WO2012010544A1

WO2012010544A1 - Device comprising a resilient detent element for locking a cover to a drainage channel

Info

Publication number: WO2012010544A1
Application number: PCT/EP2011/062217
Authority: WO
Inventors: Arne Meincke
Original assignee: Aco Serverin Ahlmann Gmbh & Co. Kg
Priority date: 2010-07-20
Filing date: 2011-07-18
Publication date: 2012-01-26
Also published as: EP2596181A1; DE102010036509A1

Abstract

The invention relates to a device for locking a cover (2) to a drainage channel or similar drainage element (4), comprising a detent element (6) which can be fastened to the cover (2) and which, as the cover (2) is placed onto the drainage element (4) in an engagement direction R_E, can be engaged in a releasable locking engagement with a complementary detent counter-element (8) on the drainage element (4), or vice versa. The detent element (6) is formed as a resilient hollow profile element (10) and is disposed such that it deforms as it is engaged with the detent counter-element (8) or is disengaged from the detent counter-element (8), and the necessary engagement force F_E in the engagement direction R_E is less than the necessary disengagement force F_A in the disengagement direction R_A.

Description

DEVICE WITH AN ELASTIC LOCKING ELEMENT FOR LOCKING A COVER ON A DRAIN TRAY

description

The invention relates to a device for locking a cover on a drainage channel or the like dewatering element with a latching element fastened to the cover, which in a latching direction with a complementary when placing the cover on the dewatering element

trained locking counter-element on the drainage element in a detachable

Locking engagement is latched or vice versa.

Under the reverse is understood here that the locking element can of course also be arranged on the drainage element and the locking counter-element on the cover.

In addition, the device for locking a cover on a drainage channel is understood to mean any type which is the locking of a cover on, in, in or in the region of a drainage channel or the like

Drainage element, so also of manhole covers, inspection shafts, etc. allowed. Of course, such a device can also serve for latching other operatively connected to each other standing elements. For example, a cover on a box or similar element.

From the prior art are a plurality of devices for locking a cover on a drainage channel or the like

Dewatering element known, ie devices in which the cover on the drainage element by means of fastening elements can be fastened.

Thus, a plurality of different systems is known in which the cover is screwed by means of screw on the frame. Although such a fixation guarantees a reliable definition, but requires for fixing and for releasing the cover naturally suitable tools. In addition, the Attachment and the release process usually very tedious and often problematic especially in strong weather conditions, since the known

Rust locking elements or weathering the like.

From DE 295 02 117 a device is known in which a cover can be fixed on a drainage channel via a quick-release system. For this purpose, a resilient latching element is arranged on the cover, which engages when inserting the cover in a frame of the drainage channel in a complementary to the resilient element formed counter element and thus locks the grate. Here, however, it has been found that with a reliable locking of the cover on the drainage channel a very high latching force is necessary, ie, such a force that must be expended when locking the cover on the drainage channel.

From DE 195 04 869 Cl a drainage channel is known, on which also a cover grate can be fixed. The locking of the cover grating is achieved by means of a leaf-shaped covering grate-locking spring, which has oppositely formed projections which engage in recesses of the side walls of the channel body. After engagement or engagement of the projections, the cover grate locking spring assumes a substantially stress-free position in the interior of the channel body. By attached to the cover grate

Arretierungsbügel with angled legs is the insertion of the cover in the gutter body overcoming the spring force locking the

Cover grille achieved by wedging the locking bracket against the Abdeckrost- locking spring.

This known drainage device requires at a high

Locking effect also a high latching force, so that the locking of the cover on the drainage channel is problematic.

In contrast to the previously described spring steel-based

Locking devices, DE 195 11 788 shows a device for locking a cover on a drainage channel, in which an elastically formed elongated Kunstoffriegel so on the cover and that across the

Main extension axis of the drainage channel is arranged to snap under action by means of locking elements and in particular locking lugs in

Undercuts on the side walls of the gutter body can be latched. Thus is the cover can be secured by pressing the grate on the gutter body via the transom bar. Since the with the locking elements in the

Undercuts latched latch is elastically deformed, this exerts due to its elastic deformation of a permanent bias on the rust.

As a disadvantage, however, has been found here that due to the transverse

extending grate, the clear cross-section of the drainage channel is limited, which have accumulated blockages of the channel cross-section. In addition, it can also be observed here that at high locking forces required also high latching forces are to be overcome, which makes the fixing of the cover on the channel body problematic.

The object of the present invention is therefore to provide a device for locking a cover on a drainage channel or a similar drainage element, which guarantees a reliable and permanent locking.

This object is achieved by a device for locking a cover according to claim 1.

In particular, this object is achieved by a device for locking a cover on a drainage channel or the like dewatering element, with a fastened to the cover locking element, which when placing the cover on the dewatering element in a latching direction R _E with a complementary formed counter-locking element on the drainage element in a detachable locking engagement can be latched, or vice versa, wherein the locking element is designed and arranged in such an elastic hollow profile element that it is when snapped into the locking counter-element or when disengaged from the

Detent locking element deformed, wherein the latching force F _E necessary in the latching direction R _{E is} less than the latching force F _A necessary in the release direction R _A.

Under latching force is understood in the scope of the invention, the force that is necessary to lock the locking element in the locking counter-element. Thus, if the cover is fastened to the drainage channel via a latching element which engages with a latching counter element, then the latching force corresponds to the force which is necessary to bring the latching element into locking engagement with the latching counter element. An essential point is that in the locking counter element in the

Drainage channel or a similar element latching latching element is designed as an elastic hollow profile element which deforms during engagement and disengagement, wherein the hollow profile element is formed so that the latching force required in the latching direction is less than the necessary in the release direction Ausrastkraft. During the latching process and the Ausrastvorganges the hollow profile element comes into contact with corresponding stop surfaces on the drainage element, so that it deforms motion-dependent. This deformation property allows the formation such that the latching forces are less than that

Ausrastkräfte, resulting in a locking system, despite the very easy insertion and Verriegeins the cover high locking or

Locking forces guaranteed.

In contrast to the devices known from the prior art, therefore, the locking element, which is in direct locking engagement with the locking counter-element, deformed and not possible bearing elements, or elements that carry the actual locking element.

Preferably, the locking element and in particular the elastic hollow profile element is made of an elastic material, which required

Deformation properties allowed. Preferably, therefore, find here elastic

Plastic materials their application. However, it is also possible to appropriate

Metal materials and in particular spring metal materials to use.

Preferably, the hollow profile element is fastened or attachable to the cover by means of a bearing body which is rigid relative to the hollow profile. This

Bearing body thus guarantees the substantially rigid support of the elastic hollow profile element, so that it comes mainly to a deformation of the hollow profile element and not to a deformation of the hollow profile element bearing bearing body during latching or Ausrastvorgang.

Preferably, the bearing body is substantially rigidly attached to the cover or fastened. Such a rigid arrangement can for example be such that the bearing body in a rigid mounting on the

Attached bottom side of the cover and orthogonal protruding from this. Also orthogonal and thus substantially parallel to the plane of extension of

Cover can then extend the elastic hollow profile element, which then again in complementary trained locking counterparts on

Drainage element can be latched or formed ausrastbar from these. Due to the rigid arrangement of the bearing body on the cover, it is possible to form the locking element or the elastic Hohprofilelement so that it performs the required latching and Ausrastverformungen to guarantee the low latching force compared to the Ausrastkraft. By "substantially rigid" is meant an embodiment which, within the tolerable

Deformations of the elastic hollow profile element and the bearing body rigid properties correspond. If, therefore, the hollow profile element is very easily deformable, lower requirements are placed on the "bending stiffness" of the hollow profile than on a hollow profile element which is deformable by higher forces just so stiff that its deformations compared to the deformations on the hollow profile element

are negligible.

Preferably, the hollow profile element has at least a first and a second hollow profile wall, which are arranged and formed such that the

Snap-in force in the first hollow profile wall and the disengaging force in the second hollow profile wall effect a pressure normal force. In this respect, so are the

Hollow profile elements in the respective load directions, ie the direction of the latching force and the direction of the disengaging force, designed as a pressure rods, which are loaded by a component of the respective acting force. When a certain bending force is exceeded, the respective one buckles

Hollow profile elements and so to a deformation that allows the engagement or disengagement. In addition to a buckling deformation, however, is also a

Bending deformation possible, namely, when the forces acting in the hollow profile elements are not completely ideal follow the extension axis of the hollow profile elements. So causes the latching or the Ausrastkraft a component which extends at an angle to the normal force axis of the hollow profile elements, it comes not only to a pure buckling, but also to a bending of the hollow profile elements.

Preferably, the latching element and in particular the hollow profile element has a latching lug and the latching counter element has a latching nose receptacle such that during the latching process the latching latch snaps into the latching latch receptacle, the two hollow profile walls enclosing or forming the latching latch. The hollow profile walls are so arranged, for example, that they each with a free end against the other free end of the other Hohlprofilwandung push and form the locking lug at this connection point. The latching lug is therefore enclosed or formed "geometrically" by the two hollow profile walls During the latching or latching procedure, the hollow profile elements are deformed in the region of this latching lug and, due to the inventive arrangement of the hollow profile elements, a lesser latching force than the latching lug

Disengaging force.

Preferably, the first hollow profile wall is arranged and

designed so that it is loaded during latching with a pressure normal force and the disengagement with a tensile normal force.

The same is preferably true for the second hollow profile wall, which is arranged and designed such that it is loaded during the latching process with a tensile normal force and the disengagement with a pressure normal force.

Such an embodiment allows, for example, the formation of the hollow profile element such that during the latching process the first hollow profile wall loaded with the pressure normal force buckles, while during the latching process the second hollow profile wall then loaded with the pressure normal force buckles and so on

Hollow profile element is deformed so that it engages in the locking counter-element from this or disengages. In such an embodiment, therefore, the variation between the latching force and the latching force on the corresponding with respect to the respective buckling load specified embodiments of the respective takes place

Hohlprofilwandung.

Preferably, the first hollow profile wall with respect to the Ausreastrichtung on a larger starting angle than the second Hohlprofilwandung with respect to the latching direction. This starting angle defines the angle between the respective hollow profile wall and a stop element on which the respective

Hollow along the profile wall, while the locking element or the

Hollow profile element is engaged or disengaged. The inventive

Arrangement of the starting angle such that the first hollow profile wall with respect to the Ausreastrichtung has a larger starting angle than the second

Hollow profile wall with respect to the latching direction, causes the second hollow profile wall is deformed less than the first when snapping and the first is less deformed during disengagement than the second Hohlprofilwandung when locking. Preferably, the first hollow profile wall has a lower buckling load than the second hollow profile wall. This means that at a pressure normal force of the first Hohlprofilwandung much faster deformation occurs, as is the case with the second Hohlprofilwandung. In this way it is possible the

Deformation of the hollow profile element as a function of the prevailing forces and in particular as a function of the latching force or the disengaging force to control. In such an embodiment, then, then, the first and the second

Hohlprofilwandung arranged so that during snap action a pressure normal force mainly on the first Hohlprofilwandung and the Ausrastvorgang a pressure normal force acts predominantly on the second Hohlprofilwandung. In the case of a reverse force game, it goes without saying that the dimensioning of the respective hollow profile wall with respect to its buckling load can also be reversed.

Preferably, the first hollow profile wall has a thinner cross-section than the second hollow profile wall. This embodiment also guarantees that the first hollow profile wall bends faster when exposed to a pressure normal force, as is the case with the second hollow profile wall. In addition, however, it also comes with bending loads of the respective Hohlprofilwandung in the thinner first

Hohlprofilwandung much faster to deformations, as is the case with the second Hohlprofilwandung.

Preferably, the first hollow profile wall and / or the second

Hollow profile wall with at least one deformation element in operative connection, which is designed such that it deforms upon the action of the latching and / or Ausrastkraft. Such a deformation element can therefore be, for example, an element adapted with respect to its cross-section, its material or its geometry, which, upon the action of a force and in particular on the

Hohlprofilwandungen initiated force deformed. Thus, if, for example, in the case of two hollow profile walls of the same design, one hollow profile wall is provided with such a deformation element, it is possible to initiate a deformation by means of a specific force on this hollow profile wall, which does not lead to deformation in the other hollow profile wall.

Preferably, at least one deformation element as

Rotationsverformungselement formed such that the first and / or second Hohlprofilwandung at a load by the latching and / or Ausrastkraft or a corresponding component deformed and / or moved in a rotational deflection movement. Such a deformation element can therefore be arranged such that a latching force acting on the latching element leads to a rotation of the respective hollow profile wall. Such a rotational movement can of course in

Combination with a kinking movement of the same or the other

Hohlprofilwandung done.

Preferably, the deformation element is between the substantially

rigid bearing element and the first or the second hollow profile wall arranged.

Further embodiments of the invention will become apparent from the dependent claims.

In the following the invention will be described with reference to an embodiment which is explained in more detail by the accompanying drawings.

Hereby show:

Fig. 1 shows a cross section through a first embodiment of a

Drainage device with an embodiment of the locking device according to the invention;

Fig. FIG. 2 shows a detailed view of the locking device according to FIG. 1; FIG.

Fig. 3 and 4, the locking device according to the invention for locking a

Cover according to Figure 1 during a latching operation.

Fig. 5 the locking device according to the invention for locking a

Cover according to Figure 1 in the locking engagement. and

Fig. 6 and 7, the locking device according to the invention for locking a

Cover according to FIG. 1 during a Ausrastvorganges.

The following are the same for the same and the same components

Reference numerals are used, with the distinction sometimes high indices find their application. Fig. 1 shows a cross section through an embodiment of a

Dehydrator. This drainage device comprises a

Dewatering element 4 and here in particular a drainage channel on which a cover 2 is releasably locked. This locking takes place by means of a plurality of devices 1 for locking a cover 2 according to the type described above.

The illustrated and used here embodiment of the locking device for locking the cover 2 each comprises a locking element 6, which in

Arretierungszustand shown in FIG. 1 with a complementary design

Lock counter element 8 on the drainage element 4 in a detachable

Locking intervention stands. To cover the drainage channel 4 with the

Cover 2, according to the invention, the cover 2 has to be lowered in the latching direction R _E onto the drainage channel 4 and loaded by a latching force F _E. As described in detail below, deforms due to this

Latching movement of each locking element 6 of the devices 1 such that it

Cover 2 locks firmly on the drainage channel 4 locking into the locking counter-elements 8.

According to the invention each locking element 6 is formed such as an elastic hollow profile element 10, that it is during the Einrastvorganges, thus the movement in the locking direction R _E caused by an engaging force F _E, and Ausrastvorganges, thus the movement in Ausrastrichtung R _A caused by a disengaging force F _A deformed, said elastic hollow profile member 10 is formed so that the necessary locking direction in engaging force F _e R _e is lower than that necessary in Ausrastrichtung R _A disengaging force F _A.

In Fig. 1 and 2, designed as a hollow profile element 10 locking element 6, which is here in the locking position with the locking counter-element 8 on the drainage element 4 in locking engagement shown. The hollow profile element 10 is arranged in this embodiment on a substantially rigid bearing body 12, which in turn is rigidly secured to the underside 3 of the cover 2. The arrangement of the locking element 6 and the hollow profile element 10 on the rigid and rigidly mounted bearing body 12 causes the engagement and

Disengaging of the hollow profile element 10 in or out of the locking counter-element 8, only the hollow profile element 10 and not the bearing body 12 or accordingly

assigned components are deformed. This in turn has the advantage of being too Expected deformations are very accurately predictable and the device 1 can be designed so that the latching force necessary for latching F _{E is} less than the necessary for disengagement Ausrastkraft F _A (see Fig. 1).

As also shown in FIG. 2, the hollow profile element 10 consists of a first hollow profile wall 14 and a second hollow profile wall 15, which together enclose a latching lug 16 which is formed in the latching lug receptacle 18

Detent locking element 8 formed snap-in or, as shown in FIGS. 1 and 2, snapped.

3 and 4 show the embodiment of the device 1 according to FIGS. 1 and 2 now in detail and in particular during the movement in the direction R _E , so the latching operation.

It can be seen that the, the hollow profile element 10 forming the first and second hollow profile walls 14 and 15 are formed differently both in their geometric arrangement in space, as well as in their cross-sectional dimensions.

Thus, the first hollow profile wall 14 in its cross section is much thinner than the second hollow profile wall 15 (dl <d2). In addition, the length LI is smaller than the length L2 of the second hollow profile wall 15. Finally, the starting angle αι or a ₂ , ie the angle that the respective hollow profile wall 14 and 15 during the movement in the latching direction R _E or Ausreastrichtung R _A with the respective starting element 5 or 7 includes, different, wherein the starting angle a ₂ between the starting element 5 and the second hollow profile wall 15, relevant to a movement in the locking direction R _E , is smaller than the starting angle αι between the starting element 7 and the first Hohlprofilwandung 14, relevant to a movement in the release direction R _A.

All these particular embodiments contribute isolated and of course in the sum increasingly to the fact that the insertion of the cover 2 in the

Rastarretierung, so a movement in the latching direction R _E necessary latching force F _{E is} less than the force F _A , which is necessary for removing and disengaging the cover 2 from the locking position shown in Fig. 1.

The fact that the latching movement R _E shown in FIGS. 3 and 4 requires only a relatively small latching force F _E is due, among other things, to the relatively small latching force F _E Starting angle α ₂ between the starting element 5 of the drainage channel 4 and the second hollow profile wall 15th

In conjunction with the relatively large length L2 of the second hollow profile wall 15 and the relatively low buckling load of the first hollow profile wall 14 or its very small cross section d1, buckling of the first hollow profile wall 14 occurs during the latching movement in the direction R _E (see FIG ) followed by a rotation of the second hollow profile wall 15 about a Einrastdrehpunkt DE _e . During the latching operation, the first Hohlprofilwandung 14 by one of the

Locking force F _E resulting pressure normal force F _{N +} in the direction of the stiff

Bearing body 12 displaced or buckled. Due to the bending movement of the first hollow profile wall 14, the second hollow profile wall 15 deforms at the same time with a very low resistance and allows the inference of the two

Hollow profile walls 14, 15 trapped or formed locking lug 16 in the latching counter 8 formed as a latching nose receptacle 18 to.

It is essential that the bearing body 12 partially shown here, on which the hollow profile element 10 is arranged with its hollow profile walls 14, 15, not at all or only insignificantly deformed during this latching movement R _E , wherein the latching deformations mainly in the first and second

Hohlprofilwandungen 14, 15 and, as described below, takes place in a deformation element 20 which is associated with the second hollow profile wall 15.

In Fig. 5 the following is shown: After the engagement of the locking element 6 in the locking counter-element 8 on the drainage element 4 is the cover 2 (see Fig. 1) in Arretierungszustand, wherein in this embodiment, the deformed first and second Hohlprofilwandungen 14 and 15 in Essentially move back to their starting position. Of course, it is also possible, the device 1 and in particular the Rastelelement 6 in such a way that it exerts a continuous locking force on the cover 2 and this so

For example, keeps permanently in the locked position under tension.

6 and 7 show the following: If the cover 2 (see Fig. 1) again removed from the locking position shown in FIG. 5, a counter to the latching force F _E acting Ausrastkraft F _{A is} applied, so that the cover 2 and move the device 1 and the locking element 6 in the release direction R _A. The now acting in the locking element 6 force flow is substantially inversely to the latching process shown in FIGS. 1 and 2.

While the first hollow profile wall 14 was loaded with a pressure normal force F _{N +} during latching process (see Fig. 4), it is now loaded with a tensile normal force and the second Hohlprofilwandung 15 instead of a tensile force normal force now with a pressure normal force F _{N +} . Due to the different geometric arrangements and in particular the different cross sections of the two

Hohlprofilwandungen 14, 15 but now results in a much higher Ausrastkraft F _A , so the force that is necessary to deform the hollow profile member 10 so that its latch 16 disengages from the locking counter-element 8.

Due to the geometric configuration of the second hollow profile wall 15, the Ausrastdrehpunkt shifts, the now acting as a tension strut first

Hohlprofilwandung 14 prevents buckling of the relatively long, but in cross section strong second hollow profile wall 15. Thus, the second hollow profile wall 15 is loaded with a pressure normal force F _{N +} , but due to the large

Cross-sectional dimensions and so only leads to a downward movement of the second hollow profile wall 15 in the direction of R _s due to the high to be supported buckling load. This movement in the direction of R _s is in this embodiment by the

Deformation element 20 allows, which is in operative connection with the second hollow profile wall 15 and deformed under the pressure acting on the second Hohlprofilwandung 15 normal pressure force F _{N +} or by acting on the cover 2 Ausrastkraft F _A , that it causes a movement of the second

Hohlprofilwandung 15 u.a. and as a result, deformation of the

Hollow profile element 10 leads, which allows the Ausrastvorgang.

By the operative connection of the second hollow profile wall 15 with the

Deformation element 20 moves through the action of the disengaging force F _A, the second hollow profile wall 15 on a circular path about the pivot point D _A i.

As shown in particular in Fig. 7, the result of this

Due to these displacements now describes the locking lug 16, held by the first Hohlprofilwandung 14, a circular path around the pivot point D _A2 , whereby with progressive movement in the unlocking direction R _A, the locking element 6 and Locking lug 16 pulled out of the locking counter-element 8 and the latching nose receptacle 18 and the locking engagement is released.

LIST OF REFERENCES

1 device

2 cover

3 bottom

4 drainage element or

drainage channel

5 starting element

6 locking element

7 starting element

8 locking counter element

10 hollow profile element

12 bearing body

14 first hollow profile wall

15 second hollow profile wall

16 latch

18 snap-in nose

20 deformation element

dl start angle

a2 start angle

D _E locking point

D _A i Ausrastdrehpunkt

D _A2 Ausrastdrehpunkt

R _E locking direction

R _A clearance direction

R _s downward movement direction

F _E latching force

F _A disengaging force

F _{N +} pressure normal force

S relative movement

Claims

claims

1. Device for locking a cover (2) on a drainage channel or the like drainage element (4), with

a fastened to the cover (2) locking element (6), the

Place the cover (2) on the drainage element (4) in one

Locking direction R _E with a complementary formed counter-locking element

(8) on the drainage element (4) can be latched in a releasable locking engagement, or vice versa,

d a d u rc h e n c i n e s that

the latching element (6) is designed and arranged as an elastic hollow profile element (10) in such a way that it engages in the latch when latched

Counter detent element (8) or in disengagement from the counter detent element (8) is deformed, whereby the necessary locking direction in engaging force F _E R _E is lower than that necessary in Ausrastrichtung R _A disengaging force F _A.

2. Apparatus according to claim 1,

d a d u rc h e n c i n e s that

the hollow profile element (10) is fastened or attachable to the cover (4) by means of a bearing body (12) that is rigid in relation to the hollow profile element (10).

3. Device according to one of the preceding claims, in particular according to claim 2,

d a d u rc h e n c i n e s that

the bearing body (12) is substantially rigidly attached to the cover (2) or fastened.

4. Device according to one of the preceding claims,

d a d u rc h e n c i n e s that

the hollow profile element (10) at least a first and a second

Hollow profile wall (14; 15), which are arranged and formed such that the latching force F _E in the first hollow profile wall (14) and the disengaging force F _A in the second hollow profile wall (15) cause a pressure normal force (F _{N +} ).

5. Device according to one of the preceding claims, dadu rc hge ke nnzeichnet that

the locking element (6) and in particular the hollow profile element (10) a

Locking lug (16) and the locking counter-element (8) have a latching nose receptacle (18) such that during latching the latching lug (16) snaps into the latching nose receptacle (18), wherein the two Hohlprofilwandungen (14; 15) include the latching lug (16) or form.

6. Device according to one of the preceding claims, in particular one of claims 4 or 5,

d a d u rc h e n c i n e s that

the first hollow profile wall (14) has a larger start-up angle α with respect to the release direction R _A than the second hollow profile wall (15) with respect to the latching direction R _E.

7. Device according to one of the preceding claims, in particular one of claims 4 to 6,

d a d u rc h e n c i n e s that

the first hollow profile wall (14) is designed and arranged such that it has a lower buckling load than the second hollow profile wall (15).

8. Device according to one of the preceding claims, in particular one of claims 4 to 7,

d a d u rc h e n c i n e s that

the first hollow profile wall (14) has a thinner cross section than the second hollow profile wall (15).

9. Device according to one of the preceding claims, in particular one of claims 4 to 8,

d a d u rc h e n c i n e s that

the first hollow profile wall (14) and / or the second hollow profile wall (15) are in operative connection with at least one deformation element (20), which is designed such that it acts upon the engagement and / or disengagement force (F _E ; F _A ) deformed.

10. Device according to one of the preceding claims, in particular according to claim 9,

dadu rc hge ke nnzeichnet that at least one deformation element (20) is designed as a rotational deformation element (22) such that the first and / or the second

Hollow profile wall (14; 15) deformed and / or moved in a rotation by the latching and / or disengaging force (F _E ; F _A ) in a rotational deflection movement.