FR2779269A1 - Coupling device for two attached modular electrical elements - Google Patents

Abstract

The two modular units (D,P) have mechanical and electrical inter coupling sections. One of the units has extending spigots (10) which couple into the side wall of the second unit and mechanically connect the units, whilst a sliding arm unit (5) couples the wiring connections (7) to the second modular unit.

Description

Device for coupling two adjoining modular electric elements La

  present invention relates to an electrical block composed of two modular type elements joined according to one of their lateral facades and comprising fixing means keeping them in contact

  each other in this configuration.

  Although the invention is potentially applicable to all elements

  modules for which coupling is necessary, the description which

  follows will be made for clarification purposes with reference to a preferred example, in which one of the elements is a differential block, the

second being a circuit breaker.

  These elements, mounted in series in the electrical cabinets, must necessarily be in contact with each other, because the electrical connection is coupled with a mechanical coupling ensuring tripping of the circuit breaker when the differential unit detects a leak in the network that he controls. The standard configuration of these elements is however such that the axis of rotation of the mechanical lock is perpendicular to the direction of electrical connection in the terminals provided for this purpose in the differential unit and in the circuit breaker. For these mechanical and electrical connections to work, there is of course interpenetration of organs from one (centering pins, lever from the lock, conductors

rigid) in the volume of the other.

  This interpenetration is done on two perpendicular axes without said members fixed to one of the elements and penetrating into the volume of the other is generally provided with a degree of freedom allowing the junction to be carried out first on an axis, then on the other. The electrician in charge of the assembly uses, to attach the two elements, the clearances at his disposal, such as the lateral clearances which remain after the insertion of the rigid conductors in the connection terminals. However, it sometimes requires complicated manipulations, going as far as bending or twisting the conductors, to arrive at the coupling along the two non-collinear axes, before proceeding to

  the installation of the block thus formed on a rail fitted to the electrical cabinet.

  One solution to this problem consists in allowing the mobility of the conductors connected to the differential unit, which is in all cases possible when they are flexible. The drawbacks relating to the use of flexible conductors are however numerous enough (connection one by one, risk of errors ...) so that most of the manufacturers of electrical equipment have chosen the solution of

rigid conductors.

  A solution allowing said mobility of the conductors is also described in European patent EP-A-0 806 784 by FELTEN and GUILLEAUME, using partly rigid conductors associated with a sliding element in the body of the differential unit. The disclosed configuration, however, has the major drawback of not operating correctly as soon as the electric power increases, since the movement of the sliding member is mechanically dependent on the components of the differential unit. Thus, this member comprises rigid welded conductors

  to flexible conductors inside said block, the latter extending -

  especially through the detection toroid - over the distance that is in

  principle supposed to run through said organ when it is actuated in translation.

  The movement of the sliding member is normally intended to separate the ends of the rigid conductors from the volume potentially occupied by the circuit breaker to be attached, so that they do not obstruct the movement aimed at bringing the two elements into contact. from each other, movement which develops in a direction perpendicular to the direction of connection of said ends in their

terminals.

  It is therefore necessary to be able to satisfactorily extract said sliding member from its housing, in this case the body of the differential unit. However, with the above configuration, the flexible wires exert an action tending to oppose the extraction of the sliding member, due to their own elasticity, which tends to recall them in the extended position, parallel to the sliding stroke. , while the exit of said organ tends to

fold in on themselves.

  When the nominal power increases, and consequently the nominal intensity, the cross section of the flexible wires increases corollarily and it becomes increasingly difficult to manipulate the sliding member. The sliding function is therefore no longer performed satisfactorily, in fact because of the interdependence of the electrical and mechanical functions which

results from this conception.

  The present invention overcomes these limitations, and further provides a complete solution to the problem of double coupling along two non-collinear axes. The recommended solution turns out to be more economically interesting, and it considerably improves reliability, since it eliminates in particular any welding between mobile elements and

fixed elements.

  A major objective of the invention is finally to propose, simultaneously with the sequential realization of said couplings, the mutual fixing of the contiguous elements, which must in any case be carried out by the electrician.

responsible for assembly.

  In general, the invention relates, as has been mentioned, to a compact electrical unit composed of two modular type elements joined together according to one of their lateral facades and comprising fixing means keeping them in contact with one another. on the other in this configuration which allows a double cooperation: - mechanical via a mechanical coupling acting through and in a direction perpendicular to the plane of said lateral facades, and - electrical via an interconnection implemented in a direction perpendicular to that mechanical coupling, and it is characterized in that one of the elements comprises a sliding member in one of said directions, ensuring simultaneously, as a function of the direction of sliding, the implementation of the means for fixing the elements together and: - either the electrical connection when the mechanical coupling is carried out; - either mechanical coupling when the electrical connection is made; the electrical power and control members of the element comprising the sliding member, including the connection terminals and all of the conductors, being dissociated from the members performing the mechanical coupling by the sliding member, and driven by a movement relative

  when the latter is in motion.

  The second of the sequential couplings along the two axes therefore causes in all cases the implementation of means for fixing the

elements.

  More precisely, according to a possible main variant, the sliding member is a drawer movable in one of the elements, to which the conductors intended to be inserted into terminals of the other element are joined, said drawer actuating when it reaches the near the position in the internal stop, said conductors then being housed in the

  terminals of the other element, means of attachment to the latter.

  Preferably, these fixing means consist of at least one hook belonging to the element housing the sliding drawer, which can pivot outwards in the vicinity of the edge of its lateral facade located opposite the orifice d insertion of said drawer, so as to penetrate into at least one recess provided for this purpose in the second element, as well as into at least one centering tab integral with the drawer and able to penetrate in the vicinity of said insertion hole of the drawer in at least one corresponding housing of the other element, the directions of insertion of the hook and

the tab being opposite.

  In the case of the hook (s), the translational sliding movement of the drawer is then transformed into a rotary movement of a

  part integral with the element housing the drawer.

  The existence of two coupling axes, imposing two sequential movements, has as a corollary the existence of two possible variants, depending on the sequence of the sequence. In the previous hypothesis, the electrical coupling is carried out last, hence the need for a drawer

  sliding along the axis of this coupling.

  However, it is possible to make the opposite choice, that is to say to make the electrical connection first, the mechanical coupling then being implemented. In this case, the sliding part must be able to

  be moved along the axis of the mechanical coupling.

  Consequently, according to a second variant of the invention, the sliding member is movable in a direction parallel to that of the mechanical coupling and consists of a part of the cover of one of the two adjoining elements, to which the parts carrying out the mechanical coupling which can be moved between two extreme positions, a position in which they do not cross the plane of the lateral abutment side of the element on which the sliding part of the cover moves, and a position in which they can exercise their mechanical coupling. As in the previous variant, said sliding portion of the cover can actuate, when it arrives in the vicinity of the exercise position of the

  mechanical coupling, means of attachment to the other element.

  In both hypotheses, the fixing between the two joined elements is preferably done in an antagonistic manner on two opposite faces of the block, by insertion of male elements in housings in which they

  are adjusted, hence a blocking along the three axes.

  As mentioned before, preferably, the first element

  is a differential block, the second element being a circuit breaker.

  In this case and according to one of the variants, the sliding member equips the differential unit and is composed of a drawer in which are mounted the connection terminals, the detection toroid and the control and power conductors, as well as a lateral wing developing parallel to the sides provided with connection terminals for the differential unit and the circuit breaker attached to it, said wing comprising the connecting conductors of the two elements, the ends of which extend parallel to the sliding axis of the drawer. This drawer is movable between two extreme positions, a closed position in which the ends of the conductors protruding from the aforementioned wing are housed in the connection terminals of the circuit breaker, and an open position in which said ends are released.

of said terminals.

  It is simply the implementation of the second coupling

  sequential, electrical connection.

  According to one possibility, the part of the drawer comprising the connection terminals of the differential unit and the lateral wing are covered with a protective cover masking said terminals and giving free access to them for tightening / loosening, and covering the conductors housed in said wing. This cover has a cover located on the drawer, hiding the

  components of the differential unit in the drawer open position.

  These latter technical aspects more specifically cover safety requirements applied to the electrical elements of the differential unit. Regarding the circuit breaker, said cover includes a terminal cover located at the side wing, and intended to protect access

  to the circuit breaker clamping members.

  Preferably, this terminal cover is sliding in a housing of the cover between a storage position and a deployed position, in which the shape of the housing allows it to rotate with an axis parallel to the direction of mechanical coupling, between said deployed position and a

  rest position hiding the connection terminals of the circuit breaker.

  A seal in this position is also possible.

  After implementation of two couplings, when the electrical connection is ready to be tightened, that is to say when the drawer is in abutment inside the differential unit, the means of attachment to the circuit breaker have

principle been operated.

  To do this, the differential unit has a lug connected to a pivoting shaft comprising two hooks, the assembly being arranged at the edge opposite the sliding opening of the drawer on the internal face of the side facade attached to the circuit breaker, said tab cooperating with

  the internal end of the drawer for moving said hooks in rotation.

  Preferably, said tab is integral in rotation with said shaft, and is inserted into a housing disposed at the internal end of the drawer, via an opening whose edges perpendicular to the bottom of the drawer have an alternative action on the tab, aimed at it communicate a rotational movement in both directions. More specifically, this tab is a bent lever whose faces perpendicular to the bottom of the drawer allow said edges of the opening of the housing to perform a relative movement along said faces, transforming the sliding of the drawer into a rotation of the tab and of

The tree supporting the hooks.

  Simultaneously with the implementation of these fixing means on one side of the block, other means are implemented, as already mentioned, on the other side. According to one possibility, the lateral wing protruding from the sliding drawer comprises centralizers developing parallel to the axis of the sliding in the direction of the terminals of the circuit breaker, under which

  are provided housing adapted to receive said centralizers.

  According to the second variant applied to the differential block / circuit breaker pair, the sliding member is a part of the cover of the differential block comprising the lock of said block, the lever for driving the circuit breaker lock, and centering pins acting in the direction of

mechanical coupling.

  The coupling is therefore carried out at several points, which guarantees perfect alignment of the two elements forming the electrical block, alignment of the rest necessary for the mounting of the block on the rail.

  can be done in good conditions.

  In addition, the differential unit may include a polarizing protuberance developing in the direction of mechanical coupling and cooperating with a corresponding orifice of the circuit breaker, said polarizing protuberance also being integral with the part

sliding the hood.

  For security reasons, the standard requires that the two elements forming the described electrical block are finally locked to each other, so that it is no longer possible to separate them without destroying a

  visible area proving the intention to dissociate them.

  Thus, preferably, the element comprising the sliding member is provided with a locking button inhibiting, when it is actuated, the sliding of said member, said button being maneuverable only once in one direction. In the configuration which is the subject of the preferred example, it is the differential unit which comprises a pusher, which slides there perpendicularly to the two directions of the electrical and mechanical couplings, said pusher, accessible from the cover of the differential unit, being extended in the direction of sliding by a rod adapted to fit in a housing provided for this purpose in the sliding drawer, and inhibiting any movement thereof, said pusher then flush with the cover and can no longer be operated there after adjustment of the end of the

rod in said housing.

  Mention has been made of the mounting of the elements on the rails equipping the electrical cabinets, but the invention also makes it possible to considerably improve the dismantling of a single element, if need be, since the travel of the sliding member is sufficient to allow a total

  mechanical independence on an axis.

  The invention goes to-. present be described in more detail, with reference to the figures placed in the appendix, for which: - Figure 1 shows a differential block associated with a four-pole circuit breaker; - Figure 2 illustrates the connection mode used for a sequential mechanical coupling, then electrical; - Figure 3 is an exploded perspective view of the differential unit with the drawer and its cover; - Figure 4 shows the elements of Figure 3 from a different angle; - Figure 5 is a perspective view of the assembled sliding drawer; - Figure 6 shows an enlarged detail of the previous figure, showing the pivoting fixing system of the elements of the electrical block; - Figure 7 shows the elements of Figure 5, with the exception of the side face of the differential unit; - Figure 8 aims to explain the operation of the locking pusher; and - Figure 9 shows in perspective the sequential mounting of the two elements forming the electrical block, as part of the second

sliding cover variant.

  The same reference numbers correspond, from one figure to another, to the same elements. The configuration illustrated in Figure 1 constitutes

  the preferred example used in the context of this description.

  The differential unit (B) is shown coupled to a circuit breaker (D) in this case four-pole. It is however clear that the invention applies to two-pole and three-pole circuit breakers with an implementation

  exactly the same as that which will be explained.

  Without going into details which are not within the scope of the present invention, the differential unit comprises a control lever (1) of a trip lock (not visible) mechanically connected to the locks of the circuit breaker (D), also controllable via the levers (2): this mechanical connection also forms the essential part of the

mechanical coupling.

  The connection terminals of the differential unit (B) are hidden by the cover (3) of the drawer (4), of which only the face situated in the extension of the flat outer face of the lateral wing (5) is visible. The part of the cover (3a) devolved to said wing (5) comprises a cacheborne (6) resting on the upper part of the connection terminals (not visible) of the

circuit breaker (D).

  Figure 2 shows more clearly the sliding drawer (4) and its side wing (5), covered with the cover (3, 3a). The drawer (4) is in the extended position, and the connection terminals (7) of the differential unit (B) are therefore kept at a distance from the body of said unit (B) since they are integral with it, but still accessible via orifices. (8) practiced

  in the upper part of the cover (3).

  The part of the cover (3a) surmounting the lateral wing (5) comprises a device for storing the terminal cover (6), composed of two lateral slides (9a, 9b) of complex shape, rectilinear grooves first allowing a translational movement upwards of said terminal cover, then offset hard points authorizing a rotation of the latter in order to fold it down in the position illustrated in FIG. 1. It is in a way an extension of the

  cover (3) to cover the terminals of the circuit breaker (D).

  This figure 2 also specifies some of the elements of the mechanical coupling: the lock of the trip unit (B), when actuated, moves a tab or lever (10) which in turn causes the tripping of the locks of the four-pole circuit breaker (D) . This tab is housed in an orifice fitted to the side wall of the circuit breaker (D), the shape of which allows movement of the tab (10) when an operating incident occurs. In addition to this tab, the side wall (P) of the differential unit (B) has centering pins (11), only one of which is visible here, and a coding pin (12) making it possible to associate components of compatible gauge. Finally, Figure 2 shows the hooks (13) for fixing pivotally connected to the differential unit (B) and which can be inserted in corresponding orifices of the circuit breaker (D) to carry out the hooking on their side. Figures 3 and 4 give a more precise idea of the four essential components of the circuit breaker block of the invention, namely: - the drawer (4) and its side wing (5) forming an entity - the cover (3, 3a) covering the latter, with a cover (30) to hide the components of the drawer when the latter is open; - a first half-shell (14) of the housing; and

  - the second half-shell (15) of said housing.

  It is in particular- particularly obvious that the cover (3) and its wing (3a) cover parts the contact of which can prove to be dangerous, namely respectively the terminals (7) of the differential unit (B) and the rigid conductors whose ends come out perpendicular to

  slots visible in the two figures.

  The drawer (4) comprises all the power and control part of the electrical circuit, namely mainly said terminals (7), the rigid conductors (25) connecting with the circuit breaker (D) and the toroid (16) which they pass through . There is therefore an almost total independence between the electrical aspect and the mechanical aspect. The control part, the "secondary" wound around the torus, is made up of fine, flexible wires, which do not alter

mechanical function.

  The upper part of the half-shell (15) comprises the lever

  control (1) disposed above the lock (not shown).

  The end of the drawer (4) cooperates with a tab (17) controlling the movement of the pivoting hooks (13). The design of the tab (17) / hook (13) assembly and its mechanical connection to the half-shell (15) appear more clearly in FIGS. 5 and 6, while the elements of the lateral mechanical coupling are better illustrated in FIG. 4, with the centering (11) and coding (12) studs, as well as the tab (10)

secured to the lock.

  In Figure 5, the tab (17) is inserted into a housing (18) of the drawer (4), having an opening (19) limited by two columns (20, 20 '). The latter slide along the faces of the tab (17) when the drawer is animated with a sliding movement, causing said tab (17) which pivots at the same time as the shaft (21) around an axis close to l edge of the differential block. The hooks (13), being themselves integral with said shaft (21), pivot at the same time, and are in the fixing position when the drawer (4)

is in internal stop.

  These same elements appear enlarged in FIG. 6. The same FIG. 5 also shows the centralizers (22) which cooperate with orifices

  (23) located under the circuit breaker terminals (see Figure 2).

  The centralizers (22) and the hooks (13) move in the opposite direction relative to the circuit breaker box (D), ensuring a firm fixing of the

  elements forming the compact electrical block of the invention.

  The respective directions of the ends of the hooks (13) and of the centralizers (22) are clearly visible in FIG. 7: at the stop, they are on parallel axes and perfectly lock the securing of the circuit breaker to the

differential block.

  Near the housing (18) is a second housing (24), more cramped, intended to cooperate with the locking pusher appearing in particular in Figure 8 under the reference (26). This pusher (26) is extended by a rod (27) which can be housed in the housing (24) when the pusher (26) is actuated. In this case, the pusher (26) is flush with the surface of the cover of the differential unit (B) and it is no longer possible to reassemble it without breaking something on the housing of said unit (B). This pusher (26) appears in particular in FIG. 9, prominent relative to the

  cover (28) because it has not been actuated.

  This FIG. 9 illustrates the second variant of the invention, with a sliding member actuated in the direction of the mechanical coupling. This is the cover (28), which is shown offset from the plane of the facade

lateral coupling.

  The coupling steps are then as follows - placement of the circuit breaker according to arrow (A), making the electrical connection; - Installation of the movable cover (28) in the direction of the arrow (C), performing the mechanical coupling, with the introduction of the pins (11) and the lever (10); - locking of the drawer by lowering the pusher (26) in the direction of the arrow (E); and

  - fitting of the terminal cover according to the arrow (F).

  The invention can, in general, also be applied to other elements of modular type, such as timers, remote control switches, etc.

Claims (20)

  1. Compact electrical block composed of two elements (D, P) of modular type joined according to one of their lateral facades, and comprising fixing means keeping them in contact with each other in this configuration which allows a double cooperation: - mechanical via a mechanical coupling acting through and in a direction perpendicular to the plane of said lateral facades, and - electrical via an interconnection implemented in a direction perpendicular to that of the mechanical coupling, characterized in that the one of the elements (P) comprises a sliding member (4, 28) in one of said directions, ensuring simultaneously, as a function of the direction of sliding, the implementation of the means for fixing the elements together and: - either the electrical connection when mechanical coupling is achieved; - either mechanical coupling when the electrical connection is made; the electrical power and control members (7, 25, 16) of the element (P) comprising the sliding member (4, 28), including the connection terminals (7) and all of the conductors (25) , being dissociated from the members (10, 11, 12) carrying out the mechanical coupling by the sliding member (4, 28), and animated by a relative movement when the latter is moving.   2. Compact electrical unit according to the preceding claim, characterized in that the sliding member comprises a drawer (4) movable in one of the elements (P), to which the conductors (25) are fastened intended to be inserted in terminals of the other element (D), said slide (4) actuating when it arrives in the vicinity of the position as an internal stop, said conductors (25) then being housed in the terminals of   the other element (D), means (13) for fixing to the latter.   3. Compact electrical unit according to the preceding claim, characterized in that said fixing means consist of at least one hook (13) belonging to the element (P) housing the sliding drawer (4), which can pivot outwards in the vicinity of the edge of its lateral facade situated opposite the insertion orifice of said drawer (4), so as to enter at least one recess provided for this purpose in the second element (D), thus that at least one centering tab (22) integral with the sliding drawer (4) and able to penetrate in the vicinity of said drawer insertion orifice (4) in at least one housing (23) corresponding to the other element ( D), the directions of insertion of the hook (13) and the tab (22) being opposed.   4. Compact electrical unit according to claim 1, characterized in that the sliding member is movable in a direction parallel to that of the mechanical coupling and consists of a part of the cover (28) of one of the two elements (P) placed side by side, to which are joined the parts (10, 11, 12) carrying out the mechanical coupling which can be moved between two extreme positions, a position in which they do not cross the plane of the lateral facade adjoining the element (P) on which the sliding part of the cover (28) moves, and a position in which they   can exercise their mechanical coupling.   5. Compact electrical unit according to the preceding claim, characterized in that said sliding portion of the cover (28) actuates, when it arrives in the vicinity of the position for exercising the coupling.   mechanical, means of attachment to the other element (D).   6. Compact electrical unit according to any one of the claims   previous, characterized in that the first element is a block   differential (P), the second element being a circuit breaker (D).   7. Compact electrical unit according to the preceding claim, characterized in that the sliding member equips the differential unit (P) and is composed of a drawer (4) in which are mounted the connection terminals (7), the toroid of detection (16) and the control and power conductors (25), as well as a side wing (5) developing parallel to the sides provided with the connection terminals (7) of the differential unit (P) and the circuit breaker (D ) which is attached to it, said wing (5) comprising the conductors (25) connecting the two elements (P, D), the ends of which protrude parallel to the sliding axis of the drawer (4).   8. Compact electrical unit according to the preceding claim, characterized in that the drawer (4) is movable between two extreme positions, a closed position in which the ends of the conductors (25) projecting from the wing (5) are housed in the circuit breaker connection terminals (D), and an open position in which said   ends are released from said terminals.   9. Compact electrical unit according to one of claims 7 and 8,   characterized in that the part of the drawer comprising the connection terminals (7) of the differential unit (P) and the lateral wing (5) are covered with a protective cover (3, 3a) masking said terminals (7) and leaving free access (8) for tightening / loosening, and covering the   conductors (25) housed in said wing (5).   10. Compact electrical unit according to one of claims 8 and 9,   characterized in that the cover (3, 3a) comprises a cover (30) located on the drawer (4), masking the components (16, 25) of the differential unit (P) in drawer opening position (4).   11. Compact electrical unit according to one of claims 9 and 10,   characterized in that the cover (3, 3a) comprises a terminal cover (6) situated at the level of the lateral wing (5), and intended to protect access to the   circuit breaker clamping members (D).   12. Compact electrical unit according to the preceding claim, characterized in that said terminal cover (6) is sliding in a housing (9, 9a) of the cover between a storage position and a deployed position; in which the shape of the housing (9, 9a) allows it to rotate with an axis parallel to the direction of mechanical coupling, between said deployed position and a rest position masking the terminals of circuit breaker connection (D).   13. Compact electrical unit according to any one of claims   7 to 12, characterized in that the differential unit (P) comprises a lug (17) connected to a pivoting shaft (21) comprising two hooks (13), the assembly being disposed at the edge opposite to the sliding opening of the drawer (4) on the internal face of the lateral front adjoining the circuit breaker (D), said tab (17) cooperating with the internal end of the drawer (4) for   move said hooks (13) in rotation.   14. Compact electrical unit according to the preceding claim, characterized in that said tab (17) is integral in rotation with said shaft (21), and is inserted in a housing (18) disposed at the internal end of the drawer (4) , via an opening (19) whose edges (20, 20 ') perpendicular to the bottom of the drawer (4) exert an alternative action on the tab (17), aimed at it   communicate a rotational movement in both directions.   15. Compact electrical unit according to the preceding claim, characterized in that said tab (17) is a bent lever whose faces perpendicular to the bottom of the drawer (4) allow said edges (20, 20 ') of the opening (19) housing (18) to perform a relative movement along said faces, transforming the sliding of the drawer (4) in a rotation of   the lug (17) and the shaft (21) supporting the hooks (13).   16. Compact electrical unit according to any one of claims   7 to 15, characterized in that the lateral wing (5) projecting from the sliding drawer (4) comprises centralizers (22) developing parallel to the axis of the sliding in the direction of the terminals of the circuit breaker (D), under which are provided housing (23) adapted to receive said centralizers (22).   17. Compact electrical unit according to claim 7, characterized in that the sliding member is a part of the cover (28) of the differential unit (P) comprising the lock of said unit (P), the drive lever (10) of the circuit breaker lock (D), and centering pins (11) acting in the direction of mechanical coupling.   18. Compact electrical unit according to the preceding claim, characterized in that the differential unit (P) has a keying protuberance (12) developing in the direction of the mechanical coupling and cooperating with a corresponding orifice of the circuit breaker (D), said protuberance keying (12) being integral with the sliding part of the cover (28).   19. Compact electrical unit according to any one of claims   above, characterized in that the element (D) comprising the sliding member (4, 28) is provided with a locking button (26) inhibiting, when actuated, the sliding of said member (4, 28) , said button (26)   being maneuverable only once in one direction.   20. Compact electrical unit according to any one of claims   7 to 16, characterized in that the differential unit (P) comprises a pusher (26) which slides there perpendicular to the two directions of the electrical and mechanical couplings, said pusher (26), accessible from the cover of the differential unit, being extended in the direction of sliding by a rod (27) adapted to fit in a housing (24) provided for this purpose in the sliding drawer (4), and inhibiting any movement thereof, said pusher (26) flush with the cover and can no longer be operated after   adjustment of the end of the rod (27) in said housing (24).