Abstract:
An extension rod for a jack arm comprises a connecting rod having a first joint and a second joint formed at the respective ends of the connecting rod. A first locking hole and a second locking hole are formed in the first and second joints, respectively. The extension rod also comprises a lockup mechanism comprising an elastic body configured to connect to either the first joint or the connecting rod and a lockup bolt formed on the elastic body, and configured to engage the first locking hole.

Description:
This application claims benefit of Chinese Application No. 200720126743.9, filed on Jul. 27, 2007 and is incorporated herein by reference in its entirety. 
     FIELD OF INVENTION 
     The present invention relates generally to hardware tools. More particularly, the present invention is an extension rod used for a jack arm. 
     BACKGROUND ART 
     As shown in  FIG. 8 , an element, customarily called an arm, is indicated as  3 , and is used for operating a jack (for example a scissor jack). At one end of the arm  3  is formed an arm hook  31 , which hooks to the hook eye  511  of a screw head  51  of a jack  5 , while the other end of the arm  3  is formed into a rectangular structure normally referred to as the rectangular joint. When a jack is to be operated, the arm hook  31  of the arm  3  is hooked up with the hook eye  511  on the screw head  51  and a handle bar  4  is secured on the rectangular joint through a hole formed in the middle of the handle bar. When the handle bar  4  is turned either clockwise or counterclockwise, the arm  3  and the screw of the jack  5  both turn accordingly so as to lift the jack  5  or restore it to its lowered position. Although the structure of the arm  3  meets the needs of operation of the jack  5 , the length of the arm  3  is so limited that the operator has to adopt a squatting position to operate the device. As a result, operation efficiency is poor and thus it is easy for the operator to become fatigued. On the other hand, if the arm  3  is made longer to enable the operator to stand while operating, a new problem is created in that the arm  3  will be too long for easy storage. Particularly, the arm  3  and the rest of the jack is a tool set used in conjunction with and carried in an automobile. Thus convenient storage is an important factor that cannot be neglected. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an extension rod for the arm of a jack which helps increase the speed of jack operation, relieves the working intensity of the operator, and can be easily stored. The object of the present invention is accomplished in the following way. An extension rod for the arm of a jack comprises a connecting rod with a first joint and a second joint formed at the respective end of the connecting rod, a first locking hole and a second locking hole formed on the first and second joints respectively, and a lockup mechanism of the connecting rod, which includes an elastic body used for connecting to either the first joint or the connecting rod and a lockup bolt formed on the elastic body and corresponding to the first locking hole. 
     The sectional shape of both the first joint and the second joint of the present invention is rectangular. 
     The diameter of said first joint of the present invention is larger than that of the second joint. 
     The two said locking holes of the present invention are round holes. 
     The elastic body of the present invention is made of a spring steel sheet which is bent into a general clip shape, with the pair of first and second clipping arms capable of pressing upon the two side walls of the first joint, and the lockup bolt extending from the middle of the upper part of the elastic body and being insertable into said first locking hole. 
     The elastic body of the present invention is made of spring steel wire which is bent into a clip shape, with the pair of first and second clipping arms capable of pressing upon the two side walls of the first joint, and the lockup bolt formed by bending the wire in the middle of the upper part of the elastic body and being insertable into the first locking hole. 
     The elastic body of the present invention is made of a spring steel sheet shaped like a “T”, with the base part of the “T” capable of firmly holding the connecting rod, and the lockup bolt extending from the front end of the “T” and being insertable into the first locking hole. 
     The elastic body of the present invention is made of spring steel wire which is bent into a clip shape, with the ends of its first and second clipping arms pivotably fixed on the connecting rod, and the lockup bolt formed by bending at the front end of the elastic body and corresponding to the first locking hole. 
     The elastic body of the present invention is made of spring steel wire, with the rear end of the spring steel wire fixed on the connecting rod and the front end as a free end; and the lockup bolt, in the form of a butterfly screw, is connected to said free end and insertable into the first locking hole. 
     Because of the adoption of the above structures, the present invention can be connected as desired with the arm of the jack so as to extend the length of the arm, and it also enables the operator to operate in a standing pose and therefore improves the working efficiency. Because the structure of the connecting rod can be assembled and disassembled easily, the present invention is convenient for storage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows the first embodiment of the present invention; 
         FIG. 2  shows the second embodiment of the present invention; 
         FIG. 3  shows the third embodiment of the present invention; 
         FIG. 4  shows the fourth embodiment of the present invention; 
         FIG. 5  shows the fifth embodiment of the present invention; 
         FIG. 6  shows the sixth embodiment of the present invention; 
         FIG. 7  is a schematic drawing of an example of the arm extension according to any of the first through fifth embodiments; and 
         FIG. 8  is a schematic drawing showing the operation of the jack arm according to the prior art. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Embodiment 1 
       FIG. 1  shows the connecting rod  1 , of which the middle part is cylindrical, and the two ends have a rectangular section. Referring to the embodiment illustrated in  FIG. 1 , for example, the connecting rod  1  is formed respectively on the first joint  11  and the second joint  12  which are rectangular shaped. At the left and right ends of the connecting rod are the first locking hole  111  and the second locking hole  121 . The preferred shape of the first locking hole  111  and the second locking hole  121  is circular, the size of which should be large enough for the lockup bolt  22  of the lockup mechanism  2  of the connecting rod, which will be described later, to be inserted. The first joint  11  on the left is larger than the second joint  12  on the right. To help understand the present invention, also shown in this figure is the arm  3 , which has at its end a rectangular joint  32  to be inserted into and fit in the joint socket  112  of the first joint  11 . Formed on the rectangular joint  32  is the third locking hole  321 . The size of the rectangular joint  32  should be such that it can fit in the joint socket  112 . The joint socket  112  is used to hold the rectangular joint  32 , and when the rectangular joint  32  is inserted in the joint socket  112 , the third locking hole  321  on the joint should be aligned with the first locking hole  111 . At the other end of the arm  3 , that is, on the left side of the figure, there is an arm hook, which can be seen and understood by referring to  FIG. 6 , although it is not shown in this figure. The second locking hole  121  formed on the right end of the connecting rod  1  is used to link and lock another connecting rod  1  for a further extension in a way which is similar to that for the rectangular joint  32  of the arm  3 . If the connecting rod  1  shown in the present embodiment is the last one of several desired connections, the operation can get started once the handle bar hole  41  on the handle bar  4  is fitted to the second joint  12 . 
     In this embodiment, the lockup mechanism  2  for the connecting rod as disclosed in the present invention, has an elastic body  21  made of a spring steel sheet which is processed into a general clip shape, that is to say, the elastic body is provided with a pair of elastic clipping arms, i.e. the first clipping arm  211  and the second clipping arm  212 , which clamp or clip onto the corresponding side walls of the first joint  11 . The lockup bolt  22  can be formed by punching in the middle of the upper part of the elastic body  21 , i.e., the spring steel sheet with a punching machine, or by providing a protrusion in a preferred cylindrical shape by means of welding, riveting, etc. onto the middle of the upper part of the elastic body  21 , and the lockup bolt  22  is to be inserted into the first locking hole  111 . 
     To insert and lock the rectangular joint  32  of the arm  3  into the joint socket  112 , the first clipping arm end  2111  and the second clipping arm end  2121  can be pressed toward the joint  11 . This causes angled portions between the clipping arm ends  2111 ,  2121  and the clipping arms  211 ,  212  to cam the clipping arms  211 ,  212  outward and upward so that the lockup bolt  22  moves out of the first locking hole  111 . Once the rectangular joint  32  is inserted in place, clipping arm ends  2111 ,  2121  can be released to return to their original positions, and the lockup bolt  22  will automatically be inserted into the first locking hole  111  and the third locking hole  321  to achieve connection of the connecting rod  1  with the arm  3 . 
     Embodiment 2 
       FIG. 2  shows the lockup mechanism  2  of the connecting rod, which is different from that of Embodiment 1. The elastic body of this lockup mechanism  2  is made of spring steel wire, which is bent into a clip shape that is generally similar to the structure shown in  FIG. 1 , and the lockup bolt  22  is directly formed out of the spring steel wire. The rest is the same as the description in Embodiment 1. 
     Embodiment 3 
     The elastic body  21  of the lockup mechanism  2  on the connecting rod shown in  FIG. 3  is shaped like a “T”. This elastic body is processed out of a spring steel sheet, with the two ends of the base part of the spring steel sheet fixed onto the connecting rod  1  by means of welding, riveting, or other similar means, and with the front end of the sheet as a free end extending towards the direction of the first joint  11 . A block  213  is provided on the end of the free end, and said lockup bolt  22  is formed at the front end of the “T”, i.e., the free end, and is insertable into the first locking hole  111 . The lockup mechanism  2  on the connecting rod in this embodiment is different from those in Embodiments 1 and 2, so when the rectangular joint  32  of the arm  3  is inserted into the joint socket  112  of the first joint  11 , pull the block  213  with fingers to lift the front end of the elastic body  21  upward to make the lockup bolt  22  move out of the locking hole  111 , then release the fingers once the rectangular joint  32  is inserted in place, and at this time, the lockup bolt  22  will, under the counterforce of the elastic body  21 , be automatically bolted into the third locking hole  321 , and so the connection of the connecting rod  1  with arm  3  is completed. The rest is the same as the description in Embodiment 1. 
     Embodiment 4 
     The lockup mechanism  2  on the connecting rod shown in  FIG. 4  is also made of spring steel wire which is bent into a mantis-like clip shape, with the tail parts of the pair of clipping arms, i.e., the first clipping arm  211  and the second clipping arm  212  pivotably fixed in pivot holes  113  on the connecting rod  1 , and the lockup bolt  22  is directly formed out of the spring steel wire at the front end of the elastic body  21  by means of bending, and is aligned with the first locking hole  111 . The rest is similar to the description of Embodiment 1. 
     Embodiment 5 
     The elastic body  21  of the lockup mechanism  2  of the connecting rod shown in  FIG. 5  is a piece of spring steel wire. One end is riveted at R onto the connecting rod  1 , and the other end (i.e., the left end as shown in  FIG. 5 ) extends to the first joint  11 , and is fixed there with the lockup bolt  22 , which, in this embodiment, is a butterfly screw. In order to achieve excellent locking effect of the butterfly screw as a lockup bolt  22  with respect to the arm  3 , the first locking hole  111  in the joint socket  112  is threaded to form a threaded hole  114 . When the rectangular joint  32  of the arm  3  is inserted in place into the joint socket  112 , the butterfly screw is aligned with the first locking hole  111  and the third locking hole  321  (not shown), and then screwed in, until it is screwed into the threaded hole  114  to complete the connection between the connecting rod  1  and arm  3 . 
     Embodiment 6 
     The lockup mechanism  2  of the connecting rod shown in  FIG. 6  includes an elastic body  21  and a lockup bolt  22 . The elastic body  21  is made of a spring steel sheet, which is riveted to the arm  3 . The lockup bolt  22  extends integrally from the other end of the elastic body  21 . The approximate middle part of the lockup bolt  22  goes through a slot  33  formed on the arm  3 , and its end (i.e., the right end as shown in  FIG. 6 ), is inserted into the third locking hole  321  of the rectangular joint  32  of the arm  3 , and as well into the first locking hole  111  formed in the first joint  11  of the connecting rod  1 , which aligns with the third locking hole  321 . An arched protrusion  221  is formed at the middle part of the lockup bolt  22  corresponding to the slot The lockup mechanism  2  of the connecting rod of the embodiment shown in  FIG. 6  is not set up on the connecting rod  1  as in Embodiments 1 through 5, but instead, is formed on the arm  3 . The first locking hole  111  is formed on the first joint  11  of the connecting rod  1 , thus when the joint socket  112  of the connecting rod  1  is joined with the rectangular joint  32 , the lockup bolt  22  will automatically be inserted into the first locking hole  111 , and therefore the connection of the arm  3  with the connecting rod  1  is completed. For disconnection, just press the arched protrusion  211  with a hand or a tool, and the lockup bolt  22  will move out of the first locking hole  111 , and then the disconnection of the connecting rod  1  and the arm  3  can be completed. 
     While six embodiments of the present invention have been set forth above, it is understood that there may be other similar variations of the present invention without deviating from the scope of the invention All similar variations are within the scope of the technical solution of the present invention. Therefore, the above embodiments are non-restrictive examples of the present invention. 
     A brief introduction to the operation of the present invention is provided with respect to  FIG. 7 . To use the jack  5 , as the first step, the arm hook  31  at one end of the arm  3  is hooked up with the hook eye  511  on the screw head  51  of the jack  5 , and the rectangular joint  32  at the other end of the arm  3  is inserted into the joint socket  112  of the first joint  11  on the connecting rod  1  as shown in any of the Embodiments 1 through 5 and is then locked by the lockup mechanism  2 , so as to complete the connection between the arm  3  and the connecting rod  1 ; then, as the second step, the handle bar  4  is fixed with the second joint  12 , and turned either clockwise or counterclockwise to drive the connecting rod  1 , the arm  3  and the screw of the jack  5  to turn accordingly. Consequently, the jack  5  will either be lifted or restored to its original position. Because of the connection of the arm  3  with the connecting rod  1 , the length of the arm  3  is extended, and as a result, during the whole process of operation, the operator can adopt a standing pose instead of a squatting pose. This benefits the convenience of the operation and reduces the working intensity of the operator. When the operation is finished, the connecting rod  1  can be disconnected from the arm  3 , and stored easily for a next use.