Abstract:
The invention concerns a sliding roof system for a vehicle, comprising at least one front roof panel ( 40 ) and one rear roof panel ( 48 ), mobile relative to each other between a flush position and an offset position in height. One of the roof panels comprises assemblies of front and rear levers articulated to tilt between a low position and a high position wherein the panel involved is offset in height relative to its flush level. One of the panels comprises driving means for driving the lever assemblies either from the front rearwards, to raise the panel, or inversely, to shift it from its offset position towards its flush position. The lever assemblies engage guides ( 41, 44 ) adapted, upon controlled displacement from the front rearwards of the lever assemblies, to guide their tilting movement upwards and, upon reverse displacement, to guide their tilting movement downwards.

Description:
FIELD OF THE INVENTION 
   The invention relates to a retractable roof for vehicles, and more precisely such a roof comprising several rigid roof panels (or elements), of which at least one can be displaced between a position in which the roof panels cover the passenger compartment, from above, and a position in which they uncover an opening in the roof. 
   BACKGROUND 
   Some roofs, including if need be that of the invention, are retractable behind the vehicle, thus allowing to transform a saloon or coupe-type vehicle into a convertible-type vehicle. 
   One of the problems encountered in the designing of this type of roof lies in the stowing of the roof elements in the rear boot of the vehicle. 
   Another problem lies in the designing and performing of the kinematics of movement of the roof elements when they are above the roof. 
   It is for this reason that a retractable roof system for a motor vehicle will be considered, as well as a thus equipped vehicle. 
   Different retractable roof systems are already known comprising at least a front roof panel and rear roof panel, these panels being moveable along a longitudinal direction (corresponding to the longitudinal driving direction of the vehicle) between a flush position in which the panels are placed substantially at the same level as each other, the front roof panel thus being located in front of the rear roof panel, along said longitudinal direction, and an off-set position in an upward direction in which the roof panels are placed one on top of the other. 
   From such a known system, an aim is to propose a reliable retractable roof system, with relatively simple mechanics, production costs compatible with mass production in association with a motor vehicle manufacturer, and which avoids the already encountered co-ordination of panel movement problems ensuring efficient and reliable kinematics. 
   SUMMARY OF THE INVENTION 
   For this reason, a major feature provides that:
         one of the front and rear panels comprises a group of front levers and a group of rear levers pivotally mounted in relation to this roof panel, so as to tip over between:       

   a low position in which the panel in question is substantially flush with a surround part of the structure of the vehicle; 
   and a high position in which said panel in question is off-set in an upward direction in relation to the level of its flush position;
         at least one of said roof panels comprising the lever groups and the other panel comprises driving means for driving the lever groups and one of the panels:       

   either from the front towards the rear, along a distance ensuring the roof panel moves from its flush position to its off-set position in an upward direction; 
   or from the rear towards the front, along said distance, but in the opposite direction, to ensure the roof panel in question moves from its off-set position to its flush position; and
         the lever groups engage, under the control of the driving means, guides extending essentially substantially parallel to said longitudinal direction, these guides being adapted for:   during the controlled displacement of the lever groups from the front towards the rear, guiding their tipping over movement from the flush position of the corresponding panel to its off-set position; and   during the controlled displacement of the same lever groups from the rear towards the front, guiding their tipping over movement from the off-set position of the corresponding panel towards its flush position.       

   To further contribute to reaching the aforementioned aims, using simple, efficient and reliable mechanical conception, another feature recommends that the lever groups individually comprise a curved lever comprising a first arm rotatingly articulated on the corresponding roof panel and firmly attached via an elbow to a second arm, which engages one of said guides, in order to guidingly drive it. 
   Still with the same aim, and drawing on the already known use of “runner” type sliding means, another feature provides that the guides of the levers fitted to the roof panel(s) in question advantageously comprise runners in which these lever groups slide, the runners locally having deflected slips extending obliquely in relation to the horizontal and in relation to said longitudinal direction, along a sufficient length to receive, individually, a part of said lever groups, so that once engaged in these deflected slips, the lever groups in question move, by pivoting, from one of their high or low positions towards the other position. 
   If, as is supposed, a benefit is found in using the two preceding features, it is moreover recommended, to simplify the slide driving as much towards the front as towards the rear of the roof panel(s) in question:
         that the second arm of some of the panels is slidingly mounted in relation to the other along said longitudinal direction, along second grooves of said runners;   that at least some of the levers fitted to the corresponding panel at least comprise a slider mounted sliding in the first corresponding groove;   that said driving means have a front end and a rear end, and that these driving means comprise a driving hook bearing a driving recess adapted for receiving said slider and driving it along the corresponding guide, the recess extending frontwards via a driving wall adapted for driving the corresponding slider backwards, along said first groove, this recess extending backwards via a short driving pin making an inlet for the slider, via the rear of said driving hook, so that the short driving pin drives the slider frontwards as long as it engages the first groove substantially along said longitudinal direction, but extricating from the slider when the latter engages in the deflected slip of said first groove that it encounters, this deflected slip thus being located in the extension of the groove and making an obtuse angle with it so that the slider can engage in the direction of its drive.       

   Such a feature is specially applicable in cases where the front roof panel is slidingly mounted in relation to the rear panel in order to move under it. 
   In this case, it is subsidiarily recommended that:
         the sliders are placed on the second arm of at least some of the levers;   that said driving means are extended along the longitudinal direction of displacement of the roof panels in relation to each other; and   that the deflected, or deflected, slips of each first groove are oriented upwards, the lever groups being linked to the rear panel under which said first groove extends.       

   In conjunction with all or part of the aforementioned features relating to these roof panel mechanics, we thus obtain a reliable and efficient mechanism for such a movement making the front roof element to move under the rear roof element. 
   Particularly in this case, another feature even recommends that the driving means comprise, towards their rear end, a contact surface adapted for engaging at least a lever of the front lever group, when said lever is in the low position and of driving it along with itself in the backwards direction of displacement of said driving means. 
   Still in the same situation, we yet again recommend that the driving means of the front roof panel comprise, towards their rear end, a second driving pin adapted for fully engaging, in the corresponding deflected slips, the second arm of the front lever group fitted to the rear roof panel, once these levers are free from the corresponding short driving pin, consecutively with a forward sliding of the front roof panel, so that the rear roof panel then moves into its flush position. 
   This second pin allows to ensure, with a simple, reliable and efficient solution, a fully engaging of the levers into the corresponding deflected slips, thus in an efficient manner displacing the rear roof panel into its flush, low position. 
   Moreover, to overcome the problem evoked at the start of the description on stowage of the roof elements in the rear boot of the vehicle, we furthermore propose that the retractable roof comprises;
         a rear central roof element, an intermediary central roof element and a front central roof element;   a rear left side roof element, a front left side roof element, a rear right side roof element and a front right side roof element;   means for sliding the rear central roof element into a tailgate;   means for placing the intermediary central roof element and the front central roof element in the closed position and for vertically folding back all the elements at the front of the rear boot;   means for placing the rear left side roof element and the front left side roof element in the closed position and for horizontally folding back all the elements in the rear boot at the rear of all the elements constituted by the intermediary central roof element and the front central roof element; and   means for placing the rear right side roof element and the front right side roof element in the closed position and for horizontally folding back all the elements in the boot above or below all the elements constituted by the rear left side roof element and the front left side roof element.       

   As it will have been understood from the above, the means for placing the intermediary central roof element and the front central roof element in the closed position advantageously comprise means for relative sliding of the intermediary central roof element and the front central roof element. 
   More precisely, said means for sliding can comprise at least a longitudinal side runner on which the intermediary central roof element is mounted, and laid out to co-operate with a slider on which the front central element is mounted. 
   It will then be possible to slide the front central roof element so as to bring it in the vicinity of the intermediary central roof element, and thus free the front section of the roof. 
   We note that, the expression “longitudinal” generally means parallel to the front/rear direction of the vehicle. Likewise, the expression “transversal” generally means perpendicular to the symmetrical plane of the vehicle. 
   Still more precisely, said slider can comprise rollers adapted for moving along a first groove of said runner. 
   Furthermore, the intermediary central roof element can be mounted on the rollers adapted for moving along a second groove of said runner. 
   Also in a specific embodiment, the means for vertically folding back all the elements constituted by the intermediary central roof element and the front central roof element at the front of the rear boot comprise at least two levers articulated about one of their ends on the vehicle chassis and creating a distortable quadrilateral. 
   In the case of a runner assembly, said levers can be articulated at their other end about said runner. 
   In a specific embodiment, the means for placing the rear left side (respectively right side) roof element and the front left (respectively right) roof element in the closed position comprise an articulation about a transversal axis between the front edge of the rear left side (respectively right side) roof element and the rear edge of the front left side (respectively right side) roof element. 
   The side section of the roof therefore folds back about an intermediary axis. 
   Also in a specific embodiment, the means for horizontally folding back, into the rear boot, all the elements constituted by the rear left side (respectively right side) roof element and the front left side (respectively right side) roof element comprise a folding device articulated on the vehicle chassis about a longitudinal axis between a closed position and a stowed position, and the rear left side (respectively right side) roof element is articulated in the vicinity of its rear edge on said folding device about a generally transversal axis when said folding device is in its closed position and generally vertical when said folding device is in its stowed position. 
   More precisely, the means for placing the rear left side (respectively right side) roof element and the front left side (respectively right side) roof element in the closed position can comprise at least a lever with one of its end articulated on the folding device at a given distance from the axis of articulation of the rear left side (respectively right side) roof element and its other end articulated on the front left side (respectively right side) roof element at a given distance from the axis of articulation of the rear left side (respectively right side) roof element. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more detailed description of the subject follows in reference to the annexed diagrammatic drawings in which: 
       FIG. 1  is a perspective view of a retractable roof operable in this instance; 
       FIG. 2  is a side view of the means for folding the side roof elements in  FIG. 1  in the closed position and in the intermediary folding position; 
       FIG. 3  is a perspective view of the means for stowing the central roof elements in their closed position and in their stowed position; 
       FIG. 4  is a deflected section of the runners in  FIG. 3 ; 
       FIG. 5  is a side view of the roof elements in the stowed position; 
       FIG. 6  is a rear view of these elements in the stowed position; 
       FIG. 7  demonstrates another roof mechanism allowing relative sliding of a front roof element (panel) in relation to a rear roof element (panel), the two panels being in the closed position, substantially in line one in front of the other in  FIG. 7 , whereas the front panel moves under the rear panel in  FIG. 8 ; 
       FIGS. 9 ,  10  and  11  demonstrate three different sliding possibilities and positions of the front and rear panels in question; and 
       FIGS. 12 and 13  demonstrate an alternative embodiment in which the front roof panel moves over the rear panel when it moves backwards, thus freeing an opening above the passenger compartment, in the roof. 
   

   DETAILED DESCRIPTION 
   The roof shown in  FIG. 1  comprises a rear central roof element  1 , generally constituted of the rear windscreen, an intermediary central roof element  2  and a front central roof element  3  coming into contact with the upper edge of the front windscreen. The roof according to the invention also comprises a rear left side roof element  4 , a front left side roof element  5 , a rear right side roof element  6  and a front right side roof element  7 . 
   These roof elements consequently link from front to back the upper edge of the front windscreen to the upper edge of the tailgate  9  of the rear boot and on the sides the upper edges of the side windows of the vehicle (not represented). 
   Known means, and thus consequently not described below, allow to slide the rear central roof element, and more precisely its window, in the tailgate  9 . Moreover, this tailgate  9  is articulated along its lower edge of the chassis of the vehicle along a transversal axis of rotation  10 , and operable via an actuator  11  allowing it to open and the insertion of the rear central roof element  1 . 
   The layout described below is generally of the same type on either side of the vehicle. 
   As demonstrated in  FIG. 3 , the front central roof element  3  is laterally mounted on sliders  13 . The front central element  3  is mounted on the sliders  13  via a transversal axis of rotation located on the front edge of the element  3  and at the far end of the sliders  13 . This axis of rotation allows an upward and downward movement according to the arrow F 1  of the rear edge of the element  3 . 
   Each slider  13  is mounted via rollers  15  and  16  on a runner  17 . The runner  17  comprises two grooves  18  and  19 , the groove  18  receiving the rollers  15  and  16 . 
   The groove  19  receives two rollers  20  an  21  integral with two fittings  22  and  23  supporting the intermediary central roof element  2 . 
   Drive means of any known type allow to slide the sliders  13  in the runners, as well as the sliding of the rollers of the fittings  22  and  23  in the same runners. 
   Two levers  24  and  25  are articulated about a transversal axis, respectively  26  and  27 , to the chassis of the vehicle at one of their ends. At their other end, these levers are articulated, also about a transversal axis to the runner  17  about axes  28  and  29 . These levers  24  and  25  are represented at the top of  FIG. 3  in the position they take when the roof covers the passenger compartment, and at the bottom of the drawing when the roof is stowed in the rear boot. 
     FIG. 2  demonstrates the left side roof elements  4  and  5  as well as their folding mechanism. The right side roof elements are similar. 
   The rear edge of the front side roof element  5  is articulated on the front edge of the rear side roof element  4  about a transversal axis  30 . The rear edge of the rear side roof element  4  is articulated on a tipping-up device  31  about an axis  32 . The axes  30  and  32  are transversal when the roof is, as shown in  FIG. 2 , either in the closed position or in the folded position, and are substantially vertical when the roof is in the stowed position as described below. 
   A reinforcement device  33  has one of its ends articulated on the axis  32  and its other end articulated on the axis  30 . A lever  34  is articulated on the folding device  31  also on a transversal axis  35  but located at a given distance from the axis  32  and its other end articulated on the roof element  5  about a transversal axis  36  located at a given distance from the axis  30 . 
   The folding device  31  is pivot mounted in relation to the chassis of the vehicle about a longitudinal axis  37 . 
   Known driving means, and therefore not represented, are provided to actuate the elements described above. 
   The movement of the roof from its closed position to its stowed position is performed in the following manner. Its opposite movement from the stowed position to the closed position is performed in the opposite manner. 
   Firstly, the tailgate opens via rotation about the axis  10  using an actuator  11  and the roof element  1  is slid into the tailgate  9 . 
   The element  3  is then tilted downwards about the axis  14  then slid under the element  2 . The levers  25  and  26  are then tilted so as to bring the elements  2  and  3  into the position represented at the bottom of  FIG. 3  where they are in the vertical position in front of the rear boot of the vehicle. 
   The levers  33  and  34  then provoke the lifting and the folding of the roof elements  4  and  5  into the position represented in  FIG. 2 , then a folding about the axis  37  brings the latter elements into the substantially horizontal position in  FIG. 5  where they are at the rear of the elements  2  and  3 , stacked in pairs. 
   In the embodiment in drawings  7  to  12 , the front roof element (panel)  40  is mounted on a first runner  42 , which is engaged in a second runner  44 , which in turn is engaged in a third runner  46  supported by the roof element  48  which, in the closed position of the roof above the passenger compartment as shown in  FIG. 7 , is located behind the panel  40 , level with it, that being flush with the surrounding chassis of the vehicle (which can be constituted by the elements  4 ,  5 ,  6  and  7  as shown in  FIG. 1  or by the body). 
   The roof panels  40  and  48  define two substantially plane panels located in front of a rear roof element  52 , which normally incorporates the rear windscreen. 
   Possibly, the part  52  can all the same consist in a fixed part of the vehicle, that being defining a windscreen fixed to the body. 
   Being such, in this case, in drawing  7  we can assimilate the roof elements  40 ,  48  and  52  with the respective roof elements  3 ,  2  and  1  in  FIG. 1 , so that the front roof element  40  then comes, in its closed state as in drawing  7 , into contact at the front of the transversal skirt  54  which limits the upper section of the windscreen  56  of the vehicle (see  FIG. 1 ). 
   Also note that in order to ensure the relative displacement of the panels  40  and  48 , the runner system  42 ,  44  and  46  principally extends substantially parallel to the longitudinal forward direction  58  of the vehicle. 
   If, once put in their stacked position as in drawing  8 , the panels  40  and  48  should be stowed in the rear boot of the vehicle, then we advantageously provide that the third runner  46  is solidly linked to an arm  60 , in the same manner as the rear roof element  52  (if it is movable) can itself be linked to another arm (not represented), these two articulation arms can correspond to the arms  24  and  25  in the embodiment represented in drawing  3 , articulated about the transversal axes  26  and  27 . 
   As can be seen in  FIGS. 7 to 11 , the embodiment presented here is such that, to open the front roof panel  40 , it must be slid from the front (AVT) backwards (ARR), this sliding provokes the lifting of the rear panel  48  so as to free a space below it adapted for receiving the substantially axial sliding (practically no difference in height) of the front panel  40 . 
   The panel  48  is linked to the runner  46  (also called the “first groove”) via respectively front  53   a  and rear  53   b  arms extending under it and on each of which a lever articulates (such as  62  and  64 , see below). 
   Thus, the roof part  48  will rise to allow the front roof part  40  to move under it. Once these front and rear roof parts are stacked on top of each other in a substantially horizontal position they can each pivot via the drive arm into the stowage space so as to be, for example, substantially vertical in position. 
   As already evoked, the front roof element  40  is mounted on the front runner  42 , whereas the rear roof element is slide mounted on the rear runner  46 , the intermediary runner  44  controlling the upward movements of the movable panel (in this case the rear panel  48 ). 
   During the stacking of the roof elements  40  and  48 , the rear roof element  48  will be off-set upwardly along the third runner  46  to allow the front roof element  40  to move under it. 
   As shown in  FIGS. 9 to 11 , the rear roof element  48  is thus engaged in the third runner via the front  62  and rear  64  lever groups each being advantageous curved. Each elbow is articulated to the rear roof  48  via an axis of rotation perpendicular to the longitudinal direction  58 . The end opposite the axis of rotation of the elbow in question is inserted into the third runner  46  via two sliders, such as  66  and  68 . 
   When the roof elements  40  and  48  are in their closed position as in drawing  7 , these elements are level with each other. 
   The third runner  46  comprises two deflected, or deflected, slips  70  and  72  oriented upwards and frontwards (in the direction of their free end) and respectively located at the front end and not far from the rear end of the runner. When the rear panel is “flush”, at the bottom in drawings  7  and  9 , the two sliders  66  and  68  of each elbow are fully inserted into these deflected slips, via the arm  62   b  of the lever in question which ends in articulating the roof ( 74 ), whereas the other part  62   a  of the elbow located between the sliders the furthest back and the point of articulation of the elbow in relation to the rear roof element is substantially horizontal along the third runner. This position of the elbow allows to have the rear roof in the low position and level with the front element of the rear roof  52 . 
   During the backward sliding of the panel  40 , the intermediary runner  44  will lean against a rear surface  76  on the sliders  66  then engaged as far forward and to the top of the front deflected slip  70 , to allow the roof element  48  to tip upwards and to drive it backwards. 
   Thus, this second runner  44  can comprise at its rear end a contact surface (pusher  76 ) whose end is curved upwards and backwards. This curved surface will lean against the furthest forward and highest roller  66  and displace it along the deflected slip and downwards. The second slider  68  the furthest back will also move along this deflected slip in order to engage into the substantially horizontal part of the third runner. The curved part located between the second slider and the articulation  74  of the roof and of the curve will then will then be off-set upwards driving the rear roof upwards and backwards. 
   The runner  44  also comprises a zone creating a hook  78 . This hook is located in retreat compared to said contact surface when said second runner moves backwards; it is therefore place to the front of the second runner  44  (see  FIG. 10 ). This said hook zone will allow to continue the upward movement of the roof element  45 , as well as driving it “horizontally” towards the rear, over a short distance, adapted for allowing the tipping-up of the front and rear levers  62  and  64 . This hook  78  also allows to drive this same roof element  48  frontwards as far as the start of the deflected slip of the runner, when the front panel  40  is closed. 
   To aid this dual directional sliding, each drive hook  78  advantageously has a drive well  80  adapted for receiving the corresponding slider  66  and driving it along the guide  46  in question, the well extends forward via a driving wall  82  adapted for driving the slider backwards, along the groove or runner  46 , this well extending backwards via a short driving pin  84  making an access hole  86  for the slider, via the rear of the hook. Thus, the short driving pin will drive the slider  66  (and therefore the panel  48 ) frontwards as long as it engages into the groove  46  substantially along said longitudinal direction  58 , but extricating from the slider when the latter engages in the deflected slip  70  when it meets it, of course this deflected slip thus being located in the extension of the groove and creating an obtuse angle α with it so that the slider can engage in the direction of its drive ( FIG. 11 ). 
   Moreover, another contact surface  88  extending downwards and integral with the second runner  44  is located in front of said first contact zone  76 . This second contact zone is on the rear part of the runner  46  (also called the first groove). In a backward displacement of the panel  40 , when the furthest forward slider  66  of the lever  62  is engaged in the deflected slip  70  of the runner  46  and that this slider is moreover extricated from the hook  78 , the second contact surface (or driving pin)  88  then leans against the furthest backward slider  68  so as to fully engage the two sliders into this deflected slip and thus position the rood panel  48  in its closed and low position, level with the front element  52  and the front panel  40 . 
   For other details related to the relative disposition of the runners (or grooves) and their possible power-driven control, we refer to patent FR-A-2 797 226 (FIGS. 1, 2, 6 and 7 and their corresponding description). 
   As illustrated in  FIGS. 12 and 13 , in an alternative embodiment, the front central roof element (or front panel)  100  can be slidingly mounted on a first groove  210  of a runner system  700  globally extending substantially parallel to the longitudinal direction  58 . A second intermediary central roof element (or rear panel)  300  is in this case slide mounted on a second groove  230  of the runner  700 . 
   In this case, the roof elements  100  and  300  stack one on top of the other so that the front roof element  100  moves above the roof element  300  ( FIG. 13 ). 
   The runner  7  can be laterally fixed to the chassis  53  of the vehicle along bars fixed to the rood extending longitudinally at least along the side edges of the opening made in the roof of the vehicle to house the retractable roof. 
   An element creating a hook  270  is located on the front edge  100   a  of the roof element  100 . 
   This roof element is driven backwards via known means that can consist in power-driven flexible cables. It is engaged in the first groove  210  via two sliders  290  and  310  with an axial distance L between them. The first slider  290  located the furthest forward from the front roof element is engaged in a deflected slip  210   a  (corresponding to an increase in the inclination of the groove  210 ) oriented towards the front of the vehicle and downwards. Said deflected slip is located at the front end of the groove  210 . The second slider  310  located the furthest back from the roof element  100  is engaged in a second rear deflected slip  210   b  with the same orientation as the first and set apart from the latter by the same aforementioned length L. When the front roof  100  is driven backwards it is off-set in an upward direction thanks to the orientation of the first deflected slip  210   a , as well as to the orientation of the second deflected slip  210   b . The curve of the groove  210  thus allows the front roof element to move above the roof element  300 . 
   When the roof element  100  slides backwards, the slider  290  displaces in the groove  210  and, in the vicinity of the deflected slip  210   b , this slider moves along a rocking lever  690  then in the downward sloping position, until it makes this lever tilt upwards so that its rear part  690   b  blanks off the upper end of the deflected slip, once the slider  310  has been extracted. We understand that this selective guiding system with a lever tilts at the same location as the other rear deflected slip  230   b  in connection with the corresponding slider  350 . Furthermore, when the roof panels are being deployed into their closed position above the passenger compartment, the opposite travel of the front sliders of each panel actuates the return rocking of the levers in question, prior to the associated rear sliders engaging into the corresponding deflected slips. 
   The roof element  300  is mounted on the second groove  230  via two sliders  330  and  350  also separated by a length L. The first slider  330  the furthest forward from this roof element is engaged in the deflected slip  230   a  oriented towards the front of the vehicle and downwards. This deflected slip is located at the front end of the second groove  230  of the runner. The second slider  350  located the furthest back from the roof element  300  is engaged in the second deflected slip  230   b  with the same orientation as the first and set apart from the latter by the same length L. When the roof element  300  is driven backwards by the front roof element it is off-set in an upward direction thanks to the orientation of the deflected slips  230   a  and  230   b.    
   The front edge of the roof element  300  comprises an arm  410  extending downwards and comprising, at its lower end, a pin or a roller  430 . When the front roof element reaches a horizontal position above the roof element  300  ( FIG. 13 ), the hook  270  located on the front edge of the front central roof element leans against said pin. The hook will then drive the roof element  300  backwards and off-set it in an upward direction along said two deflected slips  230   a  and  230   b , to allow the intermediary central roof element to move above another roof element further back (not represented), the curve of the runner which extends upwards, moreover, ensures that the front roof element  100  moves above this roof element that is further back. 
   In  FIGS. 12 and 13  we also note the shape of the hook  270  which is highly compatible with the hook  78  in drawing  10 , with its well  271  adapted for receiving the slider  430  and driving it along the corresponding guide. The well extending forward via the wall  272  adapted for driving the slider backwards (ARR), along the groove  230   a  and then  230 , this well extending backwards via the short pin  273  making an inlet for the slider, behind the hook, so that this pin drives the slider forward as long as it is engaged in the groove substantially along said longitudinal direction  58 , but extricating from the slider when the latter engages in the deflected slip  230   a  when it meets in the continuation of its forward movement.