[Fig. 834] represents the construction of the Horton chuck. Upon the screws that operate the jaws are placed pinions that gear into a circular rack, so that by operating one jaw with a wrench the rack is revolved and the remaining jaws are operated simultaneously. The chuck being constructed in two halves, the rack may be removed and the jaws operated separately, or independently as it is termed.
Fig. 835.
[Fig. 835] represents one of the jaws with its operating screw and pinion removed from the chuck. The gripping surfaces of the steps in the jaws are serrated to increase their grip upon the work, and the nuts a, a, against which the works rests, are ground true with the face of the chuck. The corner between the faces a and the bite or gripping surfaces of the jaws are recessed so that the work cannot bind in them, but will bed fairly against the faces a, a, which serve to set the work against and hold it true instead of the face of the chuck.
Fig. 836.
[Fig. 836] represents a Horton chuck for work up to four inches diameter.