Abstract:
A bearing block to support and guide movement of a slat support arm forming part of a slat support assembly in which the slat support arm is movable to deploy a slat attached to one end of said slat support arm from a leading edge of an aircraft wing is disclosed. The bearing block comprises a plurality of bearings mountable therein so as to lie in rolling contact with an associated bearing track on a slat support arm extending through the bearing block. Each bearing comprises a bearing element rotatable about a shaft fixed to the bearing block an and is configured so that an axis of rotation of each bearing element angularly adjusts, relative to an axis of the shaft on which it is rotatably mounted, to compensate for misalignment between said shaft and an associated bearing track. A slat support assembly and an aircraft wing is also disclosed.

Description:
INTRODUCTION 
       [0001]    The present invention relates to a bearing block to support and guide movement of a slat support arm forming part of a slat support assembly in which the slat support arm is movable to deploy a slat attached to one end of said slat support arm from a leading edge of an aircraft wing. A slat support assembly comprising the bearing block is also disclosed, together with an aircraft wing comprising the slat support assembly of the invention and a method of mounting a slat support arm between adjacent spaced parallel ribs of an aircraft wing so that the slat support arm is movable to deploy a slat attached to one end of said slat support arm from a leading edge of said wing. 
       BACKGROUND 
       [0002]    Aircraft need to produce varying levels of lift for take-off, landing and cruise. A combination of wing leading and trailing edge devices are used to control the wing coefficient of lift. The leading edge device is known as a slat. On larger aircraft there may be several slats spaced along the wing edge. During normal flight the slats are retracted against the leading edge of the wing. However, during take-off and landing they are deployed forwardly of the wing so as to vary the airflow across and under the wing surfaces. The slats usually follow an arcuate or curved path between their stowed and deployed positions. By varying the extent to which the slat is deployed along said path, the lift provided by the wing can be controlled. 
         [0003]    An assembly is required to support and guide movement of a slat between stowed and deployed positions and a typical arrangement showing a cross-section through part of a wing  1  and a slat  2  in its stowed position is illustrated in  FIG. 1 . As can be seen from  FIG. 1 , the slat  2  has an arcuate support arm or slat track  3 , one end  4  of which is rigidly attached to the rear of the slat  2  and extends into the wing  1 . 
         [0004]    The slat track  3  penetrates machined rib  5  and wing spar  6  forming the wing structure. The slat track  3  defines an arc having an axis and is mounted within the wing so that it can rotate about that axis (in the direction indicated by arrows “A” and “B” in  FIG. 1 ) to deploy and retract the slat  2  attached to one end of the slat track  3 . 
         [0005]    To drive the slat rack  3  so as to deploy or retract the slat  2 , a toothed slat rack  7  having an arcuate shape corresponding to the arcuate shape of the slat track  3  is mounted within a recess  3   a  on the slat track  3  and a correspondingly toothed drive pinion  8  is in engagement with the teeth  7   a  on the slat rack  7  so that when the drive pinion  8  rotates, the teeth  8   a  on the drive pinion  8  and the teeth  7   a  on the rack  7  cooperate to pivot or drive the slat rack  7  and the slat attached thereto, into a deployed position, i.e. in the direction of arrow “A” in  FIG. 1 . Typically, the slat track  3  rotates through an angle of 27 degrees between its fully stowed and fully deployed positions. Rotation of the pinion  8  in the opposite direction also drives the slat track  3 , in the direction of arrow “B”, back into its stowed position, as shown in  FIG. 1 . 
         [0006]    The drive pinion  8  is mounted on a shaft  9  that extends along, and within, the leading edge of the wing  1 . Several gears  8  may be rotatably mounted on the shaft  8 , one for driving each slat  2  so that when the shaft  9  is rotated by a slat deployment motor close to the inboard end of the wing  1 , the slats are all deployed together. 
         [0007]    The slat track  3  has a generally square cross-sectional profile such that its upper and lower surfaces  3   b ,  3   c  each define a portion of a curved surface of a cylinder each having its axis coaxial with the axis of rotation of the slat track  3 . The slat track  3  has an arcuate mid-line, indicated by X-X in  FIG. 1 , that extends through the centre of the slat track  3  parallel to and equally spaced from each of its upper and lower surfaces  3   b ,  3   c  which defines the path along which the slat track  3  travels. 
         [0008]    The slat track  3  is supported between roller bearings  10   a ,  10   b  both above and below the slat track  3  and the axis of rotation of each bearing  10   a ,  10   b  is parallel to the axis of rotation of each of the other bearings  10   a ,  10   b  and to the axis about which the slat track  3  rotates in the direction of arrows “A” and “B” between its stowed and deployed positions. The upper bearings  10   a  lie in contact with an upper bearing track  3   b  of the slat track  3  and the lower bearings  10   b  lie in contact with a lower bearing track  3   c  so that they support the slat track  3  and guide it during deployment and retraction. The bearings  10   a ,  10   b  resist vertical loads applied to the slat  2  during flight both in stowed and deployed positions and also guide movement of the slat track  2  during slat deployment and retraction. 
         [0009]    It will be appreciated that the bearings  10   a ,  10   b  resist loads that are applied in the vertical direction only. By vertical loads are meant loads that act in a direction extending in the plane of the drawing or, in the direction that acts at right-angles to the axis of rotation of each bearing. 
         [0010]    It will be appreciated that there can be significant side loads acting on a slat  2  in addition to loads acting in a vertical direction during flight, especially as the slats  2  generally do not extend along the leading edge of the wing  1  exactly square to the direction of airflow. By side-loads is meant loads that act in a direction other than in a direction that extends in the plane of the drawing or, in other words, those loads that act in a direction other than at right-angles to the rotational axis of each bearing  10   a ,  10   b.    
         [0011]    To counteract side-loads, it is common to support the slat track  3  by further bearings  11  disposed on either side of the slat track  3  as opposed to the vertical load bearings  10  mounted above and below the slat track  3 . These side-load bearings  11  may not be rotational and may just comprise bearing surfaces, pads or cushions against which the side walls of the slat track  3  may bear when side loads are applied to the slat  2 . 
         [0012]    It will be appreciated that space for components within the wing structure close to the leading edge of the wing  1  is very limited, especially once the slat track  3  together with its vertical and side load bearings  10   a ,  10   b ,  11 , and the drive pinion  8  have all been installed. The requirement to house all these components places considerable design restrictions on the shape of the wing  1  in addition to increasing weight, manufacturing costs and complexities. 
         [0013]    As the additional side-load bearings  11  are disposed between each of the upper and lower bearings  10   a ,  10   b , these bearings must be spaced from each other in the circumferential direction about the axis of the slat track  3  by a distance which provides sufficient space between the bearings  10   a ,  10   b  to receive the side-load bearings  10   a ,  10   b . As a consequence of this, a further disadvantage with the conventional assembly is that the slat track  3  must be relatively long to accommodate the desired maximum deployment angle for the slat  2  whilst ensuring that the slat track  3  is adequately supported by two vertical load bearings  10   a  above the slat track  3  and two vertical load bearings  10   b  below the slat track  3 , even at maximum deployment. As a result of its extended length, the slat track  3  penetrates the spar  6  and so the free end of the slat track  3  must be received within a track can  13  to separate the slat track  3  from the fuel stored within the wing  1  behind the spar  6 . However, it is undesirable to have openings in the spar  6 . It will also be appreciated that the requirement for a track can  13  also presents additional problems and assembly issues with the need to provide an adequate seal where the track can  13  is attached to the spar  6 . 
         [0014]    The Applicant has developed a slat support assembly that substantially overcomes or alleviates the issues identified above and which is described in detail in WO2010/026410, which is incorporated herein in its entirety. 
         [0015]    WO2010/026410 discloses a slat support assembly in which at least some of the bearing tracks of the slat support arm and the associated bearings are configured so that each bearing counteracts load applied to the slat support arm in more than one direction. More specifically, the slat support arm may have a pair of adjacent upper bearing surfaces which are arranged at an angle relative to each other so that a bearing associated with one upper bearing track on the slat support arm does not share a common axis with the bearing associated with the other upper bearing track on the slat support arm. Furthermore, the slat support arm may have a pair of adjacent lower bearing tracks that are arranged at an angle relative to each other so that a bearing associated with one lower bearing track does not share a common axis with the bearing associated with the other lower bearing track. Alternatively, the lower bearings may be arranged with their axes coaxial so it is only the upper bearings whose axes are angled relative to each other. 
         [0016]    For convenience and ease of assembly, the bearings are mounted in one or more bearing blocks each of which are attachable between ribs of the aircraft wing to retain the bearing block in position. Each bearing block is provided with an opening through which the slat support arm passes, together with four cavities that surround the opening each of which receives and mounts a bearing within the block so that each bearing has its bearing surface in rolling contact with its associated bearing track on the slat support arm that extends through the opening. 
         [0017]    The above-described arrangement provides an assembly in which each of the bearings is able to withstand loads applied to the slat support arm in multiple directions, so additional side-load bearings or cushions are no longer required. 
         [0018]    Thus, more space is provided within the leading edge of the wing that enables bearings to be positioned closer together in the deployment direction and allowing a shorter slat support arm to be used than is usual. 
         [0019]    Whilst the slat support assembly known from WO2010/026410 offers a number of advantages, the present invention seeks to provide modifications that enable a degree of adjustment during assembly of the slat support assembly to compensate for, for example, manufacturing tolerances and/or to enable a pre-load to be applied between the track and the bearings. 
       SUMMARY OF THE INVENTION 
       [0020]    According to the invention, there is provided a bearing block to support and guide movement of a slat support arm forming part of a slat support assembly in which the slat support arm is movable to deploy a slat attached to one end of said slat support arm from a leading edge of an aircraft wing, the bearing block comprising a plurality of bearings mountable therein so as to lie in rolling contact with an associated bearing track on a slat support arm extending through the bearing block, wherein each bearing comprises a bearing element rotatable about a shaft fixed to the bearing block, each bearing being configured so that an axis of rotation of each bearing element angularly adjusts, relative to an axis of the shaft on which it is rotatably mounted, to compensate for misalignment between said shaft and an associated bearing track. 
         [0021]    In a preferred embodiment, a spherical or self-aligning bearing member mounts each bearing element to its associated shaft. 
         [0022]    The bearing block preferably comprises a pair of spaced end walls and is configured so that, when it is received between spaced ribs forming a structural part of an aircraft wing, an end wall is positioned so that it faces a surface of a respective rib. 
         [0023]    Each end wall may have an arcuately shaped shoulder for cooperation with a corresponding engagement surface on said rib such that the bearing block is rotatable about a central axis extending through the bearing block perpendicular to the ribs, with the arcuately shaped shoulder sliding against said corresponding engagement surface. 
         [0024]    In a preferred embodiment, an adjustment and clamping member is provided to enable rotation of said bearing block about said central axis and to clamp said bearing block in position after rotation. 
         [0025]    The adjustment and clamping member may comprise a body positionable on a side of a rib opposite to the side facing the bearing block, and legs that extend from the body and pass through arcuately-shaped slots in the rib to locate in holes in the end wall of the bearing block. The legs may be slidable within the slots so that the bearing block rotates about said central axis in response to rotation of the body. 
         [0026]    Preferably, the body is spaced from said rib by said legs and the legs are slidable in an axial direction into the bearing block, after an angular position has been reached, to clamp the adjustment and clamping member to the rib and prevent further movement of the bearing block. 
         [0027]    The body may comprise cooperating elements for engagement with corresponding cooperating elements on the rib when the body is slid in an axial direction towards the bearing block to prevent further movement of the bearing block. 
         [0028]    In some embodiments, the cooperating elements on the body comprise a serrated or toothed ring which is received within an aperture in the rib when the body is slid in an axial direction, to cooperate with corresponding serrations or teeth around the periphery of said aperture in the rib. 
         [0029]    According to another aspect of the invention, there is provided a slat support assembly comprising a slat support arm and at least one bearing block according to the invention, the slat support arm having a plurality of bearing tracks extending along its length and being supported by, and movable within, said at least one bearing block to deploy a slat attached to one end of said slat support arm from a leading edge of an aircraft wing. 
         [0030]    At least some of the bearings are preferably configured so that each bearing counteracts load applied to the slat support arm in more than one direction. 
         [0031]    According to another aspect of the invention, there is provided a wing for an aircraft comprising a slat support assembly according to the invention, and a pair of parallel ribs forming part of the structure of said wing spaced from each other with the or each bearing block extending between said ribs. 
         [0032]    Each rib preferably comprises a recess or seat to receive a respective end wall of the bearing block extending between the ribs. The recess or seat in each rib may be shaped to allow rotation of the bearing block about a central axis of said bearing block within said recess or seat. 
         [0033]    In some embodiments, the recess or seat may extend to an edge of each rib to enable insertion of the bearing block into the seat or recess between said ribs in a direction perpendicular to the plane of each rib. 
         [0034]    According to another aspect of the invention, there is provided a method of mounting a slat support arm between adjacent spaced parallel ribs of an aircraft wing so that the slat support arm is movable to deploy a slat attached to one end of said slat support arm from a leading edge of said wing, the method including the steps of: 
         [0000]    (a) mounting a bearing block having a plurality of bearings received therein so that it extends between adjacent spaced parallel ribs;
 
(b) inserting a slat support arm into the bearing block so that each bearing in the bearing block lies in rolling contact with an associated bearing track on the slat support arm to support and guide movement of the slat support arm relative to the bearing block in a plane parallel to said ribs between which said bearing block is mounted,
 
(c) pivoting the bearing block about a central axis of the bearing block that extends perpendicular to said plane into a tilted position; and
 
(d) locking the bearing block in said tilted position.
 
         [0035]    If each rib includes a recess step (a) may include the step of positioning the bearing block so that its end walls are received within a respective recess in each rib. The recess may extend to an edge of each rib so that a bearing block may be slid into the recesses between said ribs. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0036]    Embodiments of the invention will now be described, by way of example only, and with reference to  FIGS. 2 to 10  of the accompanying drawings, in which: 
           [0037]      FIG. 1  is a prior art side-sectional view through a portion of a leading edge of a wing of an aircraft with a slat shown in its stowed position; 
           [0038]      FIG. 2  is a perspective view of part of a slat support arm extending through two bearing blocks according to an embodiment of the present invention; 
           [0039]      FIG. 3  is a perspective view similar to that of  FIG. 1 , but with the bearing blocks removed for clarity and so that the bearings are visible; 
           [0040]      FIG. 4  shows a plan view of part of a slat support arm supported on bearings received in a bearing block mounted between spaced structural ribs of an aircraft wing, with the bearing block in a neutral, non-angled, position; 
           [0041]      FIG. 5  shows a plan view similar to  FIG. 4  but with the bearing block tilted through an angle of 12 degrees to compensate for misalignment or for pre-loading; 
           [0042]      FIG. 6  is an enlarged view of part of  FIG. 5  showing one bearing to illustrate the bearing misalignment with the track that occurs when the bearing block is tilted out of its neutral position shown in  FIG. 5 ; 
           [0043]      FIG. 7  is shows an embodiment of the present invention in which the conventional cylindrical roller bearings are replaced with self-aligning or spherical bearings to correct misalignment of the bearings with the track when the bearing block is tilted; 
           [0044]      FIG. 8  shows a cross-sectional side elevation through the bearing of  FIG. 7  to show a secondary direction of bearing adjustment provided by self-aligning or spherical bearings; 
           [0045]      FIG. 9  is a perspective view of a bearing block and part of a rib of an aircraft wing to show how the bearing block may be tilted relative to the rib during assembly; 
           [0046]      FIGS. 10   a  to  10   c  is a series of drawings to illustrate how the bearing block may be attached to a rib and tilted into its desired position before being clamped in place using a clamping ring, and 
           [0047]      FIG. 11  is a plan view of a wing for an aircraft comprising slats deployable using the slat support assembly according to an embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0048]    Referring to  FIGS. 2 to 11  of the accompanying drawings, there is shown a slat support arm  15  forming part of a slat support assembly according to an embodiment of the present invention and which has a pair of upper bearing tracks  16   a ,  16   b , and a pair of lower bearing tracks  17   a , 17   b . Each of the upper bearing tracks  16   a ,  16   b  are not co-planar but are angled relative to each other, as are each of the lower bearing tracks  17   a ,  17   b . However, it will be appreciated that only the upper  16   a ,  16   b  or the lower bearing tracks  17   a ,  17   b  may be angled relative to each other, as required. If only the upper bearing tracks  16   a ,  16   b  are angled relative to each other, the lower bearing tracks  17   a ,  17   b  may lie in the same plane. A slat rack  18  is received in a groove  19  in the slat support arm  15  and has teeth  20  for engagement with a drive pinion (not shown), similar to the arrangement described with reference to  FIG. 1 . 
         [0049]    The slat support arm  15  extends through an opening  21  in each of a pair of bearing blocks  22  which are spaced from each other in the direction of travel of the slat support arm  15  between its deployed and retracted positions along an arcuate path defined by the mid-line X-X extending through the slat support arm  15  as shown in  FIG. 2 . Each bearing block  22  mounts and holds a set of four bearings  23 , 24 , 25 , 26  (see  FIG. 3 ), each having bearing surfaces that lie in contact with an associated bearing track  16   a ,  16   b ,  17   a ,  17   b  on the slat support arm  15 . Each set of bearings  23 , 24 , 25 , 26  includes a pair of upper support bearings  23 ,  24  and a pair of lower support bearings  25 ,  26 . Each bearing block  22  has recesses  27 , accessible via openings  28  in opposing end walls  29  of each bearing block  22 , to facilitate insertion of the bearings  23 , 24 , 25 , 26  into the bearing block  22  and their removal therefrom. 
         [0050]    The bearings  23 , 24 , 25 , 26  can be seen more clearly from  FIG. 3 , which is identical to  FIG. 1  except that the bearing blocks  22  have been omitted so that the bearings  23 , 24 , 25 , 26  and their positions relative to the slat support arm  15  are more clearly visible. Each bearing  23 , 24 , 25 , 26  comprises a cylindrical bearing element  30  having a curved outer peripheral bearing surface  31  that is mounted on a shaft  32  having an end cap or head portion  33 . The end of the shaft  32  remote from the cap  33  is part-threaded at  34  for threaded engagement with a corresponding thread (not shown) in the recess  27  in the bearing block  22  when the shaft  32 , together with the bearing element  30  mounted thereon, is inserted into their recess  27  through the openings  28  in the end walls  29  of each bearing block  22 . The upper end face  35  of the cap  33  has holes  36  to cooperate with a tool (not shown) to enable the bearing  23 , 24 , 25 , 26  to be located within and tightened within the bearing block  22 . 
         [0051]    Each bearing element  30  is cylindrical and has a longitudinal axis A-A. Each bearing element  30  is freely mounted for rotation about its fixed shaft  32 , which has a longitudinal axis B-B. Whilst the axis A-A of the bearing element  30  and the axis B-B of the shaft  32  may be coaxial with each other, as shown in  FIG. 3 , the bearing element  30  is mounted to its shaft  32  via a self-aligning or spherical bearing member  37  (see  FIG. 8 ), so that the bearing element  30  has a limited freedom of movement in all directions relative to its shaft  32  and can tolerate a small angular misalignment with its associated shaft  32 . Therefore, the axis A-A of the bearing element  30  may lie at an angle relative to the axis B-B of the shaft  30 . This freedom of movement of the bearing element  30  relative to the shaft  32  to which it is mounted provides the bearing elements  30  we a degree of adjustability in their position so that each bearing  23 , 24 , 25 , 26  self-aligns and maintains a full and accurate line of contact with its corresponding bearing track  16   a , 16   b ,  17   a , 17   b  across its full width, irrespective of whether the bearing block  22  has been tilted out of its neutral position to compensate for any misalignment, deflections or improper mounting or, to enable the bearings  23 , 24 , 25 , 26  to be pre-loaded against the bearing track  16   a , 16   b , 17   a , 17   b , as will now be explained in more detail below. 
         [0052]      FIG. 4  is a plan view of part of a slat track  15  extending through a single bearing block  22 . The upper bearings  16   a ,  16   b  mounted in the bearing block  22  are also shown for clarity although they would be hidden within the bearing block  22  and so would not be visible in practice. During assembly, the bearing block  22  is received between spaced ribs  40 ,  41  forming part of the structure of the aircraft wing  1  (which is shown in part in  FIGS. 4 and 5  and in full in  FIG. 11 ), and is immovably fixed in position, as will become apparent from the description that follows. In  FIG. 4 , the bearing block  22  is shown in a ‘neutral’ or upright position in which the axis B-B of each bearing shaft  32  lies at right-angles to the direction of travel of the slat support arm  15  through the opening  21  in the bearing block  22 , as indicated by line R-R, and the axis of rotation A-A of each bearing element  30  is coaxial with the axis of rotation B-B of its associated bearing shaft  32 . In this position, there is no compensation for manufacturing tolerances and no pre-loading of the bearings against the bearing track  16   a ,  16   b.    
         [0053]      FIG. 5  is similar to  FIG. 4 , except that the bearing block  22  has now been tilted about an axis H-H, which extends through a centre of the bearing block  22  at right angles to the ribs  40 ,  41  and which intersects the arcuate mid-line X-X extending through the centre of the slat support arm  15  along which the slat support arm  15  moves. In  FIG. 5 , the angle of inclination of the bearing block is shown as being in the order of 12 degrees, although other angles in excess of, or lower than, 12 degrees may also be employed. It will also be appreciated that the bearing block  22  can be tilted about axis H-H in either direction. 
         [0054]    Despite the bearing block  22  being tilted out of its neutral position shown in  FIG. 4 ,  FIG. 5  still shows the bearing elements  30  in their original positions in which the axis of rotation A-A of each bearing element  30  is still coaxial with the axis of rotation B-B of its associated bearing shaft  32 , so as to illustrate the misalignment that occurs between the bearing surface  31  of the bearing element  30  and the bearing track  16   a , 16   b  on the slat support arm  15  when the bearing block  22  is tilted as shown in  FIG. 5 . It will be appreciated that the axis of rotation A-A of the bearing elements  30  and the axis of rotation B-B of the shaft  32  lie at a right angle to line D-D, whereas the bearing elements  30  need to be rotating about an axis that lies at right angles to line R-R to maintain alignment and a full line of contact with the bearing track  16   b ,  16   a.    
         [0055]    The misalignment referred to above is shown in greater detail in  FIG. 6 , which illustrates a single bearing element  30  whose axis of rotation A-A remains coaxial with the axis of rotation B-B of the shaft  32  on which it is mounted. 
         [0056]      FIG. 7  is a similar view to  FIG. 6 , except that the bearing element  30  is now shown in a self-aligned position in which it has pivoted about arrow F upon tilting of the bearing block  22  into the position shown in  FIG. 5 , so that the axis A-A of the bearing element  30  is no longer coaxial with the axis B-B of the bearing shaft  32  and so that the bearing element  30  is now properly aligned with its associated bearing track  16   a.    
         [0057]    Whilst the bearing adjustment that is required is generally all in the same plane, i.e. in the plane occupied by arrow F in  FIG. 7 , there is also a small degree of adjustment required in a secondary plane at right angles to the plane occupied by arrow F. This is illustrated by arrow G in the cross-sectional side view through a bearing  30  shown in  FIG. 8 . Only approximately +/−2 degrees of bearing adjustment is generally required in this plane, whereas approximately +/−6.5 degrees of bearing adjustment is generally required in the plane occupied by arrow F in  FIG. 7 . 
         [0058]      FIG. 9  is a perspective side view showing the bearing block  22  and one of the ribs  40  shown in  FIG. 4 , to illustrate how the bearing block  22  may be inserted between adjacent ribs  40 ,  41  and accurately positioned and angled or tilted to provide the required degree of tolerance compensation or pre-load, before being immovably fixed to the ribs  40 ,  41  during assembly. 
         [0059]    As can be seen in  FIG. 9 , a machined relief or depression  45  is formed on the inner surface  46  of each rib  40 ,  41  that extends inwardly across the plane of the rib  40  from its upper edge  47 . An aperture  48  is also formed in each rib  40 ,  41  within the area occupied by the depression  45 . Two separate depressions  45  are shown in the rib  40  in  FIG. 9 , with a bearing block  22  positioned in only one of them. The end wall  29  of a second bearing block  22  would be received in the other depression  45  and the slat support arm  15  would extend through both bearing blocks  22 , as shown in  FIG. 2 . 
         [0060]    It will be understood that each bearing block  22  is inserted between the ribs  40 , 41  by engaging the opposing side walls  29  of the bearing block  22  with the ribs  40 , 41 . The distance between adjacent ribs  40 , 41  and the width of the bearing block  22  is selected so that the bearing block  22  will be a snug or frictional fit between the ribs  40 , 41  with the side walls  29  received in the depression  45  in each rib  40 , 41 . The bearing block  22  can be inserted into facing depressions  45  between ribs  40 ,  41  from the upper edge  47  of each rib  40 ,  41  where the depression  45  meets edge  47  (i.e. in the direction indicated by arrow ‘Y’ in  FIG. 9 ), and slid home, i.e. until side walls  29  engage with a lower arcuately shaped edge or step  49  of the depression. The end walls  29  of the bearing block  22  are formed with arcuately shaped shoulders  50  that correspond with the arcuately shaped step  49  forming the lowermost edge of the depression  45  and the bearing block  22  is slid into the depression  45  between ribs  40 ,  41  until the shoulder  50  on each end wall  29  engages or contacts the step  49 . In this position, the bearing block  22  is held loosely between the ribs  40 ,  41  and cannot drop further between them. Once in this position, the slat support arm  15  may be inserted through the openings  21  in each bearing block  22 . The bearing block  22  may then be tilted about the centre line of the slat support arm  15  (i.e. about its central axis H-H in  FIG. 9 , which intersects mid-line X-X of the slat support arm  15 ), with the curved shoulder  50  sliding against the step  49 . The depression  45  is formed with shaped cut out regions  70  to allow the bearing block  22  to pivot about its central axis H-H within the depression  45 . 
         [0061]    Once the optimum angular position for the bearing block  22  has been reached, it is necessary to lock the bearing block  22  in place so that it is no longer capable of moving. The locking or clamping mechanism should be capable of lasting the life of the aircraft and needs to enable the bearing block  22  to be positioned in an infinite number of locking positions within the desired angular range, whilst still allowing access to the bearing block  22  and bearings for inspection and maintenance. It should also be possible to release the clamping mechanism so that the bearing blocks  22  can be removed and replaced, without causing any damage to the surrounding structure or to the ribs  40 ,  41  to which the bearing blocks  22  are attached. 
         [0062]    An appropriate adjustment and clamping mechanism  55  will now be described, with reference to  FIGS. 10   a  to  10   c .  FIG. 10   a  shows a perspective view of one end wall  29  of a bearing block  22  received within a machined depression  45  in a rib  40  and in which the bearing block  22  has been rotated about axis A-A in order to counteract any misalignment or to preload the bearings against the bearing track  16   a ,  16   b ,  17   a ,  17   b . Once the bearing block  22  has been inserted between the ribs  40 ,  41 , an adjustment and clamping ring  56  is attached to the bearing block  22 . The adjustment and clamping ring  56  has a pair of diametrically opposed arcuately shaped legs  57  each of which extend through, and are slideably received within, a corresponding arcuately shaped through slot  58  in the rib  40 . The legs  57  are received in holes  59  in the end wall  29  of the bearing block  22 . The legs  57  are retained in the holes  59  in the bearing block  22  under friction. As the adjustment and clamping ring  56  is rotated, such as in the direction of arrow S in  FIG. 10   b , the bearing block  22  also rotates together with the ring  56  into its desired angular position about axis H-H, with the legs  57  of the ring  56  sliding in their arcuate slots  58  in the rib  40 . 
         [0063]    Once the desired angular position of the bearing block  22  has been reached, the adjustment and clamping ring  56  is pushed inwardly, i.e. the direction of axis H-H and as shown by the arrow I in  FIG. 10   c . An inner peripheral surface of the opening  21  in the rib  40  is provided with serrations  60  or has a toothed profile and the adjustment and clamping ring  56  is similarly provided with corresponding serrations  61  or teeth that engage with the serrations or teeth  60  on the rib  40  when the ring  56  is moved inwardly along axis H-H. 
         [0064]    It will be appreciated that the holes  59  in the end wall  29  of the bearing block  22  in which the legs  57  of the adjustment and clamping ring  56  are received are deep enough for the legs  57  to slide further into them as the adjustment and clamping ring  56  is pressed inwardly in the direction of arrow I. The adjustment and clamping ring  56  is pushed inwardly until a flange  62  on the ring  56  contacts the outer surface of the rib  40  in a region surrounding the opening  21  in the rib  40 . In this position, the bearing block  22  is held in place due to engagement between the serrations  60 ,  61  or teeth on the rib  40  and on the ring  56 . To further retain the ring  56  in position and prevent it from working loose, bolts or other fasteners (not shown) are inserted through holes in the flange  62  of the adjustment and clamping ring  56  and extend through the opening  48  in the rib  40  to threadingly engage in holes  63  in the end wall  29  of the bearing block  22 . It will be appreciated that the clamping ring  56  can be easily removed to allow the position of a bearing block  22  to be further adjusted or to allow it to be removed and replaced. 
         [0065]    As the bearing block  22  is tilted out of its neutral position, the bearing elements  30  adjust their axes A-A relative to the axis of their associated shafts B-B in order so that full-line contact between the bearing element  30  and its associated bearing track  16   a , 16   b ,  17   a , 17   b  is maintained and any required pre-load is applied. 
         [0066]    It will be appreciated that the foregoing description is given by way of example only and that modifications may be made to the slat support assembly of the present invention without departing from the scope of the appended claims.