Abstract:
A boom clamp for a work vehicle having a lock and a boom is provided, the lock being configured to prevent movement of the boom in a first direction, the clamp comprising a restraint configured to engage the boom; and a sleeve fixed to the restraint, the sleeve configured to engage the lock; wherein the restraint prevents the boom from moving in a second direction.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates generally to agricultural and construction vehicles, and more particularly to skid steer loaders. The invention, in combination with existing locking pins, prevents loader arms from moving in two directions.  
       BACKGROUND OF THE INVENTION  
       [0002]     Skid steer loaders and other work vehicles with traversing booms typically require maintenance both in the field and in a dedicated repair shop. The repairman needs access to all parts of the vehicle. Lifting the booms to an intermediate position is required, allowing manual access to the otherwise blocked area of, for example, a skid steer loader. Skid steer loader arms, or booms, are hydraulically controlled. If there are small leaks in the hydraulic system, the booms will slowly lower over time. To avoid this, there are various common mechanisms for preventing booms from lowering inadvertently. These include locking the boom control levers in the operator cab, placing a block such as a drum under the implement at the end of the booms, and locking the boom(s) itself.  
         [0003]     In the area of boom locking devices the prior art teaches various methods of locking a boom for transport. Typically the boom is lowered against the chassis such that the chassis blocks movement in one direction and the boom lock blocks movement in the opposite direction. One example of a transport boom lock uses an operator in-cab control with a linkage to a pin or hook assembly that locks a backhoe boom against the chassis in the boom&#39;s fully upright position. While this locks the backhoe boom against all movement, it requires the boom to be in a non-working position, i.e. fully upright, as for transport. This blocks access to part of the backhoe for repair.  
         [0004]     The prior art also teaches locks that are carried on the boom itself, either on the housing, rod or cylinder, locking the boom in an intermediate position. One example teaches a lock that is placed on the end of the hydraulic cylinder, and acts against the rod and cylinder, preventing retraction of the rod into the cylinder and thereby preventing the loader arm from lowering. This method only prevents the boom movement in one direction relative to the boom itself, that of the rod retracting into the cylinder, i.e. boom contraction.  
         [0005]     The prior art also teaches locking pins that extend through the cab wall and extend into the plane of the skid steer loader arms, locking the booms in an intermediate position. This method prevents the loader arms from lowering with respect to the cab, but not from raising.  
         [0006]     However, in the case of a skid steer loader with a removable combined cab and boom assembly, the situation is different. The cab and boom are tilted away from the base of the vehicle during the repair. As a result, the boom overhangs the end of the vehicle considerably. While the skid steer loader may be equipped with locking pins or sliding bars that prevent the loading arms from lowering (see U.S. Pat. No. 3,730,362 for a complete description of the layout and function of such locking pins), the weight of the cab and boom assembly will tend to pull the boom arm upwards from the cab and away from the locking pins. During repair, the implement at the end of the boom arms (bucket, rake, blade, dozer blade, etc) will typically be supported on a stand. By the force of gravity, the tilted cab boom assembly will descend toward the ground if there is a hydraulic leak, causing the boom arms to pivot upward with respect to the cab. In other words, the existing locking device only prevents the boom from pivoting downward with respect to the cab, and what is needed is a second complimentary device, or boom clamp, to prevent boom movement in the other direction. What is further needed is a simple, low cost-to-manufacture boom clamp. What is also needed is a clamp that a repairman or operator can install and remove quickly without tools when needed. What is further needed is a boom clamp that will not pinch hydraulic cables.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with a first aspect of the invention, a boom clamp for a work vehicle having a lock and a boom, said lock configured to prevent movement of the boom in a first direction is provided, the boom clamp comprising a restraint configured to engage the boom, and a sleeve fixed to the restraint, the sleeve configured to engage the lock, wherein the restraint prevents the boom from moving in a second direction.  
         [0008]     The second direction may be opposite the first direction. The lock may be movable between a first position and a second position, wherein the lock does not prevent the boom from moving in the first direction when the lock is in the first position, wherein the lock prevents the boom from moving in the first direction when the lock is in the second position, and further wherein the restraint prevents the boom from moving in the second direction when the lock is in the second position. The clamp may be configured to be installed and removed by an operator without tools. The boom clamp may further comprise a handle configured to be grasped by an operator during installation and removal of the clamp. The sleeve may be configured to surround the lock. The lock may be a pin and the sleeve may be a cylinder. The restraint may comprise a first plate fixed to the sleeve and configured to face a lower surface of the boom, a second plate fixed to the first plate and configured to extend parallel to the boom, and a third plate fixed to the second plate configured to face an upper surface of the boom. The boom may further include hydraulic lines, and a shroud surrounding the hydraulic lines, wherein the restraint is configured to surround the shroud.  
         [0009]     In accordance with a second aspect of the invention, a boom lock for a skid steer loader, said skid steer loader having a chassis, an operator cab removably attached to the chassis, and a boom pivotally coupled to the operator cab is provided, the boom lock comprising first means for preventing the boom from pivoting in a first direction with respect to the cab, and second means for holding the first means and the boom together.  
         [0010]     The second means may prevent the boom from pivoting in a second direction with respect to the cab. The first means may comprise a locking pin movably attached to the cab. The second means may comprise a boom restraint and a pin sleeve. The second means may be removably attached to the first means and the boom.  
         [0011]     In accordance with a third aspect of the invention, a method for locking a boom on a work vehicle is provided, comprising the steps of extending a locking pin to prevent motion of the boom in a first direction, and coupling a clamp to the locking pin after the step of extending, to prevent motion of the boom in a second direction.  
         [0012]     The step of extending may include extending the locking pin from an operator cab. The step of extending may include moving the boom to a position adjacent the locking pin. The step of coupling may include sliding the locking pin into a hole in the clamp after the step of extending. The clamp may be c-shaped and the step of coupling may include sliding the clamp around the boom. The step of coupling may include sliding the clamp around a protective shroud. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a side view of a skid steer loader with the invention attached.  
         [0014]      FIG. 2  is a partial perspective view of the skid steer loader from  FIG. 1  showing a loader arm with locking pin extended and without the invention attached.  
         [0015]      FIG. 3  is identical to  FIG. 2  except the invention is attached.  
         [0016]      FIG. 4  is a cross section view of the skid steer loader taken at line  4 - 4  of  FIG. 3  showing the cab wall, boom and extended locking pin, with the invention attached.  
         [0017]      FIG. 5  is a perspective view of the invention from the handle (back) side.  
         [0018]      FIG. 6  is a perspective view of the invention from the front side. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]      FIG. 1  shows a skid steer loader  100  for material handling viewed from the left side, with the booms locked in an intermediate position according to the present invention. The “front” of the vehicle is defined as the direction of normal forward movement and the direction the operator will face when operator will face when operating the vehicle to handle materials, and is shown in  FIG. 1  by the directional arrow F. The directions of boom movement of “up” and “down” are relative to the operator cab.  
         [0020]     The loader includes wheels  102 , a main body frame  104 , and a cab boom assembly  106 . The wheels  102  (left front and rear wheels shown, right front and rear wheels not visible in this drawing) are rotatably coupled to and support the main body frame  104 . The main body frame  104  encloses the engine, drive mechanism, and hydraulics (not shown), and supports the cab boom assembly  106 .  
         [0021]     The cab boom assembly  106  is removably attached to the main body frame and rests on top of the frame. The assembly  106  includes the operator cab  108 , the boom structure  110 , and the boom clamp  111 . The operator sits in the operator cab while operating the skid steer loader. Operator controls and seat (not shown) are enclosed by the cab. The cab is composed of left and right sidewalls  112 , a roof, and a (left, right) pair of boom locking pins  113 . The right sidewall and roof are not visible in  FIG. 1 . The boom structure  110  is pivotally attached to the left and right side of the cab  108 .  
         [0022]     The boom structure  110  uses hydraulics and a four-bar linkage to move materials with an implement according to operator commands issued via control levers in the cab  108 . The  FIGS. 1-4  show only the left side portion of the boom structure  110 . An identical mirror-image right side boom structure (not shown) is coupled to the right side of the cab. The left side portion and the right side portion together comprise the boom structure  110 . In all ways other than as stated below, the function and interconnection of the right boom elements is identical to that of the left boom elements. The boom structure comprises left side and right side upper boom arms  114 , left and right side lower boom arms  116 , left and right side supporting links  118 , left and right side hydraulic cylinders  120 , left and right side linkage plates  122  and an implement mounting plate  124 . Further description relates to the left side interconnections of the boom structure, however the right side of the boom structure is interconnected identically.  
         [0023]     The upper boom arm  114 , the supporting link  118 , the hydraulic cylinder  120  and the lower boom arm  116  are all coupled to the linkage plate  122  and, together with the cab, create a four-bar linkage. One end of the lower boom arm  116  is pivotally attached to a rearward section of the sidewall  112  of the cab  108  and extends generally rearwardly and upwardly. The other end of the lower boom arm is pivotally attached to a lower portion of the linkage plate  122 . The cylinder end of the hydraulic cylinder  120  is pivotally attached to a central section of the sidewall  112  and extends generally rearwardly and upwardly. The rod end of the hydraulic cylinder is pivotally attached to a central section of the linkage plate  122 . One end of the supporting link  118  is pivotally attached to an upper section of the sidewall  112  and extends generally rearwardly. The other end of the supporting link is pivotally attached to an upper section of the linkage plate  122 . One end of the upper boom arm  114  is pivotally attached to the implement holder  124  and extends generally rearwardly and upwardly, curving down. The other end of the upper boom arm is fixed to an upper section of the linkage plate  122 .  
         [0024]     The boom structure  110  operates in a left vertical plane parallel to the left sidewall  112  and a right vertical plane parallel to the right sidewall  112  (not shown). By extending the hydraulic cylinder  120 , the four-bar linkage moves such that the implement holder  124  located at the front end of the upper boom arms  114  moves upward. Conversely, retracting the hydraulic cylinder moves the implement holder downward. Further details of the boom structure can be found in U.S. Pat. No. 3,215,292.  
         [0025]     Locking pins  113  (only the left side shown, an identical pin exists on the right side) are slidably supported by the cab of the vehicle. They are configured so the operator can slide them laterally and horizontally from a first position in which they do not interfere with the movement of the boom to a second outward position where they interfere with the movement of the boom, preventing it from pivoting downward. (See  FIGS. 2 &amp; 3  and additional details in U.S. Pat. No. 3,730,362 which is incorporated herein by reference for all that it teaches.)  
         [0026]     In  FIG. 1 , the operator has extended the hydraulic cylinder  120  far enough such that the lower boom arm  116  is above locking pin  113 . The operator has then engaged the locking pin  113  by moving it from the first non-interfering position laterally outward from loader  100  to the second interfering position. The locking pin  113  extends through the sidewall  112  of the operator cab  108  and crosses the left vertical operation plane of the boom structure  110 . The operator has then retracted the hydraulic cylinder and lowered the lower boom arm  116  until it is close to or resting on the locking pin  113 . The operator has then installed the boom clamp  111 , by getting out of the vehicle, picking up the boom clamp, orienting it with the locking pin  113 , orienting it with the lower boom arm  116 , and simultaneously sliding it over the lower boom arm  116  and the locking pin  113 . The combination of the locking pin and the boom clamp prevent the lower boom arm, and thus the entire boom structure  110 , from pivoting either upward or downward with respect to the cab  108 . The hydraulic cylinder  120  is under compression from the weight of the boom structure  110 .  
         [0027]      FIG. 1  also shows, in phantom, a tilted position  126  of the cab boom assembly  106 . This is a common position during repairs, allowing the repairman access to the components contained within the main body frame  104 . It can be seen that tilting the cab boom assembly  106  toward the front moves more of the boom structure  110  and cab  108  closer to or forward of a vertical centerline of the vehicle. This causes the weight of the cab, implement holders  124  and upper boom arms  114  to act upon the hydraulic cylinder  120  such that the cylinder is under extension rather than compression. When the cab  108  is tilted thusly, if there is a hydraulic leak the weight of the cab will tend to cause the cylinder to extend and the lower boom arm  116  to pivot upward with respect to the cab unless the lower boom arm is locked from upward movement (with respect to the cab) with the boom clamp  111 . Thus the boom clamp provides additional useful boom locking functionality as compared to the locking pin  113  which only prevents the lower boom arm  116  from moving downward (with respect to the cab).  
         [0028]      FIGS. 2 &amp; 3  show the left lower boom arm  116  in intermediate locked position and the locking pin  113  in its second interfering position. The FIGURES are identical except  FIG. 3  shows the boom clamp  111  installed and does not show the hydraulic cables  206 . The locking pin  113  extends outward through the sidewall  112  and beneath the lower boom arm  116 . The lower boom arm includes a lower surface  200 , a wear plate  201 , an outer surface  202 , an upper surface  400  ( FIG. 4 ), an inner surface  402  ( FIG. 4 ), a protective shroud  204  and hydraulic cables  206  (shown in phantom). The lower surface, inner surface, outer surface and upper surface are fixed to each other such that they form a beam of rectangular cross section. The wear plate  201  is parallel to and fixed to the bottom of the lower surface  200 , and strengthens the area where the boom rests on the locking pin  113 . The wear plate only extends 4-6″, providing a stop for the locking pin to rest against. The shroud  204  is also generally rectangular in cross section, and is attached to the upper surface  400  of the lower boom arm  116 . In the present embodiment, the shroud does not extend the entire length of the lower boom arm, but only extends 6-8″, and is open at both ends. This is sufficient to restrain the hydraulic cables  206  inside the shroud. The cables run parallel to the lower boom arm  116 , entering the shroud  204  at one open shroud end and leaving at the other open shroud end.  
         [0029]     The lower boom arm  116  pivots about a point  208  where it is connected to the sidewall  112 . The lower boom arm pivots in a first direction downward, shown by arrow A. The lower boom arm also pivots in a second direction upward, shown by arrow B. The locking pin  113  contacts the wear plate  201  of the lower boom arm  116 , preventing the lower boom arm from pivoting in the first direction A beyond it&#39;s current intermediate locked position. In  FIG. 2  there is nothing preventing the lower boom arm from pivoting in the second direction B.  
         [0030]      FIG. 3  shows the lower boom arm  116  in its intermediate locked position, the locking pin  113  extended to its second interfering position, and the boom clamp  111  installed onto the lower boom arm  116  and locking pin  113 . The lower boom arm is locked from pivoting upward or downward. The boom clamp comprises a pin sleeve  300 , a boom restraint  302  and a handle  304 . The pin sleeve  300  is configured to slide around the locking pin  113 . The sleeve is cylindrical with an inside diameter slightly larger than the outside diameter of the locking pin. The restraint  302  is c-shaped and fixed to the sleeve, and is configured to slide around the lower boom arm  116 . The handle  304  is a rod bent into a generally semicircular shape, fixed at one end to the restraint  302  and fixed at the other end to the sleeve  300 . The restraint is further made up of a first plate  306 , a second plate  308  and a third plate  310 . The first plate  306  is fixed to the top of the sleeve  300  and is disposed generally parallel to the lower surface  200  of the lower boom arm  116 . The second plate  308  is fixed to the first plate and is disposed generally vertically and parallel to the outside surface  202 . The third plate  310  is fixed to the second plate and is disposed generally parallel to the upper surface  400 . The second plate is long enough such that the first plate  306  and third plate  310  define an opening therebetween wide enough to surround the lower boom arm  116 .  
         [0031]     In  FIG. 3  the lower boom arm is prevented from pivoting in the second direction B by the third plate  310  of the restraint  302 . Thus the addition of the boom clamp locks the lower boom arm  116  (and thus the entire boom structure  110  via the four-bar linkage) in the intermediate position.  
         [0032]      FIG. 4  shows a partial cross section of the lower boom arm and locking mechanism taken at line  4 - 4  of  FIG. 3 . The rectangular cross section of the lower boom arm  116  beam is clearly evident, as a box formed by surfaces  400 ,  402 ,  200  &amp;  202 . The protective shroud  204  is a similar cross section extending upward from the beam. The wear plate  201  is fixed to the bottom of the lower surface  200  of the lower boom arm  116  and touches the top of the locking pin  113 . The handle  304  is fixed to the third plate  310  and the bottom of the sleeve  300 . By grasping the handle and pulling, the boom clamp  111  may be quickly removed from the vehicle without the use of any tools.  
         [0033]      FIGS. 5 and 6  show two perspective views of the boom clamp  111  removed from the vehicle. Typically, the boom clamp is installed after the lower boom arm  116  has been lowered all the way to the locking pin  113 . This means that there is no space between the locking pin  113  and the wear plate  201  of the boom. Thus the sleeve  300  has a gap  500  in the outside of the cylinder along the top edge of the cylinder, and the first plate  306  has a corresponding gap  502  in the central section. The sleeve  300  and restraint  302  are joined by a weldment along each side of the gaps  500 ,  502 . If a different intermediate position of the lower boom arms is desired, the boom clamp could be configured with a continuous cylinder sleeve  300  and a spacer between the sleeve and the restraint  302 . This would lock the arms in a position higher than that of the locking pins alone, equal to the original height plus the width of the spacer. In this case, the locking pins would not directly contact the lower boom arm.  
         [0034]     It will be understood that changes in the details, materials, steps, and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. For example, the boom clamp may be attached upside down, after the boom has been lowered below the locking pin, such that the pin prevents upward movement and the boom clamp prevents downward movement—allowing the pin/clamp combination to work with the boom at two different levels with only one pin predetermined height. There may be multiple locking pins at predetermined heights on each side of the skid steer loader, and the clamps may be attached at any pair of pins, thereby locking the arms at a plurality of predetermined heights. The coupling between the sleeve and the restraint need not be fixed, as in a weldment, but may be variable. The coupling may be fixed with a spacer such that there is a considerable separation between the locking pin and the boom. The locking pin may be a rectangular bar or other shape, and may project in a non-orthogonal manner across the plane of boom movement. The sleeve may be rectangular or some other shape, as long as it captures the locking pin. The restraint may be made of one continuous plate, and may be semicircular in shape. The protective shroud surrounding the cables may be inside the boom arm housing rather than outside. The handle may be a different shape, may be attached at only one end, and may be attached to either the restraint or the sleeve or both.  
         [0035]     Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.