DK143527B - Feeding mechanism, especially for a punched card stamping device. - Google Patents

Abstract

The invention in question concerns a feeding mechanism of the type relating to the introductory part for requirement 1.In a conventional mechanism of the type discussed here, see for ex the description for Danish patent nr. 118.106, the coupling units are designed as a series of separate leaf springs which are individually mounted, just as the mechanism overall contains a substantial number of individual parts. This leads to expensive and awkward production and installation problems; as well as the fact that adjustment, both at the installation stage, and during routine maintenance and repair, is time consuming.The aim of the invention is to provide a mechanism, of the type discussed here, in which fewer individual parts are required than is normal.

Description

(19) DENMARK \ via /

W (12) PRESENTATION C cm 1 ^ 3527 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 3644/67 (51) IntCI. * 0 06 K 1/02 (22) Filing date 14 Jul. 1967 (24) Race day 14 Jul. 1967 (41) Aim. available July 1st. 1968 (44) Presented 51. August 1981 (86) International Application No. - (86) International Filing Day - (85) Continuation Day - (62) Master Application No. -

(30) Priority 14 Jul. 1966, 565309, US

(71) Applicant HONEYWELL INC., Minneapolis, US.

(72) Inventor Earl Edgar Masterson, US.

(74) Associate Engineer Hofman-Bang & Boutard.

(54) Feed mechanisms, in particular for a punch card punching apparatus.

The present invention relates to a feeding mechanism of the kind set forth in the preamble of claim 1.

For example, by a known mechanism of the kind in question, In the specification of Danish Patent No. 118,106, the coupling means are designed as a series of separate leaf springs which are mounted separately, and the mechanism also contains a considerable number of individual parts. This results in expensive and cumbersome manufacturing and assembly, just as the adjustment, both during assembly and routine inspections and repairs, requires a lot of time.

d-

The object of the invention is to provide a mechanism of the kind in which fewer individual parts are required than in the known ones.

U3527 z

This object is achieved by the design according to the characterizing part of claim 1. This results in simplified assembly and simplification of setting operations, both during manufacture and during routine inspections. It will be clear that the optimum operation of the apparatus will be dependent on well-defined operating times at the lateral movements of the coupling means. Small deviations from these will cause them to be in a disparate position with respect to the respective driven organs (eg punches). In the design according to the invention a high degree of uniformity is achieved.

The measures set out in claim 2 relate to the appropriate details of the guide members of claim 1.

By providing one of the flexible sheets with the projections specified in claim 3, irregularities in the sheet material, such as unevenly distributed material stresses from the rolling of the sheet, will have little significance in relation to the importance of the sheets for well-defined bending properties of the sheet.

The invention will be explained in greater detail by the following description of some embodiments, with reference to the drawing, in which: 1 is a perspective, somewhat diagrammatic, partially sectional view of a fast-acting punch card apparatus performed in accordance with the invention; FIG. 2 on a larger scale, a cross-section through part of the embodiment of FIG. 1, FIG. 3 is a perspective view of one of the parts shown in FIG. 1, together with associated scrapers, punches and magnetic selector means, with certain parts in a slightly altered embodiment; 4 is a perspective view, on a larger scale, of one of FIG. 1 in conjunction with associated punches; FIG. 5 is a section approximately similar to FIG. 2, with the moving parts in the lowest position, by punching, while FIG. 6 shows a large-scale section through one of the sections of FIG. 3.

The embodiment shown in the figures constitutes a transfer mechanism for a fast working serial punching apparatus with two columns or groups of punches, each with two punches.

In FIG. 1 is a combined transfer activating unit A in association with a pair of associated magnetic selectors ML and MR,

Unit A contains a pair of identical transfer assemblies IL and IR, both arranged to form a driving connection between a driving means in the form of a punch head, of which a part H is shown, and selected punches in a corresponding double row of punches P and P '. FIG. 3 · These elements constitute the main parts of the punching apparatus. An eccentric drive shaft not shown is adapted to rotate at high speed, e.g. ca. 5000 rpm minute, thereby moving the punch head H in a generally rectilinear punching motion. The punch head is preferably coupled to the drive shaft by a leaf spring, and is also preferably suspended in leaf springs. The punch head H has an upright portion HF for connection to the drive shaft. According to the present invention, the punch head may be formed in conjunction with a downwardly wiping assembly ST; 1 and 2.

The two transfer units IR and II are mounted on the punch head H symmetrically around the stripper assembly ST. The two aggregates IR and II are the same and each have a multifaceted flexible plate, 30 and 30 * respectively, of which the first germ is devoted in FIG. 3 · Each of the tabs 3 of the plate is arranged so that it can be selected to drive one of the punches P or P *. As mentioned, there are two sets of P and P1 with each twelve punches, intended to hole corresponding rows and columns in a suitable hole card. This is advanced in the known way during the punches

As mentioned, the assembled unit A is arranged between the two magnetic assemblies ML and MR, which in FIG. 1 and 3 for clarity are shown drawn to the side. The venetary series of punches, denoted F1 to P-12, are arranged so that each stent may engage one of the flexible tabs, designated 3-1 to 3-12, respectively, of which only the first are shown. in FIG. 3 · Similarly, the second row of punches P * -l to P * -12 belong to the respective tabs 3 * -l to 3f-l2 on plate 30 * of the right transfer assembly IH.

The stripper assembly ST is designed as a top hanging plate

together with the punch head H and below are completed in a series of stripper legs ST-1 to ST-13 »each completed in one foot SH. Feet SH

is arranged for two and two to grip about two related punches. Legs ST-1, etc. are separated by cut slits, SC-1 to SC-12, with a width giving way to the upper part of a pair of associated punches as shown in FIG. 4 * As shown in this figure, the feet SH engage along corresponding cuts and along each side of a punch. The cutouts pg are adapted such that the feet SH will engage with the upper end of the cutout just after punching is completed, i.e. when the punch head Ξ has completed its downward stroke, holding the unused punches as detailed below, while the feet SH will return the selected punches as the punch head H goes upward. Thus, a pair of feet SH enclosing a punch will retract or "wipe" it from the punch card and lead it to the passive, upper position as shown in FIG. 2nd

The punches P go in holes known per se in a guide plate D, fig. 2 so that they lie in the correct positions next to the tabs 3. For retaining the punch P in the upper position there is for each punch a leaf spring SP as shown in FIG. 2, each punch having a cutout PS with a corresponding spring, e.g. a spring SP-1 to the punch P-1, a spring SP * -1 to the neighbor punch P * -l, etc. The upper edge of the cutouts PS is, as shown, at different heights in the two punches, so that the corresponding springs SP as shown in the figure can be placed on one side in a common holder. Thus, the upward pressure from these springs is limited at the end stop so that the upper edge of the punches in the upper position will lie in a predetermined plane R-R; 2 and 5, just below the driving tabs 3 and without interfering with them. This is done by means of a simple stop means, as shown by a stop pin SX, fig. 2, which is adapted to engage with the lower edge of both cutouts PS.

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Each of the punches also has a magnet MG for feedback. The magnets MG, consisting of permanently magnetized material, are fixedly fixed to the punches and are adapted to be brought out by a feedback detector PCM, fig. 5 »when the punch has been properly moved to its lower position. Thus, each of the detectors PGM will, with the help of the corresponding magnet, give feedback that the associated punch has pierced the card.

The punches P consist of tool steel or other tough metal, preferably the upper part of the punches is PT. 4, made separately from a particularly durable abrasion resistant non-magnetic material, such as "Stellite", and is e.g. by welding attached to the shaft of the punch. This provides a durable impact-resistant tip for engagement with the associated driving tab. This "pointed" material is also chosen non-magnetically to prevent false message, as described below, i.e. that the punch may not be moved downward to activate the detector PGM when the punch head H goes down if the punch in question is not selected.

Pette could occur if a punch is magnetized and by magnetic attraction follows a moving magnetic part. The stripper feet SH can e.g. be magnetized by the fields of the magnetic aggregates MR and MP and will then be able to attract an adjacent punch and bring it to the lower position.

Pet will readily recognize that such false movement of unselected punches P is inadmissible thereby interfering with the transport of a card, and a false feedback signal may also be induced from one of the detectors POM. In this connection, it will also be understood that the stripper with the legs ST and the feet SH should preferably consist of non-magnetic, preferably de-magnetized tool soles or similar material so that they are tough and strong and yet have no magnetization that could displace the punches. as described.

Pet left magnet assembly ML contains an elongated, strong permanent magnet in rod form 23 »enclosed in a non-magnetic housing 21 preferably of aluminum, to which are attached two rows of poles, respectively 27 and 29. The magnet 23, which consists of highly ferromagnetic material, has two protruding poles, 23-P at the top and 23-PP at the bottom respectively, of opposite polarity. The pole legs 27 and 29 consist of two rows of vertically connected low-reluctance flux conductor parts mounted on the housing 21 to have flux conductive connection with the magnetic poles, respectively 23-P and 23-PP · The lower row of pole 29 consists of fourteen regularly distributed similar projections 29-0 to 29-13, a portion of which is seen in FIG. 3, all projecting perpendicular to the lower magnetic pole 23-PP and substantially perpendicular to the direction of movement V; FIG. 2, for the punch head * The fourteen upper projections 27-0 to 27-13 project from the upper magnetic pole 23-P at an oblique angle to the direction V »The housing 21 is arranged to control the flux from the magnet 23 to the pole legs 27 and 29 ·

Fourteen identical pole pairs are thus formed, each consisting of a horizontal pole leg.29 and an inclined pole leg 27 · Each of the twelve "inner" pole pairs 27-1 / 29-1 through 27-12 / 29-12 is arranged to be pairs will emit a permanent magnate flux substantially perpendicular to the corresponding of the twelve magnetic tabs 3-1 to 3-12. Thus, each of these pole pairs may attract (and repel) a corresponding tab against (or from) itself, from (and into) the pressure transmitting position "on" (and the passive position "off"). These different positions are shown in FIG.

4 and 5. In FIG. 4 is tab 3 * -2 in the "on" position and tab 3 * -3 in the "off" position. The two outermost pole pairs in the assembly MI, namely the pole pairs 27-0 / 29-0 and 27-13 / 29-13, Fig. 3, have no operational connection with any of the tabs, but are intended to control the magnetic field of the outermost tabs. , 3-1 and 3-12, respectively, in conjunction with the outer stripper legs ST-1 and SI-13 · All pole pairs are usually adapted to flow from the permanent magnet 23, so that the flexible tabs 3-1 to 3 -12 is attracted, ie so that the tabs are usually in the "off" position. Furthermore, the twelve "inner" pole pairs are each provided with a counter-magnetizing winding, such as 27-31 and 29-31 Fig. 3, respectively, around each pole leg. These windings are adapted to abolish the attracting flux of the permanent magnet by a current pulse, as described below, so that the associated flexible tab goes into the punch position "on". Selector means not shown will supply the required selector flow to each such pair of pole windings at times when the associated fingers are "selected", i.e. that the associated punch must be activated. The magnetic field produced by this current will act against and cancel the corresponding permanent magnetic flux, thereby releasing the flexible tab, so that by its own elasticity it will return to the punching position. The punching position is the position where the tab rests on the associated inner guide surface 5, so that it is stiffened by it while driving the associated punch through the card during the downward stroke of the punch head.

Thus, e.g. the punch head H is in its upper position, the starting position, ready to start downward in a new punching cycle, if a hole is to be punched under the punch P'-2, fig.

4, a current signal is passed through the associated coils which will cancel the permanent magnetic flux holding tab 3'-2 in the "off" position, i.e. resting against the outer guide surface 1 *. In this position, the tab is deflected most and is biased so that it will bounce back against the inner guide surface 5 * when released, thereby covering slot C'2 therein as shown in FIG. 4. As the punch head H goes down, the free end IT of the tab supported by the guide surface 5 'strikes the head PPf-2 on the punch P * -2 and drives it down to punch in that position on the card. When the punch head H then moves upward, the associated pair of stripper feet SH-2 and SH-3 gripping the head PP'-2 as described above will pull the stencil P'-2 to the upper position.

The magnet 23 consists of a permanently magnetized ferromagnetic material, (with high beam), while the protruding pole legs 27 and 29 consist of a light magnetisable material of low residue. The magnetic assembly ML may also be provided with a magnetic shunt 25, fig. 2, which is movably clamped behind the upper pole legs 27 so that it can be adjusted to different positions between the poles 23-P and 23-PP and form a variable shunt slot "dy * shown fully open in Fig. 1 and partially closed. in Figure 2. The shunt 25 is of a high permeability and low reluctance material and is mounted so as to return a variable portion of the magnetic flux from the pole 23-P to the magnet 23, determined by the length of the gap dy. do not pass between the associated poles 27 and 29 and they can be controlled by the force exerted on the corresponding tabs 3 to pull them to the passive position. Such an adjustable shunt is an extremely convenient means of adjusting the resulting magnetic force on the movable tabs and is thus suitable for standardizing the pull of the magnets MR and MI, either during manufacture or in production. and thus the manufacturing tolerances and the mounting tolerances become less critical both for the ML and MR assemblies and for the whole unit A. Of course, other equivalents, e.g. purely mechanical means for performing these control functions of the magnets.

E.eks. For example, on the die head, a small lug could be mounted behind each tab 3 for selectively transferring the tab to the • Off position, with an advantageous location at the slightly elastic tab.

It is to be understood that the magnetic assembly MR arranged symmetrically on the opposite side of the unit A is arranged precisely as the assembly ML * described above.

As mentioned, the transfer assembly II has a thin resilient flexible plate 30 divided into a series of tabs 3 and inserted in a space between two guide plates, namely 5 inside and 1 outside, with a spacer 13 being inserted at the top · Plates 1, 30 and 5 are together bent inwards against the stripper ST, the plates being clamped between two clamping pieces 7 and 15, see fig. 2. The outer baffle 1 consists of flexible non-magnetizable metal sheet which bends in said manner and so that its lower edge lies along the outside of all the stripper feet SH as shown in FIG. 1 and 5 · The plate 1 thus constitutes the one guide for the flexible tabs, in that in the passive position the "off" position of the magnets is held against the plate without drive connection with the associated punch. A corresponding plate 1 on the right side of the figures is made in a similar manner. In FIG. 5, it is shown that the tab 3-1 is in the passive position attracted by the permanent magnetic flux from the associated poles 29-1 / 27-1, so that it lies along the plate 1. By the uniform curvature it is obtained that a tab 3 can lie smoothly and evenly against plate 1, without deformation or other damaging stresses or shocks.

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It is particularly desirable that the guide plate 1 be formed as a single continuous plate. This has proved surprisingly effective in transferring the magnetic flux to the tabs, where it was previously thought to require flux cuts in the plate. There may be one or a few holes, such as a hole 1-H in the plate 1;

3 for observing the flexible tabs when adjusting and mounting these.

The inner guide plate 5 consists of a corresponding unmagnetizable plate, which is clamped at the top in the same way and which rests at the bottom against the side of the stripper ST. The flexible fingers 3 will rest in the fully unaffected state against the plate 5, thereby being in the active state Honfl. The lower edge of the plate is obliquely cut, by S-F, fig. 4 * to end smoothly against the scraper. The plate 5 will act as a clamped bent beam which is curved to provide a predetermined stiffening reinforcement for the tabs 3, lying along with them almost all the way down to the tip, thereby preventing them from bending or bending as they pressing against an associated punch. Thus, since the plate 5 is immediately above the associated punches P, there must be some clearance for the punches not selected, the plate 5 being passed down past them during punching. 5. There are therefore a number of cuts C-1 to C-12, fig. 3 and 4, at the lower edge of the plate 5, arranged and aligned so that they will clear the peaks PP on the punches. The lower position or the stance phase M is shown in FIG. 5, where the top PB-1 of an unselected punch PI enters the cut-out C-1 in the plate 5.

The tabs 3 are preferably formed so wide that such a tab will cover the associated cutout C and is therefore slightly wider than the associated punch fit in the cutout.

The outer plates 1 and 1 »each have a size of approx. 80 x 60 mm. A thickness of 0.46-0.51 mm proved satisfactory. All the guide pins 1, 1 ', 5 and 5' are made of non-magnetic material as plates, are quite even, e.g. is an evenness around TIR 0.003 found acceptable. In this embodiment, it is preferable to give the inner guide plates 5 and 5 'a thickness of approx. 0.63 mm and the exterior a thickness of 0.48 mm. Of course, these guide plates must be somewhat thicker than the transfer plates 30 and 30 "to have higher stiffness. The plates 30 and 30 must be magnetizable, lightweight and highly elastic. Preferably, a thickness of 0.254 mm is used, the sheet being made of "* 10-10 cold rolled steel" or "flared spring" (1095) carbon steel or other hard non-magnetic steel.

It also contains ferromagnetic material as later described in connection with FIG. 4. The spacers 15 and 15 'have a thickness of approx. 0.254 mm.

By mounting the assemblies IR and IL on the punch head H, several advantages are obtained, including that the stripper ST protrudes from the punch head to control the transfer elements without friction occurring, and further that the stripper feet SH and the overlying parts of the stripper also act to position the curves. control.

As shown in FIG. 3 and 6, the plates 1 and 5 and the 1 'and 5' are formed to form a pattern of small projections DP on the sides facing the intermediate flexible plate 30. The projections are spaced regularly so as to define a smooth engagement surface. corresponding to the exactly smooth surface 30. Such printing can be provided quite simply by various methods, e.g. By embossing, one of the most important advantages of this embodiment is that the surfaces 1 and 5 can be formed in a simple manner with a very high predetermined uniformity required for the proper controlling engagement between the guide pins and the leaf springs 3. A guide plate can f. eg. have certain surface irregularities, for example, "casting", "low places", dents, etc .. Smoothness would normally be provided by expensive and complicated treatments with grinding, polishing, etc.

The required uniformity, on the other hand, can be provided in a simple manner by printing according to the invention. The plate is clamped in an "embossing press" whereupon the printed reference surface is pressed into the piano, whereby a flat engaging surface can be produced over the tops of the prints with a high degree of uniformity, e.g. up to 0.001 to 0.002 TIR evenness. As described below, the prints in the last pressing process can be depressed to a greater or lesser degree, whether their height on the reference surface corresponds to a "high spot" or "low spot". Such reprinting provides another important advantage.

When a transfer surface, e.g. 30, are pressed intimately against a guide surface and both faces are smooth and conformable, separating forces seeking to separate the two faces, e.g. originating from the magnetic field, creating suppression between the surfaces that counteract and slow down the movement. It has been found that when a leaf spring rests against a guide surface with the described depressions, this aerodynamic effect will be greatly reduced. This makes the movement of the leaf springs both faster and easier.

FIG. 6 is a schematic section through a portion of the outer guide plate 1 of FIG. 3, through a pair of annular prints. The section is enlarged and further plotted, showing a somewhat exaggerated uneven engaging plate 100 on the guide surface 1. It is to be understood that the plate 1 has been provided with a number of similarly embossed impressions DP, DP ', etc. distributed regularly over the surface. Each of these prints consists of a cavity 117 or 107 surrounded by an annular force, 111 and 101, respectively. has been formed in that a similar array of similarly projecting cups has been pressed against the surface 100. These projections 101, 111, etc. will project above the engaging surface 100, i.e. the side of the plate 1 facing the plate 30. By this pressing or embossing, annular volumes 111, 101 etc. are formed around each cavity and in some cases a small bulge will also be produced on the opposite side as shown. at 115 and 105. However, such bulges will not usually appear if the plate rests firmly against a flat reference surface during embossing. However, these dents do not cause any problems, as it is the engaging surface 100 that must be embossed and smoothed.

It is assumed that the line F-F corresponds to the desired engaging surface with precisely prescribed uniformity to be provided at the surface 100 of the plate 1 for optimal engagement with the tabs 3 of the plate 30.

A flat pressing surface of high predetermined uniformity can now be pressed down against the projections 111 and 101, etc. until all their peaks are in plane F-F. This plane is defined so that it will hit all the projections so that they are all smoothed to some extent, depending on their location relative to plane F-F. The projections 111, etc., during the smoothing, will be deformed by plastic flow, e.g. to some extent into the associated cavity, e.g.

When the printing is smoothed after the reference plane FF, the plate 1 will have a very flat and even engagement surface for abutment of the plate 30, this surface being the smoothed peaks of the various projections 111, 101 etc. which lies with the desired accuracy in the reference plane FF.

The three plates constituting the transfer assembly IL, namely the flexible plate 30 and the control plates 1 and 5, are together clamped on the punch head H such that they are curved in a predetermined manner by the stripper part ST. As shown in FIG. 2, these plates are clamped by means of an inner clamping piece 15 which is bolted at the ends to the punching head and whose outer abutment surface is inclined at an angle a in relation to the axis V shown to such an extent that the required curvature of plates 5 and 1. This abutment surface of clamp 15 has a longitudinal center groove 15-G, with a depth of approx. 0.03-0.1 mm. The outer clamping piece 7 is intended to attach the plates to the middle part of the piece 15, e.g. with bolts through corresponding holes, as shown in FIG.

3. The clamping piece 7 has a corresponding longitudinal groove 7-0 which fits with the groove in the clamping piece 15. These grooves define a deflection zone along the line TT shown so that the plates are curved from a fixed point or line, thereby guaranteeing a predetermined uniform curvature. irrespective of variations in the smoothness of the surfaces, the engagement form, etc. along the clamping surfaces of clamping pieces 7 and 15. Such variations can easily occur in the production of different units and may change the deflection effect and thus the operation of the transfer units from unit to unit.

The outer clamp 7 also has a pair of guide pins 1p. 3, which is intended to be inserted through guiding holes not shown in the plates and the clamping piece 15 for accurate placement under tension. A spacer 13 between the outer guide plate 3 and the plate 3Q is approximately the same width as the plate 30 - the drawing is not targeted - and is intended to provide the required distance therebetween so that the tabs 3 will clear the associated punch P when they is in the passive position. It has further been found that the clearance spaces d1 and d2 between the outer guide plate 1 and the pole legs 27 and 29 should correspond approximately to the width of a tab 3, e.g. about 0.4 mm.

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FIG. 4 shows part of the right assembly IR in connection with the adjacent parts of the stripper ST and the associated punches. Here, it is assumed that the entire assembly is in the phase corresponding to the top position where the punches and transfer tabs are all out of engagement. The punches that have holes in the previous cycle will then have just been brought up to the upper position of the stripper. As previously described, all the punches will be retained in the upper position of the springs SP with a defined clearance, e.g. ca. 0.1 mm above the stripper feet SH. Thus, the punches have their upper surface lying in predetermined plane R-R, fig. 2, determined by the stop means SX described above. The planet lies a predetermined stretch d3, here approx. 0.25 mm below the tips of the tabs 3 and 3 '. In this arrangement, no noticeable shock will occur between a transfer tab and the associated punch when the two are engaged, as the engagement will be very close to the upper portion of the stroke, where the relative velocity along axis V is very small.

This results in a soft smooth intervention, which is highly desirable.

In FIG. 4 is also shown the design of the transfer tabs, the tabs 3 'and 3, θϊ · made of several parts, with a tough, durable elastic part I-A, e.g. of hard blue spring steel, and part I-B of high-ferromagnetic material, e.g. soft iron, which is intimate with the part I-A. It has been found that by cold rolling under high pressure, molecular bonding can be achieved so that the two parts are bonded satisfactorily. These layers must be intimately connected so that, when deflected, they act as a coherent beam without creating greater internal stresses, such as shear stresses which would seek to separate the parts, especially at the point of insertion. In an alternative form, the tabs may consist of three layers, with two outer layers of spring steel around an intermediate ferromagnetic iron layer. It has been found that the mechanical strength and durability of the flexible members thus produced are improved without appreciable deterioration of the magnetic attraction properties.

Further, a wear layer IT can be provided on the free end of the flexible tabs which are to hit the corresponding punches as shown in FIG. 4. By welding a relatively thin layer of wear material such as "Stellite" on the ends of the tabs 3 and 3 ', followed by machining to provide the desired exact dimensions, sharpness, etc., the risk of wear is reduced. Such wear is equally unfortunate in that the tips can be skewed so that they strike the top of an associated punch unevenly. Such oblique intervention can quickly lead to irregular operation of the punches and will also cause further wear of the two parts, e.g. so that the top of the punch is eroded.

FIG. 5 shows substantially the same parts as FIG. 2, but at a different stage in the duty cycle, i.e. at the punching phase, with the punching head down, while fig. 2 shows the resting phase with the stop head up. FIG. 5 shows "selected" and "unselected" transfer tabs and punches. Tab 3'-1 is shown in the "selected" state along with the associated punch P'-1. The second tab 3-1 is shown in the unselected, passive state, so that the associated punch P1 is inactive. It will be seen here that the inner guide surface 5 * controls tab 3f-1 such that it depresses the associated punch P * -l downwardly to punch. described previously triggered by the magnetic attraction as a result of a current shock through the demagnetizing windings so that it rests against and is controlled and stiffened by the control surface 5 '·

Corresponding transmission systems for other mechanisms of movement may be provided where the selective activation of driven means is provided by selective coupling with a driving flexible member. Such systems could be used for activating pressure hammers in a fast-working line printer, for other markers or similar devices.