Abstract:
A prying tool, such as to pry open a door or window, having a forked blade on one end formed with a dimpled shoulder. The dimpled shoulder helps to prevent tools striking he shoulder from glancing off, and eliminates sharp corners to reduces stress points which cause cracking and breaking.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a multi-purpose prying tool, commonly referred to as a Halligan bar. 
       BACKGROUND OF THE INVENTION 
       [0002]    Prying tools are commonly used by firefighters for a variety of purposes, including breaking through doors or other entry points to enter buildings. Some of these types of tools have come to be known as Halligan bars in the firefighting industry, and are typically a long bar having a forked blade on a first end, and a solide blade and tapered pick on a second end. This tool is often carried with an axe with the set commonly referred to as “irons.” 
         [0003]    Referring to  FIG. 2 , when breaking through a door, it is common to force the forked end  100  of such a tool between a door  140  and door jamb  150 . If needed, an axe  130  can be guided along the shaft  110  of the tool and struck against the shoulder  120  of the forked end to wedge it into position. The door  140  can then be pried loose. However, as  FIG. 1  shows, the existing shoulders  120  of the forked ends are slanted away from the tool which encourages the axe to glance of the shoulder  120 . 
         [0004]    For this reason, it is known that individuals sometimes file down these shoulders to create flatter surfaces for easier striking by the axe head. However, this creates sharp corners at the shoulder that cause stress concentrations leading to cracking or fracturing of the tool. 
         [0005]    Therefore, it would be advantageous to have a halligan bar that can be struck by an axe or other impact tool to easily wedged in between a door and door jamb. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In an aspect of the invention, this is accomplished by creating a dimpled shoulder on the forked end of the tool, which discourages the axe head from glancing off while maintaining the strength of the forked end. 
     
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         [0007]    Further features and advantages of the present invention will be better understood by reference to the following description, which is given by way of example and in association with the accompanying drawings, in which: 
           [0008]      FIG. 1  is a view of a forked end of a prior art halligan bar; 
           [0009]      FIG. 2  shows a halligan bar of  FIG. 1  being wedged into a door; 
           [0010]      FIG. 3  is a perspective view of a halligan bar according to an embodiment of the invention; 
           [0011]      FIG. 4  is a close up view of the forked end of the bar of  FIG. 3 ; 
           [0012]      FIG. 5  is front view of the shoulder portion of the forked end of  FIG. 3 ; 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Referring to  FIG. 3 , a multi-purpose prying tool of the present invention, commonly known as a halligan bar, is shown. The halligan bar  200  is typically made of a forged metal having a long shaft  202  with various prying implements on its ends, such as a forked blade  210  at a first end, and a solid blade  220  and a tapered pick  230  at a second end. Also included on the shaft is a ring  240  that can be used to attach the bar to a carrying strap or otherwise secure the tool. The forked blade, solid blade and tapered pick are examples of the types of implements that can be used this invention and not meant to be exclusive. 
         [0014]    In use, the pick  230 , which is generally cone-shaped ending in a sharp point, is typically forced into a shackle (or eye) of a padlock or hasp and twisted or pried to break it free. It can also be driven into a roof to provide a foothold for firefighters engaged in vertical ventilation. 
         [0015]    The solid blade  220  or forked blade  210  can be used to quickly pry open a door by inserting in between a door and door jamb, and prying the door loose. The solid blade  220  is formed as a generally rectangular implement with a single cutting surface  221 . In contrast, the forked blade  210  includes a split  211  down its middle to form two smaller blades  212 , and has other uses, such as to shut of gas meter valves. 
         [0016]    Additionally, the fork  210  has shoulders  250  (see  FIG. 5 ) with a curved dimple  260 , which forms the inside depression. This dimple  260  has a first radius R 1 , which should be as large as possible to help aid material flow during the forging process, which in the preferred embodiment is approximately 5 mm. This dimple  260  naturally forms an adjacent outer protrusion  270 , which has a second radius R 2 , which in the preferred embodiment, is also approximately 5 mm. The combination of R 1  and R 2  provide a shoulder depth of X, which in the preferred embodiment is approximately 2 mm. The combination of R 1  and R 2  also contribute to the width Y between the shaft  202  and the outer edge of the forked  210 . This width Y should be large enough to ensure that the striking tool firmly impacts the interior portion of the protrusion  270  (rather than the outer surface which would force the striking tool to glance off), but not so large as to allow the striking tool to impact the dimple  260 . In the preferred embodiment, the width is approximately 16 mm. 
         [0017]    The protrusion  270  and dimple  260  are formed with smooth curves so that no sharp corners exist, which prevents stress concentrations from forming. Sharp corners lead to high stress values in localized areas, and after repeated impact from a striking tool, the material at the root of the corner becomes overstressed and can crack. This is important since users will often use an axe or other striking tool to strike the shoulder  250  of the forked end to wedge it further into prying position. 
         [0018]    The present invention thus improves upon prior art devices, which have flat sloping surfaces that tend to encourage the striking tool to glance off the shoulder. The dimpled shoulder of the present invention discourages this glancing effect, since only a small portion of the protrusion  270  faces away from the shaft  202  (eg. the outwardly facing portion of the protrusion  270 ). 
         [0019]    While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. For example, one or more of the pick, blade, or fork can be replaced with other types of cutting or breaking elements in any variety of combination thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification, but that the invention will include any embodiments falling within the description of the appended claims.