Rotary switch with lockable switch position blocking

Abstract: A rotary switch with locking of at least one switch position, comprising a switch housing, in which fixed contacts are accommodated. The switch housing contains a number of movable contacts on a switch bridge. The movable contacts are brought into contact with or separated from the fixed contacts through translation of the switch bridge. The rotary switch also comprises a rotation-translation converter, in which the rotatable input element is coupled to a switch shaft and the translatable output element is coupled to the switch bridge. A blocking means is present for blocking a position of the rotary switch, which blocking means comprises a neutral position blocking element provided at the input or output element, which blocking element in the neutral position of the rotary switch can be locked in a releasable manner at the housing of the rotary switch.

Description: The invention relates to a rotary switch with locking of at least one switch position, comprising a switch housing, fixed contacts accommodated therein, a switch bridge provided with a number of movable contacts which are brought into contact with or separated from the fixed contacts through translation of the switch bridge, a switch shaft, a rotation-translation converter, in which the rotatable input element is coupled to the switch shaft and the translatable output element is coupled to the switch bridge, and a locking means of the rotary switch. Such a rotary switch is known in various embodiments, and in general comprises a switch shaft, whose free end projects beyond the switch housing, for the fitting of a rotary knob. The switch housing contains a number of fixed contacts with which a corresponding number of movable contacts can be brought into contact, or from which they can be separated. The movable contacts are fixed on a switch bridge, which are moved in a straight line for the abovementioned contacting or separation. In order to convert the rotary movement of the switch shaft produced by operation of the rotary knob into the linear movement of the switch bridge, a rotation-translation converter is used, in which the rotatable input element is coupled to the end of the switch shaft situated inside the switch housing, and in which the output element, which through rotation of the input element carries out a reciprocating movement, is coupled to the switch bridge. In order to ensure that in cases where the contacts are welded, the control knob cannot be moved into the OFF or neutral position, thus causing an unsafe situation to occur through the fact that the impression is given that the switch contacts are open, according to a first aspect of the invention the blocking means comprises a welded-state blocking element provided at the input element, and the rotation-translation converter is designed in such a way that in the welded state of at least two fixed and movable contacts of the rotary switch which belong together, and on rotation of the input element, said element carries out a translation, whereby the welded-state blocking element is blocked by the housing of the rotary switch and further rotation of the input element is impossible. The obstruction of the rotary movement occurs in the switch itself, and is thus not accessible from the outside. It is observed that from CH-A-631828 a remote blocking is known per sé, but not a blocking at the input element and thus in the switch itself. A further advantage is that the switch is blocked automatically if a movable contact is welded to a fixed contact. The rotary switch therefore cannot be moved into another position when the contacts are welded. The internal blocking ensures that the switch positions of the rotary switch are well-defined, and it is ensured that the position of the control knob corresponds to the position of the switch contacts. In order to prevent further unsafe situations, measures can be taken to lock the OFF or neutral position of the switch. When the switch is in the locked state, it is then safe to work on the dead side of the switch. US Patent Specification 5,243,157, for example, discloses a rotary switch which is provided with a locking means for locking one or more positions of the control knob. The body of the control knob is provided with a hole, which in the lockable position of the rotary switch lies in line with a hole in a part of the switch housing. When a padlock is inserted into the holes brought into line with each other and said padlock is moved into the closed state, the control knob of the rotary switch cannot be turned out of the locked position by an unauthorized person, and switching on the rotary switch is thus impossible. The solutions known hitherto for locking, for example, the neutral position of the rotary switch have the disadvantage that the locking is carried out by fixing the control knob. This means that it is not possible to place the control knob at a fairly great distance from the switch housing, for example in order to be able to operate it through a cover of a switch box. A further object of the invention is to provide a rotary switch of the type mentioned in the preamble, in which, in addition to the locking in a particular switch position, provision is also made in a simple manner for blocking in that switch position, as a result of which even greater safety is ensured. This object is achieved according to a first aspect of the invention through the fact that a blocking means provided with a neutral-position blocking element at the input or output element is present, which blocking element can be locked in a releasable manner in the neutral position of the rotary switch on the housing of the rotary switch. In this case again, blocking occurs in the switch itself, and optimum safety is thus ensured. This applies in particular if the control element of the blocking element is locked, since the rotary switch can then no longer be moved into another position without removal of the switch housing. A further advantage of the internal blocking is that the switch position can be locked in a very secure way even when an extended switch shaft is used, i.e. where the control knob is not fitted directly on the switch. In the case of the switch according to the second aspect of the invention the neutral-position blocking element can preferably be locked to the housing only in the neutral position of the rotary switch. In order to permit locking of the neutral-position blocking element in a simple manner, the blocking means also comprises a blocking slide, which is mounted in the switch housing in such a way that it can be slid parallel to the axis of rotation of the rotary switch, and is provided with a gripping element which in one position of the blocking slide acts upon the neutral-position blocking element and in another position thereof releases said element. A simple and cheap solution of the neutral-position blocking element is achieved through this element consisting of a blocking disc which is immovably connected to the input or output element and extends at right angles to the axis of rotation of the rotary switch, and which has a recess in which the gripping element of the blocking slide can engage. The blocking slide is preferably an L-shape, one leg of which is mounted in the switch housing in such a way that it can be slid parallel to the axis of rotation of the rotary switch, while the other leg is provided with the gripping element. Through dimensioning of the length of the other leg, the leg which is slidable in the switch housing can come out of the housing at such a distance from the rotary knob of the rotary switch that there is sufficient space to operate the rotary switch, and in particular to fit a padlock through a hole provided in the slidable leg and lying outside the switch housing when the rotary switch is locked. The other leg of the blocking disc extends at least partially below the blocking disc, and in any position deviating from the neutral position of the rotary switch the blocking disc blocks the sliding of the blocking slide. This ensures in a simple and cheap manner, i.e. by selecting the position of the other leg, that the switch can be blocked only in the neutral position, and not in a position deviating therefrom. A simple and sturdy rotation-translation converter is formed by a screw drive, in which the screw, which is rotatably mounted in the switch housing, is coupled to the switch shaft, and in which the screw housing, which surrounds the screw and is provided with corresponding internal screw thread, is coupled to the switch bridge. In a preferred embodiment of the rotary switch, according to the first aspect of the invention, the rotation-translation converter is also a screw drive, in which the screw, which is rotatably mounted and can be slid in the lengthwise direction in the switch housing, is coupled to the switch shaft, and in which the screw housing, which surrounds the screw and is provided with internal screw thread, is coupled to the switch bridge. This embodiment has the advantage that the sliding of the screw can be used to initiate the blocking of the rotary switch. If one or more movable contacts are welded to the corresponding fixed contacts, the screw housing is fixed as a result, and the screw will be slid upwards through rotation thereof, which sliding can be used for the abovementioned initiation of the blocking. In a further development the switch bridge is coupled to the screw of the screw drive in such a way that in the case of welded contacts the screw housing is blocked, and in such a way that a stop element immovably connected to the switch housing is present, which stop element in the normal positions of the rotary switch is situated at a distance above the welded-state blocking element and in the welded state through rotation of the screw engages with the welded-state blocking element before the rotary switch reaches the switched-off position. Various embodiments of the blocking element and the stop element are described in the subclaims. In order to be absolutely sure that where the contacts are not welded together, i.e. in the normal operating state of the rotary switch, the welded-state blocking element does not accidentally engage with the stop element, the screw of the screw drive is prestressed in the direction of the switch bridge. This prestressing is advantageously obtained by the screw being mounted rotatably and slidably in a wall of the screw housing running at right angles thereto, and by prestressing springs being disposed between the screw housing of the screw drive and the abovementioned wall of the switch housing. The invention will be explained in greater detail below with reference to the drawings, in which: Fig. 1 shows a section of a part of a preferred embodiment of the invention, in the switched-on position; Fig. 2 shows the embodiment of Fig. 1, in the switched-off position; Fig. 3 shows the rotary switch according to Fig. 1, in a position in which one or two of the movable contacts are welded to the corresponding fixed contacts; Figs. 4 - 6 are diagrammatic illustrations in order to explain the principle of the invention; Fig. 7 shows a cut-away top view of the rotary switch according to Fig. 1; Fig. 8 is a similar view of the rotary switch according to Fig. 2; Fig. 9 is a side view of the rotary switch according to Fig. 8, in which the cover is omitted. In Fig. 1, for the sake of clarity, a section of only part of the rotary switch according to the invention is shown. The rotary switch is accommodated in a switch housing 1, only the top part of which is shown. Fitted in the switch housing are fixed contacts, only the fixed contacts 2 and 3 of which are shown, while the fixing thereof in the housing is not shown, since this can be carried out in any known manner. The rotary switch is also provided with a switch bridge 4, at the ends of which movable contacts 5 and 6 are situated. The switch bridge 4 is preferably accommodated in a space in the switch housing 1, in such a way that said switch bridge 4 can carry out an up and down movement and in doing so is sufficiently accurately guided to bring the contacts 5, 6 reliably into contact with the fixed contacts 2, 3. The switch bridge 4 is coupled by means of a rotation-translation converter to the switch shaft 8, which is rotatably mounted in a second top wall 9 of the switch housing 1. A rotary knob 10 is fixed on said switch shaft 8, in order to control the switch. Turning the rotary knob 10 causes the switch shaft 8 to rotate, which rotation is converted by the rotation-translation converter 7 into translation of the switch bridge 4. The switch is shown in the switched-on position in Fig. 1, so that the movable contacts 5, 6 rest with a suitable contact pressure against the fixed contacts 2, 3. Starting from the position shown in Fig. 1, the switch shaft 8 is turned by turning the knob 10 and, driven by the rotation-translation converter, the switch bridge 4 is moved downwards, with the result that the switch is moved into the switched-off or neutral position shown in Fig. 2, in which the movable contacts 5, 6 are separated from the fixed contacts 2, 3. In the case of the embodiment shown in Figs. 1 - 3, the rotation-translation converter is formed by a screw drive, the screw 11 of which is immovably connected to the switch shaft 8, while the screw housing 12 thereof is coupled to the switch bridge 4. Other rotation-translation converters can also be used, for example a disc immovably connected to the switch shaft 8 and a second disc connected to the switch bridge 4, on whose mutually opposite faces lobes which are in continuous engagement with each other, for example by means of springs, are disposed. As a result of the interaction of the lobes of the discs and rotation of the disc connected to the switch shaft 8, the second disc with the switch bridge connected thereto is set in motion in an up or down movement. However, the screw drive is preferable, since the least wear can be expected with it, and the screw 11 can advantageously be provided with several leads, so that an advantageous distribution of forces is achieved. The internal screw thread of the housing 12 therefore has, for example, two starts. The screw housing 12 is coupled to the switch bridge 4 by means of a through hole 13, in which the centre part of the switch bridge is accommodated. In order to obtain improved contact pressure between the fixed contacts 2 and 3 and the movable contacts 5 and 6, a contact pressure spring 15 is disposed between the bottom side of the switch bridge 4 and the bottom wall 14 of the hole 13. The way in which this contact pressure spring 15 works can be seen most clearly in Figs. 1 and 2. It can be seen from Fig. 2 that the switch bridge 4 is pressed by this contact pressure spring 15 against the top wall of the hole 13. In the switched-on position of Fig. 1 the top wall of the hole 13 is clear of the contact bridge 4, and the contact pressure spring 15 presses the switch bridge 4 in the upward direction, as a result of which the movable contacts 5, 6 are pressed with the necessary contact pressure against the fixed contacts 2, 3. According to the invention, the rotary switch is provided with a blocking means for the neutral position of the rotary switch and/or a blocking means for the rotary switch for blocking the welded state of one or more movable contacts to the corresponding fixed contacts. The invention will now be explained first with reference to the diagrammatic views of Figures 4, 5 and 6. The blocking takes place inside the switch, and not at the rotary knob, as in known devices. The neutral-position locking can be produced by blocking the output element, for example the screw housing of a screw drive, but the neutral-position blocking is preferably achieved by means of the input element 16 - shown diagrammatically as a disc - of the rotation-translation converter. Said input element 16 is coupled in a manner not shown to the switch shaft, and is provided with a recess 17 which can interact with a blocking slide 18 which is slidable in the vertical direction, and for that purpose is slidably mounted in the switch housing. Said slide 18 can be in the form of a bar, the bottom end of which can be brought into engagement with the recess 17, with the result that rotation of the input element 16 is prevented. However, according to Figures 4, 5 and 6, the blocking slide 18 is preferably an L-shape, the vertical leg 19 of which is slidably mounted, in a manner not shown, in the switch housing. The horizontal leg 20 is provided at the free end with a gripping element in the form of a gripping face 21. In the neutral position of the rotary switch shown in Fig. 5 the gripping element or gripping face 21 of the blocking slide 19, 20 can be brought into engagement with the recess 17 by sliding the blocking slide upwards. The blocked position is shown in Fig. 6. As can be seen most clearly from Fig. 4, the horizontal leg 20 of the blocking slide 18 extends below the input element 16, and in the switched-on position shown in Fig. 4 the blocking slide 18 cannot be slid upwards, due to the fact that the vertical leg 20 of the blocking slide 18 goes against the bottom side of the input element 16, and the sliding movement of the blocking slide 18 in the upward direction is thereby prevented. This gives the advantage that the switch can be locked only in the neutral position (Figs. 5, 6). Moreover, through selection of the length of the leg 20 of the blocking slide 18, or its shape, the leg 19 of the blocking slide 18 can be passed out of the switch housing at any desired point. It is only in the neutral position shown in Fig. 5 that the blocking slide 18 can be slid freely in the upward direction, in order to engage with the recess 17 in the input element 16. The input element 16 is also provided with automatic blocking for cases where, in the switched-on position of the rotary switch shown in Fig. 4, one or more movable contacts are welded to the corresponding fixed contacts. For this purpose, the input element 16 is provided with a welded-state blocking element, in the form of a second recess 17' or as an alternative in the form of a lobe. A stop element 22 is immovably fixed to the switch housing above and at a short distance from the input element 16. In the normal operating position of the switch the input element runs clear of the stop element 22, and the latter is thus inactive. When one or more movable contacts are welded to the corresponding fixed contacts, the stop element 22 engages in the second recess 17'. For this purpose, the rotation-translation converter is designed in such a way that in the welded state of one or more movable contacts, through rotation of the input element 16 in the direction of the arrow P, said input element 16 carries out a movement in the upward direction, and the stop element 22 thereby falls with the free end into the recess 17'. Although the blocking of the welded state is advantageously provided in combination with the neutral-position locking of Figs. 4, 5 and 6, it is conceivable for the neutral position of the rotary switch also to be carried out in another way. For example, each of the two functions can be achieved in a separate part of the input element 16. The neutral-position blocking in the preferred embodiment shown in Figs. 1, 2, 3, 7, 8 and 9 will now be explained. As already mentioned, the rotation-translation converter is in the form of a screw drive 7, comprising the screw 11 which is rotatably mounted in the switch housing, and which is coupled to the switch shaft 8 and the screw housing surrounding said screw, which screw housing is provided with corresponding internal screw thread and is connected to the switch bridge. The neutral-position blocking is implemented inside the switch housing 1, 9. For this purpose, the screw 11 is provided at the top side with a blocking disc 23, which has a slightly larger diameter than the screw 11. The blocking disc 23 can be a separate disc or ring which is immovably fixed to the screw 11. As has been shown, said disc 23 is preferably integral with the screw 11. A flange on the screw 11 would also be sufficient. The screw 11 is rotatably mounted in the horizontal wall 1 of the switch housing, and the blocking disc 23 lies as a flange accommodated to some extent in a recess of the wall 1 of the switch housing. The screw 11 is provided with a top part 24 which is rotatably mounted in a recess 25 of the horizontal wall 9 of the switch housing. The wall 9 of the switch housing is provided with a cylindrical raised part 26, which is accommodated in a correspondingly shaped recess 27 in the rotary knob 10. The rotary knob is screwed down on the top part 24 of the screw 11 by means of, for example, a screw 28. A fixed coupling is thus obtained between the rotary knob 10 and the screw 11. For the neutral-position locking, the blocking disc 23 is provided with a recess 29, which can be seen only in Figs. 2, 7 and 8. Said recess 29 in the blocking disc 23 can interact with a blocking slide 30 only in the neutral position of the rotary switch, i.e. the switched-off position thereof (see Figs. 7, 8 and 9). Said blocking slide 30 has a vertical leg 31 and a horizontal leg 32. These two legs 31, 32 are accommodated in a space in the housing, which is of such a complementary shape to the blocking slide 30 that said slide 30 can be slid only upwards and downwards. Fig. 7 shows the rotary switch in the switched-on position, in which the blocking projection 33 of the horizontal leg 32 of the blocking slide 30 is situated with its end below the blocking disc 23, so that the latter cannot be slid upwards from its bottom position. In the switched-off position or neutral position shown in Fig. 8 the recess 29 is situated precisely above the blocking projection 33 of the horizontal leg 32 of the blocking slide 30. In this neutral position the blocking slide 30 can be pushed upwards. The vertical leg 31 is of such length and is in such a position in the switch housing that in the bottom position of the slide 30 said leg extends slightly above the top surface of the switch housing and can be gripped, and in the extended position the leg will project even further above the outer top surface of the switch housing 34. In the position of the blocking slide 30 slid upwards, the blocking projection 33 of the vertical leg 32 thereof engages in the recess 29, as a result of which the blocking disc 23 - and thus the screw 11 - is blocked in the abovementioned neutral position, due to the confinement of the blocking slide 30 in the complementary space of the switch housing 34. The projection 33 is preferably provided with an upward directed thickened part, in order to reduce the friction with the disc 23. The vertical leg 31 of the blocking slide 30 is also provided with a hole 35, through which a padlock can be fitted and locked by means of the respective key. The lock ensures that the blocking slide 30 cannot be slid downwards. The advantages of the L-shape of the blocking slide 30 have already been discussed with reference to Figs. 4, 5 and 6. For fitting the parts of the switch, the switch housing 34 is in two parts, the cover part 36 being screwed down on the bottom part 38 by means of the screws 37. The blocking in the case of welded contacts will now be described. The screw 11 and the top part 24 thereof are not only rotatably, but also slidably mounted in the vertical direction in the parts 1, 9 of the switch housing. The welded-state blocking element of the blocking means for blocking the welded state of the rotary switch is formed by blocking lobes 39 projecting above the top surface of the top part 24 of the screw 11. However, the blocking element can also be formed by one or more recesses in the top surface of the top part 24 of the screw 11. In the switched-on position of the rotary switch one or more stop elements are situated above and at a distance from the blocking lobes 39 or possibly the recesses in the top part 24 of the screw 11, with which stop elements the lobes or recesses can be brought into engagement in the welded state of the rotary switch. The stop element is fixed to the housing and in the case of the present preferred embodiment the stop element is formed by stop lobes 40 on the bottom surface of the cover part 9, 36 of the rotary switch. The stop element can, of course, also be formed by stop lobes or stop recesses which are immovably fixed by means of an arm to the bottom part 38 of the switch housing 34. If, as shown in Fig. 3, one of the movable contacts 5, 6 is welded to the corresponding fixed contacts 2, 3, the screw housing 12 of the screw drive is retained by the switch bridge 4. Through rotation of the rotary knob 10, the screw 11 will also be set in rotation, as a result of which the screw 11 and the top part 24 are driven upwards through interaction of the leads on the screw and in the screw housing, so that the blocking lobes 39 engage behind the stop lobes 40 and the switched-on, welded state of the rotary switch is automatically blocked. In the normal operating state of the rotary switch, i.e. in which the contacts are not welded, when the rotary knob is rotated, in this normal state the blocking lobes 39 will remain at a distance from the stop lobes 40 and thus run clear of them. In order to be sure that in the abovementioned normal state the blocking lobes 39 remain clear of the stop lobes 40, in the abovementioned state the screw 11 is prestressed in the downward direction. In the welded state of the rotary switch, turning of the rotary knob 10 causes the screw 11 and the top part 24 thereof to slide in the upward direction against the switch bridge, as a result of the reaction force, with the result that an engagement is then produced between the blocking lobe 39 and the stop lobe 40. As can be seen in Figs. 1, 2 and 3, the prestressing of the screw 11 is produced by compression springs 41, which are accommodated in recesses in the screw housing 12. The end of the springs 41 projecting outside the screw housing rests against the bottom surface of the wall part 1 of the switch housing. Due to the fact that the springs 41 are under some prestress in the mounted position, the screw housing 12 is always prestressed in the downward direction, which prestress is transmitted by way of the screw leads of the screw housing 12 and the screw 11 to the screw 11 and the top part 24 thereof.

Claims: Rotary switch with locking of at least one switch position, comprising a switch housing(1), fixed contacts (2, 3) accommodated therein, a switch bridge provided with a number of movable contacts (5, 6) which are brought into contact with or separated from the fixed contacts (2, 3) through a translation of the switch bridge (4), a switch shaft (8), a rotation-translation converter (7), in which the rotatable input element (11, 16) is coupled to the switch shaft, and the translatable output element (12) is coupled to the switch bridge (4), and a locking means for locking a position of the rotary switch, characterized in that a blocking means provided with a welded-state blocking element (17') on the input element (11, 16) is present, and in that the rotation-translation converter (7) is designed in such a way that in the welded state of at least two fixed (2, 3) and movable contacts (5, 6) of the rotary switch which belong together, and through rotation of the input element (11, 16), said element carries out a translation, whereby the welded-state blocking element is blocked by the switch housing (1) of the rotary switch. Rotary switch according to claim 1, characterized in that a blocking means provided with a neutral-position blocking element (16) at the input or output element (11, 12) is present, which blocking element in the neutral position of the rotary switch can be locked in a releasable manner at the switch housing (1) of the rotary switch. Rotary switch according to Claim 2, characterized in that the neutral-position blocking element (16) can be locked to the switch housing only in the neutral position of the rotary switch. Rotary switch according to Claim 2 or 3, characterized in that the blocking means also comprises a blocking slide (19, 20), which is mounted in the switch housing (1) in such a way that it can be slid parallel to the axis of rotation of the rotary switch, and is provided with a gripping element (21) which in one position of the blocking slide acts upon the neutral-position blocking element (16) and in another position thereof releases said element. Rotary switch according to Claim 4, characterized in that the neutral-position blocking element (16) consists of a blocking disc which is immovably connected to the input or output element (11, 12) and extends at right angles to the axis of rotation of the rotary switch, and which has a recess(17) in which the gripping element (21) of the blocking slide (19, 20) can engage. Rotary switch according to Claim 4 or 5, characterized in that the blocking slide is an L-shape, one leg (19) of which is mounted in the switch housing in such a way that it can be slid parallel to the axis of rotation of the rotary switch, while the other leg (20) is provided with the gripping element (21). Rotary switch according to Claim 6, characterized in that the other leg of the blocking slide extends at least partially below the blocking disc (16), and in any position deviating from the neutral position of the rotary switch the blocking disc (16) blocks the sliding of the blocking slide (19, 20). Rotary switch according to one of Claims 2, 3 - 7, characterized in that the rotation-translation converter (7) is a screw drive, in which the screw (11), which is rotatably mounted in the switch housing (1), is coupled to the switch shaft (8), and in which the screw housing (12), which surrounds the screw (11) and is provided with corresponding internal screw thread, is coupled to the switch bridge (4). Rotary switch according to Claim 1, characterized in that the rotation-translation converter (7) is a screw drive, in which the screw (11), which is rotatably mounted and can be slid in the lengthwise direction in the switch housing (1), is coupled to the switch shaft (8), and in which the screw housing (12), which surrounds the screw (11) and is provided with corresponding internal screw thread, is coupled to the switch bridge (4). Rotary switch according to Claim 9, characterized in that the switch bridge (4) is coupled to the screw (11) of the screw drive in such a way that in the case of welded contacts the screw housing (12) is blocked, and in such a way that a stop element (22) immovably connected to the switch housing (1) is present, which stop element in the normal positions of the rotary switch is situated at a distance above the welded-state blocking element (17') and in the welded state through rotation of the screw engages with the welded-state blocking element before the rotary switch reaches the switched-off position. Rotary switch according to Claim 10, characterized in that the screw (11) has a surface extending at right angles to the axis of rotation and facing away from the screw housing, and in that the welded-state blocking element is a blocking lobe (39) projecting beyond this surface. Rotary switch according to Claim 10, characterized in that the screw (11) has a surface extending at right angles to the axis of rotation and facing away from the screw housing, and in that the welded-state blocking element is a recess disposed in this surface. Rotary switch according to Claim 12, characterized in that the stop element is a stop lobe or stop recess disposed in a top wall of the switch housing. Rotary switch according to Claim 11 or 12, characterized in that the stop element is a stop recess disposed in a top wall of the switch housing. Rotary switch according to one of Claims 9 - 14, characterized in that the screw (11) is prestressed in the direction of the switch bridge (4). Rotary switch according to Claim 15, characterized in that the screw (11) is rotatably and slidably mounted in a wall of the switch housing (1) running at right angles thereto, and in that prestressing springs (15) are disposed between the screw housing (12) of the screw drive and the abovementioned wall of the switch housing (1).

Inventors: HOEKSTRA JACOB ALBERT, KNOL HILBERT GEZIENUS, HOEKSTRA, JACOB ALBERT, KNOL, HILBERT GEZIENUS
Applicants: HOLEC HOLLAND NV, HOLEC HOLLAND N.V.
Application year: 1995
Main classification: H01H9
IPC codes: H01H19, H01H9