US3403569A - Apparatus for bringing two stationary gearwheels into engagement with one another ona lapping or testing machine - Google Patents

Description

Oct. 1,. 1968 A. J. LAUTENSCHLAGER 3,403,569

APPARATUS FOR BRINGING TWO STATIONARY GEARWHEELS INTO ENGAGEMENT WITH ONE ANOTHER ON A LAPPING OR TESTING MACHINE 4 Sheets-Sheet 1 Filed Jan. 30, 1967 Oct. 1, 1968 A. J. LAUTENSCHLAGER 3, 6

APPARATUS FOR BRINGING TWO STATIONARY GEARWHEELS INTO ENGAGEMENT WITH ONE ANOTHER ON A LAPPING OR TESTING MACHINE Filed Jan. 50, 1967 4 Sheets-Sheet 9 Fig. 4

WW 0% 1) aua Oct. 1, 1968 A. J. LAUTENSCHLAGER 3, 69

APPARATUS FOR BRINGING TWO STATIONARY GEARWHEELS INTO ENGAGEMENT WITH ONE ANOTHER ON A LAPPING OR TESTING MACHINE Filed Jan. 30, 1967 4 Sheets-Sheet 3 i W lhven'for 4%20 floufensch/o 8 WM (2nd? M fiffom s 1968 A. J. LAUTENSCHLAGER 3,403,569

APPARATUS FOR BRINGING TWO STATIONARY GEARWHEELS INTO ENGAGEMENT WITH ONE ANOTHER ON A LAPPING OR TESTING MACHINE Filed Jan. 50, 1967 4 Sheets-Sheet 4 Fig.6

Fig.7

J11 venfor United States Patent 3,403,569 APPARATUS FOR BRINGING TWO STATIONARY GEARWHEELS INTO ENGAGEMENT WITH ONE ANOTHER ON A LAPPING OR TESTING MACHINE Alfred Johann Lautenschlager, Zurich, Switzerland, assignor to Oerlikon-Buhrle Holding Ltd., Zurich, Switzerland Filed Jan. 30, 1967, Ser. No. 612,378 Claims priority, application Switzerland, Feb. 1, 1966, 1,394/66 18 Claims. (Cl. 74-388) ABSTRACT OF THE DISCLOSURE Apparatus for bringing into engagement two gearwheels on a lapping or testing machine. The gearwheels are displaced towards one another until they come into mutual contact and in the vent of the tips of two teeth contacting one gear wheel is rotated through a fraction of the tooth pitch and engagement of the two gearwheels is prevented until a tooth of one gearwheel is opposite a gap in the other gearwheel.

The invention relates to a method of bringing two stationary gearwheels into engagement with one another on a lapping or testing machine, wherein the two gearwheels are moved towards one another, turned relatively to one another and in the event of the tip of one tooth on one gearwheel coming opposite a gap in the other gearwheel, brought into engagement with one another by being advanced. The invention further relates to a device for carrying out the method.

In lapping machines, it is known to bring two gearwheels which are to be lapped into engagement with one another, step by step, because there is a high probability that, in the event of direct advance, the tip of a tooth on the one gearwheel will strike against the tip of a tooth on the other gearwheel. With this step-by-step procedure, the two gearwheels at first approach with a rapid motion to a distance of a few millimeters apart, then one of the two gearwheels is turned by hand until the tip of a tooth on the one gearwheel is opposite a gap in the other gearwheel, whereupon the gearwheels are brought into engagement with one another.

Furthermore, a device is known whereby the two gearwheels to be brought into engagement with one another are first aligned in relation to one another (see US. Patent No. 2,150,313). In this device, a pivoted lever is provided which before the gearwheels are driven towards one another, is pressed against the gearwheels in the course of which a ball detent on the lever is pressed into a gap in one gearwheel while at the same time a sharpedged dog on the lever engages in a gap in an adjusting wheel which is provided with sharp-edged teeth and which is rigidly connected to the second gearwheel. As a result of this swivel movement of the lever, the two gearwheels to be brought into engagement with one another are aligned in relation to one another so that they are sure to come into engagement with one another when advanced.

These two known methods of bringing two gearwheels into engagement with one another require the presence of an operator and are time-consuming and inconvenient. In the method first mentioned, the operator must take care each time to ensure that the tip of a tooth on the one gearwheel is in fact opposite a gap in the teeth on the other gearwheel. The other method is even more inconvenient for lapping machines because the operator first has to ensure, when securing the one gearwheel in position, that it is in the correct position with respect to the adjusting 3,403,569 Patented Oct. 1, 1968 wheel. Then, during the swivelling of the lever, the operator has to ensure that the ball detent does in fact enter a gap in the other gearwheel.

It is an object of the invention to overcome these disadvantages and to provide a method which can also be used for gearwheels which are not accessible or visible to an operator and which can be carried out easily and automatically by a device without the presence of an operator. 1

A further object is to provide a construction wherein the gearwheels are moved towards one another until they come into mutual contact and, in the event of mutual contact between the heads of two teeth, one gearwheel is turned through a fraction of the tooth pitch and entrainment of the second gearwheel by the first-mentioned gearwheel is prevented until a tooth in one gearwheel is opposite a gap in the other gearwheel.

In a preferred example of the method, entrainment of one gearwheel by the other gearwheel can be prevented by the mutual contact between the two gearwheels being discontinued again by withdrawal of one gearwheel.

In another example of the method, entrainment of the one gearwheel by the other gearwheel can be prevented by braking the first-mentioned gearwheel, and the second gearwheel can be pressed against the first gearwheel and, at the same time, turned in relation to the first gearwheel until a tooth in one gearwheel engages in a gap in the other gearwheel.

A further object is to provide a device for carrying out the method on a lapping machine or testing machine with a servo-mechanism which comprises a stop adapted for automatic displacement, for the displacement of one gearwheel towards the other gearwheel, so that an inching control mechanism is provided in order to turn one of the two gearwheels through a fraction of the tooth pitch.

In a preferred embodiment of the device, the servomechanism may comprise a switch member which, in the case of mutual contact between the tips of two teeth, discontinues the contact again. The inching control mechanism may comprise a rolling segment which has a friction lining and is displaceable in its longitudinal direction by means of a first working cylinder with a piston so as to come into engagement with a pulley driving the one gearwheel, and which is displaceable transversely to said longitudinal direction by means of a second working cylinder with a piston in order to rotate the pulley and hence the gearwheel by a fraction of the tooth pitch.

Two examples of carrying out the method according to the invention are described in detail below with reference to the accompanying drawings in which a single embodiment of the device according to the invention is illustrated and in which:

FIGURE 1 is a perspective illustration of two hypoidtoothed bevel wheels in which the tips of two teeth are striking one against the other;

FIGURE 2 is a perspective illustration of the same two gearwheels in engagement;

FIGURE 3 is a plan view of a lapping machine with the device for bringing two gearwheels, to be lapped on the machine, into engagement with one another;

FIGURE 4 shows a section on the line IV-IV in FIG- URE 3 with the servo-mechanism whereby the two gearwheels to be lapped together are displaceable towards and away from one another, with a slide in its initial position;

FIGURE 5 shows a section on the line VV in FIG- URE 3 with an inching control mechanism to turn one of the two gearwheels through a fraction of its tooth pitch;

FIGURE 6 is an electric wiring diagram for a first example of the method with the contacts in a position corresponding to the initial position shown in FIGURE 4 and FIGURE 7 is an electric wiring diagram for a second example of an embodiment with the contacts in the initial position corresponding to FIGURE 4.

According to FIGURES 3 and 5, a spindle slide 11 is mounted for displacement in guides 12 on a bed 10. A spindle 13 is mounted for rotation on this slide 11. Secured to one end of this spindle 13 is a belt pulley 14 which is in driving connection with a motor 16 through two belts 15. This motor 16 serves to drive the spindle 13 during the lapping operation. One of two gearwheels 17, 18 to be lapped together is fixed to the other end of the spindle 13. Further secured to the bed Ill) is a spindle housing 19 in which a second spindle 20 is mounted for rotation. The other of the two gearwheels 17, 18 to be lapped together is fixed to this second spindle 20.

As shown in FIGURE 4, a housing 21 is secured to the spindle slide 11. In this housing 21 there is a piston 22 which is rigidly connected to the bed 10' through a piston rod 23. Also in the housing 21 is a. copying valve piston 24 which is connected to a valve magnet 25. The energized valve magnet 25 tends to urge the valve piston 24 into its right-hand end position. If the valve magnet is de-energized, the spring 26 tends to urge the valve piston 24 into the left-hand end position. When the slide 11 is in the initial position, the valve piston 24 is held at its left-hand end in its netural position by a stop on the housing 10.

When the valve piston 24 is in the right-hand end position, a hydraulic pipeline 27 is in communication with a chamber 28 at the right-hand side of the piston 22. When the valve piston 24 is in the left-hand end position, on the other hand, the hydraulic pipeline 27 is in communication with a chamber 29 at the left-hand side of the piston 22. If the chamber 28 at the right-hand side is in communication with the hydraulic pipeline 27, the chamber 29 at the left-hand side of the piston 22 is in communication with a discharge pipeline 30 and conversely, if the chamber 29 at the left-hand side of the piston 22 is in communication with the pressure line 27, the chamber 28 at the right-hand side of the piston 22 is in communication with the discharge pipeline 30.

When the right-hand chamber 28 is in communication with the pressure line 27, the slide 11 is displaced towards the right and, conversely, when the left-hand chamber is in communication with the pressure line, the slide 11 is displaced towards the left. Thus a displacement of the valve piston 24 towards the right likewise causes a movement of the slide 11 towards the right and conversely a displacement of the valve piston 24 towards the left likewise causes a displacement of the slide 11 towards the left. The mechanism described is termed a servo-mechanism.

Further secured to the bed 10 is a limit switch 31 which can be actuated by the slide 11 in the left-hand end position. Two limit switches 32 and 33 which can be actuated by the valve piston 24 are secured to the housing 21. These electrical switches are described in detail below.

A stop slide 34 is further mounted for displacement on the bed 10. A spindle 35, to the left-hand end of which there is secured a hand wheel 36, is provided for the displacement of this stop slide 34. At its left-hand end, this spindle is also mounted for rotation in the bed 10 and secured against axial displacement, while the right-hand end of the spindle 35 comprises a thread 37 and is screwed into an extension 38 on the slide 34.

By turning the hand wheel 36, the slide 34 can be displaced towards the right or left with respect to the bed 10. A stop 39 is mounted for displacement on the slide 34. A spindle 40, to the right-hand end of which there is secured a worm wheel 41, is provided for the displacement of this stop 39. The spindle 40 is: mounted for rotation on the stop slide 34 and held against axial displacement. The spindle 40 is threaded and is screwed into an extension 39' on the stop 39.

The worm wheel 41 is in engagement with a worm 42 which is secured to a motor 43 which in turn is secured to the stop slide 34. The stop 39 has a cam 44 for the actuation of two electric switches 45 and 46, of which the limit switch 46 comprises a break contact 46.1 and a make contact 46.2 (see FIG. 6) which are described below. The stop 39 is in the path of the valve pis ton 24.

According to FIGURE 5, an inching control mecha nism is mounted on the spindle slide 11. This inching control mechanism comprises a controlling segment 50 which is provided with a friction lining 51 and which is articulated to one arm of a two-armed lever 53 for pivoting by means of a pin 52. This lever 53 is mounted for pivoting on a pin 54 secured to the slide 11. The other arm of the lever 53 is passed, by means of a spring 55, against a piston 56 which is mounted for displacement in a housing 57. At the right-hand side of the piston 56, a cylinder compartment 58 is in communication with a valve 60 through a pipeline 59. A pressure line 61 and a discharge line 62 are connected to this valve 60.

A further piston 63, which is likewise mounted for displacement in the housing 57, is provided for the actuation of the rolling segment 50. A sliding block 64, which is glided for displacement in a slot in the rolling segment 50, is pivotally mounted on the piston 63. The piston 63 further comprises an annular stop 65. A spring '66, which bears on the one hand against the stop 65 and on the other hand against a frame 67 secured to the slide 11, tends to urge the piston 63 into its lower position. This lower position of the piston 63 is adjustable by means of screwed-on adjusting nuts 68.

A cylinder compartment 69 below the piston 63 is in communication with the pipeline 59 through a throttle valve 70. Further secured to the frame 67, through a holder 71, is a limit switch 72 which is adapted for actuation by the piston 63 in its uppermost position. Secured to the valve 60, is a valve magnet 73 which is connected to a valve piston 74. When the valve magnet 73 is energized, the valve piston 74 is in its lowest position and the pressure line 61 is in communication, through the line 59, with the cylinder compartments 58 and 69. If the valve magnet 73 is deenergized, on the other hand, then the valve piston 74 is in its uppermost position, under the action of a spring 75, and the cylinder compartments 58 and 69 are connected to the discharge line 62 through line 59.

Secured to the spindle housing 19 is a brake whereby the spindle 20 can be held against rotation as a result of which, entrainment of the one gearwheel on rotation of the other gearwheel is prevented if the tips of two teeth on the two gearwhels are in contact. The brake 80 comprises a brake disc 81 as well as a lever 82 which is mounted for pivoting on a pin 83 and is provided with a brake lining 84, A spring 85 tends to pivot the lever 82 in clockwise direction. In the energized state, a magnet 86 causes the brake lining 84 to be pressed against the brake disc 81. According to FIGURE 6, a start button 90 and a stop button 91 are connected in series with a relay 92 through an adapting transformer 93. The relay 92 is further connected to a self-holding contact 92.1 in order to prevent the circuit from being interrupted on release of the start button 90. The relay 92 is further connected to a contact 92.2 which is connected, in series with the copying valve magnet 25, to a direct-current source 94 which in turn is connected to the adapting transformer 93. On actuation of the starting button 90, the copying valve 25 is thus actuated immediately.

As can be seen from FIGURE 6, the motor 43 described above rotates in the one direction when the three contacts 95.3 are closed by a relay 95 and in the other direction when the three contacts 96.2 are closed by a further relay 96. The relay 95 is connected in series with the limit switches 31 and 45, which are constructed in the form of break contacts, and with the limit switch 32 which is constructed in the form of a make contact. Furthermore, three further relay contacts 97.1, 92.3 and 96.1 are connected in series with the relay 95. A selfholding contact 95.1 prevents the circuit from being interrupted on release of the make contact 32. In order that the motor 43 may rotate in the one direction, the make contact 32 must be actuated while at the same time, both the break contact 31 and the break contact 45 must not be actuated and the two relays 97 and 96 must be deenergized, while the relay 92 must be energized.

The relay 96 is connected in series with the limit switches constructed in the form of a make contact 33 and break contact 46.1, which are connected in parallel with one another. Furthermore, the relay 96 is connected in series with the relay contacts 92.4 and 97.2 which are likewise connected in parallel with one another. Thus in order that the motor may be able to rotate in the other direction, the break contact 46.1 must be released and furthermore, one of the two relay contacts 91.4 and 97.2 must be closed, and finally the relay contact 95.2 must be closed.

The magnet 73 is connected in series with the make contact 46.2 and the relay contact 97.4. In order to energize the magnet 73, therefore, the make contact 46.2 must be actuated, but the relay 97 must be energized. This relay is connected in series with the break contact 72, however, so that on actuation of the switch 72, the valve magnet 73 is deenergized.

As shown in FIGURE 7, a start button 90 and a stop button 91 are connected in series with a relay 92 to an adapting transformer 93. The relay 92 is connected to a self-holding contact 92.1 in order to prevent the circuit from being interrupted on release of the start button 90. The relay 92 is further connected to a contact 92.2 which is connected, in series with the copying valve magnet 25, to a directcurrent source 94, which in turn is connected to the adapting transformer 93. On actuation of the start button 90, the magnet 25 of the copying valve is energized immediately.

As can further be sen from FIGURE 7, the inching motor 43, as in the wiring diagram shown in FIGURE 6, turns in one direction when the three contacts 95.3 are closed through a relay 95 and in the other direction when the three contacts 96.2 are closed through a further relay 96. The relay 95 is connected in series with limit switches 31 and 45 constructed in the form of break contacts and with the limit switch 32 constructed in the form of a make contact.

Furthermore, a break contact 33.1 is connected in series with the relay 95. This break contact 33.1 is connected to the make contact 33.2 which is connected in series with the relay 97. The break contact 33.1 and the make contact 33.2 are actuated jointly through the limit switch 33 (FIGURE 4). In addition, the two relay contacts 92.3 and 96.1 are connected in series with the relay 95. A selfholding contact 95.1 prevents the circuit from being interrupted on release of the make contact 32.

Thus, in order that the inching motor 43 may rotate in the one direction, the make contact 32 must be actuated and at the same time neither the break contact 31 nor the break contact 45 must be actuated. The relay 92 must be energized and the relay 96 must be deenergized. The relays 97 and 96 are connected in parallel with one another and in series with the break contact 46.

Furthermore, the relay 97 is connected in series with the make contact 33.2 and the time-relay contact 98.1 and in parallel with the time relay 98 which in turn is connected in series with the make contact 72. The relay 97 is connected to the relay contact 97.1 which is connected in series with the magnets 73 and 86 connected in parallel with one another. Thus when the relay 97 is energized, the inching control mechanism and the brake 80 are actuated at the same time. Finally, the relay 96 is connected in series with the relay contacts 92.4 and 95.2. The inching motor 43 runs backwards when the end switch 46 is not actuated and the relays 92 and are deenergized.

According to a first example, the mode of operation of the device described is as follows:

As soon as two gearwheels 17, 18 to be lapped with one another have been fixed to the two spindles 13 and 20, the device is switched on by means of the start button 90. The valve magnet 25 is energized as a result of which the valve piston 24 in FIGURE 4 is displaced towards the right so that the pressure line 27 is in communication with the right-hand cylinder compartment 28 and the slide .11 is displaced with a rapid motion towards the right.

In the course of this, the valve piston 24 actuates the make contact 33. The actuation of this make contact 33 does not have any further consequences, however, because the break contact 46.1 connected in parallel with the contact 33 is pressed by the stop 39. The inching motor 43 is therefore neither switched on nor off through this actuation of the make contact 33. The slide 11 is displaced towards the right with a rapid motion until the valve piston 24 strikes against the stop 39.

The stop 39 displaces the valve piston 24 towards the left until the connection between the pressure line 27 and the cylinder compartment 28 is interrupted and the slide 11 stops. The make contact 32 is actuated through the displacement of the valve piston towards the left. As can be seen from FIGURES 4 and 6, the inching motor 43 is switched on because the break contact 45 is closed and the break contact 32 is likewise closed through the displacement of the slide 11. The relay contact 92.3 is likewise closed because the relay 92 was energized on actuation of the start button 90. The relay contacts 97.1 and 96.1 are likewise closed because neither the relay 97 nor the relay 96 was energized through switches 46 and 33 as explained above.

The inching motor 43 turns the spindle 40 through the worm gear 42, 41 so that the stop 39 is displaced towards the right. The valve piston 24 which bears against the stop 39 participates in this movement and causes the slide 11 to inch towards the right. If the tips of two teeth on the gearwheels .17 and 18 strike against one another during this movement of the slide 11, as illustrated in FIGURE 1, the spindle slide 11 stops. A pressurerelief valve, not illustrated in the drawing, prevents excessive forces from arising during this impact between the tips of the teeth.

The valve piston 24 now follows the stop 39 alone and is displaced towards the housing 21 until the make contact 33 is pressed and the relay 97 is closed through the contacts 46.1 and 72. The relay contact 97.1 opens and the inching motor 43 stops. Since the break contact 46.1 is not depressed in this position of the stop 39, and the relay contact 95.2 was closed on the stopping of the motor 43 and de-energizing of the relay 95, the relay 96 is now energized and the inching motor 43 rotates in the opposite direction so that the stop 39 is also displaced in the opposite direction, that is to say towards the left, as a result of which the slide 11 is also displaced towards the left, through the valve piston 24, until the contact between the tips of the teeth is interrupted.

The stop 39 is displaced towards the left until the cam 44 on the stop 39 actuates the switch 46 again The actuation of the switch 46 has the effect, on the one hand that the motor 43 stops, since the break contact 46.1 (FIG- URE 6) is interrupted, and, on the other hand, that the valve magnet 73 is energized, because the make contact 46.2 closes at the same time. As a result of the energizing of the valve magnet 73, the valve piston 74 is driven downwards against the action of the spring 75, so that the cylinder compartments 58 and 69 are connected to the pressure line 6.1 through the pipeline 59. The piston 56 is displaced towards the left, against the force of the spring 55, and urges the rolling segment against the pulley 76.

Through the constriction 70, the piston 63 is displaced upwardswith some delayagainst the force of the spring 66, asa result of which the rolling segment is pivoted and causes rotation of the pulley 76. The rotation of the pulley 76 corresponds to a fraction of the tooth pitch of the gearwheel fitted to the spindle 13. When the piston 63 is in the uppermost position, the break contact 72 is actuated. As a result, the relay 97 is de-energized and the relay contact 97.4 opens so that the valve magnet 73 is likewise de-energized. Under the action of the spring 75, the valve piston 74 returns to its uppermost position, as a result of which the cylinder compartments 58 and 69 are connected to the discharge line 62 through the pipeline 59. Under the action of the springs 55 and 66, the pistons 56 and 63 are restored to their initial position, while the piston 56 and the piston 63 return to their initial position again under the action of the constriction 70.

Since the relay 97 was de-energized through the actuation of the switch 72, the relay contact 97.1 (FIGURE 6) has closed, as a result of which the relay 95 is energized and the inching motor 43 is switched on so that the stop 39 is again displaced towards the right as a result of which the slide 11 also travels towards the right. If the tip of a tooth on the one gearwheel is not opposite a gap on the other gearwheel, the slide 11 can be displaced towards the right until the two gearwheels are in engagement and touching one another. The stop 39 continues to move towards the right until the cam 44 strikes against the limit switch 45 and the motor 43 is switched off, as a result of which the stop 39 stops. If the tips of two teeth still strike against one another on the second displacement of the slide 11, the operation described is repeated.

As soon as the gearwheels are in engagement, the lapping operation begins. At the end of the lapping operation, the stop button 91 is actuated, the relay 92 is deenergized and the slide 11 reaches its initial position. If the tip of a tooth on the one gearwheel is already opposite a gap in the other gearwheel on the first displacement of the slide towards the right, the two gearwheels come into engagement with one another immediately without any rotation of the one gearwheel being necessary.

According to a second example, the mode of operation of the device described is as follows:

As soon as two gearwheels 17, 18 to be lapped together are fixed to the two spindles 13 and 20, the device is switched on by means of the start button 90. In the course of this, the relay 92 (FIGURE 7) is energized and the relay contact 92.2 closes as a result of which the valve magnet 25 is energized. The second time, the self-holding contact 92.1 closes so that the device does not stop again on the release of the start button 90. The energized valve magnet 25 then displaces the valve piston 24 towards the right so that the pressure line 27 is brought into communication with the right-hand cylinder compartment 28 and the slide 11 is displaced towards the right with a rapid motion.

The valve piston 24 actuates the break contact 33.1 and the make contact 33.2. The actuation of these two contacts 33.1 and 33.2 does not have any further consequences, however, because the break contact 46 which is connected in series is still depressed by the stop 39 and the make contact 32 is opened. The inching motor 43 is therefore neither switched on nor off through this actuation of the break contact 33.1. The slide 11 is displaced with a rapid motion toward the right until the valve piston 24 strikes against the stop 39. The stop displaces the valve piston 24 toward the left until the communication between the pressure line 27 and the cylinder compartment 28 is interrupted and the slide 11 stops. Through the displacement of the valve piston 24 towards the left, the make contact 32 is actuated.

As can be seen from FIGURES 4 and 7, the inching motor 43 is switched on, because the break contact 45 is closed, the break contact 31 was likewise closed through the displacement of the slide 11; the relay contact 92.3 is likewise closed because the relay 92 was energized on actuation of the start button 90. Furthermore, the relay contact 96.1 is closed because the relay 96 was not energized through the switch 33.2, and finally the break contact 33.1 is closed because the valve piston does not actuate the switch 33. The inching motor 43 turns the spindle 40 through the worm gear 42, 41 so that the stop 39 is displaced towards the right. The valve piston 24, which bears against the stop 39, participates in this movement and causes the slide 11 to be displaced towards the right with an inching motion.

If the tips of two teeth on the gearwheels 17 and 18 strike against one another during this displacement of the slide 11, as illustrated in FIGURE 1, then the spindle slide 11 stops. A pressure-relief valve not illustrated in the drawing, prevents inadmissibly heavy forces from arising on this impact between the tips of the teeth. The valve piston 24 alone continues to follow the stop 39 and is displaced towards the housing 21 until the make contact 32 is no longer depressed. The inching motor 43 continues to rotate because the contact 32 is bridged by the relay contact 95.1. The operations described so far are substantially similar to the corresponding operations in the first example. Instead of the gearwheels which are in contact being moved apart from one another again, as in the first example, however, in this second example, the gearwheels are turned relatively to one another; this is effected as follows:

As soon as the valve piston 24 releases the make contact 32 and instead actuates the break contact 33.1 and the make contact 33.2, the relay 97 is energized and the inching motor 43 is stopped because the break contact 46 has already been released by the displacement of the stop 39 and the time switch 98.1 is closed. The relay contact 97.1 is closed and the magnets 73 and 86 are energized through the energized relay 97. The inching control mechanism is actuated in the manner described.

The brake is likewise applied through the magnet 86 so that the gearwheel 18 cannot also rotate. As soon as the gearwheel has been turned so far that one tooth thereof can penetrate into a gap in the other gearwheel, the slide 11 is displaced further towards the right because the stop 39 has been displaced towards the right in the meantime and the servo-valve tends to displace the slide 11 towards the right. As a result of this displacement of the slide 11, during which the gearwheels come into engagement with one another, the limit switch 33 becomes free again and the circuit for relay is closed again, the motor 43 starts up again and is finally stopped through actuation of the switch 45.

If the stroke of the piston 63 is not sufficient for the rotation of the one gearwheel, the limit switch 72 is pressed shortly before the end of its stroke and the time relay 98 is switched on as a result. The contact 98.1 of this relay 98 is opened in the course of this, as a result of which the relay 97 becomes de-energized and so the magnets 73 and 86 are also de-energized through the relay contact 97.1. The piston 63 is displaced into its initial position. The limit switch 72 is no longer actuated. When the time set at the time relay has expired, the contact 98.1 closes. The relay 97 responds again and the magnets 73 and 86 are re-energized and the rotation of the one gearwheel is continued.

A fine stop motor, known per se, may be used instead of the inching control mechanism illustrated in FIGURE 5 to rotate the one gearwheel and may serve as a main drive motor for the lapping operation at the same time.

As a result of the de-energizing of the relay 92, the relay contact 92.4 is closed. Since the stop 39 is in its right-hand end position, the contact 46 is also closed, and since the relay 95 is not energized, the relay contact 95.2 is also closed; thus the relay 96 is energized and the inching motor 43 restores the stop 39 to its initial position. The operation is completed. Since the relay 92 is de-energized, the magnet 25 is also de-energized and the slide 11 regains its initial position.

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the process, form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the forms hereinbefore described and illustrated in the drawings being merely preferred embodiments thereof.

I claim:

1. Step-by-step control means comprising a control member formed as a revolving element with a friction coating, a control disk actuated by said control member, a first driving element for actuating said control member and a second driving element with which said revolving element can be controlled at said control disk to adjust the size of the control steps of said control means.

2. Control means as set forth in claim 1 wherein said driving elements each comprise a cylinder and a piston.

3. Control means as set forth in claim 2 wherein each of said driving elements has an initial position and means are provided for exerting a force on each driving element to maintain said driving elements in their initial position wherein said revolving element is in engagement with said control disk.

4. Control means as set forth in claim 2 wherein a common pressure line is provided for both of said cylinders and a branch line having a constricted portion leads to the cylinder actuating the tangential displacement of said revolving element.

5. The control means as set forth in claim 4 wherein a control element is provided in said common pressure line to empty said pressure line intermittently.

6. Control means as set forth in claim 1 wherein said revolving element is displaceable on one hand radially against said control disk and on the other hand tangentially towards said control disk.

7. Control means as set forth in claim 1 wherein a bolt connects one of said driving elements with said revolving element for the tangential displacement of said revolving element and a pivotally mounted two armed lever connecting said other driving element with said revolving element for a radial displacement thereof.

8. Control means as set forth in claim 7 wherein buffer adjusting means are provided for controlling the size of the stroke of said driving elements for the tangential displacement of said revolving element within a limited range from the initial position.

9. Means for engaging a first stationary gearwheel with a second stationary gear wheel comprising adjustable means for displacing said two gear wheels towards one another until their engagement, a step by step control means for rotating said first gear wheel, a control device having two parts which are displaced only at mutual contact of two tips of the teeth of said gear wheels relative to one another and means controlling said step by step control means to rotate one of said gear wheels for a fraction of a pitch which are actuated by a movement of the two parts relative to one another.

10. Means as set forth in claim 9 wherein a switch is provided which is actuated upon contact of two tips of the teeth of said gear wheels, said switch being connected with said control device to actuate said displacement parts to terminate the contact of said two tips of teeth.

11. Means for engaging a first stationary gear wheel with a second stationary gear wheel comprising a movable support for said first gear wheel, a step by step control means for rotating said first gear wheel, means on said support actuated by the movement of said support 'for controlling said step-by-step control means and for preventing movement of said second gear wheel.

12. Means as set forth in claim 11 wherein a hydraulic control piston is provided for said control means, a movable bulfer against which said control means pushes when said movable support is displaced for the mutual contact of two gear wheels and an electrical switch on said movable support actuated by a displacement of said control means.

13. Means as set forth in claim 11 wherein said step by step control means is adjustable for the rotation of said first gear wheel relative to said second gear wheel.

14. Control means on a lapping or testing machine having a servo-mechanism comprising an automatically displaceable stop, for the displacement of the one gear wheel with respect to the other gear wheel and an inching control mechanism to rotate one gear wheel through a fraction of the tooth pitch.

15. Means as claimed in claim 14 wherein said servomechanism comprises a switch member which, in the event of mutual contact between the tips of the teeth, discontinues contact.

16. Means as claimed in claim 14 wherein said inching control mechanism comprises a rolling segment having a friction lining which is displaceable in its longitudinal direction by means of a first cylinder with a piston, in order to come into engagement with a pulley driving the one gearwheel, and which is displaceable transversely in relation to said longitudinal direction by means of a second cylinder with a piston, in order to rotate said pulley and hence the gear wheel through a fraction of the tooth pitch.

17. Means as claimed in claim 16 wherein said cylinders are connected to a common pressure line, a constriction being provided in a branch pipe leading to the second working cylinder.

18. Means as claimed in claim 14 wherein adjusting members are provided on a second piston in order to adjust the initial position of said piston and hence the magnitude of the stroke, in order that a rolling segment may be urged against a pulley at a different point on its surface, depending on the size of the tooth pitch, and is pivoted into a given end position.

References Cited UNITED STATES PATENTS 2,150,313 3/1939 'Bauer -1.6 2,984,956 5/ 1961 Schicht 51-287 3,099,901 8/1963 Hunkeler 51-287 X 3,2635 6-8 8/ 1966 Kretzschmar et al 90--1.6

FRED C. MATTERN, JR., Primary Examiner.

LEONARD H. GERIN, Assistant Examiner.

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