GB2472584A - Optical-fibre connector - Google Patents

Abstract

The invention provides an optical-fibre connector, in which an end 6 of an optical fibre is secured within a ferrule 5, and the ferrule is biased, or urged by a spring, in a nominal axial direction away from a support 9 located within the connector, in which the ferrule can tilt and/or move laterally in any direction relative to the nominal axial direction. Alternatively, the ferrule support 9 tilts relative to an insert (10, figure 11), The connector is able to accommodate misalignment of a hating connector (see figure 9), due to, for example, manufacturing tolerances.

Description

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OPTICAL-FIBRE CONNECTOR AND METHOD

The invention relates to an optical-fibre connector and a method for connecting optical fibres.

In a conventional optical-fibre connector, the ends of two fibres to be connected are secured within cylindrical ceramic ferrules, and the end faces of the ferrules and the fibres are polished. The ferrules are then butted together within an alignment sleeve, usually in the form of a longitudinally-split ceramic sleeve.

Where a split sleeve is used, the internal diameter of the sleeve is slightly smaller than the external diameter of the ferrules, so that the sleeve is elastically deformed as the ferrules are inserted. The elastically deformed sleeve then acts to hold the ferrules in alignment in order to achieve a good optical connection.

In connectors of this type, two mating connectors are required. In one known example, a first connector houses an alignment sleeve. A ferrule secured to the end of an optical fibre is slidably received within the sleeve. The ferrule is axially spring-loaded, being urged by a spring towards and into the sleeve.

A second, mating connector holds a mating ferrule, secured to an end of an optical fibre. When the connectors mate, the mating ferrule enters the alignment sleeve and butts against the end of the spring-loaded ferrule. As the connectors mate fully, the spring-loaded ferrule is forced back, against the force applied by the spring, so that when the connectors are fully engaged, both ferrules are positioned within the alignment sleeve, loaded together by the force applied by the spring to the spring-loaded ferrule.

A problem can arise in such connectors due to misalignment of the ferrules, which commonly results for example due to variations in manufacturing tolerances. Any such misalignment, either in the form of lateral displacement between the ferrules or any angle between the axes of the ferrules, can dramatically damage the optical performance of the connection between the optical fibres. It is an object of the invention to solve this problem.

Summary of Invention

The invention provides an optical-fibre connector and a method for connecting optical fibres as defined in the appended independent claims. Preferred or advantageous features of the invention are set out in dependent sub-claims.

In a first aspect, the invention may therefore provide an optical-fibre connector for removably connecting an optical fibre. An end of the fibre is secured within a ferrule. The ferrule is urged by a spring in a nominal axial direction, approximately parallel to an axis of the fibre and the ferrule, away from a to support located within the connector. Advantageously, the ferrule can tilt, or be moved or deflected laterally, in any direction relative to the nominal axial direction, or relative to the support.

Preferably, the ferrule can tilt, or be moved laterally, freely in any direction, or equally freely in any direction, relative to the nominal axial direction, or relative to the support. Thus, the ferrule may advantageously be able to tilt, or move laterally, symmetrically in any direction relative to the nominal axial direction, or relative to the support.

The optical-fibre connector is connectable to a mating connector, which may be another connector embodying the invention or may have a different construction. Preferably, however, the ferrule and a mating ferrule of the mating connector are connected by means of an alignment sleeve. The alignment sleeve may be housed either in the connector or in the mating connector. If the alignment sleeve is housed in the connector embodying the first aspect of the invention described above, then the end of the fibre secured within the ferrule may be slidably located within the alignment sleeve. The ferrule may be urged by the spring in its nominal axial direction away from the support, and towards and into the sleeve. The support may be located within the connector at a predetermined distance from the sleeve.

If the alignment sleeve is located in the mating connector, then the ferrule of the connector embodying the first aspect of the invention, as described above, may enter the alignment sleeve when the connector is mated with the mating connector.

A second aspect of the invention provides a method for connecting optical fibres, comprising the following steps. A connector is provided in which a ferrule is secured to the end of the fibre. The ferru'e is spring-loaded such that the ferrule is free to tilt and/or to move laterally in any direction. When the connector is connected to a mating connector, some misalignment of a mating ferrule of the mating connector is likely, for example due to manufacturing tolerances. Such misalignment may include angular (tilting) and/or lateral misalignment In any direction. Such misalignment may advantageously be to accommodated through tilting and/or lateral movement of the ferrule in a corresponding direction.

As noted above, the ferrule may be connected to a mating ferrule of a mating connector by means of an alignment sleeve. If the alignment sleeve is housed is within the connector for implementing the method of the invention described above, then the ferrule secured to the end of the fibre may be slidably received in the alignment sleeve and the alignment sleeve may be loosely housed within the connector to allow some tilting and lateral movement or deflection of the sleeve in any direction. The ferrule may be spring-loaded towards the sleeve such that the ferrule is free to tilt and to move laterally in any direction, or symmetrically in any direction, in response to tilting or lateral deflection of the sleeve. When the connector is connected to a mating connector, misalignment relative to the mating ferrule may be accommodated through tilting and/or lateral movement of the sleeve and the ferrule in a corresponding direction.

Preferably, the fibre leading to the connector is contained within a loose tube or conduit. In this case, if the ferrule is moved axially against the load applied by the spring, as described, then the movement can be accommodated by movement of the fibre within the loose tube or conduit. Advantageously, an end of the loose tube or conduit may be secured to the support, the fibre emerging through a central passageway within the support.

In a further embodiment of the invention, the ferrule forms part of a ferrule assembly which is slidable relative to the support. In one embodiment, this may be implemented by means of a loosely-fitting sliding arrangement, such as a

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loosely-fitting piston and cylinder arrangement in which a piston fits loosely within a bore of a cylinder so as to allow tilting or lateral movement or deflection of the ferrule assembly in any direction relative to the nominal axial direction.

The tilting and/or lateral movement may be accommodated by a clearance space within the sliding arrangement, for example between the piston and the bore of the cylinder.

In a preferred embodiment, the ferrule assembly may comprise a piston and the support may comprise a cylinder within which the piston is loosely slidable.

Alternatively the ferrule assembly may comprise the cylinder and the support may comprise the piston.

Advantageously the piston and cylinder may be circular in section, to ensure that the ferrule assembly can move symmetrically in any direction relative to the nominal axial direction, or relative to the support.

Advantageously, the ferrule assembly and the support may comprise radially-extending abutment surfaces, and a compression spring may act between the abutment surfaces in order to urge the ferrule assembly away from the support.

The compression spring may be a helical spring. If the ferrule assembly and the support are linked by a loosely-fitting piston and cylinder arrangement, the helical spring may encircle the piston and cylinder arrangement.

Preferably, the piston forms part of the ferrule assembly and an axial bore is defined within the piston for receiving a fibre buffer encircling the optical fibre.

The fibre itself then extends within the ferrule.

In a further embodiment, the connector comprises an insert or housing which is fixed, or retained, in position within a body of the connector, for retaining the support at the predetermined spacing from the coupling. The insert preferably also retains the support in a nominal orientation, approximately aligning the support and the ferrule towards the alignment sleeve.

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Advantageously, the insert may retain the support in such a way that the support is able to tilt relative to the insert, and can preferably tilt in any direction relative to the insert.

The support advantageously comprises a structure for engaging with the insert.

For example, the support may comprise a radially-extending flange engageable with a resilient portion of the insert or the insert may comprise a clip or latch engageable with a recess or groove defined in the support.

io The insert may advantageously be moulded from a plastics material incorporating resilient engagement means, such as a resilient clip, for engaging the support. The support may thus be retained in a nominal position, and in a nominal orientation. However, clearance between the support and the insert may advantageously be provided to allow the support to tilt relative to the insert.

is For example, the support may engage with the insert in such a way that a clearance is left between engaging portions of the insert and the support, the clearance allowing tilting of the support relative to the insert. Alternatively, or in addition, flexing of the resilient portion of the insert or a further resilient part of the insert or the support may advantageously allow the support to tilt relative to the insert.

The insert is preferably retained within the body of the connector such that it cannot rotate relative to the body, for example by means of a key or a flat. An optical fibre connector is commonly secured to a mating connector by means of a threaded assembly nut and as the nut is tightened a torque may be applied to the connector housing. An object of the invention is to reduce any loads applied to ferrules carrying optical fibres, for example within alignment sleeves, which may tend to misalign the ferrules. It is therefore desirable to prevent torque applied to the assembly nut from being transferred to the supports which support and nominally align the ferrules. Where the supports are held in an insert, this may advantageously be achieved by preventing or limiting rotation of the insert relative to the connector body.

The use of an insert retained within the body of a connector may provide further advantages where the connector is for connecting two or more optical fibres in

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parallel. In that case a single insert, retainable within a connector body, may be used to retain two or more supports, each support carrying one of the fibres.

This aspect of the invention may advantageously reduce the total number of components of the connector and may simplify construction of the connector.

To prepare a multi-fibre cable for termination in a connector, each fibre may be terminated with a ferrule and a support. Thus only an advantageously small number of components needs to be mounted on each fibre during the cable preparation stages of epoxying (to secure the fibre within the ferrule), polishing the end of the fibre and optical pre-testing. The prepared fibres can then be engaged with a single insert for mounting within the connector. There is no need for a separate insert to mount each fibre within the connector.

Preferably, the insert may be fixed to the connector body before the supports are engaged with the insert.

Particularly preferably, the supports may be inserted, or pushed in, from a rear side of the insert, in a direction approximately parallel to the nominal axial direction for each fibre. In that case, the insert may be mounted in the connector body before the support(s) are mounted in the insert, reducing the number of separate components to be handled during assembly of the connector, thus simplifying assembly and reducing assembly time.

As described above, the ferrule should be able to tilt and/or move laterally relative to its nominal position and orientation in any direction, in order to accommodate misalignments of the alignment sleeve, due to manufacturing variations or tolerances, and/or movements of the alignment sleeve caused by misalignment of the alignment sleeve with a mating ferrule of a mating connector, Thus, the ferrule may only need to tilt through a small angle, up to about 5° or 3°, and may only need to deflect laterally through a small distance, up to about 1mm or 0.5mm, but it is important that the ferrule should be able to move within these ranges as freely as possible and/or with substantially equal freedom in any direction. The mechanisms provided by embodiments of the invention for allowing tilting and/or lateral deflection of the ferrule are preferably

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rotationally symmetrical about an axis of the ferrule and/or about a nominal axis of the alignment sleeve.

If a connector houses an alignment sleeve, the alignment sleeve is preferably loosely retained in a bore defined in a part of the connector housing shaped to mate with a mating connector. The sleeve is preferably axially substantially fixed in position but able to tilt and/or to move laterally during use. This may advaritageous!y enab!e the s!eeve and the ferrule within it to tilt and/or move laterally in order to accommodate misalignment with a mating ferrule of a io mating connector. In effect the ferrules may be self-aligning as the connector and the mating connector are engaged.

Advantageously, an optical-fibre connector or method embodying the invention may provide for removably connecting two or more optical fibres in parallel.

Alignment sleeves for each fibre may then be provided and the insert may advantageously engage with a respective support for each fibre.

A further aspect of the invention provides a method for assembling a connector of the type outlined above. An optical fibre may conventionally be surrounded by a fibre buffer which is protected by a sheath, typically of synthetic fibre. The buffer typically fits loosely within the sheath such that the fibre and buffer are slidable within the sheath. To assemble the connector a length of the sheath and the fibre buffer are stripped back from an end of the fibre. The support is then threaded over the end of the fibre and is preferably secured to the end of the sheath, for example by means of a crimped sleeve. The stripped end of the fibre may then be secured within the ferrule such that the ferrule assembly is slidable relative to the support. In a preferred embodiment, this involves sliding a piston portion of the ferrule assembly into a cylinder portion of the support, surrounded by a spring for urging the ferrule assembly away from the support and thus springloading the end of the fibre in a direction out of and away from the sheath.

if an optical-fibre cable carrying more than one fibre is to be connected, a ferrule assembly and a support are mounted on each fibre.

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The optical fibre or fibres may then be secured to the remainder of the connector by engaging each support with an insert which is fixed, or retained, at a fixed position within the connector. Advantageously, the insert may be shaped to receive all of the fibres of the optical-fibre cable to be coupled to the connector, the insert holding the supports at predetermined nominal positions and orientations so that the fibres are in position for connection to a mating connector.

Specific Embodiments and Best Mode of the Invention Specific embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a connector and a mating connector, or socket, embodying the invention, in assembled form, both connected and disconnected, with a rubber grip in place around the connector; Figure 2 shows a reverse view of the connectors of figure 1 ready for connection, with rubber grip and large assembly nut omitted; Figure 3 shows assembled and exploded views of the connector of figure 1, with rubber grip omitted; Figure 4 is an exploded view of the mating connector, or socket, of figure 1; Figure 5 is shows various components of the connector of figure 1 before assembly; Figure 6 shows the components of figure 5 aligned for assembly; Figure 7 shows two partial exploded views of the connector of figure 1; Figure 8 shows longitudinal sections of the connector and mating connector of figure 1 before engagement, or connection; Figure 9 shows longitudinal sections of the connector and mating connector of figure 1 engaged, or connected; Figure 10 shows perspective, plan, longitudinal section and rear-end views of an insert forming part of the connector and mating connector of figure 1; Figure 11 shows longitudinal sections of a fibre support engaging with an insert as shown in figure 10; and to Figure 12 shows longitudinal sections of an assembled connector as shown in figure 1, with rubber sleeve omitted.

Figure 1 shows a connector 100 and a mating connector or socket 102 according to a first embodiment of the invention. The connectors are shown is engaged, or connected, at the lower left corner of figure 1 and disengaged at the upper right corner. The socket 102 comprises a flanged main socket body 27 securable to a fixed surface such as a bulkhead in known manner, An externally-threaded sleeve 104 extends forwardly from the socket body for receiving a plug portion 106 of a main plug body of the connector 100. Two keys 28, 30 extend into the socket sleeve to engage keyways 31 formed in the plug portion. The keys prevent rotation of the plug portion relative to the socket body and are of different sizes, to ensure correct orientation of the plug portion and the socket body. A large assembly nut 15 encircles the plug portion and screws onto the externally-threaded sleeve of the socket to engage the connector and the socket.

In figure 1, the connector 100 is shown in fully assembled form, contained within a protective rubber grip 17. Figure 2 shows a reverse view of the connector and socket before engagement, with the rubber grip and the large assembly nut omitted. The connector and socket of figures 1 and 2 are for connecting an optical-fibre cable 108 containing two optical fibres. The plug portion 106 of the connector houses two alignment sleeves as described below, and has two openings 110 at its front end for receiving ferrules mounted on the ends of fibres housed within the socket and for guiding them into the alignment sleeves.

Figure 3 shows assembled and exploded views of the connector of figure 1, omitting the rubber grip 17. Figure 4 shows a corresponding exploded view of the mating connector, or socket, 102, which is of similar construction except that the alignment sleeves are housed in the connector 100 as described below. Where appropriate, the same reference numerals are used to indicate similar components in figures 3 and 4. Further details of the components and structure are shown in figures 5, 6 and 7. The optical fibre cable 108 comprises a cable outer jacket 18 surrounding a Keviar (RTM) cable sheath 19.

The outer jacket is stripped back, exposing the end of the Kevlar sheath, which is placed around a plug back-end 16 and crimped in place using a large crimp sleeve 4, shown crimped in position in the assembled connector at the upper left of figure 3. A flange 112 extends outwardly from a forward end of the plug back-end 16 adjacent to a groove for carrying a small 0-ring 12. A small assembly nut 13 encircles the plug back-end and can screw onto a rear-end 50 of the main plug body 14, abutting the flange and compressing the 0-ring against the main plug body to form a closed and sealed connector housing.

The optical-fibre cable contains two fibres 6. The structure of each fibre is shown most clearly in figures 5 and 6 and comprises the fibre 6 within a buffer 1, contained within a tube comprising a Kevlar (RIM) sheath 11 within a plastic (PVC) inner jacket 2. The buffered fibre is contained loosely within the tube and is therefore movable longitudinally within the tube.

Each fibre is terminated as follows. The plastic jacket 2 of the tube is stripped back, exposing a length of the Kevlar (RTM) 11. The buffered fibre is passed through a central bore 114 defined within a support 9, and the end of the Kevlar (RTM) is crimped onto a rear portion of the support 116, formed with circumferential ridges, by means of a small crimp sleeve 3. The Kevlar (RTM) sheath is shown crimped to the rear portion of the support in figure 7.

The end of the fibre emerging from the central bore of the support is secured to a ferrule assembly 52. A rear portion of the ferrule assembly comprises a cylindrical piston 7, which fits loosely within the bore 114 of the support 9 (as shown in figure 11). A further bore 115 is defined within the piston, sized to receive the buffered fibre 1. A front portion of the ferrule assembly comprises a fibre-optic ferrule 5. A fibre-receiving bore is defined within the ferrule, sized to receive the fibre 6. The buffer layer is removed from an end portion of the fibre, which extends within and is secured within the ferrule 5, for example using an epoxy resin.

The ferrule assembly 52 comprises an outwardly-extending flange 54 between the ferrule 5 and the piston 7, against which a helical spring 22 can abut. The support 9 is formed with a corresponding abutment surface 56, for receiving the 0 other end of the helical spring 22. When the ferrule assembly, the helical spring and the support are assembled, the piston 7 fits loosely within the support bore 114 and the helical spring encircles a forward portion of the support 117 and any portion of the piston extending from the bore. The helical spring thus acts as a compression spring urging the ferrule assembly away from the support.

In the assembled connector, the ferrule 5 for each fibre is urged by its spring 22 into an alignment sleeve 24 in the form of a split-sleeve coupling as shown in figure 3 and, in section, in figure 8. Each alignment sleeve is held within a bore 118 defined within the main plug body 14. The diameter of the bore is larger than the external diameter of the alignment sleeve, in order to allow for expansion of the alignment sleeve on insertion of the ferrule, and to allow the alignment sleeve to tilt and/or move laterally in order to accommodate any misalignment with a mating ferrule. Each alignment sleeve 24 is retained within its bore by a retaining bush 20. Each alignment sleeve is therefore free to tilt or move laterally within its bore, but is constrained from moving axially (although a small axial clearance is provided to allow for manufacturing tolerances and to ensure that each alignment sleeve can move freely within its bore).

The support 9 for each fibre is retained within a sub-assembly insert 10 as shown most clearly in figure 11. Details of the insert are shown in figures 3, 7, and 11. The insert is moulded from a plastic material and has a generally-cylindrical outer surface 120, which is shaped to fit within a corresponding recess within the rear of the main plug body 14. A key 122 extending from the outer surface of the insert fits within a corresponding keyway in the main plug

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body to align and prevent rotation of the insert relative to the main plug body.

The insert is formed with spring clips 124 which latch with corresponding recesses in the main plug body to hold the insert in place.

As shown in figure 10, the insert is formed as a unitary component including an outer sleeve 58 and a front wall 60, within which is defined an opening 128 comprising two circular portions aligned with the alignment sleeves 24 within the main plug body 14. In the assembled connector, the forward ends of the supports and the helical springs 22 pass through the opening 62 in the front io wall of the insert and the opening is sized to allow clearance (as shown at 126 in figure 11) between the opening and the support assemblies so that the support assemblies can tilt and/or move laterally freely in any direction.

Two opposed pairs of resilient clips 64 extend rearwardly from the front wall 60 is of the insert, within the outer sleeve 58 of the insert, and each clip is provided with a snap-fit hook 66 for engaging with a corresponding circumferential groove 130 defined in one of the supports 9, between the spring-abutment surface 56 and the small crimp sleeve 3. Each support, assembled with its helical spring and ferrule assembly, can thus be inserted through the rear end of the insert 10 until its groove 130 engages with the snap-fit hooks 66 of the resilient arms 64 behind one of the openings 62. Advantageously, the assembly of the connector can be simplified by first assembling the insert and the main connector body, and then pushing each of the ferrule assemblies into the rear of the insert, in a direction substantially parallel to each fibre axis, until the supports engage with the spring clips of the insert.

The width of each groove 130 is greater than the width of the corresponding snap-fit hook 66, and the external diameter of the portion of each support and spring located within the insert is smaller than the distance between the corresponding resilient arms 64, as shown in figure 11. This provides some clearance 127 for each support to tilt and/or move laterally freely within the insert in any direction. The flexibility of the resilient arms 64 may also allow tilting or movement of the support within the insert sleeve. Meanwhile the engagement of the support within the insert maintains a substantially fixed spacing between the support and the corresponding alignment sleeve. This is achieved by appropriately shaping the grooves 130 in the supports and the snap-fit hooks 66. The front surface of each groove and the corresponding surface 129 of each snap-fit hook is radial, rather than inclined, and so abutment of these surfaces retains the supports at a fixed axial position within the insert.

In addition each support is formed with a square flange 132 at the rear edge of the groove 130. The flat outer surfaces of the square flange seat within corresponding flat surfaces 134 of the resilient arms 64 to prevent or limit io rotation of each support relative to the insert. In other embodiments the flange 132 of the support and the corresponding surfaces 134 of the resilient arms may be of any suitable shape to prevent or limit rotation of each support relative to the insert.

Figure 8 shows the connector in cross section, disengaged from the socket, and figure 9 shows the connector and socket engaged, or connected, in cross section. As seen most clearly in the enlarged Detail Z in figure 9, when the connector and socket are engaged the ferrules 5 are butted together within each alignment sleeve 24. Each ferrule is urged into the alignment sleeve by its respective spring, and each spring is compressed by the abutment of the two ferrules. This can be seen by comparing Detail AE in figure 8, in which the flange 54 of the ferrule assembly of the connector is pressed by the spring 22 into contact with the alignment-sleeve-retaining bush 20, with Detail Z in figure 9, in which the flange 54 has moved away from the bush 20 to produce an axial clearance 136. A corresponding axial clearance 138 can be seen in the socket adjacent the flange 54 in Detail Z. As can be seen most clearly in Detail Z, clearances are provided around all external surfaces of the springs, the ferrule assemblies and the alignment sleeve in the engaged connector and socket, allowing all components to self-align by tilting and/or moving laterally to accommodate any misalignments and so to optimise the contact between the connected fibres. In addition, clearances are provided around all external surfaces of the supports, except for the contact between the radial surfaces of the grooves 130 and the snap-fit hooks 66 of the insert. These contacts define the distance between the supports and the alignment sleeve, but the clearance around all other external surfaces of the support allows the support to tilt and/or to move laterally to accommodate any misalignments. Further, the snap-fit hooks are supported on resilient arms 64 within the insert, which may also deflect resiliently to allow tilting and/or lateral deflection of the supports.

In use, in the assembled connector, the supports 9 are thus held at a fixed spacing from the alignment sleeves 24, and the ferrules 5 are urged into the alignment sleeves by the springs 22. The supports are each held in the insert io in a nominal orientation, with the supports pointing towards the alignment sleeves. The compression springs urge the ferrule assemblies away from the supports, holding the ferrule assemblies in a nominally axial direction, again directed towards the alignment sleeves. However, the supports are free to tilt andfor move laterally away from the nominal orientation in any direction, relative to the insert, and the ferrule assemblies are free to tilt, and/or move laterally, in any direction relative to the supports, due to the loose fit of the pistons of the ferrule assemblies within the bores of the supports. Thus, if either or both alignment sleeves tilt or move laterally when the connector is coupled with a mating connector, in order to accommodate misalignment within the connector or with a mating ferrule, the respective ferrule assembly of the connector can freely move in any direction and to any tilt or orientation in response to the movement of the alignment sleeve. Advantageously, this may reduce any lateral or tilting load between the alignment sleeve and the ferrule, and optimise the ability of the alignment sleeve to hold the ferrule and the mating ferrule in accurate alignment.

Parts and Features Lists for Figures

PART# DESCRIPTION

1 Fibre Buffer 2 Fibre Inner Jacket 3 Small Crimp Sleeve 4 Large Crimp Sleeve Fibre-Optic Ferrule 6 Optical Fibre -15- 7 Ferrule Back (Piston) 8 Adhesive Heat Shrink (12mm) 9 Rear Support Sub-Assembly Insert (SAl) 11 Synthetic Fibre 12 Small 0-Ring 13 Small Assembly Nut 14 Main Plug Body Large Assembly Nut io 16 Plug Back End 17 Rubber Grip 18 Cable Outer Jacket 19 Synthetic Fibre Retaining Bush 21 Rubber Washer 22 Spring 24 Alignment Sleeve Socket Back End 26 Large 0-Ring 27 Main Socket Body 28 Key PinA 29 Tube Strain Relief Key Pin B Rear End of Main Plug Body 54 Flange of Ferrule Assembly 56 Support (9) Spring Abutment Surface 62 Insert (10) Front Wall 64 Insert (10) Resilient Clips 66 Insert (10) Snap-Fit Hooks 100 Connector 102 Mating Connector or Socket 104 Externally Threaded Socket Sleeve 106 Plug Portion of Connector 108 Optical-Fibre Cable 110 Openings in Front Surface of Plug Portion of Connector 114 Central Bore of Support (9) Bore Within Ferrule Back (Piston) for Receiving Buffered Fibre 116 Rear Portion of Support (9) 117 Forward Portion of Support (9) 118 Bore in Rear Portion of Main Plug Body (14) Insert Outer Surface 122 Key on Insert Outer Surface 124 Insert Spring Clips 128 Opening in Insert Front Wall (62) io 130 Support (9) Groove 132 Support (9) Square Flange, or Shaped Flange 134 Surface of Resilient Arm Corresponding to Square Flange (132) 136 Clearance Between Ferrule-Assembly Flange and Bush in Engaged Connector is 138 Clearance Between Ferrule-Assembly Flange and Socket Body in Engaged Socket