 89 stationarily pivoted at 90 to the machine framework. To the other arm of each bell crank 80 is articulated, by a pin-andslot connection SI, a sensing bar generally indicated at 92. One leg 93 of sensing bar 92 extends through an opening is (see Fig. 5) in the framework of the machine, and another leg 95 thereof is guided in a groove 96 cut into the machine framework. At its upper end, each sensing bar is provided with a guide member 91 riding within a slot 98 in a stationary member 99 and with a sensing spur I for a purpose to be presently described. Each of the sensing bars 02 is urged to its inactive position by a relatively light spring 92, as shown in Fig. 5.

A register clearance detecting bail bar IOI has side arms I02, which are pivotally mounted upon side plates I03 of a register frame. Only one of the side plates I03 is shown in Fig. 5, and inasmuch as the plates I03 correspond to plates IOI of my Patent No. 2,436,055 and the registers to be used in the present machine may be identical with the registers described in detail in said patent, reference is to be had thereto for the details thereof. The particular machine chosen for illustration is of the interspersed register type, as disclosed in my said patent and for that reason, the bar IOI is illustrated in Fig. 1 as having a row of cam-bevel-sided teeth I05 and interdental notches I05. As described in said patent, a register consists of a plurality of wheels I06 for each denominational order, and a detent arm I0? is provided for each wheel. Each wheel is provided with a pair of crescents I00 out into adjacent teeth. When the wheel is in the rotative position corresponding to 0, the crescents I08 are aligned with a tail portion of detent arm IN. A spring I09 urges each arm I Ill toward its wheel. It will, therefore, be apparent that when the crescents are aligned with the tail, portion of said arm, the arm will not stand out as far as when the wheel is in a position other than 0 and the crescents are not so aligned. The purpose of the interdental notches is to allow the detent arms I01, corresponding to the Wheels of a non-selected register of the interspersed group, to be positioned outwardly by wheels of that group which are not in a 0 position without affecting the bail bar I 0| all as described in my Patent No. 2,456,055, referred. to above.

Bail bar MI is urged by a spring IIO toward the arms I03 and when a register is clear, that is to say when all the wheels of the register are standing at 0, bar IOI is so positioned as to be out of the path of downward movement of spur I00 of feeler member 92, as may be seen in Fig. 5. When any one or more wheels of a register are standing at a position other than 0, arms I0! corresponding to such wheels are moved outwardly thereby moving the bail bar IOI outwardly and into the path of, and preventing downward movement of, spur I00, as shown in Fig. 1.

Thus it will be seen that the spring-urged foreand-aft movable slide SI, together with the sensing bar 92 and its sensing spur I00, constitutes 10 a sensing means for ascertaining whether a register is clear or whether there is an amount standing in the wheels of said register.

While above, reference is made to a selected register for purposes of explaining the presence of the interdental notches I05 in the bail bar IOI, for the remainder of the specification it is to be understood that when reference is made to a selected register, the term is intended to include a single register of a multiple single-register machine, as well as one register of an interspersed group.

Each of the slides 8I is provided with a notch MI in the side thereof, and extending into each notch I I i is an arm I I 2 fixed to a cross shaft 5 I3. Also fixed to said cross shaft is an arm I I4 pivotally connected at I I 5 to a vertically movable member I I6 guided in a stationary cross piece III', as seen in Fig. 5.

The upper end of member II 6 abuts a flange II8 on one end of a lever H9 pivotally mounted upon a stationary shaft I20. The lever H9 is urged by a spring I2! in a clockwise direction, as viewed in Fig. 1, about the shaft IN, and at the end opposite the flange H8 is provided with a flange I 22 overlying one end of a draw link I23. The draw link 5223 is urged to inoperative position by a spring I24 and is provided at one end with a toothed pawl I 25 for engagement with the usual snatch roll I26. Intermediate its length, the draw link I23 is pivotally connected to one end of a stationarily fulcrumed lever I27 to the opposite end of which is operatively connected by a link I28, a type bar I29 carrying a star or other clear sign I30.

When any one of the slides 0| is moved by its spring 8'! toward the rear of the machine, the forward edge of the notch III will pull the arm H2 toward the rear thereby rocking cross shaft H3 and causing the vertically movable member M0 to be raised. This raising of member I I5 will, of course, rock the lever H5 and thereby cause the pawl I25 on draw link 5223 to be moved into enga ement with the snatch roll I26. As

' the draw link I 23 is moved by the snatch roll, the

type bar I 20 will be moved into engagement with the work sheet carried by the platen of the typewriter unit, as is well known.

While that part of the star printing train from the lever M9 to the type bar I29 is shown in Fig. 1 as being located to the left of the vertically movable member I I6, it has been so shown only for the sake of clearness of illustration, and in the actual construction of the machine, it is located to the right of member I6.

When work is being performed, which in a machine with which this invention is primarily concerned may be either a manual item entry or an automatic total in a column on a work sheet, it is essential that a star or other clear sign be printed only if the particular register in which the work is being performed in that column becomes clear. In other words, unless the particular register selected to be moved to its adding or subtracting position from its normally neutral position is cleared during the cycle which follows the printing operation, a star should not be printed.

To insure that clear sign printing is controlled by the particular register selected for operation in a given column, an interlock has been provided between the state control means for each register and the clear condition sensing means for that register which will prevent the operation of the sensing means at all times when the state control slide has not moved forward.

. In Fig. l is shown a member I3I pivotally mounted upon the pin 83, which, as previously pointed out, also serves to guide the forward end of slide. 8i. A pin-and-slot connection I32 serves to operatively. connect each of the members I3I to its state control slide, and each member I3! is provided. with a hook I33 extending into the path of'movement of a pin I34 mounted in each of the sensing slides BI. Until a state control slide 56 has been moved forward to'determine an adding or subtracting condition of its register, the. hook I33 will prevent rearward movement of the associated sensing slide 8| and, therefore, prevent operation of the clear sign printing train. When a state control slide 58 moves forward, the member IBI associated therewith will be caused to swivel about the pin 83 due to the pin-andslot connection I32, and this swiveling of member I3I Will cause the hook I33 thereon to move out of the path of movement of the pin I35, as will readily be appreciated.

In some instances, it is desirable to prevent the printing of a clear sign at all times except when a. register has been selected for subtraction, and for accomplishing that'result, the arrangement shown in Fig. 8 is contemplated. Attached by a screw I35, or otherwise, to the member i3! is a member I36 having an upturned lip 13? for bearing against one edge of the member I3I and having an elongated tail I38 for extending beyond the end of book I33.

If the add latch 45 is withdrawn and the state control slide 55 consequently moved forward, in the direction of its arrow in Fig. 8, to the position wherein its register will be rocked to its adding position during the cycle, as previously explained, the hook I33 of member ISI will be withdrawn from the path of movement of pin I es, but the elongated tail I38 of member I3 3 will not be moved far enough to be out of the path of pin I34. Consequently, the sensing means cannot operate when a register has been selected for addition. If, however, the subtract latch 52 is now withdrawn to allowthe slide 58 to continue its forward movement, such additional forward movement will cause the member I35 and member I36 attached thereto {to be rotated about the pivot point 83 to a position wherein the elongated tail portion I38 is out or" the path of movement of pin I34, and'the sensing slide 85 will consequently be able to move toward the rear of the machine, indicated in Fig. 8 by the arrow on member 8|.

Should it be desirable to prevent printing of a clear sign at all times except when a register is selected for addition, it is contemplated to employ the arrangement shown in Fig. 9, wherein the member I36 of Fig. 8 is replaced'by a member 315. The member I39 is fastened to the member I3! by a screw IdIl, or otherwise, and is provided with a lip MI, similar to the lip I31 "of'member I36, for bearing against the side of the member I3I. Member I39 is provided with a tail portion M2, which is longer and wider than the tail portion I38 of member I36 and is cut away at It to provide a space between the hook I 33 and the end of tail portion I42 into which the pin I3 on slide BI may move. If with the construction shown in Fig. 9, the add latch 59 is withdrawn to allow the state control slide 59 to move in the direction of its arrow in Fig. 9

' to the position wherein the register is selected for addition, the member I3I and the m mb I39 connected thereto will be rotated about the pivot 83 to a position wherein the hook I33 is outof the path of movement of' the pin It'd, but the end of tail portion I42 will not have moved to a point of alignment with said pin. The sensing slide SI will, therefore, be free to move to' the rear, the direction shown by its arrow in Fig. 9, and consequently institute the-printing of a clear sign, as previously explained.

In the Fig. 9 construction, if both the add and subtract latches are withdrawn from the state control slide, said slide will move all the way forward and thereby rotatemembers IS'I and I39 to a point where the end of tail portion I62 will block rearward movement of slide Eli. It will later become apparent that there is no possibility of the slide SI moving to the rear during the time required for the state control slide so to move to its subtract position. That is to say, whenever a register is selected for subtraction, the opening formed between the hook I33 and the end of tail portion I52 by the cutaway I43 is momentarily exposed to the pin I3 3, but the slide 8! is prevented from movement at that time by other means.

When a clear sign is to be printed in a column on a work sheet, it is desirable that said sign be printed at only one particular letter space position of the carriage and said letter space may appropriately be the one immediately following the lowest denomination of the column of numbers.

Column unit hid, in addition to the tappets 328 and S29 previously referred to, is provided with a tappet 335 for depressing seriatim the aforementioned denominational jacks see; As described in my prior Patent No. 2,323,622, as the carriage escapes from the position wherein the tappet 338 is resting upon the jaoksil i corresponding to the lowest denominational order, a cycle instituting tooth 33? on the column unit I44 passes over a cycle trip lever partially indicated at 338 in Fig. 10. Depression of the cycle trip lever 338 causes the machine to cycle, as explained in my said'Patent No. 2,328,622.

After the tooth 33? passes over the cycle trip lever 338, the carriage comes to rest in the letter space position immediately following the lowest order letter space position, and it is in this letter space position that it is desirable to print the clear sign. For enabling the slides 3| to move rearward to. thereby institute clear sign printing, the column unit I 34 is provided with a tappet, or dog, I 35 for cooperating with a tooth I46 one plate I47. The dog IE5 is so shaped and positioned as to rest upon the tooth I46 only when the carriage is in the letter space position immediately following the lowest denomination.

Referring now particularly to Fig. 1, it will be seen that the tooth I is a part of a member I48 carrying a headed stud I69 mounted within a slot I59 in the plate i4? and a headed stud I5I mounted within a slot I52.

Member I48 is urged upward toi'the position shown. in Fig. 1 by a spring I53 extending between the headed stud I5I and a hole I55 in the plate I41. The plate I ll and its tooth carrying member I48 are constructed as more particularly explained in my prior Patent No. 2,372,681, and by referring to said patent, it will readily be understood that when the tooth I46 is depressed by a pressure applied from the right, the plate I41 will be depressed, but when the tooth is struck from the left, the member I48 is merely depressed 13 with the headed studs I49 and II riding down in their respective slots without depressing the plate I41. The purpose of using such a plate is so that the plate I41 will not be depressed during carriage return operations.

When the plate I41 is depressed, it in turn depresses a plate I55, which through a push rod I55 rocks a crank arm I51 fixed to a shaft I58.

The shaft I58 carries three rods I59 which are normally held in alignment with the sensing slides BI, as shown in Fig. 1, by a helical spring I60 acting upon the shaft I58. Therefore, it will be obvious that the sensing means comprising the slides 8i can operate at only one columnar letter space position, since at only one letter space position in a column is the shaft I58 rotated by the depression of plate I41 to remove the rods I59 from alignment with said slides.

A dog I45 for depressing plate I41 may, of course, be placed upon any column units which control columns in which it is desired to print a clear sign.

If desired, the plate I51 may be made to rock to the rear whenever a total is taken in a manner similar to that described in respect to plate 455 of my hereinbefore mentioned Patent No. 2,372,681, so that a clear sign may be printed in any column whenever a total is automatically taken in said column but not printed when an item is merely entered in said column. If the plate I41 is made rockable during automatic tota1 taking operations, a dog I45 is provided upon each column unit I44 in a position to be in operative alignment with the tooth I46 when plate It? is in its total position. In any column, for example a proof column, wherein it is desired to print a clear sign at times when a total is not automatically taken, the dog I45 will, of course, be so positioned as to be in operative alignment with the tooth I45 when plate I41 is in its unrocked or non-total-taking position.

In addition to the clear sign printing being confined to one particular columnar letter space position and being dependent for its operation upon register selection, it is necessary that said printing be delayed until after the cycle has progressed to a point where the register wheels have been completely turned. Not until after the differential operator bars have completed their forward movement and the tens carry over has had time to operate is it possible to ascertain whether the computation has resulted in a clear register. For the purpose of delaying operation of the clear sign printing train until the second half of the cycle, the following mechanism is employed.

A crossbar l6i, the operation of which will later be more fully explained, is normally positioned as shown in Figs. 1, 2 and 5. Each of the sensing slides BI is provided with a post I52, which is in abutting relation to the crossbar ISI when the machine is in its normal condition, that is, when a cycle is not in progress. When a cycle has progressed to approximately the one quarter point, the crossbar ISI begins to move toward the rear of the machine so that by the time the cycle has progressed to the halfway mark, the crossbar I5I has moved to the position shown in Fig. 4, wherein it no longer interferes with free rearward movement of the slides 8|.

Fixed to the cross shaft 36, which, as previously explained, is rocked clockwise, as viewed in Figs. 1 to 4, at the beginning of a cycle, is an arm I53 to which is pivotally connected at I54 a link I65 having a slot I56 in one end thereof. To the cross shaft H3, which, as previously explained,

must be rocked counterclockwise, as viewed in Figs. 1 to 4, to institute operation of the clear sign printing train, is fixed an L-shaped arm it! provided with a pin I68 extendin into the slot I66. Arm I61 is also provided with a pin I69 between which and a stop pin I10 on the framework of the machine extends a light tension spring I1I for resiliently holding said arm against said stoppin and consequently holding the cross shaft II 3 in its neutral position.

The general operator mechanism is so timed as to cause the cross shaft 36 to complete its clockwise rocking movement before the crossbar I6I begins its rearward movement. Therefore, the link I55 is moved forward to the position shown in Fig. 3 wherein the pin 58 on arm It? is positioned in the back of slot I55 before the crossbar I5I has started to move away from posts I62. Thus while the crossbar IiiI serves to lock the clear condition sensing slides 8i before the cycle begins, it will be apparent that this function is taken over by the link I55 and its pinand-slot connection with the L-shaped arm I51 as the cycle gets under way.

Eearly in the second half cycle, the cross shaft 36 is rocked counterclockwise of its Fig. 4 position to return the selected register to its normal position, and shaft I I3 would at that time be free to be rocked were it not for the following arrangement.

Fixed to the cross shaft II3 near the end op posite the L-shaped arm I51 is an arm I12 carrying a roller I13 on the free end thereof. Secured to the general operator bar It! by means of a screw I14, or otherwise, is a member 15. As the general operator bar II) advances to the half cycle position, the member I15 moves over the roller I13 on arm I12, as shown in Fig. 4, to thereby prevent the cross shaft I I3 from being rocked. As will readily be appreciated, the member I15 will remain in engagement with the roller I13 until the second, half of the cycle has progressed far enough for the register to be returned to its neutral position wherein the bail bar IBI will be in a position to block downward movement of the sensing bar 92 if the register is not clear, as previously explained.

Thus it will be seen that means has been provided for delaying operation of the clear sign printing train until the second half of a cycle has gotten under way. By varying the length of the member I15 or the arm I12, clear sign printing may be instituted at any time during the second half cycle that is found desirable.

After a register has been selected. for addition or subtraction by forward movement of its state control slide 58, it is necessary to return the state control slide to its neutral position during the cycle following the computation, and, for this purpose, the hereinbefore mentioned bar is employed. Attached to the bar 86 is an arm I pivotally connected at I11 to an arm i'ia fixed to a shaft I19. Also fixed to the shaft I19 is an arm I80 pivotally connected at l8I to a hook link I82. Hook link I62 is cooperative with the general operator bar II) in a manner fully described in my copending application No. 2,654, filed J an uary 16, 1948, it being sufficient here to mention that the hook link I32 is provided with a step I83. As the general operator bar it) moves forward, the hook link 182 is lifted so that during the return stroke of said general operator bar, step I83 is caught by said bar, and the hook link I82 is thereby drawn toward the rear of the machine. Rearward movement of the hook link I82, will, of course, result in rearward movement of the bar 85, aswill readily be appreciated; Each of the'state control slides 58 isprovided with a pin Its extending. into the path of movement of the bar 83, so that as said; bar moves toward the rear of the machine, any slide 53 which has been allowed to move forward will be picked up by the bar 85 striking the pin ISIS thereon and returned to its normal position. At the very end of the cycle, the step I83 is kicked down out of engagement with the general operator bar It, and a spring I85 attached to the bar 86 returns said bar and the hook link I32 to the position shown in Fig. 1, as described in my copending application-No. 2,654, referred to above.

After any sensing slide 8| has moved rearward toinstitute action of the-clear sign printing train during acycle, as previously described, it is necessary thatsaid slide be returned to its normal position in order that it may be ready to perform its sensing. function during the next computing operation. Since the particular means employed hereinfor' that purpose-is a part of the usual tens-transfer and fugitive-one mechanism, said tens-transfer and fugitive-one mechanism will be briefly described, but for a full description of the-operation thereof reference is to be had to my prior Patent No. 2,192,365.

Referring now to Fig. 5, one of the differential operator bars is indicated at I85. Said bar car ries a plurality of index pins I8? and has rack teeth I83 located upon the forward end thereof. By referring to my Patent No. 2,192,365, mentioned above, it will readily be apparent that there is a differential operator bar I239 for each denominational order of a register. The rack teeth on each of the bars I86 are in constant mesh with the teeth of an idler pinion I89.

The register wheels I06 are rocked rearward into engagement with the idler pinions I89 for subtractive operation and are rocked downward into direct'engagement with the rack teeth I88 for additive operation.

A lever I98 corresponding to each of the differential operator bars I96 is pivotally mounted upon a bracket IQI fixed to the general operator bar Iii. As is well known, the index pins I8? are set in accordance with the operation of the numeral types of the typewriter unit, the pin being set, as shown, when none of the other pins has been set. As the general operator bar II! is moved forward during a cycle, the differential operator bars I85 are picked up by the contact of lever I96 and whichever of the index pins I8? has been set, and moved forward to rotate the register wheels I65 by an amount corresponding to the set index pin. On its return stroke, the general operator bar It picks up an abutment I92 on each of the differential operator bars to return same to their normal position. The bars I88 are actually moved the last increment of movement to their home position by a spring I93 engaging with a notch in said bars.

If a register wheel is rotated through the transfer point, that is, from 9 to 0 or from 0 to 9, a carry-over trip lever I94 is moved outwardly of the position shown in Fig. to rock a bell crank I95 one end of which is in engagement with a carry-over bar I96. Each carryover bar I93 is pivotally connected to a stationarily pivoted lever I9? carrying a roller I93 on one end thereof. The roller I98 on the lever I9! is in lateral alignment with the lever I90 of the next highest denomination for a purpose present ly to become apparent.

A spring I99 urges the carry-over bar. I96 forward and downward, forward movementbeing normally prevented by contact of the lever I91 with a stationary shaft 209 and downward movement being arrested by contact between the forward end of'bar I 96 and a guide comb ZIII.

Before the'carry-over bars I96 can be effectively operated, it is necessary that they be drawn a short distance toward the rear of the machine so that the levers I9'I are no longer. in contact with the stationary shaft 260, and for this purpose, a crossbar 202 is provided for cooperative engagement with a shoulder. 293 on said carry-over bars. The crossbar 262 is connected to move withthe crossbar IBI, previously described, by means'of brackets 204, only one of which is shown.

Crossbar IGI is connected at its opposite'ends between a pair of slides 205, only one of which is shown. The slides 205 are each provided with a pair of cam followers 205 for cooperating with a cam 2m fixed to the cross shaft 2 I, previously referred to.

During the first half of the cycle, the cam 20! is rotated counterclockwise, as viewed in Fig. 5, to draw the crossbar IBI and consequently the crossbar 2%)? toward the rear. As the crossbar 202 moves rearward, it contacts the shoulders 293 of carry-over bars I95 and thereby moves said carryover bars rearward to position a flange 208 on one end thereof in abutment with the set 0 index pin I87 of the next highest denomination operator bar I39. If the 0 pin is not set, the flange 2% is positioned in what would be abutting relation with the 0 pin if same were set. If, at this time, a register wheel passes through the transfer point, the bell crank I95 corresponding to said wheel will be rocked to lift the shoulder 263 on the corresponding carry-over bar out of contact with the crossbar 202. Spring I99 will then be effective to draw the carry-over bar I95 forward until the lever I97 contacts the stationary shaft 269. At that time the roller I98 on lever ISI will be'positioned far enough toward the rear of the machine to intercept the forward movement of the lower end of lever I and thereby cause said lever to pivot about its connection with the bracket I9 I. The pivotal movement of lever I99 will be just sufficient to cause the upper end thereof to move the differential operator bar I85 forward by an amount equal to one digital distance and position the set index pin in contact with the flange 29B of carryover bar I 96. The additional forward movement of the difierential operator bar will cause the register wheel associated therewith to be turned by an amount equal to one digit, as will readily be understood.

A lever 209, shown in Fig. 5, operates the carryover bar I for the lowest denominational wheel and is connected by a bail 2 II? to the bell crank I95 which is operated by the highest denominational wheel, thus providing a fugitive-one mechanism, as will beunderstood and as more fully explained in my copending application, Serial No. 2,654, filed January 16, 1948.

During the second half of the cycle, the cross shaft fl is rotated clockwise, as viewed in Fig. 5, as previously explained. The resultant clockwise rotation of cams 201, by cooperation with the cam followers 2%, will cause the slides 205 and the crossbar 202 associated therewith to move forward until the crossbar 202 clears the shoulders 203 on carry-over bars I96, whereupon the 17 springs -l 99 will pull said carry-overbar down to the position shown in Fig. 5.

As the crossbarl6l' moves forward, it carries forward to its normal position any sensing slide 8|, which has moved rearward,by cooperation with the post [62 thereon. Thus it will be seen that the usual 'tens-carry-over restorer bar 'IBI is-utilized as a primary lock to prevent operation of the clear condition sensing means and has also been'made to serve as a-restoring means for said sensing means.

From the foregoing description, it will be apparent that an arrangementhas been provided,

in a combined typewriting and accounting machine, whereby a star or other clear sign may be printed in-any desiredcolumn'of a work sheet whenan operation in that column has resulted in clearing the register whichhas been selected foroperation at thatcolumnarposition. It is to be particularly noted that in accordance with the present invention, it is of no consequence whether the register iscleared as a result of an automatic total taking operation or as a result ofan item entry. It is-also to benoted that with an arrangement such'as herein disclosed, the 9 star or other clear sign will only be printed at definite preselected columnar letter space positions.

'It isalso to be noted that clear sign printing and register selection are both under control of p the carriage. It is, therefore, possible to check back over a work sheet and determine the place where any error mayehave occurred. For example, if a clear-sign does not appear in a column wherein an automatic total was taken, it will 7 be evident that an-error occurred at the time of the automatic total taking operation and the particular register wherein the error occurred may be identified, since at that'columnar position it will be-known that a certain register was in operation.

Having thus described'my invention, I claim:

1. In a computing machine adapted for printing amounts in a column on a work sheet and having a letter spacing carriage,-a unit on said carriage for controlling various functions of the machine, a register comprising a plurality of axially aligned'wheels, and a cycling general oper ator for runningindexed amounts into the wheels of the register; the improvement comprising spring-operated sensing means for'ascertaining the" clear condition of the register, a pair of normally effective locks each of which is capable of preventing operation of "said sensing means, means'fonreleasingoneof said looks at a predetermined columnar letter'space position of the carriage, means for releasing the other of said locks during a machine cycle, and a clear sign printing trainoperable only when both of said locks are released and when the sensing means finds the register to be clear.

2. In a computing machine adapted for printing v amounts in a column on a work sheet and having a letter spacing carriage, a unit on said carriage for controlling various functions of the machine, a register comprising a pluralityof axially aligned wheels,.and.a cycling general operatorfor running indexedamounts into' the wheels of the register; the improvement comprising spring-operated sensing means for ascertaining the clear conditionof the register, a pair of normally efiective-locks each of which is capable of-preventing operation of'said sensing means, means' for releasing one-of said locks at a predetermined columnar letter space position of the carriage, means for releasing the other of'said locks during a machine cycle, and a poweractuated clear sign printing train the action of which is instituted by said sensing means'when both'of said locks are released and when the sensing means-finds the register to be clear.

3.- In a credit balance computing machine having a register Whichis movable to different positions-from a normally neutral position for adding and subtracting, a cycling generaloperator-ior running indexed amounts into the wheels of the register, a state control means for determining whether the register is to be moved during a cycle from its neutral position into its adding or subtracting position, a spring-urged member associated with said state control means, an interlock between said state control means and said springurged-rnember constructed and arranged to prevent operation of said spring-urged member at all times when said state control means has not been moved to determine an adding or subtracting condition of the register, and a sign printing train the operation of which is instituted by said spring-urged member.

4. In a credit balance computing machine having a register which is movable to different positions from a normally neutral position for adding and subtracting, a cycling general operator'for running indexed amounts into the wheels of the register, a state control means for determining whether the register is to be moved duringa cycle from its neutral position into its adding or subtracting position, sensing means associated with the register for ascertaining a clear condition thereof, an interlock between said state control means and said sensing means constructed and arranged to prevent operation of said sensing means at all times when said state control means has not been moved to determine an adding or subtracting condition of the register, and a clear sign printing train the operation of which is instituted by said sensing means'when said sensing means is operated and upon operation finds the register to be clear.

5. In a credit balance computing machine having a register which is movable to different positions from a normally neutral position for adding and subtracting, a cycling general operator for running indexed amounts into the wheels of'the register, a state control means for determining whether the register is to be moved during a cycle from its neutral position into its adding or subtracting position, sensing means associated with the register for ascertainin a clear condition thereof, an interlock between said state control means-and said sensing means-constructed and arranged to preventoperation'of said sensing means at all times when said state control means hasnot been moved to determine a subtracting condition of the'register, and a clear sign printing train the operation of which is instituted by said sensing means when said sensing means is allowed to operate and upon operation finds the register to be clear.

6. In a credit balance computing machine having a register which is movable to different positions from a normally'neutral position for adding and subtracting, a cycling general operator for running indexed amounts into the Wheels of the register, a state control means for determining whether the register is to be moved during a cycle from its neutral position into its adding or subtracting position, sensing means associated with the register for ascertaining a clear condition thereof, an interlock between said state control means and said sensing means constructed and arranged to prevent operation of said sensing means at all times when said state control means has not been moved to determine an adding condition of the register, and a clear sign printing train the operation of which is instituted by said sensing means when said sensing means is allowed to operate and upon operation finds the register to be clear.

'7. In a credit balance computing machine having a register which is movable to difierent positions from a normally neutral position for add- "ing and subtracting, a cycling general operator for running indexed amounts into the Wheels of the register, a fore-and-aft movable slide for determining whether the register is to be moved during a cycle from its neutral position into its tracting condition of the register, and a clear sign printing train the operation of which is instituted by said sensing means when said sensing means is allowed to operate and upon operation finds the register to be clear.

8. In a credit balance computing machine having a register which is movable to different positions from a normally neutral position for adding and subtracting, a cycling general operator for running indexed amounts into the wheels of the register, a state control means for determining Whether the register is to be moved during a cycle from its neutral position into its adding or subtracting position, a spring-urged member associated with said state control means, an interl cl: between said state control means and said spring-urged member constructed and arranged to prevent operation of said spring-urged member at all times when said state control means has not been moved to determine an adding or subtracting condition of the register, a sign printing train the operation of which is instituted by said spring-urged member, and means associated with said cycling general operator for delaying the operation of said spring-urged member until the last half of the cycle.

9. In a credit balance computing machine having a register which is movable to different positions from a normally neutral position for adding and subtracting, a cycling general operator for running indexed amounts into the Wheels of the register, a state control means for deter- 'mining whether the register is to be moved during a cycle from its neutral position into its adding or subtracting position, sensing means associated with the register for ascertaining a clear condition thereof, an interlock between said state control means and said sensing means constructed and arranged to prevent operation of said sensing means at all times when said state control means has not been moved to determine an adding or subtracting condition of the register, a clear sign printing train the operation of which is instituted by said sensing means when said sensing means is allowed to operate and upon operation finds the register to be clear, and means associated with said cycling general oper- 20 ator for delaying the operation of said sensing means until the last half of the cycle.

10. In a credit balance computing machine adapted for printing amounts in a column on a work sheet and having a letter spacing carriage, a register which is movable to difierent positions from a normally neutral position for adding and subtracting, a unit on said carriage for controlling various functions of the machine, and a cycling general operator for running indexed amounts into the wheels of the register; the improvement comprising a state control means for determining whether the register is to be moved during a cycle from its neutral position into its adding or subtracting position, a spring-urged member associated with said state control means, an interlock between said state control means and said spring-urged member constructed and arranged to prevent operation of said spring-urged member at all times when said state control means has not been moved to determine an adding or subtracting condition of the register, a normally effective lock for preventing operation of said spring-urged member, said lock being releasable at only one predetermined letter space position in a column, and a sign printing train the operation of which is instituted by said spring-urged member.

11. In a credit balance computing machine adapted for printing amounts in a column on a work sheet and having a letter spacing carriage, a register which is movable to difierent positions from a normally neutral position for adding and subtracting, a unit on said carriage for controlling various functions of the machine, and a cycling general operator for running indexed amounts into the register; the improvement comprising a state control means for determining whether a register is to be moved during a cycle from its neutral position into its adding or subtracting position, sensing means associated with the register for ascertaining the clear condition thereof, an interlock between said state control means and said sensing means constructed and arranged to prevent operation of said sensing means at all times when said state control means has not been moved to determine an adding or subtracting condition of the register, a normally efiective lock for preventing operation of said sensing means, said lock being releasable at only one predetermined letter space position in a column, and a clear sign printing train the operation of which is instituted by said sensing means when said sensing means is allowed to operate and upon operation finds the register to be clear.

12. In a credit balance computing machine adapted for printing amounts in a column on a Work sheet and having a letter spacing carriage, a register which is movable to different positions from a normally neutral position for adding and subtracting, a column unit on said carriage for controlling various functions of the machine, and a cycling general operator for running indexed amounts into the register; the improvement comprising a fore-and-aft movable slide for determining whether a register is to be moved during a cycle from its neutral position into its adding or subtracting position, spring-operated sensing means associated with the register for ascertaining the clear condition thereof, an interlock between said fore-and-aft movable slide and said sensing means constructed and arranged to prevent operation of said sensing means at all times when said fore-and-aft movable slide has not been moved to determine an adding or subtract- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Hart Aug. 13, 1918 Sohluns June 7, 1932 Schluns Oct. 4, 1938 Pitman Mar. 5, 1940

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