DE10209567A1 - Disc brake and method for controlling an adjustment system for a disc brake - Google Patents

Abstract

A disc brake with a brake caliper (1) spanning a brake disc and an application device for applying brake pads and with an adjusting system to compensate for brake pad wear has at least one adjusting rotating device with an electromotive drive (5), whereby in addition to the electromotive drive ((5 ) a loosening device supporting the loosening of the adjuster rotating device is used to set the desired air gap.

Description

The invention relates to a disc brake according to the preamble of claim 1 and a method according to the preamble of claim 20.

Application devices for disc brakes are already known, in which one Electro wear adjustment device independent of brake application is mechanically driven.

For example, distance sensors can be used to adjust the clearance, whose signals are used to control the actuator of the adjusting device.

Such controls are due to the expense of sensing and electronic control but complex and prone to failure. Systems of this type who for example in EP 0 995 921 A2, in EP 0 995 923 A2 and in PCT / WO 99/08018.

A significantly simpler and moreover reliable mode of operation of the one Electromechanical drive operated wear adjustment system is possible if the turning device when the brake is not applied, the brake shoes with the brake brings the disc into contact briefly and then passes by from this position agreed amount that corresponds to the target air gap. Such Operation is described in DE 197 31 696 A1. Have controls of this type  proven itself. However, they require a special operating case another improvement.

The moment the adjusting system turns the brake shoes on position of the air play on the brake disc, another braking initiated and also warm the brake shoes and brake disc as a result of the first If the heat builds up noticeably, the brake can be caused as a result of the expansion stay so tense after the end of this braking process that the relative small-sized drive motor of the wear adjustment system due to the as As a result of the tension created frictional resistance in the self-locking put adjustment threads between the adjustment nut and the adjustment spindle Adjustment system can no longer turn back. As a result of these effects is the air game cannot be restored on the brake. As a result of this effect, the brake grinds while driving, which is another high braking temperature and an extremely high one Brings wear.

It is therefore the object of the invention, the generic disc brake in this way to further develop that in procedural and constructive terms in simpler and reliable securing of the air play of the brake is guaranteed.

The invention solves this problem with regard to the disc brake by the Ge subject of claim 1 and in relation to the method by the subject of claim 20.

According to the idea of the invention it is provided that the adjustment system in addition to electromotive drive supports the loosening of the adjuster zende release device.

When the disc brake is operating, there is an operating situation in which the elec motorized drive no longer has a loosening game due to the tension in the brake can set correctly, the additional release device supports this release process. Through the combined effect of the electric motor drive and the supplement  The release play remains precise despite the tension in the brake adjustable.

It is advisable to design the release device purely mechanically. Alternatively it is also conceivable, electromechanically or electronically operated systems for support use the release effect. Piezo elements are ideal here, which can release the tension of the brake when energized.

According to a preferred embodiment of the invention it is provided that the Adjustment rotating device has an adjusting nut in which a rotating spindle is screwed, which at one of its ends acting on the brake pad Has pressure piece, the release device on the adjusting nut or Acts on the rotating spindle.

This simple constructive implementation of the adjusting device with a Adjusting nut and a rotating spindle, each of which is powered by an electric motor driven, makes it possible to have a separate one on each side of the disc brake Adjustment device to be provided with an electric motor drive. This offers itself, for example, for disc brakes that are designed as fixed calipers or as a brake caliper with a very small displacement or pivoting path.

Alternatively, it is conceivable for the adjuster rotating device to have a rotating spindle has, on which an adjusting nut is screwed, which at one of its ends has a pressure piece acting on the brake pad, the release device on the adjusting nut or the rotating spindle acts.

With regard to the release device for an adjuster with adjuster A wide variety of mechanical implementations are conceivable for the nut and rotating spindle.

The ramp profile is expedient directly in the end face of the adjusting nut or the rotary spindle molded, in particular stamped.  

The support element is expediently the brake caliper or an element of the application unit. The (further) ramp profile can be directly in the brake caliper or the Element of the clamping unit must be molded.

Advantageously - since it is easy to manufacture - the ramp profile is inserted into a ramp disc forms the non-rotatable on the end face of the adjusting nut or the rotating spindle rests.

A particularly inexpensive variant is characterized in that the release device is formed in that the pressure support surface of the adjusting nut with a Ramp profile is provided, with a support disc on the pressure support surface has an opposite ramp profile and the flat rear of the Support disc rests on a support surface of a support element.

This support element can be, for example, the brake caliper or on the Side of the application device a brake lever or between brake lever and Rotary spindle or adjusting nut set additional power transmission element.

Preferably, the release device is only on the application device ge arranged opposite side of the brake. For loosening or adjusting the release in the special case of the brakes applied, it is sufficient if the brake is released from its tension at least on one side. Due to the Supporting the rotating spindles on the brake caliper is the solution to arrange device between brake caliper and pressure piece. It goes without saying also a variant with release device on both sides of the brake disc or conceivable on the side of the application device.

The invention makes it possible in a simple manner each time the Adjustment system the brake lever and / or the piston unit by a predetermined th amount by an actuation device even when the brake is applied releasable or self-releasing mechanism to ver in the direction of the brake disc after the electromechanical actuator with the support of  Release device has moved the pressure pieces so far away from the brake disc that in the event of an inadmissibly small clearance due to heating and tension the brake has at least reached the target air gap.

The wear adjustment device is operated until the brake shoes Have contact with the brake disc. Then by loosening the air gap Securing mechanism restores the target air gap by the brake lever and / or the piston unit by the actuator or automatically around the be agreed amount to be moved away from the brake disc.

This procedure also makes it easier to set the air gap itself, since the target Air gap by the amount of the delivery stroke of the air gap safety mechanism or the release mechanism is specified as a fixed design features and not set by electronically controlled backward adjustment spindles must become.

As an alternative to the ramp system described, it is also possible to use a type of clamp roller freewheel or a sprag freewheel to provide as a release device. Also these two variants of the release device are inexpensive to construct and also particularly compact between the adjusting nut and the brake caliper or another Ren support element attachable. So it is possible to adjust the end face mother or in a ring placed on these recesses, which take up the sprags. In the case of a pinch roller system, these are vertical preferably ramped. In the case of the sprag system, they will preferably formed parallel to the support surface.

With the method according to the invention, it is first possible to adjust the air play in one Activation of the drive motor first resets the rotary setting spindles The minimum clearance is ensured. Then another control takes place in the In the sense of an infeed movement of the adjusting rotary spindles, the at the same time actuating movement of the air safety device is triggered. After a sufficiently measured sen waiting time, which is designed so that the brake shoes on the brake disc  can be placed, the actuator creates a reversing release pulse for the air gap security initiated to secure the target air gap. That way, with very simple means and low sensation and control effort a very reliable electromechanical wear adjustment implemented.

As an alternative to waiting for a waiting time, you can also start by sensing the end the rotation of the motor (stop detection) or via an overcurrent sensor Stop time of the actuator can be determined.

Further advantageous embodiments of the invention are the other subclaims refer to.

Exemplary embodiments are described in more detail below with reference to the drawing.

It shows:

Figure 1 shows a section through part of a disc brake with an after adjusting system for adjusting the lining wear.

Fig. 2 to 4 sections through elements of different variants of release devices for wear adjustment systems;

Fig. 5, 6 show sections through elements of adjusting rotating;

Fig. 7 is an exploded view of an adjusting nut with a ramp disc and a view of the assembled elements; and

Fig. 8 shows a section through a disc brake.

First, FIG. 1 is described.

Fig. 1 shows a substantially adjusting module for a disc brake having a brake caliper 1.

The area opposite the application device is shown here Brake.  

The application device can, for example, according to the type of generic pressure scripture.

However, the present construction also relates to a fixed-caliper disc brake or a disc brake with only a very small displacement or pivoting path of the brake caliper, with the brake lining wear preferably also having to be readjusted on the side of the brake disc opposite the application device (see FIG. 8).

An adjustment module 2 is arranged in a recess of the brake caliper 1 . This adjustment module 2 comprises a first mounting plate 3 and a plate 3 attached to the first mounting plate 2 . Here, an electric motor 5 is arranged on the mounting plate 3 , which drives a chain 9 via a gear 6 with gears 7 and 8 , which is guided around two parallel adjusting devices 10 , 11 , each of which has a rotating spindle 12 , 13 , which are screwed into adjusting nuts 14 , 15 , on which gears 16 , 17 are placed, with which the chain 9 meshes. It is also conceivable to arrange the electric motor on the outside of the brake caliper and to connect it to the transmission via a shaft passing through the brake caliper (not shown).

At its end facing away from the brake disc, ie lying towards the brake caliper, the adjusting rotating device is supported on the brake caliper 1 . At their end facing the brake disc, the adjusting spindles 12 , 13 each have thrust pieces 18 , 19 , which act on the brake pads, not shown here.

To readjust the brake, the adjusting nuts are rotated by means of the electric motor 3 and the gear as well as the gears 7 , 8 and the chain 9 , so that the rotating spindles 12 , 13 are displaced in the direction of the brake disc.

Between the adjusting nuts 14 , 15 and the brake caliper 1 , different elements are arranged, purely by way of example, in the case of the left adjusting nut 15 and the right adjusting nut 14 in order to explain the invention in more detail using two different variants. In practice, the release devices 20 , 21 are laid out identically.

According to the invention, the loosening of the rotating spindles from brake linings or the loosening of the brake linings from the brake disc is facilitated by mechanically acting release devices 20 , 21 . This means that the action of the electric motor 5 is supported when the adjusting device 10 , 11 is released.

In the functional principle of the release device 20 shown in the left area of the drawing and in FIG. 2, the support surface of the adjusting nut 15 is provided with a ramp profile 22 (see FIG. 2), which interacts with a corresponding ramp profile 23 of a support disk 24 , which axially connects to the adjusting nut 15 and is supported on the brake caliper 1 by its surface facing away from the adjusting nut. In this form, the flat rear side of the support disk 24 on the brake caliper ensures that the reaction force is transmitted from the piston system.

When the brake is actuated, the reaction force resulting from the application force of the brake is exerted by the pressure piece 19 via the adjusting thread between the rotating spindle 13 and the adjusting nut 15 on the adjusting nut 15 and via its end face remote from the brake disk and provided with the ramp profile on the support disk 24 and from there derived on the support surface on the brake caliper 1 .

This facilitates the loosening of the readjustment device to simple mechanical ones Wise.

The ramp profile can be stamped directly into the corresponding end face of the adjusting nut 15 or can be introduced there in some other way. The ramp profile can also be contained in an additional ramp disk which rests on the end face of the adjusting nut (not shown here).

In the case of a clearance adjustment process by the electromechanical drive 5 , the adjusting nut 15 is first rotated in the sense of unscrewing the pressure piece 19 connected to the adjusting threaded bolt or the rotating spindle 13 or in one piece.

At the start of the adjustment movement, the adjusting nut 15 first rotates against the ramp disc 24 by a predetermined angle of rotation until a stop is reached. Then it moves according to the slope of the ramp profile by a predetermined amount together with the screwed pressure piece 19 against the brake disc.

The amount of this shift corresponds to the design target Clearance.

In this first, limited part of the actuating movement, an adjustment of the pressure piece 19 can already take place relative to the adjusting nut 15 via the adjusting thread. In this case, the target air gap results from the sum of the axial adjustment movements of the adjusting nut 15 relative to the brake caliper 1 and the pressure piece 19 relative to the adjusting nut 15 .

It is also possible to avoid the adjustment of the thrust piece 24 relative to the adjusting nut 15 in the area of the rotation of the adjusting nut 15 provided for securing the air play by the anti-twist device of the thrust piece 15 or of the adjusting screw bolt (rotating spindle 13 ) being provided with a swivel play which the amount of the twist angle necessary for securing the clearance corresponds to the adjustment nut ter 15 .

To ensure the functionality of the release device, it is advantageous if the torsion resistance of the support disk 24 against the support surface on the brake caliper 1 is greater in every operating state than the torsion resistance between the adjusting nut 15 and the support washer 24 .

This means that at the start of the rotational movement of the adjusting nut 15, the support disk with the ramp profile 23 during the displacement of the adjusting nut 15 in the ramp toothing adhere to the brake caliper without rotation and only after reaching the rotation stop in the sense of the actual adjusting movement of the pressure piece 19 with the Adjusting nut 15 is to be rotated further.

Such an anti-rotation of the ramp disc can be realized in a simple manner bar.

For example, a friction-increasing coating can be provided on the support surface of the ramp disk 24 . Alternatively or additionally, it is also possible to provide a friction-reducing coating on the side of the ramp profile 22 , 23 .

An increase in friction is, for example, due to a diamond dust coating possible at coefficients of friction of 0.5. Reducing friction can be done easily can be realized by a sliding lacquer coating.

Alternatively, it is also possible to provide a type of braking mechanism on the ramp disc 24 to increase the anti-rotation. This can be achieved, for example, by a frictional force on the circumference of the ramp disk 24 , preferably by a sliding spring element in the manner of a tolerance ring (not shown here).

Alternatively, it is also possible to use a release device 21 in the manner of a pinch roller or sprag free run for axial adjustment instead of a Rampensy stem according to the type of FIGS . 2 and 3.

... As can be seen in the right part of Figure 1 and in Figures 3 and 4 are both in an implementation as a clamping roller freewheel as well as a realization as a sprag clutch at the end face of the adjusting nut 14 or - shown here - in between the adjusting nut and support plate 24 arranged ring 26 recesses 25 are provided which receive the clamping body 27 or the clamping rollers 28 .

In the case of a pinch roller system ( FIG. 3), these depressions 26 are provided with a ramp shape. In the case of the sprag system ( Fig. 2) they run parallel to the support surface.

In the clamping body system, the clamping bodies 27 pivot due to their free-running clamping action at the beginning of the adjustment movement. The resulting difference in height of the clamping body causes the axial adjustment of the adjusting nut 14th

In the case of the pinch roller system of FIG. 4, on the other hand, when the adjustment begins, the free-wheeling locking action of the pinch rollers 28 . Since because of the torsion inhibition of the upper, in the case flat support disc 24 this can not be moved who can, the pinch rollers 28 roll up on the ramp levels and thereby cause the axial adjustment of the adjusting nut 14th

Preferably, the further course of the clearance adjustment takes place in such a way that the pressure piece 18 is screwed out so far by a further turning of the adjusting nut 14 that the brake shoe or the brake lining comes into contact with the brake disc. The further adjustment movement is stopped by the friction forces now acting in the force transmission path (pressure piece contact surface, adjustment thread, ramp disc support surface). After recognizing this condition z. B. on the current consumption of the electric motor or after a sufficiently dimensioned holding time in this state, the adjusting nut 14 is turned back by the angle of rotation required to release the air gap.

In the critical case that just at the moment when the brake shoes are applied to the brake disc during an air clearance process, a new braking is initiated, the adjusting nut 14 can now by the electrical adjustment mechanism's even with the brake applied in a simple manner in its the starting position restoring the air play can be turned back. This is possible because the resistance to rotation in the clamping body, ball ramp or sliding ramp mechanism in the release direction is so low due to the selected geometries on the ramp or in the clamping system that the release is possible with very little force or takes place almost automatically.

So it is possible, for example, in the ramp system of FIGS . 1 and 2 to choose the ram pen angle with approximately 10 ° in such a way that, given the friction conditions (steel on steel, hardened), self-locking freedom already occurs.

In the case of the clearance adjustment process, the ent standing reaction force proportionally through corresponding actuating forces of the Rotation device can be compensated because of the self-locking slide ramp a reverse torque is generated.

If service braking is now carried out with high force, the adjusting force of the adjusting rotary drive is overcome and the adjusting nut 14 , 15 is automatically turned back into its starting position which ensures the air play. When using a ball ramp or sprag system, this process takes place in an equivalent form.

With a disc brake of the generic type with a slide saddle, it is also possible that when initiating an air clearance adjustment process Brake lever by a certain amount corresponding to the minimum clearance Is delivered in the sense of an application movement. The air gap is then set in the manner described in DE 197 31 696 A1. After applying the brake bake, the lever is returned to its original position and thus the Air play set. The forward stroke of the brake lever that secures the air play can be achieved by  a separate actuator, but preferably by the electromechanical Actuator in which an element operated by the same actuator as z. B. an eccentric cam at the start of the adjustment of the advance stroke of the brake lever is generated.

It is also possible in the generic brake, the crossbar relative to Brake lever to shift the amount of air play in the direction of the brake disc ben. So z. B. in the case of an adjustment axis running through the eccentric axis Synchronization shaft with bevel gears at the ends when actuating the adjuster systems through eccentric or curves connected to the synchronization shaft disc the eccentric bolt from its seat by the amount of the specified clearance lifted in the traverse.

According to FIG. 6, the adjuster rotating device 10 has the adjuster nut 14 , into which the rotating spindle 12 is screwed, which has the pressure piece 18 acting on the brake pad at one of its ends. The ramp profile is formed on the one hand in the brake caliper 1 and on the other hand on the end face of the adjusting nut 24 .

According to FIG. 5, however, the adjusting nut 14 the pressure piece 18 (it is formed here to) and the rotary spindle 12 with a screw-like head is supported at its end remote from the adjusting nut axial end - that is, in the region of its head - even at a ramp disc 24 and has a corresponding ramp profile itself in the area of the face of the head.

Fig. 7 shows a perspective view of an adjusting nut 14 which has the ramp profile on its end face. On this end face, the ramp disc 24 can be placed on, which is encompassed by a friction spring 29 as the torsion-inhibiting braking element.

Pins 30 on the ramp disc 24 engage to ensure the release function in suitably dimensioned recesses 31 of the adjusting nut and serve to secure the angle of rotation. A unit which is preassembled from the elements shown in the left part of FIG. 7 can be seen on the right edge of FIG. 7.

Fig. 8 shows a section through a pivoting caliper disc brake, in which the elements shown in FIGS. 1 to 7 are used.

The application device comprises a rotary lever 32 which can be actuated by a piston rod of a brake cylinder (not shown here) and which is supported on the brake caliper 1 by means of bearing elements, such as balls, which cannot be seen here. The rotary lever 32 acts on its side facing away from the brake caliper 1 at one or two points on an intermediate element 33 which has a hemispherical extension 34 at one end.

If the rotary lever 32 is pivoted, the lower eccentric end (not visible here) of the rotary lever 32 causes the intermediate element 33 to be advanced in the direction of the brake disk 41 . The intermediate element 33 in turn presses an adjusting nut 14 forward, in which an adjusting spindle is screwed to a pressure piece, which rests on a brake pad 35 and advances this during braking.

So that with increasing brake pad wear this does not have to be compensated for by a correspondingly large pivoting movement of the brake caliper 1 , an adjusting device is also provided on the side of the brake disk 41 opposite the application device (one or two adjusting rotary drives), the adjusting nuts 14 of which are supported here on ramp disks 24 , whose flat backs are on the inside of the brake caliper.

The brake caliper 1 only has to bridge the working stroke when the brake is applied by pivoting. This is realized by a kind of elastic spring 36 , which is arranged between the brake caliper 1 and a shoulder 37 attached to a wheel axle, the pivoting angle of two stops 38 , 39 being fastened between a lower shoulder 40 of the brake caliper and the wheel axle shoulder 37 .

On the side of the brake disk opposite the application device, the ramp disks 24 are arranged between the brake caliper and the adjusting nut.

LIST OF REFERENCE NUMBERS

1

caliper

2

adjusting module

3

mounting plate

4

mounting plate

5

electric motor

6

transmission

7

gear

8th

gear

9

Chain

10

adjusting rotating

11

adjusting rotating

12

spindle

13

spindle

14

adjusting

15

adjusting

16

gear

17

gear

18

Pressure piece

19

Pressure piece

20

release device

21

release device

22

ramp profile

23

ramp profile

24

support disk

25

recess

26

ring

27

clamping bodies

28

pinch roller

29

friction spring

30

spigot

31

recesses

32

lever

33

intermediate element

34

approach

35

brake lining

36

feather

37

approach

38

attack

39

attack

40

approach

41

brake disc

Claims (21)

1. Disc brake, especially for commercial vehicles, with

• a) a brake caliper ( 1 ) spanning a brake disc,
• b) an application device arranged in the brake caliper for applying brake pads;
• c) and at least one adjusting system arranged in the brake caliper, preferably designed as an adjusting module ( 2 ), to compensate for brake lining and / or disc wear by adjusting the distance between the brake lining ( 7 ) and brake disc ( 3 ),
• d) the adjusting system having at least one adjusting rotating device ( 10 , 11 ) on which an electromotive drive ( 5 ) acts,

characterized in that

• a) the adjustment system in addition to the electromotive drive ( 15 ) has at least one release device that supports the release of the adjustment rotary device ( 10 , 11 ).

2. Disc brake according to claim 1, characterized in that the adjuster-rotating device ( 10 , 11 ) has an adjusting nut ( 14 , 15 ) in which a rotating spindle ( 12 , 13 ) is screwed, which at one of its ends on Brake pad acting pressure piece ( 18 , 19 ), the Löseein direction ( 20 , 21 ) acts on the adjusting nut ( 14 , 15 ) or the rotating spindle ( 12 , 13 ). 3. Disc brake according to claim 1, characterized in that the adjuster ler-rotating device ( 10 , 11 ) has a rotary spindle ( 12 ) onto which an adjusting nut ( 14 ) is screwed, which at one of its ends has a pressure piece acting on the brake pad ( 18 ), the release device ( 20 , 21 ) acting on the adjusting nut or the rotating spindle. 4. Disc brake according to claim 2 or 3, characterized in that as a release device, the pressure support surface of the adjusting nut ( 14 , 15 ) is provided with a ramp profile ( 22 , 23 ), with a ramp disc ( 24 ) with an opposite ramp profile ( 22 , 23 ) and a flat back of the support disc ( 24 ) rests on a support surface on a support element ( 1 ). 5. Disc brake according to one of the preceding claims, characterized in that the ramp profile is molded directly into the end face of the adjusting nut ( 15 ) or the rotating spindle ( 12 ), in particular is stamped. 6. Disc brake according to one of the preceding claims, characterized in that the support element of the brake caliper ( 1 ) or an element of the application unit. 7. Disc brake according to one of the preceding claims, characterized in that the ramp profile is molded directly into the brake caliper ( 1 ) or the element of the application unit. 8. Disc brake according to one of the preceding claims, characterized in that the ramp disc ( 24 ) on the end face of the adjusting nut ( 14 ) or the rotating spindle ( 12 ) rests non-rotatably. 9. Disc brake according to one of the preceding claims, characterized in that the anti-rotation of the ramp disc ( 24 ) against the support surface on the brake caliper is designed such that it is greater than the anti-rotation between the adjusting nut ( 15 ) or the rotating spindle in each operating state and the ramp disc ( 24 ). 10. Disc brake according to one of the preceding claims, characterized in that the ramp disc ( 24 ) is provided with a friction-increasing coating on the support surface of the ramp disc ( 24 ) and / or a friction-reducing coating on the side of the ramp profile. 11. Disc brake according to one of the preceding claims, characterized records that the friction-increasing coating is a diamond dust coating is. 12. Disc brake according to one of the preceding claims, characterized records that the friction-reducing coating is a sliding varnish coating is. 13. Disc brake according to one of the preceding claims, characterized in that acts against the ramp disc ( 24 ) acts on the anti-rotation brake element, in particular a sliding spring element in the manner of a tolerance ring or a friction spring ( 29 ). 14. Disc brake according to one of the preceding claims, characterized records that the release device as a clamping roller or clamping body Freewheel is designed. 15. Disc brake according to one of the preceding claims, characterized in that recesses ( 26 ) are inserted on the end face of the adjusting nut and / or in a set ring, which take up clamping bodies ( 27 ) or clamping rollers ( 28 ). 16. Disc brake according to one of the preceding claims, characterized in that the recesses ( 26 ) have a ramp shape. 17. Disc brake according to one of the preceding claims, characterized in that the recesses ( 26 ) are formed parallel to the support surface to form a sprag system. 18. Disc brake according to one of the preceding claims, characterized records that the ramp angle in the sliding ramp system is designed such that self-locking freedom is achieved. 19. Disc brake according to one of the preceding claims, characterized in that the release device ( 20 , 21 ) is designed electromechanically. 20. Disc brake according to one of the preceding claims, characterized in that the release device ( 20 , 21 ) is designed as a piezo system, where piezo bodies are presented, which change their geometry when energized so that the release movement of the adjustment mechanism supports becomes. 21. A method for controlling the adjustment system of a disc brake, in particular a disc brake according to one of the preceding claims, characterized in that
First of all, to adjust the clearance, the re-turning spindle is reset to ensure the minimum clearance,
whereupon a renewed activation takes place in the sense of an infeed movement of the adjusting rotating spindles,
whereby the infeed movement of the air gap safety device is triggered and then after a sufficiently long waiting time, which is so laid out that the brake shoes or pads can be applied to the brake disks - or after a determination of the stopping time of the motor by sensing the end of the rotary movement of the motor (stop detection) or with an overcurrent sensor - the drive initiates a reversing release pulse for the clearance clearance in order to secure the desired clearance, and
wherein the brake is released with an electromechanical drive ( 5 ) under the action of an additional release device ( 20 , 21 ).