Optical fiber organizer

0001The present invention relates to the management of optical fiber connections and in particular concerns an optical fiber organizer and splice holder.

0002A known type of optical fiber organizer is described in <patcit id="pcit0001" dnum="WO9732231A1"><text>PCT application WO 97/32231 A1</text></patcit> and in the <patcit id="pcit0002" dnum="WO2009106874A1"><text>PCT application WO 2009/106874 A1</text></patcit>. The optical fiber organizer comprises an optical fiber storage means which is fixed to a support. The support comprises a cable termination retention means for securing incoming/outgoing cables having at least one optical fiber. The support is fixed to a casing of the optical fiber organizer. For each optical fiber storage means, one cable termination retention means is provided. The optical fiber storage means is rotatably connected to the support. The cable is guided in an area between the fiber storage means and the support.

0003The object of the invention is to provide an improved optical fiber organizer. The object of the invention is achieved by the optical fiber organizer according to claim 1. The optical fiber organizer has the advantage that the proposed organizer provides a higher flexibility. This advantage is attained by a first support which is rotatably connected to a further element.

0004Further embodiments of the invention are disclosed in the dependent claims.

0005An embodiment of the optical fiber organizer has the advantage that the area between the first support of the fiber storage means and a second support can easily be accessed. This advantage is achieved by rotatably connecting the first support to a second support. For this reason, it is possible to rotate the first support away from the second support. Thus, it is possible to more easily access elements such as the cable, splitters, optical fiber etc. which may be arranged between the first and the second support.

0006In one embodiment, the storage means and the first support comprise clip means which clip the storage means in an open position relative to an adjacent storage means. For this reason, it is possible to fix the position of the storage means and, if it is advantageous, to loosen the clip means and to rotate the storage means in a further position.

0007In a further embodiment the first support comprises a first and a second section, which are rotatably connected. Therefore, it is possible to use the first support in different application, for example for a FOSC application or a FIST application. It is not necessary to produce different first supports. Furthermore, the application can be changed without having the need to use different first supports. Preferably, there is a second locking means which allows the locking of the first section in an inclined position referred to the second section. Furthermore, the first and/or second section may be fixed to a second support.

0008In a further embodiment, the first and the second support comprise second clip means which allow clipping the first support in a closed position relative to the second support. This means that, if it is not necessary to access the space between the first and the second support, the second clip means fix the first support closely to the second support. This provides a fiber organizer with a small constructed space. If it is necessary to access the space between the first and the second support, the second clip means can be loosened and the first support can be moved into an open position which means that through the larger space available between the first and the second support elements such as the cable, the fiber, optical components and/or splitters can easily be accessed.

0009In a further embodiment, several storage means are fixed to a first support and/or to a first and second section of the first support.

0010In a further embodiment, the optical fiber organizer comprises several first supports which are adjacently arranged and which are rotatably connected to the second support. As a result, it is possible to access all sections of the second support for accessing the elements.

0011In a further embodiment, the storage means is embodied as a plate with a guiding means for an optical fiber and/or a fixing means for a splice of optical fibers.

0012In a further embodiment, the optical fiber organizer comprises two first supports with a first and at least one second section, whereby the first supports are adjacently arranged and the respective first sections are rotatably connected to the respective second section in opposite directions.

0013Depending on the used embodiment, the fiber storing means are arranged in parallel to the second support or with a predetermined angle.

0014In a further embodiment, the first support is embodied as a groove plate, e.g. as a T-groove plate. The T-groove plate allows bending and straight routing of the fiber.

0015Various embodiments of the present invention will now be described in more detail by way of example only, with reference to the accompanying drawings in which: <ul id="ul0001" list-style="none"><li><figref idref="f0001">Figure 1</figref> is a perspective view of a part of an optical fiber organizer with fiber storage means, a first support and a second support and a fiber cable;</li><li><figref idref="f0002">Figure 2</figref> shows the optical fiber organizer of <figref idref="f0001">Figure 1</figref> whereby a storage means is in an open position;</li><li><figref idref="f0003">Figure 3</figref> shows the optical fiber organizer of <figref idref="f0001">Figure 1</figref> whereby all fiber storage means are arranged in the open position;</li><li><figref idref="f0004">Figure 4</figref> shows the optical fiber organizer with a first support being in an open position;</li><li><figref idref="f0005">Figure 5</figref> shows a schematic drawing of a first support with two sections;</li><li><figref idref="f0006">Figure 6</figref> shows a further embodiment of an optical fiber organizer with two first supports with fiber storage means which are arranged in parallel to the second support;</li><li><figref idref="f0006">Figure 7</figref> is a schematic drawing of the optical fiber organizer of <figref idref="f0006">Fig. 6</figref> with the first supports being in an open position;</li><li><figref idref="f0007">Figure 8</figref> is a further embodiment of an optical fiber organizer;</li><li><figref idref="f0007">Figure 9</figref> is a further embodiment of an optical fiber organizer;</li><li><figref idref="f0007">Figure 10</figref> is a further embodiment with an optical fiber organizer;</li><li><figref idref="f0008">Figure 11</figref> shows a further embodiment of an optical fiber organizer;</li><li><figref idref="f0008">Figure 12</figref> is a further embodiment of an optical fiber organizer; and</li><li><figref idref="f0008">Figure 13</figref> shows a further embodiment of an optical fiber organizer.</li><li><figref idref="f0009">Figure 14</figref> shows a cross sectional view of a housing of the optical fiber organizer.</li></ul>

0016<figref idref="f0001">Figure 1</figref> shows the main parts of the optical fiber organizer 1 with a second support 2 with a first support 3 and several storage means 4. The second support 2 is embodied as a base plate 8, e.g. as a grooved plate which comprises first means 5 for receiving, storing and guiding optical cables and optical fibers. The second support 2 may be part of a housing for the organizer. The first means 5 may be embodied as walls, openings or pins. The second support 2 furthermore provides a receiving area 6 for receiving a cable 7 which may comprise several optical fibers. The cable 7 may end in the receiving area 6 or may be guided through the receiving area 6. The receiving area 6 is disposed in an edge region defined by the base plate 8 of the second support 2 and a sidewall 9 of the second support 2. The cable 7 may be fixed to the second support 2 by cable-fixing elements (not shown).

0017Above the base plate 8, several storage means 4 which are embodied as organizer trays 10 are disposed. The organizer trays 10 have a basic shape of a plate and are arranged in parallel to each other and in parallel to the base plate 8. The organizer trays 10 may be constructed identically. Each organizer tray 10 may comprise fiber guiding means 11 and splice fixing means 12. Each of the organizer trays 10 is rotatably connected to the first support 3 by hinge means 13. The hinge means 13 allows for a rotation of the organizer tray 10 around a predetermined rotational axis. In this embodiment, the rotational axis is arranged in parallel to the direction of the cable 7 in the receiving area 6 and to a plane of the first support 3.

0018The first support 3 may be embodied in the shape of a plate which is also rotatably fixed to the second support 2 by means of a second hinge means 15. The second hinge means 15 is arranged at a first rim of the first support 3 which is dedicated to the base plate 8. At an opposite rim, second clip means 16 are disposed which fix the first support 3 in the shown closed position. The second clip means 16 comprise a nose and a recess which are arranged on the first support 3 and on the sidewall 9. In the shown embodiment, the sidewall 9 has two bars 17, 18. At free ends of the first and second bar 17, 18, a part of the second clip means 16 are disposed.

0019The trays 10 constitute individual optical fiber storage means for storing lengths of fiber, commonly referred to as "pig tails" for connecting to other optical fibers or components located on or in the individual trays. The trays comprise fiber guide elements and holders 12 which are designed to hold optical fiber splices. The first support 3 comprises a molded structure having a plurality of pairs of mounting means in the form of integrally molded protrusions containing apertures for receiving hinge pins formed on the respective optical fiber storage trays 10. The protrusions and the respective hinge pins define a hinge axis around which the respective trays 10 rotate relative to the first support 3.

0020The second support 2 has a second sidewall 44 which is arranged in parallel to the first sidewall 9. The second sidewall 44 has a recess 50 in an area adjacent to rims of the trays 10.

0021Each of the trays comprises a slit 52 which is arranged in the middle of the tray 10 and in parallel to a moving direction of the trays from an open to a closed position. Therefore, it is possible to fix the trays 10 with one bolt which is screwed in a thread 53 on the bottom of the base plate 8 (<figref idref="f0003">Fig. 3</figref>).

0022<figref idref="f0002">Figure 2</figref> shows the upper organizer tray 10 which is rotated from the close position of <figref idref="f0001">Figure 1</figref> into an open position. In the open position, a second organizer tray 19 is accessible. This is necessary for mounting the fiber and/or the splices in the second organizer tray 19. There are first clip means 20 disposed on the first support 3 and the trays 10, 19 for fixing the tray 10 in the closed and/or open position.

0023The first clip means 20 are constructed for example as a nose and a recess which are configured to fix the trays 10, 19 in the closed position (<figref idref="f0001">Figure 1</figref>) relative to the first support 3 and in the open position (<figref idref="f0002">Figure 2</figref>) relative to the first support 3.

0024<figref idref="f0003">Figure 3</figref> shows the situation in which all the trays 10, 19 are rotated in the open position. In this situation, the second hinge means 15 can be seen, which rotatably connect the first support 3 to the second support 2.

0025<figref idref="f0004">Figure 4</figref> shows the situation that the first clip means 20 are loosened and the first support 3 is rotated in an open position. In the open position, the first support 3 is arranged vertically to the base plate 8. The first support 3 comprises two snap arms 21, 22 at a side which is dedicated to the sidewall 9. The snap arms 21, 22 engage with recesses 23, 24 of the first and second bars 17, 18 to fix the first support 3 in the closed position. The snap arms 21, 22 and the recesses 23, 24 constitute the second clip means 16.

0026Furthermore, a locking means 26 is arranged which locks the first support 3 in the open position. The locking means 26 is embodied as a pin which is stuck into the second opening 27 of the base plate 8. If the first support 3 is in the open position as shown in <figref idref="f0004">Figure 4</figref>, the area 28 between the first support 3 and the second support 2 can easily be accessed. In the area 28, the optical fiber cable 7 is broken out to separate the individual mini-tubes, each of which may contain a dozen or so optical fibers that are to be arranged and spliced within the optical fiber organizer. Thus, it is possible to easily access a cable 7, optical components, splitters or other elements which may be disposed in the area 28. In the open position of the first support 3, rims of the trays 10, 11 protrude in the recess 50 of the second sidewall 44.

0027Due to this new construction, it is possible to provide an optical fiber organizer with a small constructed size which allows large free access to the cable 7 and other components which are arranged in the area 28 between the first and the second support 2, 3.

0028As becomes obvious when comparing the situation of <figref idref="f0001">Figure 1</figref> and <figref idref="f0004">Figure 4</figref>, the height of the staple of the trays 10, 19 of the optical fiber organizer 1 in <figref idref="f0004">Figure 4</figref> is higher than in the position of <figref idref="f0001">Figure 1</figref>. Furthermore, free space is available for accessing the cable 7 in the area 28 between the first support 3 and the second support 2 in the position of the first support of <figref idref="f0004">Figure 4</figref>.

0029In <figref idref="f0001 f0002 f0003 f0004">Figures 1 to 4</figref>, a cover is not shown which is fixed to the base plate in order to enclose the optical fiber organizer.

0030<figref idref="f0005">Figure 5</figref> shows a basic embodiment of the optical fiber organizer with a first support 3 comprising a first and a second section 31, 32. The first and the second section are connected by third hinge means 33, which allows a rotation of the first section 31 relative to the second section 32 as shown in <figref idref="f0005">Figure 5</figref> and as depicted by the arrow. Furthermore, there are second locking means 51 disposed which lock the two sections 31, 32 in a straight and/or in an inclined position as shown. The locking means 51 may be embodied as a pair of a latch and a recess. This basic idea of using a first support 3 with several sections can be applied to different types of optical fiber organizers, e.g. the type FIST application, and to the type FOSC application, as shown in <figref idref="f0005">Figure 5</figref>. The main difference between the FIST organizer the FOSC organizer is that in the FIST organizer, the storage means are arranged at a predetermined angle relative to the plane of the first support 3. The FOSC organizer uses storage means 4 which are basically arranged in parallel to the plane of the first support 3. For the FOCS application the first section 31 is locked in the inclined position. For the FIST application the first section 31 is locked in the straight position. The first and second section may be embodied identical, especially have fixing means for fixing storage means 4, especially storage trays. In the shown embodiment, the first support comprises a third and a fourth section 34, 35. Each section may be rotatably connected by third hinge means may be arranged between adjacent sections. The embodiment of the optical fiber organizer shown in <figref idref="f0001 f0002 f0003 f0004">Figures 1 to 4</figref> relates to a FIST application.

0031<figref idref="f0006">Figure 6</figref> shows a schematic drawing of a FOSC application, whereby on a second support 2 two first supports 3 are disposed. Between the two first supports 3, the cable 7 and/or further elements are arranged. Each first support 3 comprises several sections 31, 32, 34, 35 which are connected to the second support 2. The first section 31 of the first support 3 is detachably connected to the second support 2 by first clip means 20. The two first sections 31 of the two adjacently arranged first supports 3 are disposed at a predetermined angle of about 45° with regard to the plane of the second support 2. The two first sections 31 of the first supports 3, which are arranged in an inclined manner, cover the area 28 in which the cable 7 and/or other optical components is disposed. Instead of the first chip means 20, there might be a second locking means 51 which locks the first section in the inclined position as explained referring to <figref idref="f0005">fig. 5</figref> with third hinge means 33 and second locking means 51 between two adjacent section of a first support 3. In a further embodiment, two first supports 3 may be designed as explained referring to <figref idref="f0005">fig. 5</figref>.

0032The storage means 4 are rotatably connected to the first section 31 by a hinge means 13, as explained in <figref idref="f0001 f0002 f0003 f0004">Figures 1 to 4</figref>.

0033If a free space for accessing the area 28 or the cable 7 is required, the first clip means 20 of the first sections 31 of the two first supports 3 are removed and the first sections 31 are rotated away from the area 28, as shown in <figref idref="f0006">Figure 7</figref>. In this position, it is possible to have an enlarged free space in order to access the area 28 or the cable 7. Furthermore, in the area 28, several elements, e.g. optical components, splitters etc. may be disposed. If there are second locking means between the first and the second section 31, 32, the first chip means 20 is not required.

0034The first section 31 of each first support 3 is rotatably connected to the second section 32 of the respective first support 3 by third hinge means 33.

0035<figref idref="f0007">Figure 8</figref> shows a further embodiment of a FOSC optical fiber organizer 1 with a first support 3 with a first, second, third and fourth section 31, 32, 34, 35. The second, third and/or the fourth section 32, 34, 35 are fixed to the second support 2. The first section 31 is arranged with a predetermined angle relative to the other sections 32, 34, 35 being disposed above the other sections 32, 34, 35. The first section 31 covers the area 28 in which the cable 7 or further elements, e.g. splitters, optical components etc., are arranged. The first section 31 is rotatably connected to the second support 2 by second clip means 16. The storage means 4 which are disposed as trays 10, 19 are rotatably connected to the first section 31 by hinge means 13. The first section 31 is rotatably connected to the second section 32 by third hinge means 33. The first section 31 of the first support 3 may be connected to a sidewall 9 of the second support 2 by the second clip means 16. If the area 28 is to be accessed, the second clip means 16 are loosened and the first section 31 can be rotated via the rotational axis of third hinge means 33 away from the sidewall 9 as depicted by the arrow shown in <figref idref="f0007">Figure 8</figref>. Thus, it is possible to access the area 28. The first support 3 may be embodied in the same design as the first support 3 of <figref idref="f0005">figure 5</figref>, whereby each section is rotatably connected to one adjacent section and second locking means are arranged between two adjacent sections.

0036<figref idref="f0007">Figure 9</figref> shows a further embodiment of a FIST optical fiber organizer 1 with a second support 2 and a first support 3. The first support 3 is made of a first, a second, a third and a fourth section 31, 32, 34, 35. At least the fourth section 35 is detachable fixed to the base plate 8. The first section 31 is connected to the second support 2 by a second clip means 16, e.g. to the sidewall 9. In the shown embodiment, each section 31, 32, 34, 35 is rotatably connected to the adjacent section by a third hinge means 33. However, in this embodiment storage means 4 are also rotatably connected to the first, the second and the third section 31, 32 and 34. The storage means 4 are embodied as trays 10, 19 which are connected by hinge means (not shown), as shown in detail in <figref idref="f0001 f0002 f0003 f0004">Figures 1 to 4</figref>. For this reason, second locking means 51 are arranged between the first and the second section 31, 32 and between the second and the third section 32, 34. The locking means 51 hold the first, second and third section 31, 32, 34 in one plane in a stable manner. If the area between the base plate 8 of the second support 2 and the first support 3 in which e.g. the cable 7 or further elements are disposed is to be accessed, the second clip means 16 is removed and the first, the second and the third section 31, 32, 34 are rotated around the rotational axis of the third hinge means 33 which is disposed between the third and the fourth section 34, 35. Depending on the used embodiment, the second clip means 16 is not provided. The first support 3 is designed as explained referring to <figref idref="f0005">fig. 5</figref>.

0037<figref idref="f0007">Figure 10</figref> shows a combination of a FIST and a FOSC optical fiber organizer 1 with a first support 3 and a further first support 43. The further first support 43 comprises a first and a second section 31, 32, the first and the second section 31, 32 being fixed to one another and to the second support 2. The second section 32 is rotatably connected to the second support 2 by second hinge means 15. Furthermore, the first and/or the second section 31, 32 are connected to the second support 2 by detachable second clip means 16. If the area 26 between the first and the second support 3, 2 is to be accessed, the second clip means 16 is released and the first support 3 is rotated in the direction of the adjacent sidewall 9 of the second support 2, as depicted by the arrow. Adjacent and in one plane to the first support 3, a further first support 43 is disposed. The further first support 43 comprises a T-groove plate 45. Two storage means 4 embodied e.g. as trays 10, 19 are rotatably connected to the T-groove plate 45 by hinge means. The storage means 4 are arranged in parallel to the plane of the further sections 32, 31 of the further first support 43. The T-groove plate 45 is fixed to the second support 2 by a further clip means 46. Furthermore, the T-grooved plate 45 is rotatably connected to a second section 32 of the first support 3 by a third hinge means 33. If the area 28 between the T-grooved plate 45 and the base plate 8 of the second support 2 is to be accessed, the further clip means 46 is removed and the T-groove plate 45 is rotated around the rotational axis of the third hinge means 33 in the direction of a second sidewall 4, as depicted by the arrow.

0038<figref idref="f0008">Figure 11</figref> shows a further embodiment of an optical fiber organizer 1 with a first support 3 with a first, second, third, fourth, fifth and sixth section 31, 32, 34, 35, 36, 37. The first and the second section 31, 32 are fixed to each other by second locking means 51 and several storage means 4 are fixed to the first and second section 31, 32 by hinge means (not shown). The third section 34 is fixed to the second support 2. The third, the fourth and the fifth section 34, 35, 36 are fixed to one another. The sixth section 37 is rotatably connected to the fifth section 36 by a third hinge means 33. Furthermore, there are second locking means 51 arranged between the fifth and sixth section 36, 37. The sixths section 37 is fixed in the inclined position as shown. Moreover, the second section 32 is rotatably connected to the third section 34 by a third hinge means 33. The sixth section 37 is bent away from the base plate 8 of the second support 2. Storage means 4 are rotatably connected to the sixth section 37 by hinge means 13. The storage means 4 of the sixth section 37 are arranged as plate-shaped trays which are disposed in parallel to the base plate 8. Depending on the embodiment, the first section 31 and the fifth section 36 may be connected to the second support 2 by means of second clip means 16. Between the first section 31 and the base plate 8 or between the sixth section 37 and the base plate 8, the cable or other optical components such as splitters may be disposed. If the area 28 between the first section 31 and the base plate 8 or the area 28 between the sixth section 37 and the base plate 8 are to be accessed, the respective second clip means 16 and/or the second locking means 51is loosened. The first and the second section 31, 32 can then be rotated in the direction of the sixth section 37 around the axis disposed by the third hinge means 33. Furthermore, if a person would like to access the area 28 beneath the sixth section 37, the respective second clip means 16 and/or the second locking means 51 is loosened and the sixth section 37 is rotated around the rotational axis which is disposed by the third hinge means 33, as depicted by an arrow in <figref idref="f0008">Figure 11</figref>.

0039<figref idref="f0008">Figure 12</figref> shows a further embodiment of an optical fiber organizer 1 with a first support 3 comprising a first, second, third, fourth, fifth and a sixth section 31, 32, 34, 35, 36, 37. The first and the second section 31, 32 are connected to the second support 2. The third section 34 is rotatably connected by a third hinge means 33 to the second section 32. The third section 34 is e.g. embodied as a T-groove plate. A part of the third section 34 is inclined in a direction away from the base plate 8. At the inclined section, storage means 4 are rotatably connected to the third section 34 by hinge means 13. The third section 34 is connected to the base plate 8 by second clip means 16. The fourth and fifth section 35, 36 are connected to the base plate 8 of the second support 2. The sixth section 37 is rotatably connected to the fifth section 36 by a hinge means 33. An end part of the sixth section 37 is inclined in a direction away from the base plate 8. At the inclined section, two storage means 4 are rotatably connected to the sixth section 37 by hinge means 13. The sixth section 37 is connected to a sidewall 9 of the second support 2 by further clip means 46. If the area 28 between the third section 34 or the sixth section 37 is to be accessed, the second clip means 16 or the further clip means 46 have to be released. The third section 34 can then be rotated around the rotational axis of the third hinge means 33 in direction of a second sidewall 44 of the second support 2, as it is depicted by an arrow. Furthermore, the sixth section 37 can be rotated around the axis of the third hinge means 33 in the direction of the second sidewall 4, as it is depicted by the arrow. In the area 28, the cable 7 or other components, e.g. optical components of splitters may be disposed. Depending on the used embodiment each section may be connected with an adjacent section rotatably by a third hinge means and by a second locking means 51 as explained referring to <figref idref="f0005">fig. 5</figref>.

0040<figref idref="f0008">Figure 13</figref> shows an embodiment with two first sections 3 as explained in <figref idref="f0005">fig. 5</figref>. The first sections 31 are detachably fixed by a second clip means 16 to the second support 2. At least one of the fourth, third or second section 35, 34, 32 is detachable fixed to the second support 2. The second support 2 may be part of a housing. Depending on the use embodiment, one of the first support 3 may be proposed as shown in <figref idref="f0007">figure 9</figref> in a straight position with trays arranged in an inclined manner relative to the plane of the second support 2.

0041<figref idref="f0009">Figure 14</figref> shows a cross-sectional view of a housing for the embodiment of the <figref idref="f0001 f0002 f0003 f0004">figures 1 to 4</figref> The second support 2 is covered by a cover 55. A bolt 54 is guided from the cover 55 via the slits 52 of the trays 10 to the thread 53 fixing the cover 55 to the second support 2. Depending on the used embodiment, there is a guidance 56 from the cover 55 to the thread 53, whereby the bolt 54 is arranged in the guidance 56.

Reference list

0042<dl id="dl0001" compact="compact"><dt>1</dt><dd>optical fiber organizer</dd><dt>2</dt><dd>second support</dd><dt>3</dt><dd>first support</dd><dt>4</dt><dd>storage means</dd><dt>5</dt><dd>first means</dd><dt>6</dt><dd>receiving area</dd><dt>7</dt><dd>cable</dd><dt>8</dt><dd>base plate</dd><dt>9</dt><dd>sidewall</dd><dt>10</dt><dd>tray</dd><dt>11</dt><dd>fiber guiding means</dd><dt>12</dt><dd>splice fixing means</dd><dt>13</dt><dd>hinge means</dd><dt>15</dt><dd>second hinge means</dd><dt>16</dt><dd>second clip means</dd><dt>17</dt><dd>first bar</dd><dt>18</dt><dd>second bar</dd><dt>19</dt><dd>second tray</dd><dt>20</dt><dd>first clip means</dd><dt>21</dt><dd>first snap arm</dd><dt>22</dt><dd>second snap arm</dd><dt>23</dt><dd>first recess</dd><dt>24</dt><dd>second recess</dd><dt>26</dt><dd>locking means</dd><dt>27</dt><dd>second opening</dd><dt>28</dt><dd>area</dd><dt>31</dt><dd>first section first support</dd><dt>32</dt><dd>second section first support</dd><dt>33</dt><dd>third hinge means</dd><dt>34</dt><dd>third section first support</dd><dt>35</dt><dd>fourth section first support</dd><dt>36</dt><dd>fifth section first support</dd><dt>37</dt><dd>sixth section first support</dd><dt>43</dt><dd>further first support</dd><dt>44</dt><dd>second sidewall</dd><dt>45</dt><dd>T-grooved plate</dd><dt>46</dt><dd>further clip means</dd><dt>50</dt><dd>recess</dd><dt>51</dt><dd>second locking means</dd><dt>52</dt><dd>slit</dd><dt>53</dt><dd>thread</dd><dt>54</dt><dd>bolt</dd><dt>55</dt><dd>cover</dd><dt>56</dt><dd>guidance for a bolt</dd></dl>