Adjustable pipe wrench
BACKGROUND OF THIS INVENTION 
     The present invention relates to a wrench for holding or turning pipes or other circular objects, that is instantly adjustable and capable of exerting high gripping and turning forces. 
     Presently available and patented pipe wrenches are adjusted either by screw adjusting jaws, or by a cam action, or by changing interchangeable pads or jaws. 
     The adjustable by screw types are limited in the range of pipe size that they can accomodate by the length of the jaws, are heavy and complex in construction. Their gripping action is limited and obtained by spreading the jaws round the half of a pipe against a spring, and are liable to slippage, particularly when operated in a difficult position or confined area. 
     The types with interchangeable jaws to accomodate varying pipe sizes are complex and expensive and require mechanical work to adjust. 
     Since, in the case of this invention, the grip applying members are driven towards each other around the pipe, by the mechanical action of interfacing gear forms, an automatic and powerful gripping action is provided that accepts a wide range of pipe sizes that is a greater size range than existing devices. The wrench can easily be &#34;wrapped&#34; around a pipe in close proximity to other obstructions and can be laid almost into a straight line for transporting or stowing. 
     SUMMARY OF THE INVENTION 
     The invention relates to an adjustable, self locking pipe wrench. This invention is an improvement to my previous invention of an adjustable, self locking pipe wrench for which an application for a patent was filed under number 445,744, now abandoned. 
     The wrench is formed from a series of hinged links, so arranged that a pipe, or other round object, enclosed within the links is gripped by serrations, or teeth, formed on the inner faces of two or more of the links and, as a force is applied to the handle, a force is applied to the anvil by means of meshing gear form teeth on the handle mating with identical teeth on the anvil and thus driving the anvil into contact with the pipe which is, in turn, forced against the inner teeth on the other links on the far side of the pipe. Further application of force to the handle rotates the entire assembly thus turning the pipe. 
    
    
     The invention is further described in connection with the accompanying drawing in which: 
     FIG. 1 is a plan view of the wrench engaging a small diameter pipe. 
     FIG. 2 is a plan view of the wrench engaging a larger diameter pipe. 
     FIG. 3 is an end view of the wrench. 
     FIG. 4 is a view of the wrench showing the anvil entering a slotted connecting link to permit a small diameter pipe to be gripped. 
    
    
     The main link (1) is slotted at each end to accept, at one end the connecting link (2) and, at the other end, the handle link (5). The opposite end of the connecting link (2) is slotted to accept the anvil link (3). All the links are connected by means of swivel pins (6) which permit rotary motion between any pair of pieces or all pieces, in one plane only. 
     The inner face of the handle (4) which is connected by a pin (6) to the handle link (5), has formed upon it teeth of gear form of identical shape and pitch to teeth also formed on the outer face of the anvil link (3). 
     As a force is applied to the handle (4) in the direction indicated in the drawings FIGS. 1, 2 &amp; 4, the anvil link (3) is driven against the pipe in such a way that the teeth on the inner faces of the anvil (3) grip the pipe. At the same time, responding to the same force, the pipe is forced by the anvil link (3) against the teeth formed on the inside face of the main link (1). 
     The teeth on handle (4) and anvil link (3), being meshed together as gears, prevent any loosening motion between these pieces and, in fact, tend to drive the anvil into firmer contact with the pipe, so that the pipe is firmly held by the wrench. 
     As force is continued to be applied to the handle, and since the pipe is gripped and prevents further rotary motion of the anvil (3) the entire assembly is rotated. 
     To accomodate smaller pipe sizes, handle (4) may be so slotted as to permit anvil (3) to pass through the slot as shown in FIG. 4. Because the turning force applied also causes the gear forms on the anvil (3) and handle (4) to attempt to move relative to one another, the greater the turning force applied to the assembly, the greater the gripping force on the pipe. 
     Removable, replaceable hardened teeth may be fitted in lieu of fixed teeth.