TECHNICAL FIELD 
       [0001]    The present invention relates to the field of retractable equipment for aircraft, and more particularly it relates to actuating such equipment together with flaps for protecting the equipment. 
         [0002]    The invention is intended in particular for remote detection equipment, such as optronic sensors. 
       BACKGROUND 
       [0003]    It is known to fit aircraft with remote detection equipment. 
         [0004]    When such equipment is arranged in a high portion of an aircraft, the equipment can be mounted so as to remain in position. This applies for example to optronics pods for certain fighter airplanes. 
         [0005]    In contrast, when the equipment is arranged on a low portion of an aircraft, e.g. under the wings or under the fuselage, it is desirable for the equipment to be retractable into a compartment having movable protection means, such as one or more flaps, suitable for protecting the equipment from possible projectiles while the equipment is not in operation, and in particular while running along a runway during takeoff and landing. 
         [0006]    The protection means generally require dedicated drive means for driving them, i.e. means that are independent of the means for driving the equipment itself, and such dedicated means are found to be penalizing in terms of weight, of fabrication costs, of maintenance costs, and of overall size. 
         [0007]    There thus exists a need for a drive device that is compact, lightweight, and inexpensive. 
       SUMMARY 
       [0008]    To this end, the invention provides a system for an aircraft, the system comprising:
       a frame for mounting on an aircraft structure;   equipment movable relative to said frame along a predetermined path between a “retracted” position and a “deployed” position;   protection means movable between a first position in which said protection means intercept said path of said equipment in order to protect it, and a second position in which said protection means are spaced apart from said path in order to allow said equipment to pass therealong; and   at least one drive device for driving said protection means between said first and second positions.       
 
         [0013]    According to the invention, the drive device comprises:
       a cam secured to said frame;   a cam follower co-operating with said cam;   a drive member connected to said protection means so as to drive them between said first and second positions;   first coupling means mechanically coupling said cam follower to said equipment; and   second coupling means mechanically coupling said cam follower to said drive member.       
 
         [0019]    Furthermore, said cam, said first coupling means, and said second coupling means are configured in such a manner that said cam follower converts straight-line movement of said equipment along said path into straight-line movement of said drive member in such a manner that the ratio of the respective speeds of said drive member and of said equipment varies during the movement of said equipment. 
         [0020]    In conventional manner, the term “cam follower” designates an element that is constrained to remain in contact with said cam. 
         [0021]    The drive device thus makes it possible to provide mechanical coupling between said equipment and said protection means so that a single motor member can be used for driving both said equipment and also the protection means. 
         [0022]    The variation in the ratio of the respective speeds of the drive member and of the equipment that is obtained by the drive device makes it possible to optimize synchronization between the respective movements of the equipment and of the protection means. 
         [0023]    In particular, it is thus possible to cause the protection means to move relatively quickly from their first position towards their second position so as to ensure that the protection means do not constitute an obstacle to the passage of the equipment while it is being deployed. In analogous manner, the movement of the protection means from their second position towards their first position can be caused to take place for the most part or entirely during a final part of the equipment retraction stroke. 
         [0024]    Consequently, the invention allows the equipment in the “retracted” position to be relatively close to the protection means in their first position, and the invention makes it possible to limit the extent to which the protection means need to be spaced away from the path of the equipment when the protection means are in their second position. 
         [0025]    Preferably, said cam, said first coupling means, and said second coupling means are configured to couple the movement of said drive member with the movement of said equipment when the equipment lies between its “retracted” position and a predetermined intermediate position, and to decouple the movements of said drive member and of said equipment when said equipment lies between said predetermined intermediate position and its “deployed” position. 
         [0026]    During the deployment of said equipment, the drive device thus enables the protection means to move from their first position towards their second position while the equipment is passing from its “retracted” position to said intermediate position, and it the enables the protection means to be held in their second position while the equipment is passing from said intermediate position to its “deployed” position. 
         [0027]    In analogous manner, during retraction of the equipment, the drive device enables the protection means to be held in their second position while the equipment is passing from its “deployed” position to said intermediate position, after which it enables the protection means to move from their second position towards their first position while the equipment is passing from said intermediate to its “retracted” position. 
         [0028]    The decoupling of the respective movements of the drive member and of the equipment should not be understood as meaning that these two elements are mechanically decoupled. On the contrary, the cam and the first and second coupling means serve to maintain a mechanical connection between the drive member and the equipment even when their movements are decoupled. This mechanical connection makes it possible to control the position of the drive member all along the stroke of the equipment. 
         [0029]    In a preferred embodiment of the invention:
       said cam is formed by a first slideway secured to said frame;   said second coupling means comprise a second slideway movable in parallel with said path of said equipment; and   said cam follower is engaged simultaneously in said first and second slideways.       
 
         [0033]    Under such circumstances, the shape of the first and second slideways makes it possible to define the transfer function that defines the straight-line movement of the drive member as a function of the straight-line movement of the equipment. 
         [0034]    In a preferred embodiment of the invention, said first slideway has a first portion extending parallel to said path of said equipment, a second portion extending orthogonally to said path of said equipment, and a curved portion serving to enable said cam follower to be guided from one to the other of said first and second portions. 
         [0035]    The first portion of the first slideway defines a path for the cam follower that is parallel to said path of said equipment, while the second portion of the first slideway defines a path of the cam follower that is orthogonal to said path of said equipment. 
         [0036]    In addition, said second slideway preferably extends orthogonally to said path of said equipment. 
         [0037]    The first portion of the first slideway defines a path of the cam follower in which the cam follower drives the second slideway and thus the drive member under the effect of the equipment moving. 
         [0038]    The second portion of the first slideway defines a path of the cam follower in which the cam follower holds the second slideway stationary, together with the drive member, independently of any movement of the equipment. 
         [0039]    The system advantageously includes a support on which said equipment is mounted. 
         [0040]    The support is preferably provided with hinge means. 
         [0041]    In addition, said first coupling means advantageously comprise a connecting rod having a first end hinged to said hinge means of said support, and a second end hinged to said cam follower. 
         [0042]    In co-operation with the cam, the connecting rod makes it possible to cause the cam follower to be driven parallel to the path followed by the support during the movement of said equipment, when the support is situated in a first portion of said path, and it enables the cam follower to be blocked in the direction of said path when the support is situated in a second portion of its path. 
         [0043]    Said connecting rod is preferably designed in such a manner that its two ends are movable relative to each other. This makes it possible in particular to shorten the length of the above-mentioned second portion of the first slideway while avoiding risks of the connecting rod jamming during the movement of said equipment. 
         [0044]    Under such circumstances, the connecting rod advantageously includes resilient means interconnecting its two ends so as to damp any vibration between said ends. By way of example, these resilient means may be formed by a double-acting spring. 
         [0045]    In a preferred embodiment of the invention, said hinge means of said support are arranged in such a manner that the orthogonal projection of a hinge axis of said first end of said connecting rod onto a line parallel to said second portion of said first slideway is offset from a hinge axis of said second end of said connecting rod in a direction going from said second portion towards said first portion of said first slideway, when said protection means are in said first position. 
         [0046]    In a variant, the first coupling means may comprise a cam secured to said support and co-operating with said cam follower in such a manner as to drive the cam follower under the effect of said equipment moving, at least when the equipment is in a predetermined portion of said path. 
         [0047]    Under such circumstances, said cam secured to the frame and said cam secured to the support act to determine the path followed by the cam follower during movement of said equipment. 
         [0048]    In general, said protection means are preferably movable in turning about an axis orthogonal to said path of said equipment. 
         [0049]    Furthermore, said protection means advantageously comprise two flaps movable in turning about a common axis of rotation and in respective opposite directions. 
         [0050]    Furthermore, said drive device preferably comprises two first arms hinged together to said second coupling means by means of a pivot forming said drive member, together with two second arms having:
       respective first end portions hinged respectively to said first arms;   respective second end portions fastened respectively to the two flaps of said system; and   respective middle portions hinged together to said frame in such a manner as to pivot about a common hinge axis such that said second arms form a scissors mechanism.       
 
         [0054]    The second arms thus form a scissors type mechanism. Spacing apart the respective first end portions of the second arms causes the respective second end portions of the second arms to be spaced apart because of the respective middle portions of the second arms being hinged together to said frame. In analogous manner, movement of the above-mentioned first end portions towards each other causes the above-mentioned second end portions to move towards each other. 
         [0055]    The second arms thus make it possible to alternate between moving the two flaps forming said protection means between moving apart from each other and moving towards each other. 
         [0056]    Furthermore, the first arms make it possible to convert the straight-line movement of the drive member into the above-described movement of the second arms moving apart and moving towards each other. 
         [0057]    In a variant, said drive member may be formed by a rack extending in the direction of the path of said equipment and co-operating by meshing with two pinions secured respectively to the two above-mentioned flaps and movable in rotation about the common axis of rotation of the flaps. 
         [0058]    In general, said equipment comprises an optronic sensor, for example. 
         [0059]    In a variant, the equipment may comprise any other type of sensor or detector, or indeed any other type of equipment. 
         [0060]    Furthermore, each of said flaps is preferably in the form of a portion of a sphere. 
         [0061]    In their first position, the two flaps can thus together form a dome or a portion of such a dome. 
         [0062]    This configuration is particularly advantageous when the above-mentioned equipment includes an element of spherical shape, such as an optronics pod. 
         [0063]    The invention also provides an aircraft having at least one system of the above-described type. 
         [0064]    In a preferred embodiment of the invention, said protection means of said system close an opening formed in a fairing of said aircraft when said protection means are in said first position. 
         [0065]    The fairing may in particular form a portion of the fuselage or of the wings of an aircraft, or indeed of a landing gear nacelle fitted to the fuselage of an aircraft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0066]    The invention can be better understood and other details, advantages, and characteristics thereof appear on reading the following description made by way of non-limiting example and with reference to the accompanying drawings, in which: 
           [0067]      FIG. 1  is a fragmentary diagrammatic side view of a system comprising retractable equipment and means for protecting it, in a preferred embodiment of the invention, shown with said equipment in a retracted state; 
           [0068]      FIG. 2  is a view similar to  FIG. 1 , in which a side plate of the frame is omitted in order to reveal a drive device for driving the protection means; 
           [0069]      FIG. 3  is a view similar to  FIG. 2 , showing the system in a deployed state of said equipment; 
           [0070]      FIG. 4  is an exploded fragmentary diagrammatic view in perspective of the drive device for driving the protection means of said equipment, the drive device being shown on its own; 
           [0071]      FIGS. 4   a ,  4   b , and  4   c  are fragmentary diagrammatic views in perspective of the  FIG. 4  drive device, respectively showing three states of the drive device corresponding respectively to the retracted state, to an intermediate state, and to the deployed state of said equipment; and 
           [0072]      FIGS. 5   a  and  5   b  are fragmentary diagrammatic views in perspective as seen from below showing an aircraft landing gear nacelle including the system of the above figures. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0073]      FIGS. 1 to 3  show an aircraft system  10  comprising retractable equipment, e.g. constituted by an optronic sensor  12  of the type that can be referred to as an “optronic pod”. 
         [0074]    By way of example, the system  10  is for housing in a landing gear nacelle of a military transport airplane, as can be seen more clearly below. 
         [0075]    The system  10  comprises a frame having in particular two laterally-arranged columns  16 , one of which is hidden by the other in  FIGS. 1 to 3 , together with a top platform  18  ( FIG. 1 ) fastened to the respective top ends of the columns  16 , and a bottom platform  20  ( FIG. 2 ) fastened to the respective bottom ends of the columns  16 . The platforms  18  and  20  extend orthogonally to the columns  16 . The frame also has two side plates  14  fastened to the bottom platform  20 , one of which is visible in  FIG. 1 , these side plates being omitted in the other figures for reasons of clarity. 
         [0076]    The system  10  also has a motor  22  mounted on the top platform  18 , together with a threaded rod  24  coupled to a rotor of the motor  22  and extending parallel to the columns  16 . The threaded rod  24  has smooth end portions that are rotatably mounted respectively in two respective orifices in the platforms  18  and  20 . 
         [0077]    The system  10  also has a support  26  comprising a movable platform  28  mounted to slide on the columns  16 , together with a fork mount  30  fastened on a support column  32 , itself mounted on a bottom face of the movable platform  28  so as to enable the support column  32  to turn about a first axis of rotation  34  parallel to the columns  16 . 
         [0078]    The optronic sensor  12  is mounted on the fork mount  30  in such a manner as to enable the optronic sensor to turn about a second axis of rotation  36  orthogonal to the first axis of rotation  34 . 
         [0079]    The movable platform  28  has a tapped orifice or nut  35  into which the threaded rod  24  is screwed so as to enable the support  26  to be driven in translation along the columns  16  by a “lead-screw” type effect between a position in which the optronic sensor is retracted ( FIGS. 1 and 2 ) and a position in which the optronic sensor is deployed ( FIG. 3 ). 
         [0080]    The system  10  also has two flaps  38 , each in the form of one-fourth of a sphere, together with two drive devices  40  enabling the flaps  38  to be driven between a first position ( FIGS. 1 and 2 ) and a second position ( FIG. 3 ) in a manner that is synchronized with the movement of the support  26 , as can be seen more clearly below. In their first position, the flaps  38  serve substantially to close an opening formed in a fairing forming part of the above-mentioned landing gear nacelle and designed to allow the optronic sensor  12  to pass therethrough. It should be observed that the two drive devices  40  are arranged on either side of the system  10 , so that one of these drive devices is masked in  FIGS. 1 to 3 . 
         [0081]    In the first position ( FIGS. 1 and 2 ) the flaps  38  are substantially in contact with each other and they are arranged facing the optronic sensor  12 , which is in its “retracted” position. The flaps  38  thus intercept the path followed by the optronic sensor  12  on moving between its “retracted” position and its “deployed” position. 
         [0082]    In the second position ( FIG. 3 ), the flaps  38  are spaced apart from each other and they are arranged on either side of the optronic sensor  12 , which is in its “deployed” position. The flaps  38  are then spaced apart from the path followed by the optronic sensor  12 . 
         [0083]    The two drive devices  40  are similar to each other and they are arranged on either side of the support  26 . These devices are described below in greater detail with reference to  FIGS. 2 and 3 , which show one of the drive devices  40  incorporated in the system  10 , and with reference to  FIGS. 4 and 4   a  to  4   c , which show the drive device in isolation from the remainder of the system  10 . 
         [0084]    The drive device  40  has a main cheekplate  42  fastened to the corresponding side plate  14  (see  FIG. 1 ), and a secondary cheekplate  43  fastened to a top end of the main cheekplate  42 , spaced apart therefrom, and facing it. 
         [0085]    The cheekplates  42  and  43  have two similar respective slideways  44  (see the other figures), each referred to as a “first” slideway in the terminology of the invention, and each having a first portion  44   a  extending parallel to the columns  16 , a second portion  44   b  extending orthogonally to the columns  16 , and a curved portion connecting together the first and second portions  44   a  and  44   b . Furthermore, two guide rods  46  that extend parallel to the columns  16  are fastened respectively to the sides of the main cheekplates  42 . 
         [0086]    The drive device  40  also has a slideplate  48  extending between the main cheekplate  42  and the secondary cheekplate  43 . This slideplate  48  has lateral ends mounted respectively on the guide rods  46  so as to enable the slideplate  48  to slide along the guide rods  46 . The slideplate  48  includes a slideway  50  referred to as a “second” slideway in the terminology of the invention, formed in a top portion of the slideplate and extending orthogonally to the columns  16 , and a lug  51  formed in a bottom portion of the slideplate  48 . 
         [0087]    The drive device  40  also has a slider  52  comprising a pivot  54 , two first wheels  56  ( FIG. 4 ) mounted on the pivot  54  and engaged respectively in the respective first slideways  44  of the cheekplates  42  and  43 , and a second wheel  58  mounted on the pivot  54  and engaged in the second slideway  50  of the slideplate  48 . The second wheel  58  is thus arranged between the two first wheels  56 . 
         [0088]    The drive device  40  also has a connecting rod  60  with a first end  62  ( FIGS. 2 and 3 ) hinged to a pivot  64  mounted on a side face of the movable platform  28 , and an opposite second end  66  hinged to the pivot  54  of the slider  52  ( FIG. 4   c ). In the example shown, the second end  66  of the connecting rod is interposed between the second wheel  58  and the first wheel  56  that is engaged in the first slideway  44  of the secondary cheekplate  43 . 
         [0089]    It should be observed that the pivot  64  forms hinge means in the terminology of the invention. Furthermore, the pivots  54  and  64  define respective hinge axes for the first and second ends  62  and  66  of the connecting rod  60 . 
         [0090]    In the example shown, the connecting rod  60  is designed to damp vibration between its two ends  62  and  66 . For this purpose, these two ends of the connecting rod are slidably mounted relative to each other and resilient damper means are interposed between these two ends of the connecting rod, inside it. These resilient damper means may for example be in the form of a double-acting spring. 
         [0091]    When the optronic sensor  12  is in its “retracted” position ( FIG. 2 ), the hinge axis of the first end  62  of the connecting rod  60  as defined by the pivot  64  is offset from the hinge axis defined by the pivot  54  of the slider  52  in the direction represented by arrow F, i.e. in the direction going from the second portion  44   b  towards the first portion  44   a  of each first slideway  44 . More precisely, the orthogonal projection of the hinge axis defined by the pivot  64  onto a line  67   a  parallel to the second portion  44   b  of each first slideway  44  and passing through the hinge axis defined by the pivot  54  is offset relative to this latter hinge axis in the direction of arrow F. It should be observed that this orthogonal projection of the hinge axis defined by the pivot  64  is located where the line  67   a  intersects a line  67   b  parallel to the columns  16  and passing through this latter hinge axis ( FIG. 2 ). 
         [0092]    This property remains true throughout the deployment and retraction process. In particular, this property remains true during deployment, when the first wheels  56  of the slider  52  leave the curved portion and enter the second portion  44   b  of each first slideway  44 . This makes it possible to guarantee that the connecting rod  60  continues to push the slider  52  further along the respective second portions  44   b  of the first slideways  44  until the first end  62  of the connecting rod  60  crosses the line  67   a,  as can be seen more clearly below. 
         [0093]    The drive device  40  also has two first arms  68  and two second arms  70 . 
         [0094]    The respective top ends of the first arms  68  are hinged on a common pivot  72  mounted in the lug  51  of the slideplate  48 . The respective bottom ends of the first arms  68  are hinged respectively to the respective top ends of the second arms  70 . The second arms  70  have respective middle portions mounted to pivot about a common hinge axis  74  ( FIGS. 4   a  to  4   c ) defined by a pivot  75 , itself mounted on the corresponding side plate  14  (a part of which is visible in  FIGS. 2 and 3 ). The second arm  70  has respective bottom ends fastened respectively to the two flaps  38  ( FIGS. 2 and 3 ). 
         [0095]    It should be observed that the hinge axis  74  of the second arms  70  preferably extends parallel to a longitudinal direction of the aircraft fitted with the system  10 . Thus, the movement of the flaps  38  takes place substantially orthogonally relative to the relative wind when the aircraft is in flight. 
         [0096]    The operation of the system  10  is described below. 
         [0097]    When the system is in the state corresponding to  FIG. 2 , the optronic sensor  12  is retracted and the flaps  38  are in their first position, facing the optronic sensor, so as to protect it from any impacts against obstacles or projectiles. 
         [0098]    In this state, the drive device  40  is as shown in  FIG. 4   a . In particular, each first wheel  56  of the slider  52  is arranged substantially at the top end of the first portion  44   a  of the corresponding first slideway  44 . 
         [0099]    The optronic sensor  12  is deployed by means of a command for setting the motor  22  into operation so as to turn the threaded rod  24  in a direction suitable for causing the support  26  to move towards the bottom  20 , by the lead-screw effect. 
         [0100]    The movable platform  28  then drives the first end  62  of the connecting rod  60  along a straight-line path parallel to the columns  16 . 
         [0101]    Simultaneously, each first wheel  56  of the slider  52  is guided along the corresponding first slideway  44 . 
         [0102]    In a first stage of the deployment, each first wheel  56  moves downwards along the first portion  44   a  of the corresponding first slideway  44 , and it then moves along the curved portion thereof, thereby driving the second wheel  58  of the slider  52  downwards and thus the slideplate  48  together with the pivot  72  mounted through the lug  51  of the slideplate  48 . The downward movement of the pivot  72  causes the bottom ends of the first arms  68  to move apart from each other, thereby causing the bottom ends of the second arms  70  in turn to move apart from each other by a scissors movement effect, thereby causing the flaps  38  to move apart from each other. 
         [0103]      FIG. 4   b  shows the drive device  40  when each first wheel  56  is in the curved portion of the corresponding first slideway  44 . 
         [0104]    Under the effect of the downward movement of the first end  62  of the connecting rod  60 , the first wheel  56  continues to travel until it enters into the second portion  44   b  of the first slideway  44 . This moment marks the transition into a second stage of deployment, in which the slideplate  48  ceases to move, given the orientations of the first slideways  44  and of the second slideway  50 . The flaps  38  have then reached their second position. 
         [0105]    Driven by the threaded rod  24 , the movable platform  28  continues to drive the first end  62  of the connecting rod  60  downwards, thereby tending to push each first wheel  56  further into the second portion  44   b  of the corresponding first slideway  44 . 
         [0106]    When the first end  62  of the connecting rod  60  crosses the line  67   a  orthogonal to the columns  16  and passing via the hinge axis defined by the pivot  54  of the slider  52 , the travel direction of each first wheel  56  in the second portion  44   b  of each first slideway  44  reverses. Specifically the downward movement of the first end  62  of the connecting rod  60  then tends to pull each first wheel  56  in the direction of arrow F. 
         [0107]    Deployment terminates before each first wheel  56  reaches the curved portion of the corresponding first slideway  44 . 
         [0108]    The drive device is then in the state shown in  FIG. 4   c , and the optronic sensor  12  is deployed, the support  26  extending between the flaps  38 , as shown in  FIG. 3 . 
         [0109]    The optronic sensor  12  is retracted by means of a command to set the motor  22  into operation so as to turn the threaded rod  24  in a direction serving to move the support  26  towards the top platform  18  by the lead-screw effect. 
         [0110]    The drive device  40  then moves in opposite manner to the above description. Thus, in a first stage of retraction, the slideplate  48  remains stationary so that the flaps  38  remain spaced apart and to allow the optronic sensor  12  to pass between them, after which in a second stage of retraction, the slideplate  48  is driven upwards by the slider  52  and causes the flaps  38  to move until they reach their first position as shown in  FIG. 2 . 
         [0111]    It can clearly be seen that the drive device optimally synchronizes the movements of the support  26  and of the flaps  38 . More precisely, the slider  52  serves to convert straight-line movement of the support  26 , and thus of the optronic sensor  12 , into straight-line movement of the pivot  72  passing through the lug  51  of the slideplate  48 , while allowing the ratio of the respective speeds of the pivot  72  and of the support  26  to be varied. 
         [0112]    The curve showing variation of this speed ratio along the stroke of the support  26  is determined in particular by the shape of the first slideways  44  which together form a cam, and by the shape of the second slideway  50 . The slider  52  thus forms a cam follower, in the terminology of the invention. 
         [0113]    Furthermore, in the terminology of the invention, the connecting rod  60  forms first coupling means, while the slideplate  48  forms second coupling means, and the pivot  72  passing through the lug  51  of the slideplate  48  forms a drive member. 
         [0114]    In general, the motor  22  ( FIG. 1 ) enables the support  26  of the optronic sensor  12  and also the flaps  38  to be driven with respective optimum movements. 
         [0115]      FIGS. 5   a  and  5   b  show a rear landing gear nacelle  76  of a military transport airplane in which a system  10  of the above-described type can be housed. 
         [0116]      FIG. 5   a  shows the system  10  with the optronic sensor in its “retracted” position, only the flaps  38  being visible from outside the nacelle  76 . These flaps are in their first above-mentioned position, thereby forming a dome that projects through an orifice  78  provided in a bottom portion of the nacelle  76 . The flaps  38  thus substantially close the orifice  78 . 
         [0117]      FIG. 5   b  shows the optronic sensor  12  in the “deployed” position. Under such circumstances, the flaps  38  are retracted into the inside of the nacelle  76 , being spaced apart on either side of the above-mentioned orifice  78 , and the fork mount  30  projects through the orifice  78 . 
         [0118]    In a variant, the coupling between the support  26  and the slider  52  need not be provided by a connecting rod as described above, and may instead be provided with an additional slideway secured to the support  26  and having the slider  52  engaged therein. By way of example, such a slideway may be formed in a cheekplate extending downwards from the movable platform  28 . The additional slideway presents a shape in the form of a straight line sloping relative to the direction of the second portion  44   b  of each first slideway  44  going upwards and away from the first portion  44   a  towards the second portion  44   b  of each first slideway  44 . The slider  52  thus remains stationary relative to the additional slideway when it is in the first portion  44   a  of each first slideway. The slider  52  is then driven together with the support  26  and it drives the slideplate  48  in turn. In contrast, when the slider  52  is in the second portion  44   b  of each first slideway  44 , the slider moves in the additional slideway so as to allow the support  26  to continue moving while preventing the slideplate  48  from moving relative to the frame. 
         [0119]    In general, the above-described system  10  proposes a technique for deploying and retracting equipment  12  in the vertical direction relative to an aircraft. Nevertheless, it can clearly be seen that the operation of the system  10  is independent of its orientation. The system  10  can thus be positioned so as to enable the equipment  12  to be deployed along some other direction without going beyond the ambit of the invention.
A system for retractable equipment is proposed that has movable protection flaps and in which a flap drive device serves to drive the flaps in optimized movement, while providing mechanical coupling between the flaps and the retractable equipment in such a manner that a common motor member can be used for driving both the equipment and the flaps. The drive device includes a cam secured to a frame of the system and a cam follower mechanically coupled to the retractable equipment and to a flap drive member. The path followed by the retractable equipment can thus also be optimized.