Abstract:
A transport wheel device for a helicopter having a runner defining an axial direction. The transport wheel includes a holding frame, a wheel axle, a slide, a wheel and a lifting device. The holding frame is detachably securable to the runner. The wheel axle is attached the holding frame by the slide. The slide is continuously adjustable axially with respect to the holding frame and securable in an axial position. A wheel is disposed on the wheel axle. The lifting device is coupled to the holding frame and the wheel axle. The lifting device is configured to vertically move the transport wheel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is claimed to German Patent Application No. DE 10 2007 051 650.0, filed Oct. 26, 2007, the entire disclosure of which is incorporated by reference herein. 
       FIELD 
       [0002]    The invention relates to a transport wheel for a helicopter. 
       BACKGROUND 
       [0003]    Helicopters usually include a slide which, in order to have control over the physical effects that are peculiar to the helicopter, consists of runners and flexible tubes with a defined spring characteristic used as a landing gear. This landing gear fulfils most conditions of application of a helicopter, yet has great disadvantages in the event of movement of the helicopter on the ground. 
         [0004]    In order to render possible movement or displacement of the helicopter on the ground, the runners of the helicopter, which are aligned in parallel to each other, may each include a respective transport wheel which is capable of being jacked up. In order to prevent the helicopter from tipping or to minimize the forces for the operating personnel, the assembly of the two transport wheels should as far as possible be effected in such a way that, when viewed in the axial direction or in the longitudinal direction of the helicopter, the position of the overall centre of gravity of the helicopter lies on or in the immediate vicinity of an imaginary connecting line of the two transport wheels. 
         [0005]    Such transport wheels for a helicopter are used in Eurocopter EC 135 helicopter, for example. 
         [0006]    The position of the overall centre of gravity of a helicopter, depending on various load states of the helicopter, such as, for example, refuelling, additional loading etc., is not constant. 
         [0007]    The known transport wheels prove to be disadvantageous since they do not enable there to be sufficient adjustment to the respective position of the centre of gravity of the helicopter. The consequence of this is that the overall centre of gravity of the helicopter does not always lie above the imaginary connecting line of the transport wheels, that is, significant moments or operating forces result. In order to compensate for these moments or forces it is necessary to use trim weights. 
       SUMMARY 
       [0008]    An aspect of the present invention is to form a transport wheel for a helicopter further in such a way that adjustment of the transport wheels to the respective position of the centre of gravity of the helicopter is rendered possible. 
         [0009]    In an embodiment, the present invention provides a transport wheel device for a helicopter having a runner defining an axial direction. The transport wheel includes a holding frame, a wheel axle, a slide, a wheel and a lifting device. The holding frame is detachably securable to the runner. The wheel axle is attached the holding frame by the slide. The slide is continuously adjustable axially with respect to the holding frame and securable in an axial position. A wheel is disposed on the wheel axle. The lifting device is coupled to the holding frame and the wheel axle. The lifting device is configured to vertically move the transport wheel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Exemplary embodiments of the present invention are described in further detail below in connection with the drawings, in which: 
           [0011]      FIG. 1  shows a perspective representation of a helicopter obliquely from the front with a transport wheel in accordance with the invention that is assembled in the region of the flexible tube on the runner; 
           [0012]      FIG. 2  shows the transport wheel from  FIG. 1  in an enlarged representation; 
           [0013]      FIG. 3  shows the transport wheel from  FIG. 2  in a sectional representation; and 
           [0014]      FIG. 4  shows a top view of the helicopter with transport wheels that are arranged so that they are offset with respect to each other. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    In an embodiment of the present invention, the transport wheel for a helicopter comprises a holding frame which can be detachably secured to a runner of the helicopter, a wheel axle that bears a wheel and is operatively connected to the holding frame, and also a lifting device that is operatively connected to the holding frame and the wheel axle for vertically moving or jacking up the transport wheel. The wheel axle bearing the wheel is operatively connected to the holding frame by way of a slide, with the slide, when viewed in the axial direction or in the longitudinal direction of the helicopter, being formed so that it is continuously adjustable in relation to the holding frame and so that it can be arrested in its respective axial position. 
         [0016]    As a result of the features in accordance with the invention the transport wheels can be adapted to the position of the overall centre of gravity of the helicopter, that is, to align the transport wheels in the axial direction in such a way that the centre of gravity of the helicopter always comes to lie above the imaginary connecting line of the transport wheels. The necessary operating forces for the operating personnel on the ground are thus reduced and use of trim weights is no longer required. 
         [0017]    The slide, when viewed in the radial direction, may be guided in the holding frame in a form-locking manner. The form-locking guidance can be produced simply and inexpensively and moreover it guarantees seating of the slide in the holding frame in a secure manner to prevent loss. 
         [0018]    The slide can be operatively connected to a lever that is easily accessible. The lever has the effect that simple handling, that is, displacement of the slide, is rendered possible. 
         [0019]    In order to simplify the handling further, in an embodiment the lever also has the appropriate means for the axial arrest of the slide in relation to the holding frame. 
         [0020]    The lifting device and the wheel axle bearing the wheel can be detachably secured to the holding frame. This has the effect that both the lifting device and the wheel can be quickly disassembled and can be carried along in the cabin of the helicopter, for example. 
         [0021]    In order to reduce or minimize the bending moments acting on the transport wheel, in accordance with an embodiment of the invention the holding frame is arranged in the region of the flexible tube. 
         [0022]    For this, the holding frame may be formed in two sections. That is to say, the holding frame has two holding legs that are arranged in parallel to each other and in the assembled state the flexible tube is arranged in the intermediate space set by the two holding legs. The holding frame is detachably secured to the runner and the flexible tube by way of first and second end regions of the holding legs. The arrangement that is in two sections and receives the flexible tube between the two holding legs prevents unintentional axial displacement of the holding frame. 
         [0023]    In accordance with an embodiment, the first end regions of the holding legs are in each case formed as semicircular recesses that embrace the runner partly in a form-locking manner, and the second end regions of the holding legs in each case have a bore to receive a securing element that extends behind the flexible tube and is mounted on the two holding legs in a secure manner to prevent loss. This has the effect that simple assembly of the holding frame is guaranteed. 
         [0024]    The securing element can be formed in two parts and comprises a clip that is formed in a substantially U-shaped manner with ends that are formed in a jaw-shaped manner and a separate bolt that extends behind the flexible tube and is guided in the jaw-shaped ends. The development proves to be particularly advantageous, since the bolt is held in a secure manner to prevent loss in a simple way by way of a rotational movement of the clip, which is formed in a U-shaped manner, on account of the ends that are formed in a jaw-shaped manner. 
         [0025]    In accordance with a further embodiment of the invention, the holding frame and/or the slide are formed as cast portions. The formation of the holding frame and/or the slide as cast portions renders possible inexpensive production. 
         [0026]    In  FIG. 1  a helicopter is shown in a view obliquely from the front in a more or less diagrammatic representation. 
         [0027]    A transport wheel that is denoted as a whole by the reference numeral  10  is secured to a runner  14  of the helicopter in the region of a flexible tube  12 . A corresponding transport wheel is assembled on the opposite runner of the helicopter. 
         [0028]    The transport wheel  10  that is represented comprises a wheel  11 , a holding frame  16 , and also a lifting device  18  for vertical movement, that is, for jacking up the transport wheel  10 , as shown in  FIG. 2 . 
         [0029]    As can be inferred in particular from  FIG. 3 , a wheel axle  20  bearing the wheel  11  is operatively connected to the holding frame  16  by way of a slide  22 . 
         [0030]    The slide  22  is then guided in a form-locking manner in the holding frame  16  by way of a section that is formed in a spherical manner in cross section, when viewed in the radial direction r. The form-locking guidance is then designed in such a way that, when viewed in the axial direction a, the slide  22  can be continuously adjusted and arrested in relation to the holding frame  16 . 
         [0031]    As a result of the continuous axial adjustability of the slide  22 , simple adaptation of the transport wheels  10  to the respective position of the overall centre of gravity of the helicopter is rendered possible in the present case. The hitherto usual trim weights for compensation of the overall centre of gravity that has “migrated” on account of refuelling or additional loading, for example, are no longer required. 
         [0032]    As  FIG. 3  further shows, the slide  22  is, moreover, operatively connected to a lever  24 . The lever  24  is then arranged in such a way that it is easily accessible for the operating personnel and is used as a point of engagement for displacement of the slide  22  and thus the wheel  11  in relation to the holding frame  16 . Moreover, the lever  24  has means to arrest the slide  22  in order to fix a selected axial position of the transport wheel  10 . A representation of the means for arresting the slide  22  has been dispensed with in the present case for reasons of clarity. 
         [0033]    As already stated, the transport wheel or wheels  10  are arranged in the region of the flexible tube  12  in the present case, as shown in  FIGS. 1 and 2 . 
         [0034]    In order to render possible non-slip assembly of the transport wheel  10 , when viewed in the axial direction a, the holding frame  16  is formed in two sections, having a first and second holding leg  26 ,  28 , as shown  FIG. 2 . The holding legs  26 ,  28  are aligned in parallel to each other, and in the assembled state the flexible tube  12  is arranged in the interspace between the two holding legs  26 ,  28 . 
         [0035]    For simple assembly of the two holding legs  26 ,  28  and thus of the holding frame  16  on the runner  14  or on the flexible tube  12 , the two holding legs  26 ,  28  each have first end regions  30  associated with the runner  14  and second end regions  32  associated with the flexible tube  12 . 
         [0036]    Whilst in the present case the first end regions  30  of the holding legs  26 ,  28  are formed as semicircular recesses that embrace the runner  14  partly in a form-locking manner, the second end regions  32  of the holding legs  26 ,  28  each comprise a bore to receive a securing element  33  that extends behind the flexible tube  12  and is mounted on the two holding legs  26 ,  28  in a secure manner to prevent loss. 
         [0037]    In the present case, the securing element  33  is formed in two parts and comprises a clip  34  formed in a U-shaped manner and a separate bolt  36  that extends behind the flexible tube  12 . The clip  34  has ends  38  that are formed in a jaw-shaped manner to receive the bolt  36  so that by way of a simple rotational movement of the clip  34  the bolt  36  that is arranged behind the flexible tube  12  can be fixed with the clip  34 , and mounting of the bolt  36  in a secure manner to prevent loss is guaranteed. 
         [0038]      FIG. 4  shows an alternative arrangement of the two transport wheels  10 . The two transport wheels  10  are in this case arranged so that they are offset with respect to each other when viewed from above. The offset arrangement is then selected so that, when viewed in the axial direction a, the overall centre of gravity of the helicopter lies between the two transport wheels  10 . The advantage of this special arrangement of the two transport wheels  10  is that the tendency of the helicopter to tilt is minimized and thus the helicopter can be “held” by one operator. 
         [0039]    The offset arrangement can be combined with a suitable pulling device so that the helicopter can be pulled without an accompanying person. 
       LIST OF REFERENCE SYMBOLS 
       [0000]    
       
           10  Transport wheel 
           11  Wheel 
           12  Flexible tube 
           14  Runner 
           16  Holding frame 
           18  Lifting device 
           20  Wheel axle 
           22  Slide 
           24  Lever 
           26  First holding leg 
           28  Second holding leg 
           30  First end region 
           32  Second end region 
           33  Securing element 
           34  Clip 
           36  Bolt 
           38  Jaw-shaped ends 
         a axial direction 
         r radial direction