. The Street railway journal . ust be evident that a downward pres-sure, applied to the handle H, will be transmitted throughthe jaw J in the direction indicated by the arrow, directlytoward the center of the pipe. This pressure, on the pipe, then,is a crushing strain, increased several fold by leverage, overthe power applied to the handle. If the pipe and the wrenchcan stand this strain, the joint will loosen up, but if the jointis a stubborn one, the chances are that the pipe will give firstand be crushed. In time the wrench itself will succumb tothis abnormal strain and the jaws will be ben
. The Street railway journal . ust be evident that a downward pres-sure, applied to the handle H, will be transmitted throughthe jaw J in the direction indicated by the arrow, directlytoward the center of the pipe. This pressure, on the pipe, then,is a crushing strain, increased several fold by leverage, overthe power applied to the handle. If the pipe and the wrenchcan stand this strain, the joint will loosen up, but if the jointis a stubborn one, the chances are that the pipe will give firstand be crushed. In time the wrench itself will succumb tothis abnormal strain and the jaws will be bent out of align-ment. In the new wrench the principle of operation is entirelydifferent. There are three separate levers, compounded, andso arranged that the power applied to the handle is transmit-ted through the jaws in a tangential direction to the the power is applied in a wringing manner similar towhat would be effected in using manual means. In fact,, theBullard wrench is modeled exactly on the principle of the. FIG. 1.—COMMON TYPE OF PIPE WRENCH WHICH EXERTSA CRUSHING STRAIN. human hand. For instance, take any cylindrical object, as amailing tube, about iVz ins. in diameter, and grasp it with theright hand thumb down. Hold the tube firmly with the lefthand and turn down with the right. This gives a torsional ortwisting strain on the tube with no tendency to crush it, asis precisely the effect of this novel wrench. The outer jawcorresponds to the fingers, the inner jaw to the thumb, andthe handle to the wrist. The wrench is constructed to withstand the severest inner jaw, which takes the brunt of the work, is made ofsolid bar steel, machined to shape. The removable toothsection in the jaw is made of hardened tool steel. The spring is merely auxiliary, serving only to keep thejaws together when the wrench is used with the jaw side ordinary conditions the weight of the jaws tends tokeep them closed. There are no sliding parts and no loose, s
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
