Abstract:
A mounting assembly ( 6 ) for mounting a bulldozer blade ( 2 ) to a vehicle ( 4 ) is disclosed. The assembly comprises a lower link ( 8 ) adapted to be mounted to a vehicle, a pair of first actuators ( 16, 18 ) adapted to be pivotably mounted to the blade, and to a pair of link plates ( 24, 26 ) via respective pin joints ( 28, 30 ), and a pair of second actuators ( 36, 38 ) adapted to adjust the position of respective pin joints ( 28, 30 ) relative to the lower link to adjust the orientation of the blade relative to the vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European Patent Application No. EP 12159895, filed Mar. 16, 2012, titled “Mounting Assembly for Mounting Implement to a Vehicle,” and UK Patent Application No. GB 1204654.6 filed on Mar. 16, 2012, the contents of both of which are hereby incorporated by reference in their entireties herein. 
     FIELD 
     The present invention relates to a mounting assembly for mounting an implement to a vehicle, and relates particularly, but not exclusively, to a mounting assembly for mounting a bulldozer blade to a military work vehicle. 
     BACKGROUND 
     Blade mounting assemblies for mounting bulldozer blades to vehicle bodies are known. These often include mechanisms which allow the lift (height of the blade relative to the vehicle), pitch (orientation of the blade about an axis generally normal to the vehicle centre line plane), angle (orientation of the blade about a generally vertical axis) and tilt (orientation of the blade about a generally horizontal axis parallel to the vehicle centre line plane) to be adjusted for particular operations. Military work vehicles generally operate as conventional bulldozers, i.e. clearing debris, filling holes and so on, but in some cases also function as “earth anchors” in which the blade is buried deeply in the ground to provide a secure anchor to allow the vehicle, fitted with a suitable winch, to recover other vehicles stuck in soft terrain. 
     Since the blade is generally designed to be fitted to heavy vehicles, the assembly may be subjected to very high loads. For example, if the edge of the blade strikes a sufficiently immovable obstacle while bulldozing, the vehicle will be stopped almost instantly. The loads in the assembly in such a situation may be very large compared to normal bulldozing loads. 
     At the same time, it is also desirable to be able to adjust blade angle, for example when clearing snow from a carriageway to a roadside. In one known arrangement, one or more powered actuators are connected between the blade and a frame in order to rotate the blade relative to the frame. Such arrangements suffer from the disadvantage that when the blade is facing straight ahead, the actuator cylinders are partly extended, usually at their mid-point of travel, and actuators are then further extended and/or contracted to turn the blade left or right from its mid position. The blade is typically held rigidly in the mid position by locking the actuators. Since hydraulic cylinders are usually used as actuators, these are locked by closing hydraulic valves connected to the cylinder ports, preventing oil leaving or entering the cylinder, and thus preventing the cylinders extending or contracting. In order to avoid damage to the cylinders by excess pressure or buckling, hydraulic circuits typically include pressure relief valves which override this lock if a sufficiently high external force results in hydraulic pressures above some set threshold value, for example as a result of the blade edge striking some sufficiently immovable object and if the moving vehicle has sufficient mass and speed. 
     Such arrangements suffer from the disadvantage that in order to increase the size of load which the assembly can withstand, larger hydraulic cylinders need to be used, which significantly increases the weight and volume of the assembly. 
     SUMMARY 
     Preferred embodiments of the present invention seek to overcome the above disadvantage of the prior art. 
     According to an aspect of the present invention, there is provided a mounting assembly for mounting an implement to a vehicle, the assembly comprising:— 
     a body adapted to be mounted to a vehicle; 
     at least one pair of first actuators; each said first actuator being adapted to be pivotably mounted, at a respective first pivot, to one of said body or an implement; 
     a plurality of first link members, each said first link member being pivotably mounted, at a respective second pivot, to a respective said first actuator and adapted to be pivotably mounted, at a respective third pivot, to the other of said body or said implement; 
     characterised by a plurality of second actuators, each said second actuator being adapted to adjust the position of a respective said second pivot relative to the body to adjust the orientation of the implement relative to the vehicle, 
     wherein at least one said first link member and the corresponding said first actuator are arranged in use such that a line directly connecting said first and second pivots is arranged at an obtuse angle to a line directly connecting said second and third pivots, and at least one said second actuator is adapted to move the corresponding said second pivot from one side of a line directly joining the corresponding said first and third pivots to the other side of said line. 
     By providing first link members pivotably mounted at respective second pivots to first actuators and second actuators for adjusting the position said second pivots relative to the body to adjust the orientation of the implement relative to the vehicle, this provides the advantage of enabling the distance between the implement and an adjacent part of the vehicle to be reduced by means other than reducing the length of one or more of the first actuators. As a result, the implement can be in its angular mid position with fully compressed first actuators, which provides the advantage of significantly increasing the compressive forces which the assembly can withstand by means of actuators of a given size, as a result of which a lighter and more compact mounting assembly can be used for a given load. 
     This also provides the advantage of enabling compressive loads tending to cause the obtuse angle to change to be resisted by means of a more compact second actuator when in tension, thereby further contributing to reduction in weight and volume of the assembly. 
     This also provides the advantage of enabling the angle of the implement relative to the vehicle to be adjusted by means of a more compact assembly. 
     At least one said first link member and the corresponding said first actuator may be arranged such that loads urging the implement towards the vehicle in use tend to decrease the size of said obtuse angle. 
     At least one said second actuator may be arranged such that loads urging the implement towards the vehicle in use cause tensile loading of said second actuator. 
     This provides the advantage of enabling the loads to be resisted by means of a more compact second actuator. 
     At least one said second actuator may be pivotably mounted at a respective fourth pivot to said body. 
     The assembly may further comprise at least one third actuator for adjusting the orientation of the body relative to the vehicle. 
     At least one said third actuator may be adapted to cause pivoting of the implement relative to the vehicle about a first axis, and said first and second actuators may be adapted to cooperate to cause pivoting of the implement relative to the vehicle about a second axis substantially perpendicular to said first axis. 
     At least one said third actuator may be adapted to be pivotably mounted relative to the vehicle and to the implement. 
     The assembly may comprise a plurality of said third actuators. 
     This provides the advantage of providing a further degree of freedom of pivoting of the implement relative to the vehicle, by means of extending at least one said third actuator and/or contracting at least one said third actuator. 
     The assembly may further comprise at least one second link member adapted to be pivotably mounted relative to the implement and to the vehicle to adjust the orientation of the implement relative to the body as the orientation of the body relative to the vehicle changes. 
     This provides the advantage of enabling automatic pitch control of the implement when the implement is a bulldozer blade without the need for an additional actuator, thereby minimising increases in weight and volume of the assembly. 
     According to another aspect of the present invention, there is provided a vehicle comprising: 
     a vehicle body; 
     an implement; and 
     a mounting assembly as defined above connected to said vehicle body and said implement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the invention will now be described, by way of example only, and not in any limitative sense, with reference to the accompanying drawings, in which:— 
         FIG. 1  is a side view of a bulldozer blade attached to a vehicle by means of a mounting assembly embodying the present invention and with the blade level with a nominal ground plane; 
         FIG. 2  is a plan view of the arrangement of  FIG. 1 ; 
         FIG. 3  is a side view of the arrangement of  FIG. 1  with the blade in a raised position for travelling between work locations; 
         FIG. 4  is a side view of the arrangement of  FIG. 1  with the blade in a lowered position for earth anchoring; 
         FIG. 5  is a view from below of the arrangement of  FIG. 1  with the blade angled to one side; and 
         FIG. 6  is a side view of the arrangement of  FIG. 1  with the blade in a tilted position for breaking through a hard surface. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 ,  2  and  5 , a bulldozer blade  2  is attached to a vehicle  4  by means of a mounting assembly  6  embodying the present invention. The assembly  6  comprises a body in the form of a lower link  8  connected to the vehicle  4  by means of a pin joint  10 , the axis of the pin joint  10  being generally perpendicular to a vehicle centre line plane  12  ( FIG. 2 ). The lower link  8  is connected the blade  2  by means of a ball joint  14  ( FIG. 5 ). 
     A pair of first actuators  16 ,  18  are connected to the blade  2  by respective ball joints  20 ,  22  and to respective first link members in the form of link plates  24 ,  26  by means of respective pin joints  28 ,  30 . The link plates  24 ,  26  are connected to the lower link  8  by means of respective ball joints  32 ,  34  ( FIG. 5 ). A pair of second actuators  36 ,  38  are connected to the lower link  8  by respective ball joints  40 ,  42  and to the respective link plates  24 ,  26  and actuators  16 ,  18  at the respective pin joints  28 ,  30  such that the actuators  16 ,  18  and respective link plates  24 ,  26  form respective obtuse angles to each other in the arrangement shown in  FIG. 2 . As a result, high loads tending to urge the blade  2  towards the vehicle  4  will result in high compressive loads in the actuators  16 ,  18  and link plates  24 ,  26  tending to urge the respective pin joints  28 ,  30  outwardly to reduce the size of the respective obtuse angles, this movement being resisted by tensile loads in the respective actuators  36 ,  38  which can be resisted by means of a more compact actuator design, since actuators are more effective in tension than in compression. 
     A pair of third actuators  44 ,  46  are connected to the blade  4  by respective “point on line” joints  48 ,  50 . As will be appreciated by persons skilled in the art, a “point on line” joint is a joint having one translational degree of freedom and three rotational degrees of freedom, for example a plain spherical bearing which can slide along a pin. In the arrangement shown in  FIG. 2 , the axis of the translational degree of freedom is fixed normal to the centre line plane  52  of the blade  2 . Left actuator  46  is connected to the vehicle  4  by means of a pin joint  54 , the structure connecting the pin joint  54  to the vehicle body being omitted from the Figures for clarity, and the axis of the pin joint  54  is generally perpendicular to the vehicle centre line plane  12 . Similarly, right actuator  44  is connected to the blade  2  by “point on line” joint  48  and to the vehicle body by means of a pin joint  56 . Again, the structure connecting the pin joint  56  to the vehicle body is omitted from the Figures for clarity. 
     A top link  58  is attached to the vehicle body by means of a ball joint  60  and to the bulldozer blade  2  by means of a ball joint  62 . Referring to  FIG. 3 , the blade  2  is raised relative to ground plane  64  by retraction of actuators  44 ,  46  so that the blade  2  and mounting assembly  6  fit within an envelope  66  bounded by an approach angle plane  68  and a sight or gun line plane  70 . This enables the apparatus to be effectively stowed when not in use. 
     Referring now to  FIG. 4 , extension of the actuators  44 ,  46  causes the assembly  6  to lower the blade  2  deeply below the nominal ground plane  64 . This enables secure earth anchoring to be carried out. 
     Referring to  FIGS. 2 and 5 , in order to adjust the angle of the blade  2  relative to the vehicle  4  body, one of the second actuator  36  is extended and the other second actuator  38  is contracted. This urges one pin joint  30  outwardly of the assembly  6  and withdraws the other pin joint  28  inwardly, as a result of which the respective first actuators  16 ,  18  and corresponding link plates  24 ,  26  pivot relative to each other. As can be seen from  FIG. 5 , the pin joint  28  moves from one side of a line directly connecting the ball joints  24 ,  34  to the other side of that line, thereby enabling the distance between the blade  2  and the adjacent part of the vehicle  4  to be reduced by means other than retraction of the actuator  18 . This movement is also assisted by means of connection of the lower link  8  to the blade  2  by means of ball joint  14 . Since the blade  2  is also connected to the upper link  58  by means of a ball joint  62 , the blade  2  can rotate about an axis passing through the ball joints  14 ,  62 . 
     Finally, referring to  FIG. 6 , by extending one of the third actuators  44 ,  46  and contracting the other actuator, the blade  2  can be arranged in a tilted position for penetrating hard ground. 
     It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.