US2588539A

US2588539A - Calculator

Info

Publication number: US2588539A
Authority: US
Publication date: 1952-03-11
Anticipated expiration: 1969-03-11

Description

March l1, 1952 E, G. KEsLlNG CALCULATOR Filed y July 29 1950 2 SHEETS--SHEET l MrCh 11, 1952 G. Kl-:sLlNG CALCULATOR 2 SHEETS--SHEET 2 Filed July 29, 1950 Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE CALCULATOR Elmer G. Kesling, Bloomfield, Mo., assigner of one-half to Gladys M. Kesling, Bloomfield, M0.

Application .liuly 29, 1950, Serial No. 176,680

18 Claims. l

The present invention relates generally to calculators, and more particularly to manually operated calculators for performing addition and subtraction.

In brief, the present invention contemplates a manually operated calculator constructed almost entirely from moldable plastic material such as cellulose acetate butyrate, the only metal parts being helical springs. The calculator includes a plurality of digit dials, one each for units, lOs, lOOs, etc. Each of these digit dials has in integral relation therewith a gear, all of these gears being releasably held in the respective positions to which they are advanced in the use of the calculator mechanism by a single novel detent device. The detent device coacts with the individual gears above mentioned so as to release all digit dials of higher series than that being manually rotated, and, at the same time, to 'maintain a positive detent action in respect to all digit dials of series lower than that being manually operated. In addition, a novel spring actuated frictional braking action is provided to reduce the likelihood of inadvertent rotation of any digit dials during the period of their release from detent action as above described.

An object of the present invention is to provide a calculator mechanism of the adding and subtracting type which incorporates a novel detent device which facilitates computation.

Another object is to provide a calculator mechanism of the adding and subtracting type which incorporates a single novel detent construction adapted to maintain a plurality of digit dials each in a plurality of selectable positions, thereby to eliminate the effect of gear lash.

Another object is to provide a calculator mechanism of the adding and subtracting type which incorporates a single novel detent construction adapted to coact with a plurality of digit dials in a manner to release for computation purposes those dials which may be affected by a particular computation and to maintain stationary those dials which cannot be affected by the computation.

Another object is to provide a calculator mechanism of the adding and subtracting type having a plurality of digit dials, one or more being subject to frictional braking action.

Another object is to provide a calculator mechanism of the adding and subtracting type having a plurality of digit dials each provided with an accumulating nger to effect a partial revolution of the dial of next higher series of digits, said partial revolution of one or more dials lof higher digit series being effected without appreciable increase in the effort required to rotate a given;4 dial.

:Other objects are to provide a calculator mechanism which functions smoothly, efficiently, and effectively as desired during a computation, which renders the computation of sums and differences easy upon the operator and upon the calculator, which is of simple compact and sturdy construction, and which is well adapted to relatively inexpensive mass production.

The foregoing and other objects and advantages are apparent from the following description taken with the accompanying drawings, in which:

Fig. l is a plan view of a calculator mechanism constructed in accordance with the teachings of the present invention;

Fig. 2 is a longitudinal cross-sectional elevation thereof, taken substantially on the line 2-2 of Fig. 1;

Fig. 3 is a transverse cross-sectional elevation thereof, taken substantially on the line 3-3 of Fig. l

Fig. 4 is a cross-sectional plan view thereof, taken substantially on the line 4 4 of Fig. 2;

Fig. 5 is a fragmentary longitudinal cross-sectional view thereof, taken substantially on the line 5 5 of Fig. 4, and its various parts removed to show the assembly of the detent spring;

Fig. 6 is a top plan View of a digit dial;

Fig. 7 is a side elevation thereof;

Fig. 8 is a top plan view of a reversing gear;

Fig. 9 is a side elevation thereof;

Fig. l0 is a reduced bottom plan view of a cover; and

' Fig. ll is a reduced top plan view 'of a base.

Referring to the drawings more particularly by reference numerals, 20 indicates generally a calculator incorporating the concepts of the present invention. Broadly, the calculator includes a base 22, a cover 24, digit dials 2G, a detent 28, reversinggears 3i), brake springs 32, and a detent spring 34.

The base 22 is generally rectangular in plan as shown in Fig. 11, and forms a shallow box-like structure having a bottom 4|, side walls 42, and rounded end walls 43. The upper surfaces of the

walls

42 and 43 form a plane rim surface 44 disposed parallel to the bottom 4|.

There is a solid post 45 extending upwardly from the bottom 4I so as to have its axis disposed in a vertical plane through the longitudinal center line of the base 22', but slightly inclined from a directional normal to the rim surface 44. Additionally, Athere 'are aplurality of posts 46 having spring wells 41 likewise extending upwardly from the bottom 4l parallel to the post 45. Although the drawings show only two posts 46, any reasonable number may be employed de pending upon the size of the figures to be handled by the calculator. As shown in Fig. l1, the solid post 45 is near the right hand end of the base 22 and the hollow posts 46 are disposed in equal spaced relation thereto. At the base of each post 45 and 4B, a shoulder 48 is formed so as to have the plane of its surface normal to the axes of the

posts

45 and 46. Each of these shoulders 48 has a parallel annular recess i9 circumscribed thereabout for a purpose to appear. A post 50 having a shoulder 5l is disposed to the right of each of the posts 45 'so as to 'be'parallel thereto and in line with the

several posts

4,6.

Inside parallel surfaces 55 of the side walls l2 are broken by arcuate surfaces 56 which-are concentric with and parallel to the respective posts 45and 146. Additionally, arcuate surfaces are formed concentric with land parallel to 'the

respective posts

45 and 45. A lip 5l is formedat the 'ftop of `each of -the :arcuate surfaces 5t so that :all of the .lips '5? 'lie in planes parallel to the Ashoulders 48. AThe end walls 43 also have inner arcuate surfaces 53 which are parallel to the -respective post 45xor the post 4S vdisposed nearestthe .respective ends. Adjacent the arcuu ate surfaces 58 are arcuate surfaces 59 which surfaces are parallel to, but not ,necessarily concentric with, the .respective posts t5 and '45. forming lips 60 whichzlie in planes parallel to the adjacent shoulders 48. vA boss 6i having a post 62 projecting upwardly therefrom with all side Surfacesparallel to .the post 45 is disposed adjacent to the arcuate surface 58 :at the right hand end of the .base 22 .as shown in Fig. .11. Preferably, at each corner of `thebase 22, a blind hole 63 descends from the rim surface 44 so as tc dispose the axes vof the holes 63 parallel to the posts45and .46.

The cover 24 includes a top surface 'I8 and a parallel lower rim surface 1I. The surface 'H is adapted to fit the rim surface 44 of the base 22 soas to dispose the top surface l! of the cover 24' parallel to the bottom-4| of the base 22. Four dowel ,postsV 12 project downwardly from the surface 1l so as' to dispose the axes of the dowel posts 12 atan inclination corresponding to lthat of the posts 4.5 and 46 of the base 22. The dowel posts-"'12 -are'adapted slidably to nt the holes 't3 in the base 22 thereby to serve as positioning means vin assembling the calculator.

For each

post

45 and 45 in the base 22, there is an opening 13 'in the cover 2li. These openings 13' are circular in shape except for an inwardly projecting tab 14.

A A Ypla-ne annular surface l5 is formed on the underneath side of the cover 24 around each of the -openings 13,-each of the annular surfaces 15`beingin a different plane normal to the dowel posts 'l2 so as to provide a stepped construction -as shown clearly in Fig. 2.

. fNotches 1B preferably with sloping sides 17, as shown in Fig. '1, are formed along one side of the cover .24 opposite the tabs I4 as shown in Fig. 10.- y,

Numerals inarlthrnetic series are formed, as by engravingor embossing, on the upper surface ofgtheA cover .24 in predetermined circular arrangement aroundA each opening 73, as shown AinzFig. l.; lThe illustrated example shows the seriesvone through nine arranged. progressively in a` clockwise direction to form an'outer circle and in a counterclockwise direction to form an inner circle around each opening 13. These numerals are further arranged so as to cause the sum of a numeral in the inner circle and a numeral in the outer circle on the same radial line to equal the highest numeral of the selected series. In addition, the upper surface of the cover 24 may be suitably stylized as by forming decorative grooves as shown at 'I8 in Fig. l.

The digit dials 26 include a disk portion Sil having a flange 8i and an integral gear portion 82. The upper face of the dial 25 which includes the disk portion Sii and the flange portion 8l forms a plane surface except for a plurality of circularly spaced dialing wells 33 disposed in Wardly of the flange 3l and concentrically about thev central axisofthe dial 26. A suitable series of numerals in' arithmetic series, for example, one through nine plus a cipher (zere), is disposed in spaced circular relation on the upper surface of the flange 5i, as shown in Fig. 6, so that one numeral is disposed cn each radial line extending midway between two adjacent dialing wells 83. The gear portion 32 of the digit dial 25 is disposed immediately beiovv the disk portion S8 and has teeth S4 equal in number to the individual dialing wells and disposed on radial lines that pass through the numerals. rEhe teeth 84 may be of modified forni (with respect to recognized standards) thus to predispose them to a detent action to be described. A blind hole S5 extends upwardly from the lower surface of the gear portion 82 so as to be concentric with the mutual axis of the gear portion 82 and the disk portion Si?. The holes 85 are adapted slidably to fit over either a post @l5 or a post it of the base 22 and are of suiiicient depth to permit the lower surface of the gear portion 82 to rest slidably upon a boss 58. It will be noted, as in Fig. 2, that, when a digit disk 25 is mounted upon a post 45 or a post 5, the inclination of the post as aforesaid causes the teeth 84 to occupy a portion of a recess 39, the recesses 49 thereby providing clearance for free rotation of the digit dials upon the posts Sie and #35.

Each digit dial 25 has a single accumulating nger 86 extending radially from the disk portion 8E and disposed immediately below the fiange 8|. This accumulating finger E is disposed on the same radial Zone as one of the gear teeth 54, and .is also in a position of predetermined relation'to the numerals on the upper face of the digit dial. For example, in the illustration of the drawings, the accumuiating finger 865 is immediately below the numeral i'.

The brake springs 32 are assembled in the spring wells 41 so as to urge the digit dials 2t upwardly as indicated in Figs. 2 and 3. This causes the upper surfaces of the digit disks to bear against the surfaces l5 of the cover 2i and provides a slight frictional drag or a braking action as a deterrent pto inadvertent rotation of the digit dials.

The reversing gear Sli shown in Figs. S and 9 has teeth 9i! equal in number to the teeth 813 of the digit dial 26. A hole al .fits slidably .over the upper end of the post 5G at the base 22 so that one surface of the reversing `gear 3i] rests slidably upon the shoulder 5i of thevpost 58. Thus vassembled, each reversing gear 3c vis in mesh with avgear portion 82 of a digit dial 26,as illustrated in Fig. 1. Furthermore, each reversing Vgear 30 1s disposed relative tothe digit dial 2S of next lower digit series than the digt'dial 26 with whose'gearjportion 82 Ait is in meshyso that the accumulating nger on the digit dial 2S of lower digit series may, on passing, impart an angular movement to the reversing gear 30, the degree of angular movement being equal to the angle between two adjacent teeth of the reversing gear 30. It will be noted that no reversing gear is required for the units digit series, but that one is required for each of the 10s, 1G0s, etc., digit series.

The detent 23 is generally in the form oi a iiat

plate having openings

95 and 96, it being understood that additional openings such as and 9G would be required where more than the illustrated number of digit dials are employed. Fig. 4 shows the openings 95 and 93 to be generally oval in shape except for inwardly extending detent angles 9"! and t8. At the right hand end of the detent 28, as shown in Fig. 4, there is an additional detent angle iit extending in the same direction as the detent angles Sl and 98. Each of the detent angles 99, Si? and 98 coact with teeth 84 of a respective digit dial 25 to provide restraint against rotation thereof. Although the distance from the point of the detent angle 99 to the point of the detent angle 91 is the same as the distance between the point of the detent angle 91 and the point of the detent angle 98, the degree of angularity of each of the detent angles 59, 9i and 98 is different, becoming progressively greater from right to left as shown in Fig. 4. Due to this difference in angularity of the detent angles t9, 91 and 98, it is obvious that, in order for these detent angles to bear simultaneously against two adjacent teeth of each of the gear portions S2 of the digit dials 26, these equal distances between .the points of the detent angles must be slightly in excess of the equal distances between the

respective posts

45 and 45. This is a feature of the present invention.

Side edges of the detent 28 are generally parallel one to the other, each having, however, a plurality of arcuate portions IBI projecting transversely therefrom slidably to abut with the parallel side surfaces 55 of the base 22, thereby to maintain the detent '28 in proper longitudinal relation to the gear portions 22 mounted upon the

posts

45 and 46.

The detent 28 is continuously urged to the right, as shown in the drawing, by the detent spring 34, one end of which is hooked into a hole |03 in the detent 28 and the other end of which is hooked around the post 62 projecting upwardly from the bottom of the base 22.

Assembly and operation The above-described individual parts of the calculator 20 may be assembled as clearly shown in Figs. 1 and 2, whereupon the cover 24 may be permanently sealed tothe base 22, as by a conventional acid sealing process.

Thus assembled, it is apparent that thehumerals on the upper face of the digit dials 25 will appear one at'a time in the notches 'l5 as the individual digit dials are rotated. It is further obvious that the detent angles 9e, S'l and 28 will coact with the gear portions 82 of the digit dials 26 so as to retain a given numeral within each notch 'i6 as long as the calculator mechanism is at rest. Each of the digit dials 26 may be manually rotated by inserting a stylus or a pencil point into one of the dialing wells 83 which are accessible through the openings i3 or" the cover 24. In rotating the digit dials in this manner, however, it is apparent that the rotation will be `stopped when the stylus or pencil point is rotated B until it abuts one of the tabs 14. Whether rotated in a clockwise or a counterclockwise direction, the digit dial 26 will position a numeral centrally within a notch 16 whenever one of the dialing wells 82 is brought adjacent tc the tab 14.

If it is assumed that there are ten numerals on each digit dial, for example, 1 through 9 in addition to a cipher (zero), there will be, as above mentioned, ten teeth 84 on each gear, portion 82 and ten teeth 9i) on each reversing gear 3B. Thus, when an accumulating finger 86 of any digit dial 26 passes an adjacent reversing gear 30, a one-tenth revolution of the reversing gear will be eiected which will be passed on to the gear portion 82 of the digit dial 25 associated with the particular reversing gear thus rotated. It is further apparent that such actuation of a reversing gear 36 by an accumulating finger 86 will cause the digit dial 25 oi next higher series than that being manually rotated to turn onetenth revolution in the same direction as the digit dial being manually rotated.

The manual effort of rotation ci any given digit dial 25 overcomes the spring actuated detent action above described. However, the rotation by means of one or more accumulating ngers 8S of digit dials of higher digit series than that being manu-ally rotated is eiected without having to overcome additional detent action. At the same time, positive detent action is maintained in respect to digit dials of lower digit series than that being manually rotated. This is due to the above-mentioned relationship of distances between adjacent detent angles 99, 9'1 and 98 in respect to the distances between adjacent posts d5 and d wherein, it is apparent that, when the detent 28 is moved to the left during the rotation of any given digit dial 25, all detent angles to the left oi that associated with the digit dial being manually rotated will be carried clear of their associated gear portions 82, while all detent angles to the right of that associated with the digit dial being manually rotated, although being moved to the left, will not be moved so far as to permit inadvertent rotation of the digit dial associated there-with. The phantom outlines of detent angles shown at 92', el and 98 in Fig. 4 illustrate this selective detent action. If it is assumed that the center digit dial 2t is rotated until a tooth Eil coincides with the longitudinal axis of the detent 22 thereby causing the point of the angle 9? to rest against the end of the tooth 84', it will been seen that the point of the angle 58 extends clear ci the tooth 8i associated therewith while the point of the angle 9S', although having moved to the left, is still elective to prevent the passage of a tooth 851 ci the right hand gear portion 22. Thus, there is always a detent action effective with respect to the right hand or unit digit dial, and it is therefore unnecessary to provide additional means to prevent inadvertent rotation or" the unit digit dial. Although there are times when the digit dials of higher digit series are released from effective detent action, the above-mentioned irictional drag between the upper surface of these digit dials against the surfaces l5 of the cover 25 are effective to prevent inadvertent rotation of these digit dials during the very short periods oi release from detent action.

In the manipulation of the calculator to cornute sums or diierences, if it is assumed, for example, that the numerals in view through the notches l are all zeros, a rst number may be Ior pencil point vin .the dialing well .83 opposite 'a proper numeral in the'inner circle of iigures on 'thecover 2li and rotating the ydigit dial clockwise until the stylus or pencilipoint abuts the tab 14. 'Ihisiis done for eachdigit of the number desired to be entered upon the calculator. Forexample, if the number desired to be entered is 587, the stylus or pencil point may be placed rst in the dialing well opposite the ,in the inner circle of figures at Lthe left of the calculator Vand the 100s digit dial rotated clockwise until the stylus or pencil point abuts the tab le, whereupon the numeral 5 will appear in the left hand notch '16. In similar manner, the stylus may next be placed in the dialing well opposite the 3 in the center of the calculator, the lOs digit dial Ybeingrotated until the numeral 8 appears in the center notch le. In similar manner, the numeral 7 may be made to appear in the right hand'notch 7E, `so that the number 587 appears in the notches 'i5 as vshown in Fig. l. If it should now be desired to add to the number 587 a number such, for example, as 24, the stylus or pencil point may rst 'be placed in the dialing well opposite the 2 of the inner circle or figures associated with the lOs digit dial, and this digit dial rotated clockwise until the stylus or pencil point abuts the tab le. The stylus or pencil point may then be placed in the dialing well opposite the 4 in the inner circle of numbers associated with the units digit dial and thereupon rotated in a clockwise direction until abutment with the tab '14, whereupon the sum of V587 and 24 will appear in the notches 'i6 of the calculator. Obviously, additional numbers may be added to the number appearing in the notches 'it in a manner similar to that above described.

If, from the number appearing in the notches '16, it is desired to subtract a number as, for example, 163, the stylus or pencil point may be placed opposite the l in the outer circle of figures at the left hand end of the calculator, the digit dial being then rotated in a countercl-ockwise direction until the stylus or pencil point abuts the tab l. The remaining digits of the number to be subtracted may be utilized in similar manner, using the lOs digit dial and the unit digit dial, in each case, referring to the outer circle of figures and rotating the digit dials in a counterclookwise direction.

It is obvious that, in computing either sums or differences, the order of entering digits in the calculator is immaterial, it being only necessary to enter the respective digits on the proper digit dial; for example, units on the units digit dial, lOs on the lils digit dial, etc. To return the calculator to a neutral or zero positionl simply dial anticlockwise to subtract the digits shown in the total notches le.

. It is manifest that there has beenprovided la construction which fullls the objects and advantages sought therefor.

It is to be understood that the foregoing description and the accompanying drawing have been given by way of illustration and example. It is also to be understood that changes in the form of the elements, rearrangement of parts, and substitution of equivalent elements, which will be obvious to those skilled in the art, are contemplated as within the scope of the present invention which is limited only by the claims which follow.

What is claimed is:

1. In a calculator, in combination, a plurality v'of rotatable digit dials, means mounted between said dials and `cooperative therewith to weiect computation, and detent means Voperationally slidable in a straight line engageable with Ysaid digit dials to effect a predetermined selective detent action in respect thereto.

`2. In a calculator, in combination, a plurality of rotatable digit dials, each dial having a gear portion, detent means coactive with all of said gear portions, and a spring urging said detent toward simultaneous engagement with each of said gear portions, said detent being movable `in a straight line against the action of said spring upon manual rotation of any one dial.

3. In a calculator, in combination, a plurality of selectively rotatable digit dials mounted :in an inclined position so as to overlap one another, each dial having an Aintegral gear portion, Vmeans mounted between said dials and cooperative therewith to eect computation, detent means movable parallel to the longitudinal axis of the calculator, resilient means for urging said'detent means toward engagement with said gear portions, said detent means being 4movable through different distances against the action of said resilient means upon rotation of different dials.

4. In a calcula-tor, in combination, a plurality of rotatable digit dials each having 'a gear portion, accumulating gearing mounted between and cooperative with the gear portions of said dials, a detent mounted for reciprocative movement in a straight line including parts engaging between the teeth of said gear portions, said Iparts lbeing formed for engagement progressively to different depths, and resilient means biasing said 4detent into gear portion engagement, so .that a predetermined selective detent action is eiective'with respect to the several dials.

5. In a calculator, in combination, a plurality of rotatable digit dials, each dial having Aa gear portion, means mounted between said dials and cooperative therewith to effect computation, a detent engaging the teeth of said gear portions, said detent being slida'ole in a straight line, and a single spring for resiliently biasing said detent ina direction tending to maintain detent action with respect to each of said dials.

6. In a calculator, in combination, a plurality of rotatable digit dials, each dial having a, gear portion, means mounted between said dials and cooperative therewith to elect computation, a detent engaging the teeth of said gear portions, said detent being slidable ina straight line, and a single spring for resiliently biasing said detent in a direction tending to maintain detent action with respect to each of said dials, said detent action being predeterminately variable upon turning any selected dial so that detent action upon the dials to the left of the actuated dial are detent free as each gear tooth of the actuated dial moves theV detent to maximum moved position.

7. In a calculator mechanism including a plurality of rotatable digit dials each having a gear portion, detent means coactive with each of said gear portions, thereby to prevent inadvertent rotation of said dials, said detent means being slidable in a straight line to effect a predetermined selective detent action in respect to the said digit dials.

8. In a calculator mechanism including a plurality of rotatable digit dials each having an integral gear portion, detent means coactive with each of said gear portions, thereby to prevent inadvertent rotation of said dials, said detent means beingslidable in a straight line to 'effect asses-so a predetermined'selective detent action in respect to the said digit dials, said predetermined selective detent action being to effect elimination of detent action in respect to certain of said digit dials Whileretaining detent action in respect to all other of said digit dials.

9. In a calculator mechanism including a plurality of rotatable digit dials each having an integral gear portion, spring biased detent means, said detent means being substantially in the form of a flat plate slidably disposed in the general plane of the several gear portions and having a plurality of angular projections to coact respectively with the said gear portionsso as simultaneously to prevent substantially any inadvertent angular movement of any of said gear portions, said angular projections each forming an included angle of different degree and the points of said angular projections each being disposed in position relative to the particular one of the said gear portions with which it coacts as aforesaid so as to provide a predetermined selective detent action when the detent means is caused to slide in the general plane of the said gear portions, said selective detent action constituting a complete release of detent action in respect to certain of said gear portions and a retention of modied detent action upon all other of said gear portions, said modied detent action being sufficient to prevent such inadvertent angular movement of any of said all other gear portions as would destroy the accuracy of the calculator.

10. In a calculator mechanism including a plurality of individually manually rotatable digit dials each having integral toothed portions, said toothed portions forming a gear and said gears being disposed in iixed relation one to another generally in a single plane through their centers, spring biased detent means comprising a plate disposed parallel to the general plane of the said gears, said plate including a number of angular projections equal to the number of said gears, said angular projections each having sides converging to a point, thereby forming an included angle, each of said included angles being of different degree of angularity than all other of said included angles, said points being disposed in xed relation one to another, the relation of said points one to another being different from the aforesaid fixed relation of gears one to another, the three aforesaid characteristics of xed relation of gears one to another, iixed relation of points one to another, and diierence in angularity of the included angles of the angular projections combining to cause simultaneous abutment of each angular projection with two adjacent teeth of the individual gear with which it coacts, thereby simultaneously to restrain each and every gear against any angular movement when the detent means is in its limiting spring biased position, the detent means being also subject to sliding movement away from said limiting spring biased position, said movement being eiected through manual rotation of any individual digit dial and the extent of said movement being diierent when different digit dials are manually rotated so that the manual rotation of any digit dial except that of highest digit series will simultaneously release certain predetermined gears from detent action While retaining a modied detent action upon all other gears, and so that the manual rotation of the digit dial of highest digit series Will retain a modified detent action upon all gears other than that integral' v'vith 'the 'digit dial being rotated, Said modiiied detent action being effective to check each of said all other gears against angular movement which would be sufcient to destroy the accuracy of the calculator.

11. In a calculator mechanism including a plurality of individually manually rotatable digit dials disposed within a base having a cover, each dial gear having an integral toothed portion, said toothed portions forming a dial gear, each of said dial gears coacting with a spring biased detent, said detent being movable with respect to said dial gears, the extent of said movement being variable so `as to er'ect an elimination of the detent action in respect to certain of said -dial gears when another gear is manually rotated, brake means continuously operative to resist rotation of a digit dial and its associated dial gear subject to the aforesaid elimination of detent action, said brake means comprising spring means effective to react between the said base and the digit dial so as to urge the digit dial to bear withpositive frictional Contact against the said cover, thereby providing a frictional drag when the digit dial is caused to rotate.

l2. In a calculator, in combination, a casing, digit dials rotatably mounted in said casing, means interconnecting said digit dials for cumulative computations, a detent member in engagement with all of said digit dials when said calculator is at rest, said detent member being formed to release certain digit dials during computation with said calculator, and a resilient member biasing each releasable digit dial into `frictional engagement with a portion of said casing to prevent undesired rotation when detent released.

13. In a calculator, in combination, a casing, digit dials rotatably mounted in said casing, means interconnecting said digit dials for cumuy lative computations, a detent member in engagement with all of said digit dials when said calculator is at rest, said detent member being formed to release certain digit dials during computation with said calculator, and a resilient member biasing each releasable digit dial into frictional engagement with a portion of said casing to prevent undesired rotation when detent released, said resilient members being disposed concentrically with said digit dials.

14. In a calculator, in combination, a plurality of rotatable digit dials arranged in progressive series and including a rst dial, a last dial, -and an intermediate dial, a gear set for each dial, said gear set for the first dial including a rst dial gear portion and an accumulating nger both movable with said first dial, said gear set for the last dial including a last dial gear portion movable with said last dial and a reverse idler gear in continuous mesh with said last dial gear portion, said gear set for the intermediate dial including an intermediate dial gear portion and an accumulating nnger both movable with said intermediate dial and a reverse idler gear in continuous mesh with said intermediate dial gear portion, each of said accumulating fingers being engageable with the gear set of the dial which is next higher in series, and detent means engageable with each of said gear sets to effect a predetermined selective detent action in respect to said dials, said detent means being movable in the plane of engagement with said gear sets.

15. The combination of claim 14 further characterized by resilient means continuously urging asssgrsae said deteni'L means; in a, direoton. to; effect' enzgagement with said gear sets.

1-6. The combinationof claim 114 furthercharacterized by said detent means being sldable in a straight line in the plane of engagement with saidA gear sets. Y

17'. The combination of claim 14 further characterized by said detent means having a plurality of diierently shaped detent portions for respective engagement with said gear sets.

18. The combination of claim 17 further characterized by-said dials, said gear sets, and said detentgmeans being disposed ina case, and spring means acting between said case and said detent meansbiasing` saidvdetent portions toward simultaneous respectiye engagement with` said. gea! sets;

G.,KESLING.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED. STATES PATENTS Number` Name Date 711,392 Garrison Oct. 14, 1902 984,397 Siegfried Feb. 14, 1911 2,450,668l Kesling Oct. 5,V 19.48