Patent Publication Number: US-3878732-A

Title: Presettable number device

Description:
United States Patent 1191 Kiibler 1 1 PRESETTABLE NUMBER DEVICE [75] Inventor: Fritz Kiibler,Schwenningen,  
 Germany [73] Assignee: Fritz Kiibler Zahlerfabrik,  
 Schwenningen, Germany 122 Filed: on. 15, 1973 211 Appl. 110.; 406,315  
 [30] Foreign Application Priority Data 1451 Apr. 22, 1975 1/1971 Zielke 235/.00l C Primary E.\&#39;aminerWesley S. Ratliff, Jr. Attorney, Agent, or F1&#39;rn1Wa1ter Becker [57] ABSTRACT A presettable number device having number wheels interconnected by tens transfer gearing. Each number wheel has a centering cam frictionally connected thereto. A first key upon actuation turns all of the centering cams to one position, while simultaneously disengaging the transfer gearing from the wheels. A further key for each wheel is provided for indexing the respective wheels to a desired position. Each further key actuated a blocking mechanism which blocks the centering cams during adjustment of the respective number wheel. The first mentioned key, when released, releases the eentering cams and returns the transfer gearing into operative engagement with number wheels and locks the number wheel keys against movement.  
 32 Claims, 16 Drawing Figures SHE! 2 BF 6 PATENIEDmzams FIG. 1c  
 fi l l ni PATENlEmPazzms SHEEI 3 (If 6 FIG. 1d  
 snmunrs FIG. 20  
 PATENTEUAPR22lm5 sum 5 or e FIG. 30  
 PATENTEDAPRZZISTS PATENTEDAFRZZiBYS szzmsufgs FIG. 40  
 FIG. 8 5  
  ll IFIRIESIETTABLE NUMBER DEVHCE The present invention relates to an advance roller counting mechanism with at least one rotatably journalled number roller which is connected to a control drive and which through an engageable and disengage able rotatable clutch is connected to a heart-shaped cam of a return device. More specifically, the present invention relates to a roller counting mechanism of the above mentioned type in which the number roller is connected to an advance control drive for the respective number roller, which drive includes an advance key for advancing the number roller relative to the arrested heart-shaped cam while for arresting said heartshaped cam there is provided an arresting element adapted to be actuated by an arresting key.  
  It is an object of the present invention so to design an advance (Vorgabe) roller counting mechanism of this type that by a simple operation, a safe arresting of the heartshaped cam will be assured during the advance control of the number roller, without additional forces acting upon the return device.  
  This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing. in which:  
  FIG. I illustrates on an enlarged scale a view of the roller counting mechanism according to the invention with the housing in open condition.  
  FIG. 2 represents a section taken along the line IIII of FIG. I but on a smaller scale than that of FIG. ll.  
  FIGS. 3 to 5 respectively illustrate three different control positions of the roller counting mechanism of FIG. 2.  
  FIG. 6 is an advance bar of the roller mechanism according to FIGS. 1-5, partially in section, in conformity with FIGS. 2-5.  
  FIG. 7 shows the advance bar of FIG. 6 as seen from the right-hand side of the drawing.  
  FIGS. ilu, lb, and llc show enlarged views of the roller counting mechanism.  
 FIG. Ild shows an end view of the counter housing.  
 FIG. 2a shows an enlarged view of FIG. 2.  
  FIGS. 2b, 3a, 3b, and 4a are enlarged views of FIGS. 2, but showing different positions of the cam and latch mechanism.  
 FIG. 3 shows a detailed view of the cam and counter mechanism.  
  The roller mechanism according to the present invention is characterized primarily in that the arresting member is connected with the advance key and that the advance key carries out two successive strokes starting from the starting position, while at the end of the first stroke and during the second stroke the arresting memher is in its arresting position whereas the advance control drive is in control engagement during the second stroke. When actuating the advance key, it will thus be appreciated that the heart-shaped cam is arrested automatically whereupon during the course of the movement of the advance key, additionally the number roller is advanced by a division or a pitch. By a corresponding frequent actuation of the advance key, which may be effected manually for instance by a finger, or mechanically for instance by a moving coil magnet, a cylinder piston unit or the like, the number roller can be set stepwise to the desired advance number. Due to the design according to the invention, when advancing the number roller relative to the heart-shaped cam, the return device does not have to transmit any holding or arresting forces upon the heart-shaped cam so that the return device is saved considerable wear.  
  A very simple construction with the safe arresting of the heart-shaped cam is obtained when the arresting member comprises an arresting surface for engagement with the circumference of the heart-shaped cam, preferably adjacent to the tip of the heart-shaped cam.  
  The arresting member may be safely journalled when it is formed by a pivotally journalled lever which is preferably tiltable about an axis which is parallel to the axis of the number roller. In order in this connection to obtain particularly favorable holding forces while avoiding danger of wear to the arresting device, the arresting surface is in the arresting position of the arresting member located approximately within the region of the connecting straight line of the pivot axis of the arresting member with the axis of rotation of the heart-shaped cam, preferably between said connecting straight line and the tip of the heart-shaped curve or cam occupying its returning position.  
  In order to be able in a simple manner to actuate the arresting member, the latter is for purposes of engaging a follower cam of the advance control drive provided with a counter surface which is located at an incline with regard to the direction of movement of said follower cam. This counter surface merges with a second counter surface which is located at an angle thereto. The said second counter surface is in the arresting position of the arresting member extending parallel to the direction of movement of the follower cam and is engaged by the follower cam in the second direction of movement of the advance key. In this way, the arresting member is during the movement of the advance key first moved into the arresting position and then is secured in this arresting position during the successive movement of the advance key. A very easygoing function is obtained in this connection when the follower cam comprises two separate follower surfaces located at an angle with regard to each other, for engaging the two counter surfaces of the arresting member.  
  For purposes of obtaining favorable space conditions, the arresting member is formed by one arm of an angle lever the other arm of which, preferably at that side thereof which faces away from the heart-shaped cam, comprises the counter surface.  
  A further simplification in the construction of the counting mechanism can be obtained by mechanically, rigidly connecting the follower cam with the advance key, preferably the follower cam is provided on an advance key bar which is displaceable in its longitudinal direction and carries the advance key. The arresting member may in a space-saving manner be located between the advance key bar and the heartshaped cam.  
  Favorable lever conditions are realized also by the fact that the follower cam in starting position of the advance key is located approximately in the connecting straight line between the axis of rotation of the heartshaped cam and the pivot axis of the arresting member.  
  Expediently, the arresting member is urged to its starting position preferably by means of a helical tension spring so that the arresting member after release of the advance key will in each instance automatically return to its starting position.  
  For further simplifying the construction of the counting mechanism, all arresting members are preferably mechanically, rigidly connected to form a common structural unit. ln this instance, the counting mechanism is expediently so designed that prior to the actuation of an advance key, all number rollers have with the returning device to be brought to their starting position so that all heart-shaped cams are in a uniform manner aligned relative to the arresting members and the latter can favorably engage the heart-shaped cams.  
  -In order to prevent an unauthorized or accidental actuation of an advance key. a locking mechanism is provided for the advance control drive which is preferably releasable by means of a key. If this key is formed by thereturn key of the returning device which is preferably common for all number rollers, and if the locking member occupies its release position only when, the return key is in its return position, it will in each instance be assured that the respective advance key can be actuated only when all common rollers or heart-shaped cams have returned to their starting position.  
  For purposes of obtaining a simple construction, the locking key is connected to a bar which preferably within the range of that end thereof which faces away from the locking key is connected to the locking member. A I  
  A safe mounting and a simple actuation of the locking member will be obtained when the locking member is formed by a pivotable lever which preferably is pivotable about an axis which is parallel to the axis of the number roller. The locking member may be connected to the locking key in a simple manner by an intermediate lever which preferably is pivotable about an axis which is parallel to the pivot axis of the locking member.  
 In order to be able to arrange the locking member in spite of a simple construction in a space-saving manner,  
 the locking member is located within the range of that end of the advance key bar which faces away from the advance key while preferably the end surface of the advance key bar forms the counter surface for the locking member.  
  A very safe and reliable locking without the danger of an automatic release is assured in particular when the pivot axis of the locking member is located on that side of the locking member which faces away from the advance key bar, so that during the actuation of a locked or blocked advance key, no torque can act upon th&#39;elocking member.  
  For purposes of further simplifying the construction of the roller counting mechanism, a common preferably strip-shaped locking member is provided for all advance control drives.  
  According to a further feature of the invention, the advance control drive comprises a pawl preferably directly adjacent to the follower cam, for engagement with a gear ring which is rotatably connected to the pertaining number roller, so that a safe transmission of the advance control forces can be realized.  
  In order in this connection to obtain further improved power transmission and space conditions, the gear ring is rotatably journalled about an axis which is separate from&#39;the axis of the number roller and is parallel thereto while the gear ring is preferably located between the number roller and the key bar of the advance control drive.  
  The gear ring may directly&#39;engage a corresponding gear ring of the number roller so that for the engagement of the control pawl and for the driving connection with the number roller, only a single gear ring will be required.  
  The pawl may be pivotable preferably about an&#39;axis which is parallel to the&#39;gear ring so that the pawl can easily be moved into and out of control engagement.  
  According to the invention, especially with an advance roller counting mechanism of the described type, it is furthermore provided that adjacent advance keys are arranged in an offset manner with regard to each other and transverse to their straight connecting lines so that a plurality of advance keys can be arranged on a narrow space while avoiding the danger of accidental actuation of adjacent keys. Such an arrangement is also suitable for otheractuating keys than the advance keys of roller counting mechanisms, especially for keys adapted to be actuated by a finger. In this connection, itis important that the key surfaces proper of the keys are offset with regard to each other in the described manner.  
  With this design according to the invention, it is nevertheless possible to arrange all key bars in a common plane so that a simple construction will] be obtained.  
 - It is particularly expedient when the keys are alternately offset in opposite direction with regard to each other.  
  According to an advantageous embodiment of the invention, the -keys are offset relative to each other by half of their extension measured at a right angle to their straight connecting lines so that in spite of the offset arrangement, a small space requirement results and adjacent keys can rest against each other and can be arranged adjacent to each other. This is particularly the case when those side surfaces which face each other and pertain to adjacent keys are at least approximately located in a common plane.  
  In order with a relatively short length of the key rows to assure that large key surfaces and large keys are obmined, the keys are in a direction transverse to their straight connecting lines designed lengthy, preferably rectangularly.  
  All keys may in a simple manner be of the same design while preferably their bottom sides are provided with connecting elements for the connection to the respective key bar, said connection being changeable to two of said positions. For instance, each key may have only one connecting element located outside its center, by means of which the key can be connected in the two possible positions offset with regard&#39;to each other.  
  In order to assure a simple connection, the connecting element is designed as a block element.  
  Referring now to the drawings in detail, FIGS. 1-5 illustrate an advance-counting mechanism according to the invention which comprises a substantially rectangular housingshaped support 1 with two lateral walls 2, 3 located opposite to each other serving as bearing bracket. in these bearing brackets 2, 3 there is connected an axle bar 4 on which are rotatably journalled a plurality of number rollers 5-7 corresponding in numher to the number of digits of the roller counting mechanism. Between an outermost number roller 5 and the pertaining adjacent bearing bracket 2, there is furthermore rotatably journalled on the bar 4 a driving wheel 8 by means of which the adjacent number roller 5 is driven by a drive (not illustrated). Each number roller 5 has that end face thereof which faces the driving wheel 8 equipped with a gear 9 which may for instance form one piece with the respective roller 5. On the other end face of each number roller 5 or 6 or 7 there is provided a heart-shaped cam 10 which through a locking system is rotatably connected to the pertaining number roller in such a way and is rotatable about the axis of the bar 4 in such a manner that the heart-shaped cam 10 can be turned relative to the number roller when a corresponding high torque is obtained. During the normal control operation of the counting mechanism, however, the cam 10 will move in synchronism with the pertaining number roller. The gears 9 of adjacent number rollers are respectively in engagement with each other through a pertaining transmission gear 11 in such a way that that number roller which is closer to the driving gear wheel 8 will at the end ofa complete revolution advance the adjacent number roller by a control step. The transmission gears 11 are rotatably arranged on a common axle bar 12 which is parallel to the bar 4. The number rollers 5-7 are directly adjacent to a support wall 13 which interconnects the bearing brackets 2, 3 and extend at a right angle thereto. This support wall 13 is provided with windows (not illustrated) in order to permit an operator to view the circumferential surfaces of the number rollers, which circumferential surfaces are provided with numbers. The transmission gears 11 are located on that side of the number rollers 5-7 which faces away from said supporting wall 13.  
  That end of the bar 12 which faces away from the driving gear 8 is journalled in a rectangular window 15 of a key bar 14 which window has a diameter greater than the diameter of said end. This key bar 14 is displaceably mounted in its longitudinal direction at a right angle to the supporting wall 13 and the straight connecting line of the two bars 4, l2 and is located directly at the inner side of the pertaining bearing bracket 3. The returning key bar 14 extends through an opening in the supporting wall 13 and has a returning key 16 located on the outside of said wall 13. The returning key 14 is by means of a helical tension spring 17 urged toward the starting position in which the returning key protrudes farthest outwardly. The-bar 14 may for instance by means of a longitudinal slot 18 be displaceable on the bar 4 and may be slightly pivotable. When the returning key 16 is depressed against the thrust of spring 17 into the support 1, one end face of the window 15 will after a corresponding movement abut the bar 12 and carry the same along in such a way that the transmission gears 11 didengage the gears 9 and that the number rollers 5-7 including the heartshaped cams 10 can freely rotate on the bar 4. After release of the key 16, the returning key bar will due to the force of the tension spring again return to its starting position in which the transmission gears 11 mesh with the gears 9.  
  Between the key bar 14 and that end wall 19 of the support 1 which is closer to said bar 14, and approximately at the level of the bar 12, an axle bar 20 is connected to the bearing bracket 2, 3 on which a returning rake 21 is pivotally mounted for pivoting about an axis which is parallel to the bar 4. The rake 21 is for each heart-shaped cam 10 provided with a returning finger 22 and approximately at the level of the bar 12 is through a pivotal bearing pivot 23 linked to the returning key bar 14. When the returning key 16 is depressed against the thrust of spring 17, the bar 14 takes along the returning rake 21 in such a way that the returning fingers 22 press against the heart-shaped cam 10 so that the latter together with the number rollers 5-7 will due to the thus occurring torque rotate until the returning fingers 22 engage ratchet portions in the heart-shaped cams so that then all heart-shaped cams 10 will in axial view according to FIGS. 35 be aligned in the same manner or so as to cover each other. FIG. 2 shows the starting position of the returning rake 21 and FIGS. 3-5 illustrate the returning position of the rake 21.  
  On that side of the number rollers 5-7 which faces away from the fingers 22, an advance bar 24 is displaceably mounted for each individual number roller. The bars 24 are arranged in a row or plane adjacent to each other and are displaceably mounted on a separate support 25 so as to be displaceable parallel to the return key bar 14, said support 25 being inserted in the support 1. The bars 24 have those ends thereof which protrude from the supporting wall 13 provided with advance keys 26. Arranged opposite the inner end surfaces 27 of the bars 24 when said surfaces 27 occupy their starting positions, there is located a rail-shaped blocking member 28 which has its lever-shaped angledoffends 29 pivotally journalled on an axle bar 30 which is axis parallel to the number rollers 5-7. The bar 30 is located in the extension of the bars 24. The blocking member 28 is connected to the bar 14 through a twoarm intermediate lever 31 which is pivotable about a shaft 32 that is parallel to the bar 30. The end 33 of one arm of the intermediate lever 31, which end is pivotshaped, engages a step bearing-shaped recess 34 at the inner end of the returning key bar 14, whereas the tooth-shaped end 35 of the other arm of the intermediatee lever 31 engages a tooth space-shaped recess 36 at the side of the pertaining angled-off lever arm 29 of the blocking member 28. When the returning key 16 is depressed against the thrust of spring 17 the blocking member 28 is pivoted out of its blocking position according to FIG. 2 into its release position shown in FIGS. 3-5. After releasing the key 16, the blocking member 28 is due to the force of its spring 17 returned to its blocking position of FIG. 2 in which it is located directly opposite the end surfaces 27 of all advance key bars 24.  
  Between the advance key bars 24 and the number rollers 5-7, a further axle bar 37 is connected to the bearing brackets 2, 3, said bar 37 being spaced farther from the supporting wall 13 than the bar 4. Rotatably journalled on the bar 37 for each gear 9 is a gear ring 38 in the form of a disc-shaped gear. The gear rings 38 have the same pitch and the same diameter as the gears 9 and one gear ring 38 each is in continuous mesh with a gear 9. On that lateral surface of each bar 24 which faces toward the driving gear 8 there is pivotally journalled a control pawl 39 which is pivotable about a shaft 40 that is parallel to the bar 37. In the starting position of bar 24, this pawl 39 is located on that side of the gear ring 38 which faces away from the rollers 5-7 and is arranged between the gear ring 38 and the pertaining key 26. The control pawl 39, which in its control position is limited as to its abutment, is by means of a leg spring 41 arranged on its bearing pivot spring urged toward its control position. When the advance key 26 is depressed against the thrust of a helical tension spring 43 acting upon the pertaining bar 24, a pawl tooth 42 of the pawl 39 will approximately tangentially with regard to the pertaining gear ring 38 engage the teeth of the latter so that this gear ring 38 is advanced by the pitch of the pertaining number roller and takes the latter along. After releasing the key 26, the bar 24 will due to the thrust of spring 43 again be returned to its starting position while the control pawl 39 will against the thrust of spring 41 escape from the gear ring 38 and spring back to its control position.  
  As will be evident from FIGS. 6 and 7, the control pawl 39 may also be journalled between two webs of the pertaining advance key bar 24. 7  
  Between the bars 24 and the number rollers 5-7, a further axle bar 43 is connected to the bearing brackets 2,3. This bar 43 is located between the gears 38 and the supporting wall 13, more specifically, approximately at the level of the pivot shafts 40 of the control pawls 39 occupying their starting position. Pivotally mounted on bar 43 is an arresting rake 44 which is pivotable about an axis which is parallel to the axle bar 4. The arresting rake 44 is for each heart-shaped cam 10 provided with a finger-shaped arresting member or arm 45 the end surface 46 of which forms an arresting surface. Furthermore, the rake 44 has for each bar 24 an arm 47 which is located in the manner of an angle lever relative to the member 45. The arms 45, 47 define an angle with each other the apex of which is located toward the supporting wall l3.&#39;Each bar 24 has for the pertaining arm 47 a follower cam 48 which is located on that side of bar &#39;24 which faces toward the bar 14. The cam 48 protrudes in the direction toward the bar 43 beyond the bar 24 and is located approximately at the level of the pivot shaft 40 of the pertaining pawl 39. The outer edge of the respective arm 47 of the rake 44 is equipped with a first counter surface 49 for engagement by the correspondingly&#39;located follower surface 50 of the follower cam 48. This first counter surface 49 extends approximately at a right angle with regard to the longitudinal direction of the bar 24. This counter surface 49 merges with a second counter surface 51 which extends approximately in the longitudinal direction of the arm 47. This counter surface 51 is associated with the end surface 52 of the follower cam 48 which end surface is approximately parallel to the longitudinal direction of the bar 24.  
  When the advance key 26 is depressed against the thrust of sping 43, the follower cam 48 will by means of itsfollower surface 50 take along the pertaining arm 47 and thereby the arresting rake 44 in such a way that its arresting members 45 will pivot toward the heartshaped cams l and that their surfaces 46 will at 53 engage the circumferential edges of the earns 10. The engaging area 53 is located adjacent to the tip of the respective heart-shaped cam 10 and, more specifically, on that side which when turning the pertaining number roller by pressing the key 26 in the corresponding direction of rotation indicated by arrow 54, is located in front. The engagement of the cam 10 by the arresting surfaces 46 is effected prior to the pawl 39 engaging the pertaining gear ring 38. Before the pawl 39 engages the gear ring 38, the end face 52 of the follower cam 48 slides along the counter surface 51 of the pertaining arm 47 which counter surface is then located parallel to the direction of movement of the bar 24. This sliding movement is such that the rake 44 is held in its arresting position. Immediately after the end surface 52 starts sliding on the second counter surface 51, the pawl 39 will in conformity with F IGS. 4 and engage the pertaining gear ring 38 so that then the pertaining number roller is advanced by one number roller pitch relative to the pertaining cam held stationary by the arrestfollows:  
 ing member 45. In view of the described, arrangement and position of the arresting members 45, it will be appreciated that while the cams 10 are held stationary relative to the number rollers 5-7, practically no torque is exerted upon the rake 44. After releasing the key 16, the rake 44 returns to its starting position due to the tension spring 55 acting thereupon. In this starting position, the rake 44 is held by the counter surface 49 engaging the follower surface 50. The number rollers can now together be turned with their heart-shaped earns The change in the starting position of the number rollers 5-7 to which the number rollers can be adjusted or set by actuating the returning device is thus effected as First the returning key 16 is depressed so that the transmission gears 11 are lifted out. Then the heartshaped cams are with the returning fingers 22 broughtto their starting position, and the advance key bars 24 arereleased by pivoting off the locking member 28.  
 Thereupon, the corresponding advance keys 26 are pressed as often as necessary until in the window of the counting mechanism that number becomes visible which is desired as advance number. Subsequently, the returning key 16 is released again so that the transmistheir length so that the part 57 which protrudes on the respective side of the row with advance keys 26 and which pertains to&#39;the respective advance key 26 exposed at both sides by the width of the respective adjacent key 26 and thus even with a very narrow arrangement of the keys 26 can safely and easily be actuated.  
 The identically designed keys 26 have their inner sides respectively equipped with a connecting member in the form of a socket opening 58 for engagement by the end of the pertaining bar 24. This socket opening or connecting member 58 is located outside the center of the key 26 and closer to a narrow edge of this key and is so designed that the key 26 can in conformity with FIG. 1 be connected in two positions spaced from each other to the key bar 24.  
  The design of the roller counting mechanism according to the present invention is also suitable for other than manual actuation. For instance, it may be used for electricalactuation of the returning device inasmuchas.  
 the returning key 16 will when actuating the advance control device have to be depressed only by a slight pressure. In particular, for instance, the returning magnet for the return position may be dimensioned rather weak which fact is very favorable with regard to the returning life span of the counting mechanism because the returning mechanism is not exposed to any strong forces.  
  It is, of course, to be understood that the present invention is, by no means, limited to the specific showing in the drawings but also comprises any&#39;modifications within the scope of the appended claims.  
 What is claimed is:  
  1. In a device having number wheels therein adapted for being preset; a frame, a plurality of coaxial number wheels in the frame and tens transfer gearing interconnecting the wheels, a heart shaped rotatable return cam fricitionally connected to each wheel, an arresting member for each cam normally spaced therefrom, and a key for each wheel biased toward retracted position and having means operable when the key is actuated away from retracted position to index the respective wheel a single digit, each arresting member adapted for actuation by the key for the number wheel pertaining to the respective cam, each arresting member being moved into cam arresting position on the first part of the stroke of the respective key awy from retracted position and the number wheel pertaining to the said key being indexed under correspondingly high torque during the final part of the stroke of the said key away from retracted position.  
  2. A device according to claim 1 in which each said arresting member has a surface thereon which abuttingly engages the peripheral surface of the respective cam.  
  3. A device according to claim 1 in which each centering cam is heart shaped and each said arresting member engages the respective cam on the peripheral surface of the cam near the peak thereof on the side thereof which is leading in respect of the direction of rotation imparted to the pertaining wheel by the respective key.  
  4. A device according to claim 1 in which each said arresting member is pivotally mounted in the frame.  
 5. A device according to claim 1 in which each said arresting member is pivotally mounted in the frame and engaging the pertaining cam at a point which is substantially on the line connecting the pivot axis of the arresting member with the axis of rotation of the cam.  
  6. A device according to claim 1 which includes a protrusion on each key to actuate the pertaining arresting member, each arresting member having a finger in the path of the protrusion, said finger and protrusion having surfaces which are in slidable engagement when the key has advanced to arresting member actuating position, said surfaces being parallel to the direction of movement of said key.  
  7. A device according to claim 1 which includes a protrusion on each key having a first surface for actuation of the pertaining arresting member and a second surface extending parallel to the direction of movement of the respecitve key from one end of the first surface, said arresting member having a finger in the path of said protrusion having one surface cooperating with said first surface to actuate said arresting member into cam arresting position and another surface for slidable engagement with said second surface to hold the arresting member in cam arresting position during said final part of the stroke of the key.  
  8. A device according to claim 7 in which said arresting member is a two arm lever piotally supported in the frame near the juncture of said arm and having said surfaces on the end of one arm and a further surface at the end of the other arm to abut the periphery of the pertaining cam.  
  9. A device according to claim 8 in which the said protrusion on each key is rigid therewith.  
  10. A device according to claim 8 in which the pivotal support for each said arresting member is between the pertaining cam and the pertaining key.  
  11. A device according to claim 8 in which said protrusion in retracted position of the key is substantially on a line passing through the pivot axis of the arresting member and the axis of rotation of the cam.  
  12. A device according to claim 1 in which said arresting members are fixed together.  
  13. A device according to claim 1 which includes a blocking member normally blocking said keys in retracted position, and a locking key for moving said blocking member into effective position.  
  14. A device according to claim 13 in which said blocking member is common to all of the keys for the number wheels.  
  15. A device according to claim 13 which includes a reciprocable bar having locking key at one end and at the other end operatively connected to said blocking member.  
  16. A device according to claim 13 in which said blocking member extends beneath the keys for the number wheels and is pivoted on an axis parallel to the axes of the number wheels.  
  17. A device according to claim 15 which includes a further level pivoted intermediate the ends to said frame and having one end engaging said blocking member and the other end engaging said bar.  
  18. A device according to claim 16 in which the pivot axis for said blocking member is located on the side of the blocking member which faces away from said keys.  
  19. A device according to claim 1 in which the means on each key for actuating the respective number wheel is pawl pivoted to the respective key.  
  20. A device according to claim 19 which includes a first gear connected to each number wheel, a second gear meshing with each first gear, said second gears being coaxially arranged between said number wheels and the plane of said keys.  
  21. A device according to claim 19 in which each said pawl cooperates with a respective second gear and is pivoted to the respective key on an axis parallel to the axis of said second gears.  
  22. A device according to claim 1 in which each said key has a bar-like member connected thereto, said barlike members being in coplanar alignment and the said keys being offset on the bar-like members in a direction at right angles to the plane of said bar-like members.  
  23. A device according to claim 22 in which said keys are alternately offset in opposite directions.  
  24. A device according to claim 23 in which each key has half the length thereof coextensive with the next adjacent key.  
 25. A device according to claim 24 in which said keys are in close side by side relation.  
  26. A device according to claim 25 in which each key is rectangular and the larger dimensions of said keys are parallel.  
  27. A device according to claim 26 in which all of said keys are identical in size and shape.  
  28. A device according to claim 27 in which each key is receivable on a said bar-like member in either of two reversed positions.  
  29. A device according to claim 27 in which each key is receivable on a said bar-like member in one position only.  
 bers. a  
  32. A device according to claim 13 in which said tens transfer gearing is carried by said locking key and is dis-&#39; engaged from said number wheels when said locking key is actuated.  
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