Abstract:
A mechanism for coupling and uncoupling a motor inlet shaft and an outlet shaft, in particular, the inlet shaft is mounted in rotation on a front frame, and the outlet shaft is mounted in rotation on a rear frame. The outlet shaft rotates an outlet pinion, and the rear frame is slidably mounted to translate between a forward compact position and a backward deployed position. The mechanism includes a coupler, and first and second lockers to couple or uncouple the inlet and outlet shafts according to the translation of the rear frame between the forward compact position and the backward deployed position. The first locker locks in rotation the inlet shaft on the front frame, the second locker locks the outlet shaft on the rear frame. In particular, the second locker automatically locks the inlet and outlet shafts in rotation respectively, according to the displacement of the rear frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/FR2013/051554, filed on Jul. 2, 2013, which claims the benefit of FR 12/56438, filed on Jul. 5, 2012, and FR 12/57685, filed on Aug. 8, 2012. The disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a coupling and uncoupling mechanism for a turbojet engine nacelle equipped with a thrust reversal device. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    A nacelle generally exhibits a longitudinal tubular structure comprising, from front to back, an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section accommodating a thrust reversal device and intended to surround the combustion chamber of the turbojet engine, and is generally terminated by an ejection nozzle of which the outlet is located downstream of the turbojet engine. 
         [0005]    Modern nacelles are intended to accommodate a dual flow turbojet engine able to generate by means of the blades of the fan in rotation a hot air flow, also called primary flow, from the combustion chamber of the turbojet engine, and a cold air flow, or secondary flow, which circulates outside the turbojet engine through an annular passage, also called secondary stream, formed between a fairing of the turbojet engine and an inner wall of the nacelle. The two air flows are ejected from the turbojet engine by the rear of the nacelle. 
         [0006]    The role of a thrust reversal device is, during the landing of an aircraft, to improve the braking capacity thereof by redirecting towards the front at least part of the thrust generated by the turbojet engine. In this phase, the reverser obstructs at least the stream of cold flow and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft. 
         [0007]    The means implemented to achieve this reorientation of the cold flow vary depending on the type of reverser. 
         [0008]    In the case of a deviation grid reverser, the thrust reversal device comprises deviation grids having for function to reorient the air flow, and which are often associated with reversal shutters and at least one movable cowl. 
         [0009]    The cowl is slidably mounted in translation from front to back on the structure of the nacelle, along a direction which is substantially parallel with a longitudinal axis of the nacelle, between a forward compact position in which the cowl closes a passage intended for the diverted flow, and a backward deployed position in which the cowl opens this passage and uncovers the deviation grids. 
         [0010]    Furthermore, apart from its thrust reversal function, the sliding cowl comprises a downstream portion forming the ejection nozzle aiming to channel the ejection of the air flows. 
         [0011]    The nozzle is designed to modulate the thrust by making its outlet section vary in response to variations in the adjustment of the power of the engine and flight conditions. 
         [0012]    This type of movable nozzle with a variable section is known by the name of adapted nozzle, or under acronyms VFN for Variable Fan Nozzle or VAFN for Variable Area Fan Nozzle. 
         [0013]    According to the most known alternative forms, the adapted nozzle may be a single piece, or formed from a set of juxtaposed deflectors. 
         [0014]    The deflectors are driven in movement by means of a longitudinal outlet shaft which is onboard the movable cowl, the outlet shaft being driven in rotation by means of a motor inlet shaft which is integral with the structure of the nacelle. 
         [0015]    It is known from document WO-2011/135217-A1 to provide a mechanism which is designed to couple in rotation the inlet shaft and the outlet shaft together when the cowl occupies its forward compact position, and uncouple the inlet shaft and the outlet shaft when the cowl occupies its backward deployed position. 
         [0016]    This coupling mechanism is of claw type, the inlet shaft comprising a first toothing and the outlet shaft comprising a second complementary toothing which is designed to engage with the first toothing. 
         [0017]    The coupling of the outlet shaft and the inlet shaft is achieved by axial imbrication of the first toothing in the second toothing during the displacement of the cowl towards its forward compact position. 
         [0018]    In order to allow this imbrication, the outlet shaft must be blocked angularly in rotation. 
         [0019]    To this end, the mechanism according to document WO-2011/135217-A1 comprises a means for locking in rotation the outlet shaft which allows locking the outlet shaft in rotation as a result of the displacement of the cowl towards its backward deployed position. 
         [0020]    This mechanism is not entirely satisfactory as nothing is provided to block and lock in rotation the motor inlet shaft, thus risking jeopardizing the coupling of the inlet shaft with the outlet shaft in the event of an untimely rotation of the inlet shaft. 
       SUMMARY 
       [0021]    The present disclosure proposes a mechanism of a turbojet engine nacelle, for coupling and uncoupling a motor inlet shaft which is mounted in rotation on a front frame around a secondary longitudinal axis, and an outlet shaft which is mounted in rotation on a rear frame around the secondary axis and which drives in rotation an outlet pinion, the rear frame being slidably mounted from front to back with respect to the front frame, along a longitudinal direction, between a forward compact position and a backward deployed position, the mechanism being equipped with a coupling means which is designed to couple in rotation the inlet shaft and the outlet shaft together when the rear movable frame occupies its forward compact position, and uncouple the inlet shaft and the outlet shaft when the rear frame occupies its backward deployed position, characterized in that the mechanism comprises a first means for locking in rotation the inlet shaft on the associated front frame, and a second means for locking in rotation the outlet shaft on the associated rear frame, which are designed to automatically lock the inlet shaft and the outlet shaft in rotation respectively, under the effect of the displacement of the rear movable frame toward its backward deployed position. 
         [0022]    According to another feature, the first means for locking the inlet shaft, of claw type, comprises: 
         [0023]    a first locking pinion which is linked in rotation on the inlet shaft around the secondary axis and which delimits a first radial toothing oriented towards the front, 
         [0024]    a locking ferrule which delimits a second radial toothing arranged facing said first toothing, the locking ferrule being slidably mounted axially on the front frame between a front unlocking position in which the first toothing is arranged facing the second associated toothing, and a rear locking position in which the first toothing cooperates with the second toothing to lock in rotation the inlet shaft on the associated front frame, 
         [0025]    a first elastic return means which is axially interposed between the front frame and the locking ferrule and which automatically returns the locking ferrule towards its rear locking position, and the rear movable frame comprises a bearing portion which is designed to axially bear against the locking ferrule towards the front, such that the locking ferrule is axially constrained in its front unlocking position countering the first elastic return means when the rear frame occupies its forward compact position, and the ferrule is automatically released in its rear locking position when the rear frame is driven towards its backward deployed position. 
         [0026]    According to this feature, the locking in rotation of the inlet shaft is achieved in an automatic manner by displacing the rear frame. 
         [0027]    Similarly, the second means for locking the outlet shaft, of claw type, comprises: 
         [0028]    a third radial toothing which is integral with the rear frame and which is oriented backwards, 
         [0029]    a second locking pinion which is linked in rotation on the outlet shaft around the secondary axis and which delimits a fourth radial toothing arranged facing said third toothing, 
         [0030]    an axial sliding means for guiding the outlet shaft between a rear unlocking position in which the third toothing is arranged facing the fourth toothing, and a front locking position in which the third toothing cooperates with the fourth toothing to lock in rotation the outlet shaft on the associated rear frame, 
         [0031]    a second elastic return means which is axially interposed between the rear frame and the second locking pinion to automatically return the outlet shaft towards its front locking position, in such a manner that the outlet shaft is axially constrained in its rear unlocking position countering the second elastic return means when the rear movable frame occupies its forward compact position, and the outlet shaft is automatically released in its front locking position when the rear movable frame is driven towards its backward deployed position. 
         [0032]    According to this feature, the locking in rotation of the outlet shaft is achieved automatically by displacing the rear frame, following the locking of the inlet shaft. 
         [0033]    Moreover, the mechanism is designed in such a manner that the first locking means locks the inlet shaft before the second locking means locks the outlet shaft. 
         [0034]    This feature prevents an untimely rotation of the inlet shaft after the outlet shaft has been locked in rotation. 
         [0035]    In addition, the mechanism is designed in such a manner that the coupling means uncouples the inlet shaft and the outlet shaft after the locking in rotation of the inlet shaft and the outlet shaft. 
         [0036]    This feature allows maintaining the angular orientation of the inlet shaft and the outlet shaft to allow the recoupling of theses shafts following the uncoupling. 
         [0037]    Moreover, the means for coupling the inlet shaft with the outlet shaft is of claw type and comprises a first coupling portion with axial toothing which is arranged on a rear axial end of the inlet shaft, and a second coupling portion with axial toothing of complementary shape which is arranged on a front axial end of the outlet shaft. 
         [0038]    According to another aspect, the mechanism is designed to drive in rotation a receiving element which is mounted in rotation around a main longitudinal axis and which is designed to drive in movement an adapted nozzle of the turbojet engine. 
         [0039]    In addition, the inlet shaft is secured in rotation to a motor pinion which delimits a toothing of the same diameter as the toothing of the outlet pinion and which is axially adjoined to the outlet pinion when the outlet shaft occupies its rear unlocking position, and the receiving element is secured in axial translation to the rear frame, the receiving element delimiting a receiving toothing designed to axially slide from the toothing of the motor pinion, onto the toothing of the outlet pinion during the sliding of the outlet shaft towards its front locking position to allow the locking in rotation of the receiving element. 
         [0040]    According to this feature, the receiving element is locked in rotation when the rear frame occupies its backward deployed position and that the inlet shaft is uncoupled from the outlet shaft. 
         [0041]    In addition, the receiving element is an annular ring which comprises: 
         [0042]    an outer peripheral annular portion which cooperates with a complementary housing formed in the rear frame to secure the receiving element and the rear frame in axial translation, and 
         [0043]    an inner annular portion which delimits the receiving toothing which is designed to engage with the motor pinion and the outlet pinion. 
         [0044]    In addition, the rear frame is carried by a movable cowl of an onboard thrust reversal device of a turbojet engine. 
         [0045]    The present disclosure also relates to a turbojet engine nacelle, characterized in that it is equipped with a coupling and uncoupling mechanism according to any one of the preceding claims. 
         [0046]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0047]    In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
           [0048]      FIG. 1  is a perspective view, which illustrates a nacelle of a turbojet engine of an aircraft comprising a movable cowl represented in its forward compact position; 
           [0049]      FIG. 2  is a perspective view, which illustrates the nacelle of  FIG. 1  of which the cowl occupies its backward deployed position; 
           [0050]      FIG. 3  is an exploded perspective view, which illustrates the mechanism of coupling and uncoupling an inlet shaft and an outlet annular ring, by means of a locking shaft according to the present disclosure; 
           [0051]      FIG. 4  is a sectional longitudinal axial perspective view, which illustrates the mechanism of  FIG. 3  in which the annular outlet ring and the inlet shaft are free in rotation; 
           [0052]      FIG. 5  is a sectional longitudinal axial perspective view, which illustrates the mechanism of  FIG. 3  in which the inlet shaft is locked in rotation; 
           [0053]      FIG. 6  is a sectional longitudinal axial perspective view, which illustrates the mechanism of  FIG. 3  in which the locking shaft, the annular outlet ring and the inlet shaft are locked in rotation; 
           [0054]      FIG. 7  is a sectional longitudinal axial perspective view, which illustrates the mechanism of  FIG. 3  in which the inlet shaft and the locking shaft are uncoupled, and the locking shaft and the annular outlet ring are locked in rotation; 
           [0055]      FIG. 8  is a perspective view, which illustrates the mechanism of  FIG. 3  comprising a receiving element composed of a toothed annular ring engaging on a motor pinion; 
           [0056]      FIG. 9  is a perspective view, which illustrates another form of the mechanism according to the present disclosure, in which the receiving element is a receiving pinion; and 
           [0057]      FIG. 10  is a sectional longitudinal axial perspective view, which illustrates other form in which the annular outlet ring directly engages on the outlet pinion of the locking shaft in moving position. 
       
    
    
       [0058]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
       DETAILED DESCRIPTION 
       [0059]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0060]    In the description and claims, it is used in a non-limiting manner the expressions “front” and “back” with reference to the left part and the right part respectively of  FIGS. 1 to 10  and to marks AV for front and AR for back, on  FIG. 1 . 
         [0061]    In addition, in order to clarify the description, it will be adopted in a non-limiting manner the terminology longitudinal, vertical and transversal with reference to the trihedral L, V, T indicated in the figures. 
         [0062]    It has been represented on  FIG. 1  a tubular nacelle  10  which extends along a main longitudinal axis A and which accommodates a turbojet engine designed for equipping an aircraft. 
         [0063]    The nacelle  10  comprises in particular a structure  12  which is intended to be fixed on the aircraft, and a cowl  14  moveably mounted with respect to the structure  12 . 
         [0064]    The cowl  14  belongs to a thrust reversal device and it comprises a front portion forming the stopper  16  of a passage  18  of a diverted air flow, and a rear portion forming the ejection nozzle  20  to channel the ejection of the air flows. 
         [0065]    To this end, the cowl  14  is slidably mounted in translation from front to back on the structure  12  of the nacelle  10 , along a direction which is substantially parallel with the longitudinal axis A of the nacelle  10 , between a forward compact position represented on  FIG. 1 , in which the cowl  14  closes the passage  18  intended for the diverted flow, and a backward deployed position represented on  FIG. 2 , in which the cowl  14  opens this passage  18  to allow the diverting of the flow. 
         [0066]    Moreover, the nozzle  20  is a variable section nozzle, also called adapted nozzle, which comprises one or a set of deflectors  22  arranged in a ring shape and moveably mounted in such a manner as to make the ejection section of the air flow vary. 
         [0067]    In reference to  FIGS. 3 and 4 , the nacelle  10  is equipped with a mechanism  24  for coupling and uncoupling a motor inlet shaft  26  and an annular outlet ring  94  by means of a locking shaft  28 . 
         [0068]    The outlet ring  94  is intended to drive in movement the deflectors  22  of the nozzle  20 , when the cowl  14  occupies its forward compact position. 
         [0069]    The inlet shaft  26  is mounted in rotation on a front frame  30  secured to the structure  12  of the nacelle  10 , around a secondary longitudinal axis B, the inlet shaft  26  being driven in rotation by a motor (not represented), such as an electric motor for example. 
         [0070]    Likewise, the outlet ring  94  is mounted in rotation on a rear frame  32  around the main longitudinal axis A, the assembly constituted by the rear frame  32  and the outlet ring  94 , accompanied with its locking shaft  28  being onboard the movable cowl  14 . 
         [0071]    Thus, the rear frame  32  is slidably mounted from front to back with respect to the front frame  30 , according to the secondary axis B, between a forward compact position represented on  FIG. 4 , and a rear deployed position represented on  FIG. 7 . 
         [0072]    In a complementary manner, the mechanism  24  is equipped with a coupling means  34  which couples in rotation the inlet shaft  26  and the annular outlet ring  94  together when the rear frame  32  occupies its forward compact position, as can be seen on  FIG. 4 , and which uncouples the inlet shaft  26  and the annular outlet ring  94  when the rear frame  32  occupies its backward deployed position, as can be seen on  FIG. 7 . 
         [0073]    The coupling means  34  is of claw type and it comprises a first female coupling portion  36  with axial toothing which is arranged on a rear axial end  38  of the inlet shaft  26 , and a second male coupling portion  40  with axial toothing of complementary shape which is arranged on a front axial end  42  of the locking shaft  28 , according to  FIG. 7 . 
         [0074]    The first coupling portion  36  is designed to be imbricated in the second coupling portion  40  during the displacement of the rear frame  32  from its backward deployed position, towards its forward compact position. 
         [0075]    In a non-limiting manner, it is meant by “claw” all direct coupling devices of two mechanical pieces by cooperating teeth and grooves. 
         [0076]    In addition, the mechanism  24  comprises a first means  44  for locking in rotation the inlet shaft  26  on the associated front frame  30 , and a second means  46  for locking in rotation the locking shaft  28  on the associated rear frame  32 . 
         [0077]    The first locking means  44  and the second locking means  46  are designed to automatically lock the inlet shaft  26  and the locking shaft  28  in rotation respectively, as a result of the displacement of the movable cowl  14  containing the rear frame  32  towards their backward deployed position. 
         [0078]    To this end, the first means  44  for locking the inlet shaft  26  is of claw type and it comprises a first locking pinion  48  which is linked in rotation on the inlet shaft  26  around the secondary axis B. 
         [0079]    As it can be seen on  FIGS. 3 and 4 , the first locking pinion  48  delimits a first radial toothing  50  oriented towards the front. 
         [0080]    In addition, the first locking means  44  comprises an annular locking ferrule  52  which is constituted of a fluted axial sleeve  54  with a cylindrical portion  56  which extends axially according to the secondary axis B and an intermediary radial disk  58  which links the sleeve  54  and the cylindrical portion  56  together. 
         [0081]    The cylindrical portion  56  is axially interposed between the front frame  30  and the rear frame  32 . 
         [0082]    The radial disk  58  delimits a second radial toothing  60  arranged facing the first complementary radial toothing  50 . 
         [0083]    Moreover, the fluted sleeve  54  of the locking ferrule  52  is slidably axially mounted on a complementary fluted section  62  of the front frame  30 . 
         [0084]    Thus, the locking ferrule  52  is slidably axially mounted according to the secondary axis B on the front frame  30 , between a front unlocking position represented on  FIG. 4 , in which the first radial toothing  50  is arranged facing the second associated radial toothing  60 , and a rear locking position represented on  FIGS. 5 to 7 , in which the first radial toothing  50  cooperates with the second radial toothing  60  to lock in rotation the inlet shaft  26  on the associated front frame  30 . 
         [0085]    In a complementary manner, the first locking means  44  is equipped with a first elastic return means  64 , here a helical spring, which is interposed axially between the front frame  30  and a front face of the radial disk  58  of the locking ferrule  52 , in such a manner as to automatically return the locking ferrule  52  towards its rear locking position. 
         [0086]    Moreover, the rear frame  32  comprises a bearing portion  66  which axially extends towards the front and which is designed to axially bear towards the front against the cylindrical portion  56  of the locking ferrule  52 , in such a manner that the locking ferrule  52  is axially constrained in its front unlocking position countering the first elastic return means  64  when the rear frame  32  occupies its forward compact position. 
         [0087]    Furthermore, the locking ferrule  52  is released automatically in its rear locking position when the rear frame  32  is driven towards its backward deployed position with the cowl  14 . 
         [0088]    Similarly, the second means  46  for locking in rotation the locking shaft  28 , and hence the annular outlet ring  94  is of claw type and it comprises a third radial toothing  68  which is fashioned on a radial wall  69  of the rear frame  32  and which is oriented towards the back. 
         [0089]    The locking shaft  28  comprises a front locking pinion  70  and a second rear locking pinion  72  which are linked in rotation by an intermediary cylindrical section  74 . 
         [0090]    The second locking pinion  72  is linked in rotation on the locking shaft  28  around the secondary axis B, and it delimits a fourth radial toothing  76  arranged facing the third complementary radial toothing  68 . 
         [0091]    The intermediary cylindrical section  74  is slidably mounted in a bore  78  formed in the radial wall  69  of the rear frame  32 . 
         [0092]    The bore  78  forms an axial sliding means for guiding the locking shaft  28  according to the secondary axis B, between a rear unlocking position, represented on  FIG. 4 , in which the third toothing  68  is arranged facing the fourth toothing  76 , and a front locking position represented on  FIGS. 6 and 7 , in which the third toothing  68  cooperates with the fourth toothing  76  to lock in rotation the locking shaft  28  on the rear frame  32 . 
         [0093]    In a complementary manner, the rear frame  32  is equipped with a means ( 80 ) for slidably and rotatably guiding, which comprises a cylindrical sub plate  82  rotatably mounted around the secondary axis B in a housing  84  formed in a rear wall  86  of the rear frame  32 . 
         [0094]    Moreover, the second locking means  46  comprises a second elastic return means  92 , here a helical spring, which is axially interposed between the rear wall  86  of the rear frame  32  and the second locking pinion  72 , to automatically return the locking shaft  28  towards its front locking position. 
         [0095]    The guiding means  80  comprises a fluted guiding stem  88  which extends axially towards the front from the sub plate  82  and which cooperates with a jacket  90  of complementary shape formed at the rear end of the locking shaft  28 , in order to guide in axial translation the locking shaft  28  and allow following in rotation of the second elastic return means  92  when the locking shaft  28  is rotating. 
         [0096]    Thus, the locking shaft  28  is axially constrained in its rear unlocking position countering the second elastic return means  92  when the rear frame  32 , and the cowl  14 , occupy their forward compact position, and the locking shaft  28  is automatically released in its front locking position when the rear frame  32 , and the cowl  14 , are driven towards their backward deployed position. 
         [0097]    According to its function, the mechanism  24  according to the present disclosure drives in rotation a receiving element  94 , here the annular outlet ring  94 , which is mounted in rotation around the main longitudinal axis A. 
         [0098]    The annular outlet ring  94  is designed to drive in movement the aforementioned adapted nozzle  20 , by means of a drive device (not represented). 
         [0099]    To this end, as can be seen on  FIGS. 4 and 8 , the annular outlet ring  94  exhibits a rectangular section and it comprises a first outer peripheral annular portion  96  which cooperates with a complementary housing  98  formed in the rear frame  32  to secure the ring  94  and the rear frame  32  in axial translation. 
         [0100]    In addition, the ring  94  comprises a second inner annular portion  100  which delimits an axial receiving toothing  102 . 
         [0101]    In a complementary manner, the rear axial end  38  of the inlet shaft  26  is secured in rotation, around the secondary axis B, to a motor pinion  104  which delimits an axial annular toothing  106  of the same diameter as the axial toothing  108  of the locking pinion  70  mounted on the locking shaft  28 . 
         [0102]    Moreover, the motor pinion  104  is axially adjoined to the locking pinion  70  when the locking shaft  28  occupies its rear unlocking position, as can be seen on  FIGS. 4 and 8 . 
         [0103]    Thus, when the rear frame  32  and the cowl  14  occupy their forward compact position, the annular outlet ring  94  occupies a moving position in which the annular outlet ring  94  engages on the motor pinion  104 , in such a manner that the driving in rotation of the inlet shaft  26  causes the driving in rotation of the ring  94 . 
         [0104]    On the other hand, when the rear frame  32  and the cowl  14  occupy their backward deployed position, with reference to  FIG. 7 , the annular outlet ring  94  occupies a blocked position in which the locking pinion  70  engages on the annular outlet ring  94 . The locking pinion  70  hence locks in rotation the annular outlet ring  94 . 
         [0105]    In order to switch from its moving position to its blocked position, the annular outlet ring  94  axially slides towards the back from the axial toothing  106  of the motor pinion  104 , onto the axial toothing  108  of the locking pinion  70 , during the sliding of the locking shaft  28  towards its front locking position and the displacement of the rear frame  32  towards its backward deployed position. 
         [0106]    In the rest of the description, the automatic locking of the inlet shaft  26  and the locking shaft  28 , hence of the annular outlet ring  94 , is described in a chronological manner. 
         [0107]    With reference to  FIG. 4 , the rear frame  32  occupies its initial forward compact position in which the inlet shaft  26  and the locking shaft  28  are free in rotation and coupled in rotation around the secondary axis B. The annular outlet ring  94  engages on the motor pinion  104  secured in rotation to the inlet shaft  26 . 
         [0108]    During the displacement of the rear cowl  14  towards the rear, the rear frame  32 , which is secured in translation to the cowl  14 , is driven in displacement from its forward compact position, towards its backward deployed position. 
         [0109]    First, according to  FIG. 5 , the first locking means  44  locks the inlet shaft  26  in rotation by automatically displacing the locking ferrule  52  from its front unlocking position, towards its rear locking position. 
         [0110]    Second, according to  FIG. 6 , the second locking means  46  locks the locking shaft  28  in rotation by displacing the locking shaft  28  from its rear unlocking position, towards its front locking position. 
         [0111]    Moreover, during the displacement of the rear frame  32  towards its backward deployed position, the latter transfers the annular outlet ring  94  from its moving position, or driven, to its blocked position, thanks to the intervention of the locking shaft  28 . The annular outlet ring  94  no longer engages with the inlet shaft  26 . 
         [0112]    Third, the coupling means  34  uncouples the inlet shaft  26  and the locking shaft  28  when the rear frame  32  reaches its backward deployed position, as can be seen on  FIG. 7 . 
         [0113]    Thus, the coupling means  34  uncouples the inlet shaft  26  and the locking shaft  28  following the locking in rotation of the inlet shaft  26  and the locking shaft  28 , and the locking in rotation of the annular outlet ring  94 . 
         [0114]    According to another form represented on  FIG. 10 , the pinion  70  of the locking shaft  28  delimits a toothing  112  which is sufficiently wide axially so that the toothing  102  of the annular outlet ring  94  permanently cooperates with the toothing  112  of the pinion  70  of the locking shaft  28 , during the displacement of the annular outlet ring  94  from its moving position, to its blocked position. 
         [0115]    Thus, as  FIG. 10  shows, when the rear frame  32  occupies its forward compact position, the annular outlet ring  94  occupies its moving position in which it directly engages on the outlet pinion  70  of the locking shaft  28 . 
         [0116]    According to this form, in order to switch from its moving position to its blocked position, the annular outlet ring  94  axially slides on the axial toothing  112  of the locking pinion  70 , during the sliding of the locking shaft  28  towards its front locking position and the displacement of the rear frame  32  towards its backward deployed position. 
         [0117]    According to other form represented on  FIG. 9 , the annular outlet ring  94  is replaced with a receiving pinion  110  which is mounted in rotation around a longitudinal receiving axis C on the rear frame  32 . 
         [0118]    In a non-limiting manner, the cylindrical toothings of the different transmission pinions may be replaced with conical toothings. 
         [0119]    Likewise, the links and guiding of the components in rotation may be provided by bearings, or rollings, or other equivalent systems able to provide a rotational or sliding guiding.