US3742244A - Control means for printing apparatus, in particular for offset printing machines - Google Patents

Abstract

A control shaft for an offset printing machine, provided with cams, levers and the like for controlling the various operations during a printing cycle, is provided with a knob for manual rotation and with a ratchet wheel for step-by-step rotation by a pawl oscillated cyclically by a cam rotatable with one of the cylinders of the printing machine. The ratchet wheel has a number of switching ratchet teeth corresponding to the number of switching stages of the printing machine. Certain of the ratchet teeth have a sawtooth shape whereby, when engaged by the pawl, the ratchet wheel is advanced by one step. Other teeth of the ratchet wheel have a special shape including a protuberance on the flank leading to the radial portion of the tooth normally engaged by the pawl. These protuberances cause the pawl to travel out of its normal path of movement when engaged with one of these special form teeth. A spring biased locking disc is arranged adjacent the pawl and is axially displaceable by energization of an electromagnet. The locking disc is biased to engage beneath the ratchet pawl, when the pawl is displaced out of its normal path of movement due to engagement with a tooth of special shape, and the locking disc thereby prevents engagement of the pawl with the next succeeding tooth of the ratchet wheel even though the pawl continues to be oscillated. When the electromagnet is energized, the locking disc is axially displaced from its pawl blocking position, against the bias of a spring, allowing the pawl to again cooperate in a normal manner with the teeth of the ratchet wheel.

Description

United States Patent [191 Raible June 26, 1973 CONTROL MEANS FOR PRINTING APPARATUS, IN PARTICULAR FOR OFFSET PRINTING MACHINES [75] Inventor: Hermann Raible, St. George n, Black Forest, Germany [73] Assignee: Mathias Bauerle Gmbll, Georgen,

Black Forest, Germany [22] Filed: Sept. 1, 1971 [21] Appl. No.: 176,930

[30] Foreign Application Priority Data Primary Examiner-Herman J. Hohauser Att0meyJohn J. McGlew and Alfred E. Page [57] ABSTRACT A control shaft for an offset printing machine, provided with cams, levers and the like for controlling the various operations during a printing cycle, is provided with a knob for manual rotation and with a ratchet wheel for step-by-step rotation by a pawl oscillated cyclically by a cam rotatable with one of the cylinders of the printing machine. The ratchet wheel has a number of switching ratchet teeth corresponding to the number of switching stages of the printing machine. Certain of the ratchet teeth have a sawtooth shape whereby, when engaged by the pawl, the ratchet wheel is advanced by one step; Other teeth of the ratchet wheel have a special shape including a protuberance on the flank leading to the radial portion of the tooth normally engaged by the pawl. These protuberances cause the pawl to travel out of its normal path of movement when engaged with one of these special form teeth. A spring biased locking disc is arranged adjacent the pawl and is axially displaceable by energization of an electromagnet. The locking disc is biased to engage beneath the ratchet pawl, when the pawl is displaced out of its normal path of movement due to engagement with a tooth of special shape, and

the locking disc thereby prevents engagement of the pawl with the next succeeding tooth of the ratchet wheel even though the pawl continues to be oscillated. When the electromagnet is energized, the locking disc is axially displaced from its pawl blocking position, against the bias of a spring, allowing the pawl to again cooperate in a normal manner with the teeth of the ratchet wheel.

lllClaims, 9 Drawing Figures PATENTED JUN26 I975 SHEET R [If 5 CONTROL MEANS FOR PRINTING APPARATUS, IN PARTICULAR FOR OFFSET PRINTING MACHINES BACKGROUND OF THE INVENTION 1. Field of the Invention The invention deals with printing machine controls having a control shaft with elements in cooperation with the latter to influence the shaft for performing numerous desirable operative steps.

2. Description of the Prior Art In known machines, it was not only necessary to maintain a certain chronological order in starting and stopping various machine operations, but certain time intervals were also required in starting and stopping certain machine operations, so that printing could be performed after the first sheet has been introduced and the machine was then made ready for a new printing operation after it has been previously stopped. In a known printing machine, the machine control shaft was equipped with a great number of switching stages which effectuate individually starting and stopping of machine operations: e.g.

I Off II Motor on Washing Device on (only at reverse run);

III inking device switched on;

IV Moistening Device in operation;

V Etching Device becomes effective;

VI Inking Cloth Roller applied to sheet roller;

VII Rubber Cloth Roller applied to sheet roller;

VIII Paper feed or supply switched on for printing.

In a known printing machine, a control motor is provided for actuating the respective switching devices, which motor, after it has been started manually, drives several trip cams effecting the switching operations. The positions of the individual active flanks of these trip cams are adjusted to each other corresponding to a predetermined switching order. The purpose of this arrangement is to. make the switching time for the sequential startingand stopping movements independent of the manual switching. By pushing a key, the control motor is started through a holding relay and a program card, which is conformed to its program markings and to the respective selected printing program, moves ahead always one step forward. The program card is advanced by means of a ratchet mechanism which receives its impulses from the impulse transmitter actuated during the revolutions of the impression roll. The main disadvantage of this known control device is that it increases substantially the cost of the printing machine due to the necessary accessories and loss of time. Besides this, the program card provided for the control results in a cumbersome operation and a special control motor must be provided for carrying out the control itself. Though the forward switching of the program card is effected by means of a ratchet mechanism and of a corresponding impulse transmitter in accordance with the rhythm of the machine cycles, these accessories do not ensure the start and stop of individual machine operations in synchronism with respective machine cycles.

In another known control device used for offset printing machines, the control shaft is adjustable between a starting position, at least one intermediate operating position and a last operating position, time delay relays being provided which can be adjusted to different running times, by means of which the stepping mechanism which effects the stepping of the control shaft from one position to the other, can be controlled corresponding to the desired operating time of the units actuated by the control shaft. The purpose of this known control device is to effectuate a variation in starting and stopping time and in the duration of the operations within certain limits by means of a single control shaft which controls the operation or, if desired, by hand. However, this control device, too, is very expensive, complicated to operate and is highly susceptible to trouble, disturbances andinterruptions.

SUMMARY OF THE INVENTION The object of the present invention is to provide simple and inexpensive means, easy and reliable to operate which result in a highly economical control system which permits to regulate the switching sequence of the machine control shaft both in dependence on the control elements inherent in the machine and persuant to a preset printing program, and to switch individual and- /or several sections of the switching program by manual operation of an electric switching system by means of a ratchet mechanism, so that the end of each individual section of the switching program or system will be always predetermined.

The invention is primarily characterized in that the ratchet mechanism possesses, for cooperation with any stepwise switching of the control shaft certain means, e.g., a ratchet wheel mechanism with a number of preshaped ratchet teeth the conformation of which corresponds to the individual switching stages. A locking member which can be disengaged from the respective form of the ratchet teeth after their respective performance, is actuatable by a control magnet (electromagnet) according to the machine cycles via an oscillatable feed pawl or control lever. Consequently the particular control means are accommodated in and form parts of the ratchet mechanism itself, so that there is positively achieved a synchronism between the machine cycles and the switching functions of the control shaft. Furthermore, additional program control elements, which could influence the cost of the machine can be completely eliminated. The surveillance and operation of the printing machine will be greatly simplified.

The special advantage derived from the solution of this problem is that the switching program of the control shaft is not tied up, as in known machines, with additional separate control devices, but includes a ratchet mechanism which ensures, on one hand a positive synchronism between the machine cycles and the switching operations of the control shaft, and eliminates, on the other hand, additional program control elements which otherwise complicate the operation of and contribute to the increase of the cost of themachine. The operation is also substantially simplified, individual program sections being switched at any time corresponding to given requirements without substantially changing the total program of the machine.

According to a further development of the invention, an electromagnet or like element actuates the locking element of the pawl, several independent control circuits with electric switches being provided therefor, of which one circuit is controlled by hand, another circuit by a sheet counter, and still a further circuit by the rising table of the machine. Additionally still another circuit becomes effective by a revolution counter of the washing device of the machine.

It is one of the important objects of the present invention to provide means leading to many other advantages according to which individual program, sections of the entire switching program can be assigned in a simple manner to certain machine operations and be controlled by the latter, while other machine operations can effect the entire course of the switching program, while in addition, the course of individual program sections can be controlled by hand.

Another essential feature of the invention is that the specially formed ratchet teeth of the ratchet wheel are shaped and specifically provided on the reverse side of the teeth with protuberances and the like, while other ratchet teeth are saw-shaped, the cooperable pawl having a locking part laterally overlying its ratchet teeth which cooperate with the locking element.

In other words, the present invention makes use of and contemplates specially-shaped ratchet teeth to represent the program control elements proper. Thus, the ratchet wheel or like element comprises the switching program. The program control proper is effected in this manner strictly by mechanical means and is therefore very reliable and not susceptible to ineffectiveness or disturbances.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated preferred embodiments'of the invention.

Other advantageous features of the invention will result from the following description of a preferred embodiment of the invention in connection with the draw- Ings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of essential parts of a control device embodying the'invention as applied to an offset printing machine in which the control shaft is turned by hand for starting individual machine operations and in which the individual operations are stopped by means of a ratchet mechanism;

FIG. 2 shows in perspective the control shaft and the essential parts of said ratchet mechanism;

FIG. 3 is a side elevation view of some of the individual parts of the ratchet mechanism;

FIG. 3a depicts the ratchet wheel of the ratchet mechanism as seen in side view;

FIG. 4 illustrates the arrangement of the parts of FIG. 3 in front elevation view, partly in section;

FIG. 5 is a side elevation view of the arrangement of individual parts of the counter mechanism employable with the washing device;

FIG. 6 is a side elevation view of the adjusting means for the revolution counter mechanism;

FIG. 7 is a side elevation view of the control elements of the counter; and

FIG. 8 is a circuit diagram of the various control circuits for operating the control magnet.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring more and in greater detail to the drawings,

there is disclosed a reset ratchet mechanism of the control shaft ll of an offset printing machine. On control shaft 1 there are arranged individual cams 1 to 8, which effectuate the starting and stopping of various operations in a predetermined order. Cam 2 actuates the main switch of the machine motor, cam 3 controls the paper feed, cam 4 checks the application and removal, respectively, of the sheet or foil cylinder to and from the rubber cloth cylinder, control lever 5 controls the etching device and earns 6 and 7 operate the inking-and washing device, e.g. the inking roller. Double cam device 8 becomes operative only during the reward or reverse movement of control shaft 1 and sets the washing device in motion in stage II in which all other operations of the machine have already been stopped or deenergized (FIG. 3a) and only the main motor remains in action. Double cam device 8, which consists of two cams 9 and 10, acts on the angle lever 11 and on its feeler roller 12, which lever 11 is pivotally mounted on a stationary pivot 13 and is under the action of a spring 14 which exerts a torque in clockwise direction on angle lever 11 (FIG. 1). On the left hand end of control shaft 1 (FIG. 2) there is ar-ranged a handle 15. Rigidly connected with cam drive or disk 10 by a bushing assembly 16 is a notched star wheel 17 which is engaged by a stop roller 18 carried by stop lever 19, which in turn is pivotally mounted on a stationary pin20 and which is under the action of a tension spring pulling it radially toward notched roller 17. On stop lever 19 there is pivotally mounted relative to the latter on a pivot 21 a pawl 22 which cooperates with a locking disk 23 whose function will be described further below. A pin 24 on stop lever 19, on which roller 18 is rotatably mounted, engages a bore 25 of pawl 22 whose diameter is substantially greater than the diameter of pin 24. In this manner the pivotal movement of pawl 22 is limited by pin 24 in both pivotal directions. A tension spring 26 always pulls pawl 22 in downward direction. Rigidly connected with notched star wheel 17 and thus with control shaft 1 is a ratchet wheel 27 which is shown in FIG. 3a in side view. This ratchet wheel 27 has eight ratchet teeth I VIII, which are associated with or coordinated to the individual switching positions of control shaft 1. Ratchet tooth I corresponds to the position Off, ratchet tooth II to the position motor on, or to the operation washing in rearward operation, ratchet tooth III to the start of the inking mechanism, ratchet IV to the start of the washing device, ratchet tooth V to the start of the etching operation, ratchet tooth VI to the operation for application of rubber cloth cylinder to the impression sheet cylinder and ratchet tooth VIII to the operation of paper infeed.

As it can be gathered particularly from FIG. 3a, the rear parts of the ratchet teeth l,Il,V and VI are provided each with a protuberance while the ratchet teeth lll,lV, VII and VIII have a normal flat rear saw tooth shape. This means that ratchet wheel 27 constitutes or makes up a program according to which the individual machine operations have been developed and take place as will hereinafter be explained.

Associated with ratchet wheel 27 is a pawl 29 which is set into an oscillating motion by a cam disk 33 through intermediate levers 30 and 31 (FIG. 1) connected with each other by a link 32. Cam disk 33 is arranged on shaft 34 of the rubber cloth cylinder of the printing machine. Pawl 29 is pivotally mounted on a pivot 35 of lever 30 and is guided in a chordal slot 36 of a bush 38 pivotally mounted in the proximity of ratchet 27 on a pivot 37. In bush 38 there is secured, parallel to the longitudinal direction of the pawl 29, a spring rod 39, (FIG. 3) which loosely engages a stirrup 40 secured on pawl 29. The pawl 29 consists of two parts, namely a switching part 41 which has a ratchet tooth 42, and a locking part 43 covering the ratchet tooth 42 laterally and cooperating with the locking disk 23.

Disk 23 is mounted for axial movement on the outer end 44 of control shaft 1 and is provided with a bush 45 which has an annular groove 46. The annular groove 46 is engaged by a pin or pivot 47 of a rocker arm 48 whose other end is connected to an armature 49 of a control segment 50. Rocker 48 is mounted on a stationary journal for pivotal movement in a plane parallel to the axial direction of control shaft 1 and is under the action of a tension spring 51 which urges stop disk 23 against the ratchet wheel 27 when the control magnet 50 is not energized.

Connected to bush 38, which is provided on its circumference the chordal slot 36 for guiding the pawl 29, is a lever 52 which protrudes with its free end into the path of a pin 53 which is arranged in ratchet wheel 27 and also protrudes through an arcuate slot 54 in looking disk 23. Besides this, lever 52 is under the action of a tension spring 55 which urges it toward the axis of control shaft 1 and exerts on it a torque in counterclockwise direction.

The electric control of control magnet 50 takes place according to the diagram of FIG. 8. Several independent circuits in parallel are assigned to control magnet 50. In one control circuit there is arranged a make contact switch S7 controlled by a sheet counter 56, which is shown only schematically and which is in series with a reset contact switch 58 which is actuated by a retaining pawl 59 of a counting wheel 60 by means of angle lever 11. As mentioned above, angle lever 11 is controlled by double cam 8, comprising cams 9 and 10, respectively, on control shaft 1. In a parallel circuit there is arranged a hand-operated push button switch 61 and in parallel thereto a rising table switch 62 which is closed briefly when the rising table (not represented) drops, that is, when the paper on the rising table is used up. A third control circuit of control magnet 50 contains the make contact switch 63 which is closed by counting wheel 60 of the revolution counter 64 of the washing device when the required number of washing revolutions has run off.

The reset of control shaft-1 can thus be effected by the sheet counter 56 or manually by push button switch 61 or by the rising table by means of table switch 62 and additionally by switch 63 actuated by the revolution counter 64. The number of operational stops that must be carried out during the closing of the individual control circuits described above depends, during the actuation of the switches 57, 61 and 62, exclusively on the program incorporated in and directed to the ratchet teeth Ito VIII of ratchet wheel 27. Only by push button switch 61 is it also possible to suppress this program and to return directly into position I from position VIII by continued pressure on push button switch 61.

The above mentioned counting wheel 60 of counter 64 is rotatably mounted on a stationary pivot 65 and has a switching pin 66 in whose path is arranged the make contact switch 63. The starting pivot of the counting position of counting wheel 60 can be preadjusted by an adjustable wheel by means of pinion 67 which engages a toothed segment 69 which is pivotally mounted on pivot 68. The toothed segment 69 is in operative connection with a pinion 76 of adjusting wheel 70, by means of a pin 71 which engages an oblong slot 72 of a joint bar 73, which is operatively connected with toothed segment 74 by means of a pin 75. The toothed segment 74 is pivotally mounted on a stationary journal 77 (see FIGS. 5 to 7).

The toothed segment 69 is also under the action of a tension spring 78 which exerts a torque in clockwise direction (FIG. 6).

Counting wheel 60 is operated by finger 80 of a pawl 79 which is engaged, by means of an oblong slot 81 with a pin 82 reaching into the latter via retaining pawl 59, for displacement in the direction of the oscillatory movement of pawl 79 and which is under the action of return spring 83 (FIG. 5).

Pawl 79 with its operable finger 80 is actuated in the operating position as shown in FIG. 5 by an element 84 of pawl 29 in whose path finger 80 arrives when retaining pawl 79 comes into engagement with the teeth of counting wheel 60. This is the case when the feeler roll 12 of key lever 11 drops during the rearward switching of control shaft 1 onto the lateral curve 85 of cam 9 arranged on control shaft 1 and retaining pawl 59 releases the tension of spring 83.

Depending on the position of counting wheel 60 and its pin 66 preset by the adjusting wheel 70, a certain number of machine cycles takes place until pin 66 closes the make contact switch 63 and thus energizes control magnet 50, which then pulls locking disk 23 over rocker 48 out of the range of pawl 29 so that ratchet tooth 42 engages ratchet wheel 27 and control shaft 1 returns to its off position.

As soon as control shaft 1 reaches its off position, the feeler roll 12 of key lever 11 is again on the large radius of cam 9, as seen in FIG. 7, so that retaining pawl 59 is again disengaged and closes the rest contact switch 58 by means of pin 86. The rest contact switch 58 and its above described control mechanism is necessary so that, when the machine is stopped by sheet counter 56, the revolution counter 64 of the washing device can become operative and the make contact switch 57 actuated by sheet counter 57 is made inoperative for the duration of the washing process.

The revolution counter 64 for the washing device, which is started by means of lever 11, becomes effective only in position II of the control shaft 1, namely, only when this position of control shaft 1 is started in reverse drive direction. This condition is met by double cam 8 which includes the two single cams 9 and 10. In the forward direction of rotation of the cam corresponding to arrow 87 (FIG. 7) the feeler roll 12 of lever l 1 can not follow the dropping curve 85 of cam 9 since the latter is covered by cam 10 which is rotatable relative to cam 9 by Only during the rotation of control shaft 1 in reverse does the feeler roll 12 of lever 11 fall into a notch 88 formed between the two cams 9, 10 and displaces then cam 10 relative to cam 9, while it follows the dropping flank 85 and performs the above described operations.

The method of operation of the ratchet mechanism described above is as follows: Assuming that all machine operations are effective and that ratchet wheel 27, arrives in the position of ratchet tooth I as seen in FIG. 3a, upon corresponding manual rotation of handle 15, then locking disk 23 keeps pawl 29 out of engagement with ratchet wheel 27, so that no switching operation takes place with respect to control shaft ll, despite the fact that pawl 29 constantly oscillates in the rhythm of the individual machine cycle. While in position I of control shaft ll, pin 53 of ratchet wheel 27 keeps lever 52, pivotal on bearing pin 37, in a position in which spring rod 39 keeps pawl 29 out of engagement with ratchet teeth I to VIII of ratchet wheel 27, pin 53 being now turned so far with ratchet wheel 27, due to the rotation of control shaft I in forward direction, that it releases lever 52, which is under the action of tension spring 55, so that the latter turns lever 52 in counterclockwise direction and spring rod 39 presses pawl 29 against ratchet wheel 27 and against locking disk 23 (FIG. 4). As long as control magnet 50 is not energized, locking disk 23 is in the position of FIG. 4, in which it keeps pawl 29 out of engagement with ratchet wheel 27. Pawl 29 thus performs only idle strokes in this position of locking disk 23 and does not influence counting wheel 69 (FIGS. 1 and 5-7) of the revolution counter 64. The reverse movement of control shaft l by pawl 29 and ratchet 27 can be determined by three different causes.

Assuming that the paper supply on the so-called rising table of the printing machine is prematurely used up, the rising table switch 62 is briefly closed by the rising table when it has reached a certain level. Control magnet 50 is energized and its armature 49 pulls locking disk 23 over rocker arm 48 away from ratchet wheel 27 into the position of FIG. 2. Pawl 29 is thus released and is brought by the action of spring rod 39 into engagement with ratchet tooth VIII to turn control shaft back by one tooth division of ratchet wheel 27 as indicated by the direction of arrow 89 (FIG. 3). Though control magnet 50 has in the meantime become deenergized again, because the rising table switch 62 was opened again, locking disk 23 can at first not return into its locking position (FIG. 4) because it abuts laterally against locking part 43 of pawl 29. During the reverse stroke of pawl 29 the latter is not deflectedradially by the sawtooth form of the ratchet teeth VIII and VII of ratchet wheel 27 to such an extent that locking disk 23 could move again into the locking position, so that ratchet tooth VII is also stepped up during the next stroke. During the following reverse stroke of pawl 29, ratchet tooth 42 of pawl 29 slides over the protuberance 28 of ratchet tooth VI and is deflected radially by pawl 29 so far that locking disk 23 is urged again into the locking position represented in FIG. 4 and this keeps pawl 29 out of its engagement position. After turning control shaft I back from position VIII into position VI, the action of the ratchet mechanism is thus automatically stopped. In position VI of control shaft 1 the paper supply is shut off and the rubber cloth roller is removed from the sheeting roller so that overinking of the rubber cloth roller is prevented, while a new stack of paper sheet is placed on the rising table. Subsequently control shaft 1 can be turned again by hand into position VIII in which the printing is continued.

The same operational sequence takes place when push button switch 61 is actuated briefly by hand. The operator or supervisor has thus the possibility of stopping the printing process at any time in a simple manner without paying special attention to the printing operation in order to check, for example, the printing result.

Since switching tooth V is also provided with protuberance 28, it is possible, if necessary by again operating briefly push button switch 611, to turn control shaft 1 back from position VI into position V in which pawl 29 is then again brought automatically out of engagement.

Since the two ratchet teeth IV and III are not provided with a protuberance 28, control shaft ll moves directly from position V into position II if push button switch 611 is pressed again briefly, in which it then remains until the revolution counter 64 closes the make contact switch 63 and energizes again control magnet 59 in order to bring again pawl 29 in engagement with ratchet wheel 27 for the last stepping movement from position II into poisition I.

Naturally, by pressing constantly push button switch 61 and energizing control magnet 50 for a correspondingly long time the lock disk 23 can be kept out of range of pawl 29 so long until the control shaft has moved from position VIII directly into position I. This emergency stop must also be possible, for example, when trouble is detected in the operation of the ma chine.

Due to the above described hand-controlled reverse movement of control shaft )1 from position VIII into position V, in which, in addition to the machine motor, the inkingand the washing device, the etching device is also started, it is possible for example, to also check the operation of the etching device. I

The step-to-step shut-off of the machine by means of the paper sheet counter 56 occurs in a manner that upon reaching a pre-arranged number of the counter 56 the make-contact switch S7 is closed to the extent, until the operation shaft I has arrived at the position IV in which the engagement of the key lever Ill with the bottom of the control cam 9 opens the rest contact switch 58 (FIGS. ll, 5, 7 and 8) and the control magnet is shut off. As hereinabove mentioned the revolution counter mechanism 6 3 is then actuated which upon reaching the predetermined number of sheets closes the make-contact switch 63 and the reversal of rotation of the control shaft from position II to the operative position I is effectuated, in which the machine is completely stopped.

Even if only the programmed reverse-step operation is mentioned in the foregoing disclosure this should not be construed that the forward step control of the operating shaft from position I to the position VIII can not be effected in a similar manner. To this end it is only necessary to use a second ratchet mechanism which acts in the opposite direction of rotation and which is likewise equipped with ratchet teeth like the ratchet wheel 27. In order to provide for certain stepping halts or breaks between certain stepping positions of control shaft ll during the forward operation, similar counters can be used in the same manner, and the revolution counter 6% described above, with corresponding electric control switches. The control of the ratchet mechanism itself for the forward stepping of control shaft I can be effected in a simple manner with an auxiliary control magnet (not shown).

In order to prevent locking disk 23! from falling back into its locking position when the control magnet 50 is only briefly energized, before pawl 29 is in engagement with ratchet wheel27, the pawl 22 provided on stop lever 19 which is removed from the range of motion of locking disk 23 whenever the feeler roll 18 of key lever 19 slides over a tooth of notched star wheel 17 which drops down immediately, however, when locking disk 23 is removed from ratchet wheel 27, and prevents locking disk 23 from reverse movement.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In a control device for printing machines, particularly offset printing machines, having a control shaft provided with control elements, such as cams, for the individual machine operations, the control shaft being stepwise displaceable by hand or by a ratchet mechanism, controlled by an electromagnet, into different positions to start and stop the individual operations before, during and after printing: the improvement comprising, in combination, said ratchet mechanism including a ratchet wheel secured to said control shaft and having a number or ratchet teeth corresponding to the number of individual steps included in an operating cycle of the printing machine; a pawl mechanically oscillated in the cycle of the printing machine and engageable with said teeth to step said control shaft; each tooth having an operating edge engageable by said pawl to step the ratchet wheel and a back edge extending from its operating edge and over which the pawl moves to engage the operating edge; certain of said teeth having a special configuration of the back edge which, when engaged by said pawl, displaces said pawl out of its normal path of oscillation; a locking element engageable with said oscillating pawl when said pawl is so displaced out of its normal path of oscillation, to retain said pawl out of its normal path of oscillation to halt further stepping of said control shaft by said oscillating pawl; and means operable, responsive to energization of said electromagnet, to disengage said locking element from said pawl for return of said pawl to its normal path of oscillation to further step said control shaft.

2. In a control device, the improvement claimed in claim 1, including a plurality of energizing circuits, including electric switches, independently selectively operable to connect said electromagnet to a source of electric potential; one circuit including a normally opened manually closed switch, a second circuit including a normally open switch closed by a sheet counter included in said printing mechanism, a third circuit including a normally open switch closed by a rising table included in said printing mechanism, and a fourth circuit including a normally open switch closed by a revolution counter included in the stepping mechanism of said printing machine.

3. In a control device, the improvement claimed in claim 1, in which the special configuration of the back edge of said certain ratchet teeth comprises respective protuberances on the back edges of said certain ratchet teeth; the other ratchet teeth having a sawtooth shape; said pawl including a ratchet tooth engageable with the operating edges of said ratchet teeth on said ratchet wheel, and including a locking part juxtaposed with the ratchet tooth of said pawl and cooperable with said locking element.

4. In a control device, the improvement claimed in claim 3, in which said locking element is a circular disc; said ratchet wheel being secured to a shaft and said circular disc being mounted on said shaft for axial displacement relative to said locking part of said pawl; and a pivotally mounted rocker arm connecting said circular disc to said electromagnet for axial displacement of said circular disc.

5. In a control device, the improvement claimed in claim 1, including a spring operatively associated with said pawl and biasing said pawl relative to said ratchet wheel; the operative connection of said spring being reversible relative to said ratchet wheel.

6. In a control device, the improvement claimed in claim 5, in which said spring is a leaf spring having one end secured to a pivotally mounted lever and its opposite end operatively associated with said pawl; a protuberance on said ratchet wheel engageable with said pivotally mounted lever to swing the same in one direction; and a tension spring connected to said pivotally mounted lever and biasing the same to swing in the opposite direction.

7. In a control device, the improvement claimed in claim 4, including a blocking pawl pivoted to swing radially relative to the shaft of said ratchet wheel in the range of axial displacement of said circular disc; a pivoted stop lever pivotally mounting said blocking pawl and engaged with a star wheel fixed to rotate with said ratchet wheel; means on said locking lever engageable with play with said blocking pawl; said blocking pawl, responsive to axial displacement of said circular disc due to energization of said electromagnet, dropping behind said circular disc to prevent return of said circular disc to a position operable to move said oscillating pawl out of its normal path of oscillation; said blocking pawl being retracted out of blocking relation with said circular disc responsive to swinging of said locking lever by said star wheel.

8. In a control device, the improvement claimed in claim 2, including a make-contact switch and a restcontact switch connected in series in one of the energizing circuits of said electromagnet; said make-contact switch being actuated by a counting wheel moving stepwise in the rhythm of the printing machine; said restcontact switch being actuated by a lever controlled by said control shaft.

9. In a control device, the improvement claimed in claim 8, in which said last-named lever is constituted by a retaining pawl for a counting wheel of a revolution counter of a washing device included in the printing machine.

10. In a control device, the improvement claimed in claim 9, including a slide having a ratchet tooth mounted on said retaining pawl for tangential displacement toward said counting wheel; and a trip cam on said oscillating pawl actuating said slide when said retaining pawl is in engagement with said counting wheel. 5 i 1 4

Claims (10)

1. In a control device for printing machines, particularly offset printing machines, having a control shaft provided with control elements, such as cams, for the individual machine operations, the control shaft being stepwise displaceable by hand or by a ratchet mechanism, controlled by an electromagnet, into different positions to start and stop the individual operations before, during and after printing: the improvement comprising, in combination, said ratchet mechanism including a ratchet wheel secured to said control shaft and having a number or ratchet teeth corresponding to the number of individual steps included in an operating cycle of the printing machine; a pawl mechanically oscillated in the cycle of the printing machine and engageable with said teeth to step said control shaft; each tooth having an operating edge engageable by said pawl to step the ratchet wheel and a back edge extending from its operating edge and over which the pawl moves to engage the operating edge; certain of said teeth having a special configuration of the back edge which, when engaged by said pawl, displaces said pawl out of its normal path of oscillation; a locking element engageable with said oscillating pawl when said pawl is so displaced out of its normal path of oscillation, to retain said pawl out of its normal path of oscillation to halt further stepping of said control shaft by said oscillating pawl; and means operable, responsive to energization of said electromagnet, to disengage said locking element from said pawl for return of said pawl to its normal path of oscillation to further step said control shaft.

2. In a control device, the improvement claimed in claim 1, including a plurality of energizing circuits, including electric switChes, independently selectively operable to connect said electromagnet to a source of electric potential; one circuit including a normally opened manually closed switch, a second circuit including a normally open switch closed by a sheet counter included in said printing mechanism, a third circuit including a normally open switch closed by a rising table included in said printing mechanism, and a fourth circuit including a normally open switch closed by a revolution counter included in the stepping mechanism of said printing machine.

3. In a control device, the improvement claimed in claim 1, in which the special configuration of the back edge of said certain ratchet teeth comprises respective protuberances on the back edges of said certain ratchet teeth; the other ratchet teeth having a sawtooth shape; said pawl including a ratchet tooth engageable with the operating edges of said ratchet teeth on said ratchet wheel, and including a locking part juxtaposed with the ratchet tooth of said pawl and cooperable with said locking element.

4. In a control device, the improvement claimed in claim 3, in which said locking element is a circular disc; said ratchet wheel being secured to a shaft and said circular disc being mounted on said shaft for axial displacement relative to said locking part of said pawl; and a pivotally mounted rocker arm connecting said circular disc to said electromagnet for axial displacement of said circular disc.

5. In a control device, the improvement claimed in claim 1, including a spring operatively associated with said pawl and biasing said pawl relative to said ratchet wheel; the operative connection of said spring being reversible relative to said ratchet wheel.

6. In a control device, the improvement claimed in claim 5, in which said spring is a leaf spring having one end secured to a pivotally mounted lever and its opposite end operatively associated with said pawl; a protuberance on said ratchet wheel engageable with said pivotally mounted lever to swing the same in one direction; and a tension spring connected to said pivotally mounted lever and biasing the same to swing in the opposite direction.

7. In a control device, the improvement claimed in claim 4, including a blocking pawl pivoted to swing radially relative to the shaft of said ratchet wheel in the range of axial displacement of said circular disc; a pivoted stop lever pivotally mounting said blocking pawl and engaged with a star wheel fixed to rotate with said ratchet wheel; means on said locking lever engageable with play with said blocking pawl; said blocking pawl, responsive to axial displacement of said circular disc due to energization of said electromagnet, dropping behind said circular disc to prevent return of said circular disc to a position operable to move said oscillating pawl out of its normal path of oscillation; said blocking pawl being retracted out of blocking relation with said circular disc responsive to swinging of said locking lever by said star wheel.

8. In a control device, the improvement claimed in claim 2, including a make-contact switch and a rest-contact switch connected in series in one of the energizing circuits of said electromagnet; said make-contact switch being actuated by a counting wheel moving stepwise in the rhythm of the printing machine; said rest-contact switch being actuated by a lever controlled by said control shaft.

9. In a control device, the improvement claimed in claim 8, in which said last-named lever is constituted by a retaining pawl for a counting wheel of a revolution counter of a washing device included in the printing machine.

10. In a control device, the improvement claimed in claim 9, including a slide having a ratchet tooth mounted on said retaining pawl for tangential displacement toward said counting wheel; and a trip cam on said oscillating pawl actuating said slide when said retaining pawl is in engagement with said counting wheel.

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