. Appleton's dictionary of machines, mechanics, engine-work, and engineering. rounded off both at top and bottom, instead of being either tri-angular or square. It is thus enabled to work either in a nut orwith a tangent-wheel. This guide screw is shown at G, Fig. 3460. It is placed with-in the lathe-frame, not in the direction of the axis of the machine,but rather on one side, in order to screen it from the falling turn-ings, and the nut k, when needful, is taken out of geer by thepin /. When the guide-screw is required to answer the pur-pose of a rack—as, for instance, to bring the saddle, a
. Appleton's dictionary of machines, mechanics, engine-work, and engineering. rounded off both at top and bottom, instead of being either tri-angular or square. It is thus enabled to work either in a nut orwith a tangent-wheel. This guide screw is shown at G, Fig. 3460. It is placed with-in the lathe-frame, not in the direction of the axis of the machine,but rather on one side, in order to screen it from the falling turn-ings, and the nut k, when needful, is taken out of geer by thepin /. When the guide-screw is required to answer the pur-pose of a rack—as, for instance, to bring the saddle, and consequently the carriage, to any particularposition—the nut A: is disengaged, and the handle m, the socket of which is titled on a horizontal spindlecarrying the small meter-wheel n, which geerswith a larger one , keyed on one end of a vertical shaftplaced in the centre of the saddle 0, and on the other extremity of this shaft is a tangent wheel />,which works with the guide-screw of the lathe. Now as this last is deprived of rotary motion, it is evi- of. 744 TOOLS. dent that by turning the handle m, the tangent-wheel p, driven as already described, will produce pre-cisely the effect of a rack ; that is to say, the saddle and carriage will receive a traversing motion inthe direction of the length of the lathe-bed. In actual work the saddle, and consequently the rest itself, is placed in any required position, thehandle m being removed and the nut k brought into connection with the guide-screw G, which, actuatedand regulated by a train of wheels attached to the lathe, causes the saddle with its appurtenances totravel with any degree of speed that may be required. By a peculiar and ingenious arrangement, the guide-screw is made to drive the carriage and tool-carrier in a direction at right angles to the axis of the lathe. This is effected in the following man-ner :—with the mitre-wheel o a similar but smaller one q geers; this is keyed on the end of a shaft idthe sam
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Keywords: ., bookcentury1800, booksubjectmechanicalengineering, bookyear1861
