Abstract:
A stabilizing device for vertically extending jacks is described. The stabilizing device is comprised of a base link attached to an RV, a short connecting link, a long connecting link and a stabilizing link, forming a four link mechanism whereby the combined pivoting of each link results in a nearly straight line vertical movement at the distal end of the stabilizing link which is pivotally attached to a vertically extending jack. This combination of elements allows for the unimpeded vertical movement of the jack while at the same time restricting the horizontal movement of the jack thereby forming a stabilizer that functions automatically.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of PPA 61/855,555 dated May 16, 2013 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to jack stabilizing devices commonly found on recreational vehicles such as motor homes and trailers. Recreational vehicles or RV&#39;s typically have vertically extending jacks attached to the frame near the corners of the vehicle. When parked, these jacks are extended to the ground and provide a means for leveling the RV in addition to supporting the weight of the RV. This support prevents vertical movement of the vehicle as the occupants of the RV move about it. While offering a great deal of weight capacity, most RV jacks provide little resistance to side to side movement caused by wind or people moving inside the RV. A mechanical jack stabilizer that effectively limits lateral movement between the lower portion of the jack and the RV frame is achieved by this invention utilizing a four link mechanism as described herein. 
     2. Prior Art 
     Previously, strut type devices have been employed to stop lateral movement in RV jacks. They fall into two basic designs. The first consists of a first hollow tube telescopically fitted inside a second hollow tube. The non-telescoped ends of each tube are pivotally attached to the frame of the trailer and the foot of the jack. The result is a tube that can shorten or elongate to accommodate the changing distance from the RV frame to the foot of the jack as the jack is extended or retracted. Once the jack is lowered to its operating height, a locking nut is tightened between the two telescoped sections, fixing the length of the two telescoped sections and the strut assembly provides lateral stability to the jack. The second design employs a single piece strut pivotally attached at one end to the foot of the jack. The opposite end of the strut slides through a clamping device attached to the frame of the RV. The clamp is left loose until the jack is lowered to its operating height. The clamping device is then tightened and the jack is laterally stabilized. Both of these types of stabilizers work well, but have the disadvantage of having to be manually tightened after the jacks are extended, and then loosened prior to the jacks being retracted. The locking nuts or clamps are located underneath the RV. Depending on the conditions where the RV is parked, such as mud or wet grass, or for physically challenged people who may not have the flexibility to get under their RV, tightening and loosening the jack stabilizers can be quite inconvenient. 
     Previously, four link devices have been designed to achieve straight line support of movement over short distances. These types of devices required three or more planes of operation making them bulky. In order to achieve any significant length of straight line operation, these devices operate on both sides of a mounting link and have a center of stroke, or neutral point in their stroke where the device may actually track on to a curved path or continue in a straight line path depending on how they are loaded. This type of device is not suited to the objects of the current invention. 
     OBJECTS AND ADVANTAGES 
     The objects and advantages of the present invention are: 
     (a) To provide a jack stabilizer that automatically adjusts to the distance between the lower portion of the jack and the frame of the RV as the jack is extended downward, thereby giving lateral stability to the RV without the need to manually lock the stabilizer in place. 
     (b) To provide a jack stabilizer that is easily installed and adaptable to a wide range of jack configurations. 
     (c) To provide a jack stabilizer that has a long, near straight line path of support to accommodate high range jacks. 
     Further objects and advantages of my invention will become apparent from a consideration of the drawings and the ensuing description. 
     SUMMARY OF THE INVENTION 
     The present invention, a jack stabilizer, is directed to an easily installed, versatile four-link mechanism that gives lateral support to vertically extending jacks and automatically adjusts to the jack as it extends or retracts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of the jack stabilizer, installed and partially extended. 
         FIG. 2  is a front view of the jack stabilizer, installed and fully extended. 
         FIG. 3  is a front view of the jack stabilizer, installed and fully retracted. 
         FIG. 4  is a front view of an embodiment of the jack stabilizer assembly attached to a scissors jack where the connecting links are attached directly to the RV frame. 
         FIG. 5  is an end view of the jack stabilizer assembly shown in  FIG. 4 . 
         FIG. 6  is a side and end view of a template used to mount the jack stabilizer shown in  FIGS. 4 and 5 . 
         FIG. 7  is a front view of an embodiment of the jack stabilizer assembly, where components of the RV double as components of the invention. 
         FIG. 8  is a front view of the assembly shown in  FIG. 7 , shown fully extended. 
         FIG. 9  is a front view of the assembly shown in  FIG. 7 , shown fully retracted. 
         FIG. 10  is a front view of a mounting bracket detail of the jack stabilizer device of  FIG. 7 . 
         FIG. 11  is an front view of a mounting detail of the jack stabilizer device of  FIG. 7 . 
         FIG. 12  is a side view of the mounting bracket detail of the jack stabilizer device of  FIG. 7 . 
         FIG. 13  is a front view of an embodiment of the jack stabilizer assembly, where the base link is elongated, shown attached to two partially extended scissors jacks. 
         FIG. 14  is a front view of the assembly shown in  FIG. 7 , shown fully extended. 
         FIG. 15  is a front view of the assembly shown in  FIG. 7 , shown fully retracted. 
         FIG. 16  is a side view of an end detail of the base link of the jack stabilizer device of  FIG. 7  and associated adjustable mounting bracket. 
         FIG. 17  is an end view of an end detail of the base link of the jack stabilizer device of  FIG. 7  and associated adjustable mounting bracket. 
         FIG. 18  is a front view of an angle bracket detail of the base link of the jack stabilizer device. 
         FIG. 19  is a front view of a telescopic jack, shown in a fully retracted position. 
         FIG. 20  is a front view of a telescopic jack, shown in a partially extended position. 
         FIG. 21  is a front view of a telescopic jack, shown in a fully extended position. 
         FIG. 22  is an end view of a telescopic jack and a front view of an attached jack stabilizer in an embodiment that allows for pivotal attachment of the base link to the RV. 
         FIG. 23  is a front view of a telescopic jack and an end view of an attached jack stabilizer in an embodiment that allows for pivotal attachment of the base link to the RV. 
         FIG. 24  is a detailed view of the hinge components of an embodiment that allows for pivotal attachment of the base link to the RV. 
         FIG. 25  is a front view of the jack stabilizer shown attached to a fifth wheel jack. 
         FIG. 26  is a side view of an embodiment of the jack stabilizer, showing a nested U-channel construction. 
         FIG. 27  is a sectional view of a portion of the jack stabilizer shown in  FIG. 26 . 
         FIG. 28  is a second sectional view of a portion of the jack stabilizer shown in  FIG. 26 . 
         FIG. 29  is a schematic view of the initial design elements of the jack stabilizer. 
         FIG. 30  is a schematic view of additional design elements of the jack stabilizer, adding in construction of the path of the short connecting link. 
         FIG. 31  is a schematic view of additional design elements of the jack stabilizer, adding in progressive positions of the short connecting link and stabilizing link. 
         FIG. 32  is a schematic view of additional design elements of the jack stabilizer, adding in construction of one end location of the long connecting link. 
         FIG. 33  is a schematic view of additional design elements of the jack stabilizer, adding in construction of the other location of the long connecting link. 
         FIG. 34  is a schematic view of completion of the design elements of the jack stabilizer. 
         FIG. 35  is a schematic view of an alternate method for determining length and location of the long connecting link. 
     
    
    
     DETAILED DESCRIPTION 
     This invention relates to lateral stabilization of vertically extending RV jacks.  FIG. 1  shows the invention  10 , connected to a partially extended scissors jack  12 . Starting at the top, the first component is a base link  14  which is generally horizontal and rigidly attached to an RV frame  16 . Pivotally attached at a first end  18  of the base link  14  is a first end  38  of a short connecting link  20 . Further along the length of the base link  22 , a first end  40  of a long connecting link  24  is also pivotally attached to the base link  14 . A second end  26  of the short connecting link  20  is pivotally attached to one end  42  of a stabilizing link  28  as is a second end  30  of the long connecting link  24 . The distal end  32  of the stabilizing link  28  is pivotally attached to a foot  34  of a jack  12  via a lower pivot bolt  36  of the jack  12 . The four links  14 ,  20   24  and  28  comprise a four link mechanism structured to limit lateral movement of the jack relative to the RV, thereby stabilizing the RV. As the jack extends or retracts, the invention  10  extends or retracts, moving freely with the foot  34  of the jack  12  allowing vertical movement, but limiting lateral movement, regardless of the vertical position of the jack. The four links  14 ,  20 ,  24  and  28  are sized and positioned such that the distal end of the stabilizing link end  32  moves in a path that is essentially perpendicular to the base link  14 . While the vertical path of the distal end  32  of the stabilizing link  28  may not move in an exact straight line, the variation from a straight line can be within the lateral free play of the jack  12 . In use, the jack  12  is lowered to the ground under it and extended until a desired degree of weight bearing and or leveling is achieved.  FIG. 2  shows the same components as  FIG. 1 , but with the jack fully extended.  FIG. 3  shows the same components as  FIG. 1 , but with the jack fully retracted. 
     The invention can be configured into a number of embodiments, several of which are described as follows;  FIGS. 4 and 5  show the invention  48  in an embodiment where the short connecting link  50  and long connecting link  52  are pivotally attached directly to the RV frame  54  via bolts  56 ,  58  or other fasteners to achieve pivoting connections. The stabilizing link  60  is pivotally attached to the ends of the short connecting link  50  and long connecting link  52 , and the distal end  62  of the stabilizing link  60  is pivotally attached to the foot  64  of a jack  68  by way of an angle bracket  66 . In this embodiment, the base link of the invention  48  consists of the RV frame  54 .  FIG. 5  shows an end view of the invention  48  attached to a scissors jack  68 . In order to get the locations of the mounting holes  70 ,  72  correct, a template  74  ( FIG. 6 ) can be used to locate the mounting holes  70 ,  72  relative to the stabilizing link distal end  62 . In use, the angle bracket  66  would be attached to the pivot bolt  76  of the jack  68  ( FIG. 4 ). The bolt  78  that normally mounts the angle bracket  66  to the stabilizing link  60  is used to temporarily pivotally fasten the locating leg  80  of the template  74  to the angle bracket  66 . The jack  68  is then moved up or down until the lower horizontal face  82  of the template is flush with the bottom face  84  of the RV frame  54 . The template  74  is then clamped to the RV frame  54 , and the holes  86  and  88  in the template  74  provide guidance for drilling holes  70 ,  72  in the RV frame  54  at the proper location. 
       FIGS. 7 through 12  show an embodiment of the invention  96  where existing components of the RV and jacks also act as components of the invention. In this embodiment, the base link  92  of the invention  96  consists of the RV frame  94 . The short connecting link  102  consists of an upper outboard leg  98  of the scissors jack  100 . The stabilizing link  110  (see  FIG. 10 ) consists of a lower outboard leg  128  of the scissors jack  100 , and the long connecting link  120  is a separate component which completes the four-link mechanism of the invention. The four links  92 ,  102 ,  110  and  120  comprise a four link mechanism structured to limit lateral movement of the jack relative to the RV, thereby stabilizing the RV. In this embodiment, the short connecting link  102  is pivotally attached at a first end  104  to the base link  92 , and at a second end  108  to the stabilizing link  110 . The long connecting link  120  is pivotally attached at a first end  124  to the base link  92  and pivotally attached at a second end  122  to the stabilizing link  110 , and the distal end  128  of the stabilizing link is pivotally attached to the foot  114  of the scissors jack  100 . The stabilizing link bracket  118  forms a part of the stabilizing link  110  and properly locates the pivot axis  90 .  FIG. 8  shows the device of  FIG. 7  in a fully extended position.  FIG. 9  shows the device of  FIG. 7  in a fully retracted position.  FIGS. 10 and 11  show detailed views of the connected ends  122 ,  124  of the long connecting link  120  along with the mounting bracket  118 .  FIG. 12  shows and end view of the lower outboard leg  110  of the jack  100  along with the mounting bracket  118 . This embodiment has the advantage of minimizing the number of components needed to create the invention  96 . 
     The next embodiment of the invention  152  is shown in  FIG. 13 . In this embodiment, the base link  134  is elongated on both ends. The end  136  nearest the jack  138  being stabilized has a hole  140  formed in it to facilitate attaching directly to the upper pivot bolt  142  of the scissors jack  138 , which is rigidly mounted to the RV frame  144 . The upper pivots  142 ,  146  of the jack  138  are situated directly above the lower pivots  148 ,  150  of the jack  138 . The invention  152  is based on a perpendicular movement relative to the RV frame  144  as is the movement of the jack  138 . It is therefore advantageous to mount the end of the base link  136  directly at the upper pivot bolt  140  of the scissors jack  138 , and to mount the distal end  154  of the stabilizing link  156  at the lower pivot bolt  132  of the scissors jack  138 . At the same time, the opposite end  158  of the base link  134  can be mounted to the upper pivot bolt  160  of the jack  162  situated on the opposite side of the RV, as it is usually the case that the jacks are located in this manner.  FIG. 14  shows the embodiment of  FIG. 13 , shown in a fully extended position.  FIG. 15  shows the embodiment of  FIG. 13 , shown in a fully retracted position.  FIGS. 16 and 17  show an adjustable mounting bracket  164  for mounting the opposite end  158  of the base link  134  to the pivot bolt  160 . The adjustable mounting bracket  164  is composed of an angled section  166  that contacts the base link  134  on two sides  168 ,  170 . The angled section  166  is clamped in place via a clamping section  172  which is held in place by bolts  174 ,  176 . This arrangement allows for mounting the base link  134  on a range of frame widths and provides a rigid mounting of the base link  134  to the RV frame  144  via the jacks  138 ,  162 . This mounting of the base link  134  to the jacks  138 ,  162  is perpendicular to the extending path of the jack  138 , and has the advantage of mounting the invention  152  without the need to drill any holes in the RV. In cases where the there is no jack  162  opposite the jack  138  being stabilized, the opposite end  158  of the base link  134  can be attached to the RV frame  144  as shown in  FIG. 18 . Angle bracket  178  is attached to the end  158  of the adjustable mounting bracket  164 , and bolted  180  to the RV frame  144 . Shims  182  can be used as required to match the vertical distance between the bottom of the RV frame  144  and the top of the base link  134  from side to side. 
     Another embodiment of the invention is suited to handle situations where the path of the jack follows a vertical or non-vertical path that lies in a vertical plane. This is the case for the telescopic jack  188  shown in  FIGS. 19 ,  20  and  21 .  FIG. 19  shows a telescopic jack  188 , which is rigidly attached to an RV frame  190 , in a fully retracted position.  FIGS. 20 and 21  show the jack partially and fully extended respectively.  FIG. 21  shows the curved path  194  of the foot  192  (shown in phantom) at several locations. Telescopic jacks, due to their design, have lateral stability in a direction parallel to the length of the jack, but much less in a direction perpendicular to the length of the jack. This instability can be fixed by utilizing the invention  196  as shown in  FIGS. 22 and 23 . In this embodiment, the base link component  198  of the invention  196  is mounted to the RV frame  190 , via pivots or hinges  200 ,  202  between the base link  198  and the RV frame  190 . These hinges  200 ,  202  in addition to a rod end  204  allow the invention  196  to pivot about the center of the hinge pin  206  (see  FIG. 24 ) and simultaneously extend or retract with the curved path  194  of the foot  192  of the jack  188  while providing stability in a direction perpendicular to the length of the jack  188 . 
     The invention can also be adaptable to fifth wheel jacks as shown in  FIG. 25 . In this embodiment, a fifth wheel jack  210  has a motor  212  that drives a mechanism that extends or retracts an inner square tubular leg  214  that telescopically fits inside an outer square tube  216 . The gap between the outside of the inner square tubular leg  214  and the inside of the outer square tube  216  allows for some lateral movement of the jack foot  218 . In this case the base link  220  is attached to the RV frame  222 . The distal end  224  of the stabilizing link  226  is pivotally attached, to the foot  218  of the jack  210 , at the inner square tubular leg  214 . Alternately, the distal end  224  of the stabilizing link  226  could be pivotally attached directly to the foot  218 . 
     An alternate embodiment to the design of the links is shown in  FIGS. 26 ,  27  and  28 . In this embodiment of the invention  234 , the base link  236  is made of a channel shape with the open side facing down. This allows for nesting of the short connecting link  238  and the long connecting link  240  inside the base link  236 , and be pivotally attached using rivets  244 ,  244 A and spacers  246 . Nested inside of the short connecting link  238  and long connecting link  240  is the stabilizing link  242 . In this case, the long connecting link  240  has a similar cross section as the short connecting link  238 . This embodiment allows for all of the links to occupy the same plane of operation. 
     The instability of the RV when jacked can be in any lateral direction. Utilizing the invention gives stability in a direction parallel to the length of the invention. To fully stabilize an RV, several units of the invention can be used. For example, the embodiment shown in  FIG. 7  could be used in addition to the one shown in  FIG. 4 , even on the same jack. For the most effective stabilization, side to side stabilizing can be done on both ends of the RV, with at least one additional stabilizer in a front to back direction. 
     The design of the four-link device  152  (see  FIG. 13 ) can be constructed using a schematic diagram as shown in  FIGS. 29 through 35 . The goal is to achieve a nearly straight line vertical path for the distal end of the stabilizing link ( 36  in  FIG. 1 ). To begin, the vertical range of the jack must be considered. For example, most scissors jacks found on RVs have an extended height of about 24″. The retracted height of the jack is about 4″, meaning that the range of support of the stabilizer is about 20″. The schematic is constructed to show three different positions of the mechanism (retracted, midpoint and extended). Starting with  FIG. 29 , a horizontal line  252  is drawn to represent the base link of the invention. Then a vertical line  260  is drawn from the end  258  of the base link  252  to represent the desired path of the distal end  256  of the stabilizing link  254 . An assumption is made for the length of the stabilizing link  254  which is parallel to, under and near the base link  252 . The distal end  256  of the stabilizing link  254  also lies on line  260 . Line  250  is then drawn to represent the short connecting link, which pivots with the base link  252  at point  262  and with the long connecting link  254  at point  264 . As constructed, lines  252 ,  250  and  254  represent the base link, short connecting link and stabilizing link respectively in a retracted position. Points  258  and  256  also correspond to the upper and lower jack pivots  142  and  150  (see  FIG. 13 ). Referring to  FIG. 30 , a circle  266  is then drawn with the center  268  at the point of intersection  262  between the base link  252  and the short connecting link  250 , with its radius equaling the length of the short connecting link  250 . This circle  266  represents the potential path of rotation of the short connecting link  250 . Next midpoint  270  and extended  272  locations are marked on the vertical line  260 . These points represent the midpoint and extended travel locations of the distal end  256  of the stabilizing link  254 , which is sized to fit the range of vertical travel of the jack. Referring to  FIG. 31 , arcs, the length of the stabilizing link, are then drawn from points  270  and  272  to where they intersect the circle  266  at  274  and  276 . Lines are then drawn from point  268  to  274  and from  268  to  276 . These lines represent the short link  250  at midpoint  250 A and extended  250 B positions. Similarly, lines are then drawn from point  274  to  270  and from  276  to  272 . These lines represent the stabilizing link  254  at midpoint  254 A and extended  254 B positions. To this extent of the construction, the base link  252 , short connecting link  250 ,  250 A,  250 B and stabilizing link  254 ,  254 A,  254 B are shown at three positions within the travel of the mechanism (retracted, midpoint and endpoint). Referring to  FIG. 32 , an assumption is then made as to the joint location of the stabilizing link ( 28  on  FIG. 1 ) to the long connecting link ( 24  on  FIG. 1 ). This length can vary, but as a starting point, the length of the short stabilizing link  250  can be used. Arcs, the length of the short connecting link in this case, are then drawn from the short link to stabilizing link joints  262 ,  274 ,  276  to where they cross the stabilizing link at  278 ,  280  and  282 . These points  278 ,  280  and  282  represent the path of the stabilizing link where it is joined to the long connecting link. As shown in  FIG. 33 , a radius is then drawn that passes through points  278 ,  280  and  282 . The center of this radius  284  defines the length of the long connecting link and the location of where it joins the base link  252 .  FIG. 34  shows lines  286 ,  286 A,  286 B drawn between  284  and  278 ,  284  and  280  and between  284  and  282 , schematically showing the long connecting link  286 ,  286 A,  286 B in the retracted, midpoint and extended positions. Finally,  FIG. 35  shows an alternate method of finding the long connecting link to base link joint  284 . Lines  288  and  290  are drawn from  278  to  280  and from  280  to  282  respectively. The intersection of the perpendicular bisectors  292 ,  294  of these two lines  288  and  290  will define the same point  284  as previously described. It is noteworthy that the constructed point of intersection  284  usually does not lie directly between the end points  258  and  262  of the base link  252 . Also, it is possible to offset the assumed location of the joint  278 ,  280 ,  282  between the stabilizing link  254  and the long connecting link in order to effect a change of the location of the joint between the long connecting link and the base link  284 . An example of this can be seen in the embodiment shown in  FIGS. 7 through 12 . In addition, this method of design is only a starting point and the lengths of any of the links can be changed to produce varying lengths of near straight line vertical travel of the stabilizing link  254  distal end, varying lengths and pivot locations of the long connecting link  286  to the base link  252 , or both. Once a long connecting link  286  and pivot location  284  are selected, the actual path of the distal end  256 ,  270 ,  272  of the stabilizing link  224  can be determined using a drawing layout process or by geometry. It should also be noted that the actual path of the distal end  256 ,  270 ,  272  of the stabilizing link  254  may vary a slight amount from the vertical line  260  in between the three selected points  256 ,  270 , and  272  on line  260 . Many increments of travel of the mechanism should be determined to assure that the resulting variation of travel from line  260  is acceptable. 
     CONCLUSION, RAMIFICATIONS AND SCOPE 
     This invention provides an effective method of controlling lateral movement of RV jacks. This invention also automatically adjusts to the height of the jack as it is operated through its range of motion. In addition, this invention is readily adaptable to a wide range of jacks and is easily installed. While the description above contains many details, these should not be construed as limiting the scope of the invention, but as examples of embodiments of the invention. Accordingly, the scope of the invention should be determined by the claims, not the specifics of the embodiments.