r
the separate adjustment of the jaws. The implement is made of the best
steel, by special machinery, so that its parts are interchangeable.

[Illustration: VINTON'S LATHE CHUCK.]

Figs. 1 and 2 represent the chuck taken apart so as to exhibit the
interior. Figs. 3 and 4 are sectional views. A is a collar which
encircles the spindle, and has formed on its outer face a bevel gear
wheel, B. C, Fig. 3, is the rear portion of the shell of the chuck
inclosing the forward part of the collar, A. Also on said collar, A,
is a washer, D, which rests against the shell, C, and a nut, E, which
travels on a thread formed on the collar. As it is necessary, as will
be explained further on, to turn the entire shell in order to move the
jaws, the use of the nut just described is to jam the part, C, and the
enlarged portion of the collar, A, tightly together, and so rigidly
hold the jaws in any position in which they may be adjusted. Fig. 1
represents the outer face of the chuck with the jaws and their working
mechanism. Within the chuck, each jaw has attached to it a screw, E.
This enters a bevel wheel, F. As the jaws are incapable of any but
radial motion, it follows that, when the chuck is rotated bodily and
the bevel wheels engage on the motionless gear wheel, B, the effect of
the rotation of said bevel wheels is to cause the jaws to travel
toward or from the center of the chuck face. And it will be further
clear that this motion must be simultaneous in all the jaws. As the
outer portion of the chuck is rigidly secured to the shell, C, by
screws, of course when that shell is jammed, as already stated, by the
nut, E, it becomes impossible to turn the chuck bodily; and hence the
bevel wheels cannot be rotated around the main gear wheel, and
consequently the position of the jaws cannot be altered. The above
comprises the mechanism proper of the device, that is to say, all that
is necessary for moving or clamping the jaws.

There is, however, another feature of considerable importance yet to
be described, and that is the device for taking up any play of the
jaws due to wear, and which enables each to be adjusted so that the
motion of all may be uniform. By referring to Fig. 4, it will be seen
that, above the bevel wheel, there is a projection, into the threaded
interior of which, as already explained, the jaw screw enters.
Surrounding this projection is a sleeve, G, the outer surface of which
is threaded to fit a similarly threaded ape