Abstract:
A jack bar includes an outer tube, an inner tube and a positioner tube coaxially located. The positioner tube is extendable to adjust a length to the jack bar in use while enabling the jack bar to be retracted for storage. The jack bar further includes a clamp configured to receive tubes of various shapes. The clamp is further configured to prevent twisting or turning of clamped tubes.

Description:
FIELD OF THE INVENTION 
   The present invention relates to mechanical technologies and in particular to fixturing devices used for securing goods in a vehicle. 
   BACKGROUND 
   During the transportation of goods in vehicles, it is necessary to secure the goods in position to prevent loss or damage to the goods due to movement during transportation or by collision with other goods in the vehicle, and to retain the goods within the vehicle. 
   Typically goods are transported inside containers loaded onto vehicles. One of the tools used to secure goods in containers is a jack bar.  FIG. 1  shows a conventional jack bar  50 . The jack bar  50  includes a main body  1 , a main axle  2 , a lever  3  (also referred to as a “handle”), a gear rack  4 , and a tube  5 . The jack bar  50  has a first end  55  (also referred to as a “gear rack end”) and a second end  60  (also referred to as a “tube end”). Typically, the jack bar  50  is operated by reciprocating the lever  3 . The movement of the lever  3  drives the gear rack  4  outward to cause the two ends  55 ,  60  of the jack bar  50  to push against side walls of a container. The two ends  55 ,  60  typically include rubber feet  65 ,  70  for gripping. The jack bar  50  is positioned and located in the container to limit motion of goods during transportation. The length of this conventional jack bar  50  in operation is determined by the distance between the two side walls of the container. Accordingly, jack bars  50  of this conventional configuration are typically long with respect to the cargo space making the jack bars themselves difficult to store and transport thereby adding to shipping costs. 
   The assembly of the conventional jack bar of  FIG. 1  typically includes welds such as the weld  75  between the main body  1  and the tube  5 . The welds at times result in a less than optimal product. For example, the welds between the main body and the tube require polishing and rust proofing in order to maintain structural integrity and in order for the welds to be aesthetically acceptable. If the jack bar main body  1  and tube  5  separate, the jack bar  50  can be repaired only by rewelding which is a difficult repair. In addition, welds may include defects such as skewing, slag inclusion, or porosity. Further, the welding process requires extensive tooling. 
   For the foregoing reasons, there is a need for an improved jack bar. 
   SUMMARY 
   The present invention is directed to an improved jack bar including an extendable-retractable tubular structure. The jack bar of the present invention may be applied over a wide variety of adjustable lengths with a shorter overall length and a longer extended length compared to conventional jack bars. 
   The jack bar of the present invention includes a plurality of co-axial tubes configured to mate as at least one inner tube inside an outer tube. The length of the jack bar can be adjusted by linking the tubes together. In other words, it is possible to select various connection locations between the inner and outer tubes based on the side wall distance of the container and to fix the position through the use of a positioner. These features provide a wide range of applicable distances for the jack bar of the present invention. When the jack bar is not in use, the inner tube is retracted into the outer tube to reduce the total length of the jack bar thereby making the jack bar of the present invention easier to store than conventional jack bars. 
   The positioner has at least one spring-loaded positioning pin configured to mate with at least one positioning hole in the outer tube. The number of positioning holes is typically equal to the number of positioning pins. Each positioning hole is configured to receive a positioning pin. During positioning, the inner tube is moved to match positioning pins to positioning holes, thereby enabling the fixturing between the inner and outer tubes to fix the length of the jack bar. 
   The tube fixturing mechanism is located inside of the main body of the jack bar. The tube fixturing mechanism includes a tubular-shaped clamp located on one side of the main body. The tube-shaped clamp is used to clamp the inner tube. The clamp includes an axial opening having two lips, one on each side of the opening. A bolt passes through a hole on one of the lips for securing the clamp by screwing the bolt into a tapped hole that is on the other lip of the opening. 
   When using the tube fixturing mechanism to secure the inner tube, the bolt on the side of the lip is loosened and the inner tube is inserted into the clamp. The bolt is then tightened to clamp the two lips together to secure the inner tube to the main body of the jack bar. 
   A cross section of the jack bar clamp is a square-circular shape. This shape enables the tube fixturing mechanism to secure square tubes and round tubes as well as tubes of other geometries. The tube fixturing mechanism in the jack bar of the present invention is located in the main body. The mechanism itself is the several positioning protrusions that are on the inner walls, flat or curved, of the clamp. These protrusions allow additional friction forces to be exerted between the clamp and the tubes to be connected, thus reducing the possibility of a tube falling off or twisting. 
   The advantages of the present invention include the adjustable length of the jack bar. That is, the jack bar can be readily adjusted to accommodate differences in cargo space side wall distances, thereby increasing the versatility of the jack bar. A further advantage of the present invention is the positioning device between the inner and outer tube that simplifies the operation of the jack bar. A still further advantage of the present invention is the reduced overall length of the jack bar. When the jack bar is not in use, the length can be reduced further than conventional jack bars thereby increasing the storability and transport. 
   Compared to currently available technology, the tube fixturing mechanism is based on the combination of clamp and tightening of a bolt to realize the connection between the inner tube and the main body. The mechanism is simple and effective, with no welding required to simplify the manufacturing process. Since the clamp adopts to no particular cross-section geometry, it is possible to connect the main body with either square or round tubes, or with tubes of other geometries. 
   In the event of loosening between the tube and the main body during operation of the clamp equipped jack bar the clamp may be re-secured by tightening the bolt. This re-secures the clamp to the tube, while providing ease of operation. 
   The present invention together with the above and other advantages may best be understood from the following detailed description of the embodiments of the invention illustrated in the drawings, wherein: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a conventional jack bar; 
       FIG. 2  is a side cut-away view of a retractable tubular jack bar according to principles of the invention; 
       FIG. 3  is a side cross-section view of the jack bar showing spring-loaded positioning pins located in positioning holes; and 
       FIG. 4  is a cross-section view of the clamp for the jack bar of  FIG. 2 . 
       FIG. 5  is a second side cut-away view of a portion of a retractable tubular jack bar according to principles of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A jack bar according to the present invention includes an extendable-retractable tubular structure. The tubes are co-axial and configured to mate one inside the other. A positioning device enables the jack bar to be extended to fit a cargo container. 
     FIG. 2  is a side cut-away view of a retractable tubular jack bar  100  according to principles of the invention. The jack bar  100  includes a main body  101 . A first tube  105  connects to the main body  101 . A gear rack  104  is located on the outside of the first tube  105 . The first tube  105  is shaped and configured to mate with a second tube  107 . The second tube  107  is configured to mate with a third tube  108 , also referred to as the outer tube. The third tube  108  includes a plurality of positioning holes  109 . The main body  101  includes a clamp  106  to fix the first tube  105  with respect to the second tube  107 . The clamp  106  is on one side of the main body  101 . 
   In operation, the second tube  107  is positioned with respect to the third tube  108  with spring-loaded positioning pins and the positioning holes  109  in the third tube  108 . The positioning pins and positioning holes are described in more detail below with regard to  FIG. 3 . 
   A unidirectional driving mechanism  102  on the main body  101  acts through a reciprocating lever  103  to extend the gear rack  104  outwards from the second tube  107  to push the ends  155 ,  160  of the jack bar  100  against the side walls of a container (not shown) to secure goods. The clamp  106  clamps the first tube  105  with the gear rack  104  in position with respect to the second tube  107 . 
   In the present embodiment of the invention, the first tube  105  and the second tube  107  are inserted into the outer tube  108 . In an alternative embodiment of the invention, three or more inner tubes are coaxial with the outer tube and are configured similarly to the tubes  105 ,  107 ,  108  shown in  FIG. 2  in order to be similarly extendable and retractable. 
     FIG. 3  is a side cross-section view of the jack bar  100  showing spring-loaded positioning pins in the second and third tubes  107 ,  108  of the jack bar  100 . As shown in  FIG. 3 , positioning pins  110  are located on the surface of inner tube  107 . A spring  111  pushes against the pins  110  from inside the inner tube  107 . On the surface of the outer tube  108  are positioning holes  109  where the locations of these holes correspond to the locations of the positioning pins  110  that are on the inner tube  107 . The force available from spring  111  pushes the pins  110  outward through positioning holes  109  in the outer tube  108 . The diameters of these positioning holes are generally slightly larger than the corresponding diameters of the pins  110 . Thus the positioning between the inner and outer tubes  107 ,  108  can be realized by moving the inner and outer tubes  107 ,  108  relative to one another, such that the pins  110  mate with the positioning holes  109 . If length change is desired, all that is required is to push the positioning pins  110  down and move the inner and outer tubes  107 ,  108  to align the positioning pins with different positioning holes. 
   In the jack bar  100  of the present invention, the complete jack bar  100  can be reduced to minimal length for storage or transportation by the following: as long as the gear rack  104  is pushed all the way back to the inner tube  107 , and the inner tube  107  is pushed all the way into the outer tube  108 . 
     FIG. 4  is a cross-section through the clamp  106  of the jack bar  100  viewed perpendicularly to the jack bar axis. As discussed above (in relation to  FIG. 2 ), the clamp  106  is located on one side of the main body  101  and the clamp is connected to the second tube  107 . The clamp  106  is generally square in cross-section where each edge and each corner of the “square” is curved as shown in  FIG. 4 . This results in a square-circular combination shape capable of receiving various configurations of tubes. The clamp  106  has two parts  180 ,  185  which are secured with a rivet  112  on one side of the clamp  106 . An opening  113  on the opposite side has lips  114  bent toward the outside of the clamp  106 . One lip includes a tapped hole or nut  120  and the other lip has a corresponding through hole  118 . A bolt  115  is disposed in the through hole  118  and the tapped hole  120 . The bolt  115  is used to tighten the lips  114  together. After the inner tube  105  is inserted into the clamp  106 , the clamp  106  can be tightened around the tube  105  by turning the bolt  115 . This draws the two parts  180 ,  185  of the clamp  106  together to close the two sides of the opening  113 . 
   As shown in  FIG. 4 , the inner wall of the clamp  106  consists of two types of surfaces, flat surfaces  119  and curved surfaces  116 . The flat  119  and curved  116  surfaces include several small protrusions  117 . This inner wall design enables the coupling of clamp  106  with either a square tube or a round tube, or with tubes of other cross-sectional geometries. The presence of the protrusions  117  increases friction between the clamp  106  and an inserted tube. This prevents the inserted tube from sliding out, and from rotating inside the clamp  106 . 
     FIG. 5  is a second side cut-away view of a portion of a retractable tubular jack bar according to principles of the invention. A jack bar includes an outer tube  108 ; an inner tube  105  co-axially mated to the outer tube  108 ; and a positioner tube  107  co-axial to the inner tube  105  and the outer tube  108 . The positioner tube  107  is located in between the inner tube  105  and the outer tube  108 . The positioner tube  107  includes a positioner  109  to fix the location of the positioner tube  107  with respect to the outer tube  108 . The positioner tube  107  includes a drive mechanism  102  (shown in  FIG. 2 ) to locate the inner tube  105  with respect to the positioner tube  107 . The positioner  107  further includes a clamp  106  to clamp the inner tube  105  in position with respect to the positioner tube  107 . The clamp  106  is closed with a bolt. The jack bar further includes a fourth tube  200  co-axial to the inner tube  105 , the outer tube  108  and the positioner tube  107 . The fourth tube  200  includes a second positioner  205  that is configurable to provide additional length to the jack bar. 
   This newly designed jack bar is realized through the use of a set of inner and outer tubes inserted into one another, or a set of several tubes implemented in the same fashion to enable the adjustment of jack bar length. In other words, it is possible to select different positions based on the available cargo space in the container, with the assistance of a positioner. In this fashion, it is likely to expand the usability of the jack bar. When the jack bar is not needed, it is possible to retract the inner tube into the outer tube the furthest degree to reduce the total length of the jack bar for ease of storage. 
   In the aforementioned newly designed jack bar, the positioning device is the number of positioning pins that is on the surface of the inner tube, with the corresponding positioning springs that push the pins outward, and the mating positioning holes that are on the surface of the outer tube. The number of positioning holes matches with the positioning pins. The diameter of each of the positioning holes is slightly bigger than that of the positioning pins. When it is required to adjust the length of the tube, all that has to be performed is to move the inner and outer tube with respect to one another to allow positioning pins to mate with the positioning holes at desired locations. In this way, the desired positioning is achieved. 
   The tube fixturing mechanism is located on the main body of the jack bar, with the characteristics as follows: The tubular positioner is located on one side of the main body with an opening that opens axially. There are lips on each side of the opening that curve outward, with a through hole on one lip and a tapped hole the other. A bolt with a diameter smaller than the size of the lips is inserted into the hole to be screwed into the tapped hole, and the lips can be tightened by screwing the bolt into the tapped hole to tighten the two sides of the lips. 
   The tube diameter of the jack bar is slightly bigger than the positioner diameter when the two lips are closed. When using the mechanism to secure a tube, it is necessary to loosen the bolt to insert the tube into the positioner. Afterwards, the tube can be connected to the main body by tightening the bolt to clamp the two lips together to secure the tube onto the positioner. 
   The positioner cross section in the aforementioned jack bar is located on the main body, and is square-circular in shape, which enables the connection with square tubes, round tubes or tubes of other cross section geometries. 
   The tube fixturing mechanism is located on the main body of the jack bar, and is defined by a number of protrusions on the inner flat or curve surfaces. The protrusions will increase the friction force between the positioning mechanism and the tube to reduce the possibility of tubes falling off or twisting. 
   It is to be understood that the above-identified embodiments are simply illustrative of the principles of the invention. Various and other modifications and changes may be made by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.