Fig. 820.
Fig. 821.
[Figs. 819], [820], and [821] represent Gage’s patent chuck, in which the gripping surfaces of the jaws are serrated to increase the grip, and to further secure the same object the jaws move at an angle instead of in a radial line, so that the body of the jaws is more directly in the line of strain, and therefore resists it better. The serrations are left-handed, so that the tendency is to force the drill forward and toward the cut, supposing them to act as a nut and screw upon the drill shank. The jaws are supported by the central cylindrical piece that contains them out to the extreme end, and have in addition a lug which slides in radial grooves. [Fig. 819] is a side elevation, with a piece of the shell removed to show the jaw and its slide way, and an end view showing the arrangement of the jaws. [Fig. 820] is a sectional side elevation, and [Fig. 821], two views of the jaws removed from the chuck; a represents the jaws with the lug e to slide in the radial slots provided in b. The wings a′ of the jaws slide in the ways in b, the ways passing through the opening f in [Fig. 821]; c is the cone for causing the jaws to open and close radially. The driving piece h has a left-hand thread operating in b. It also has a collar abutting over one side against the end of b, and secured on the other by the cap i, which threads into the shell g. A pin in c secures it to the cap i, so that if rotated both move together. On the other hand, if h be rotated and g is held stationary, the thread on h operates on b as a nut, causing it to slide, carrying the jaws with it, and the jaws are simultaneously opened or closed according to the direction of rotation of h. [Fig. 819] shows the jaws screwed partly out, and therefore partially closed, while in [Fig. 820] the jaws are shown within the chuck, and therefore opened to their fullest extent.
Fig. 822.