Abstract:
A mudguard for a wheel of an agricultural vehicle comprises two or more radially stacked parts and that are movable relative to one another in the axial direction of the wheel and lockable in different relative axial positions to form a mudguard of adjustable width.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]     Priority is hereby claimed under 35 U.S.C. 119 to Great Britain Patent Application GB 0325880.3, titled “Mudguard for a Wheel of an Agricultural Vehicle”, filed Nov. 6, 2003, and having Jim Callan, Vince Ellis, and Allan Smee as inventors. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a mudguard for a wheel of an agricultural vehicle.  
         [0003]     It is desirable for the width of a mudguard of an agricultural vehicle, such as a tractor, to be adjustable. One reason for this is that it is possible to use the same tractor with wheels of different widths and the mudguard is needs to be adapted to the width of the wheel. Also during transportation, or to pass through narrow gates, it may be desirable to reduce the width of the mudguards.  
         [0004]     It has hitherto been proposed to provide mudguard extensions that can be attached to the edge of a mudguard or removed therefrom to allow the mudguard width to be increased and decreased. GB-1,477,628 shows an example of a mudguard having such extensions. In the latter patent, the mudguard is for a lorry and it is formed with extensions to allow only part of a mudguard to be replaced in the event of it being damaged. Despite these differences, the latter patent does demonstrate the principle that has been used in the past to extend the width of mudguards.  
         [0005]     The use of extensions that attach to one another edge to edge has several disadvantages. Aside from the cost implications of manufacturing parts that interlock with one another, a problem is posed by the length of time that it takes to attach and separate the extensions. Also, carrying and aligning the extensions as they are being mounted is a difficult and cumbersome task which often cannot be carried out single handed. A still further problem is presented by the need to be able to store extensions when they are not in use.  
         [0006]     The present invention seeks therefore to provide a mudguard that mitigates these disadvantages and enables the width of the mudguard to be adjusted simply to suit the prevailing requirements.  
       SUMMARY OF THE INVENTION  
       [0007]     According to the present invention, there is provided a mudguard for a wheel of an agricultural vehicle comprising two or more radially stacked parts that are movable relative to one another in the axial direction of the wheel and lockable in different relative axial positions to form a mudguard of adjustable width.  
         [0008]     In the preferred embodiment of the invention, the mudguard is formed of two parts, of which one is mounted when in use directly on the vehicle body and posts of adjustable length are provided for mounting the second part on the vehicle body.  
         [0009]     Of course, it would be alternatively possible for the mudguard to be formed of more than two parts. It would also be alternatively possible to mount a first part on the vehicle body and to support a second part on the first.  
         [0010]     The posts of variable length may suitably be formed of a telescopically collapsible tube of which the sections are lockable relative to one another in different positions. To allow for continuous adjustment of the width, it is preferred for the sections to be lockable relative to one another in all relative positions.  
         [0011]     To lock the sections of the tube to one another, the end of a section may be formed with axially extending slots to allow the diameter of the end of that section to be increased or decreased to clamp against an adjacent section.  
         [0012]     Preferably, the end of an inner section is slotted and expandable to grip the next larger section by means of an internally threaded nut engaged by a tightening bolt passing through the inner section, the nut having a conically tapering outer surface received within the end of the inner section.  
         [0013]     It is an important advantage of the adjustable mudguard of the preferred embodiment of the invention that all its parts remain attached to the vehicle and correctly aligned radially with respect to one another in all settings of the width of the mudguard. Therefore, adjusting the width of the mudguard can readily be carried out single-handedly, as it only requires one of the parts to be released, moved to its desired new position and then re-locked. The weight of the part being moved is supported at all times and even when the mudguard is reduced to its minimum width, all the parts of the mudguard remain attached to the vehicle body and it is not necessary to find an alternative place for them to be stored.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0014]     The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:  
         [0015]      FIG. 1  is a perspective view showing a mudguard of the invention mounted above the rear wheel of a tractor; and  
         [0016]      FIG. 2  is a section through the mudguard passing through one of the adjustable mounting posts supporting the radially inner part of the mudguard. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]     The mudguard  10  shown in the drawings comprises a fixed part  12  and an axially adjustable part  14 , which is also be referred to as an extension, mounted radially inwards of the fixed part  12 . The fixed part  12  is mounted directly on the body of the tractor in a conventional manner and does not move. The extension  14 , on the other hand, is mounted on the vehicle body by means of three adjustable posts  20  of which one is shown in section in  FIG. 2 .  
         [0018]     Each of the adjustable posts  20  is constructed as a telescopically collapsible tube having an outer section  22  secured, such as by welding, to the vehicle body and an inner section  24  secured to, and supporting the weight of, the extension  14 . The inner end of the inner section  24  has one or more axially extending slots to allow its radius to be expanded. A nut  26  with a conically tapering outer surface is received in the end of the inner section  24  and it engages a bolt  28  passing along the length of the inner section, the head  16  of the bolt  28  being accessible from the side of the vehicle.  
         [0019]     The extension  14  is shown in both drawings in an intermediate position in which it has been set to suit the width of the wheel  30 . The position of the extension  14  can be adjusted to suit a different wheel or to allow the tractor to be driven through a narrow opening or close to a hedge.  
         [0020]     To effect such adjustment, the heads  16  of all the bolts  28  are turned to release the clamping action of the inner section  24  of each mounting post  20  on its outer section. Next, the extension  10  is pulled out or pushed in to increase or decrease the width of the mudguard  10 . Hence, if pushed to the left as shown in  FIG. 2 , the extension  14  will lie entirely beneath the fixed part  12  and the mudguard  10  will only be as wide as the fixed part  12 . If pulled further to the right, on the other hand, the extension  14  can be moved to a position where it lies beyond the fixed part  12 , thereby increasing the width of the mudguard to the combined width of the two parts  12  and  14 . Once the mudguard  10  has been set to desired width between these two limits, the bolts  28  are once again tightened. The interaction of the conical surfaces of the nuts  26  with the inner sections  24  of the posts  20  expands the ends of the inner sections  24  to clamp within the outer sections  22  and thereby lock the extension  14  in the desired new position.  
         [0021]     It is an important advantage of the described adjustable mounting posts  20  that mud thrown up by the wheel  30  does not interfere with the locking and releasing of the extension  14 . One however may envisage other adjustable brackets for mounting the extension  14  either on the vehicle body or on the fixed part  12  of the mudguard to enable the extension  14  to be moved axially and locked in any position or at least in certain preset positions.