wheel-turning machine (fig. 4, a variety of face-plate lathe) is used for turning car- and locomotive-wheel flanges. In turning the axle the wheels and flanges remain upon it, thus forming one piece; and this, by reason of its liability to spring, requires to be driven from both sides. For this purpose each wheel is connected with a face-plate receiving independent although synchronous rotation, whereby all chatter due to the heavy cut is avoided. The slide-rests must be of sufficient height for the tools to work nearly at the height of the axle.
Copying-/athe.—There is a strong analogy between copying-lathes for metal and those for wood, the latter having, however, higher speed. One peculiar modification of the lathe allows the production of irregularly shaped articles and copies of a pattern. Part of this so-called "copy ing-lathe'' is shown in Figure 9 (b/. 20), and has some relationship to the gauge-lathe referred to under the head of wood-working machinery (p. 94). The pattern and the work to be shaped like it are secured between chucks by means of a head-stock with two spindles and a double sliding poppet, and are turned at equal speeds and in the same direction. Against the pattern there is constantly pressed a smooth-edged disc attached to the same cross slide with the rotating cutter. This cutter, thus receiving a certain dis placement from the axial line depending on the pattern, reproduces on the work, if properly set, the form of the latter. As the rotating cutter replaces, in this case, the ordinary turning-tool, this machine may be classed with milling-machines as well as with lathes. (See p. 122.) The shown in Figure i (p. 22) has its power transmitted from the counter-shaft to a cone in the head-stock, which, when discon nected, revolves loose upon the main spindle. If moderate work not requiring much power is to be performed, the cone is connected to the spindle by a small clutch between the large gear on the spindle and the inside edge of the cone. If great power is needed, the clutch is unlocked and the back gearing engaged, which considerably multiplies the power. The " work " is placed between the centres, the tool being held in the tool-post and guided by the several hand-wheels in the apron-carriage and compound slide.
For cutting threads combinations of change-wheels are placed at the end of the live head, to connect the spindle with the screw in such ratio as the index-plate on the lathes shows will be the result. Means are pro vided in the apron for automatically running the carriage to the right or to the left and for moving the tool in or out, for cross-feeding. The bed of this lathe has a hollow and double centre-rib, which stiffens it, while adding comparatively little weight.
The Lathe (fig. 2) is intended for the production of cir cular work of all kinds in metal up to an extreme diameter of 62 inches, or of 46 inches should it have to rotate over the carriage. The machine consists of a combination of mechanisms, (1) for imparting motion to the work (the live head), (2) for holding and guiding a tool (the carriage), (3) for imparting motion to the tool in given ratio to the motion of the work (the feed), and (4) for supporting the outer end of the work (the dead or poppet head), the whole being supported on a long box-like frame called the bed.
The live head consists of a framework containing a cone pulley (A) running upon a horizontal shaft or live spindle (R), on the outer end of which is a large circular face-plate (C) provided with slots, to secure work to it by means of bolts. It is necessary, 011 account of varying sizes of work, to be able to vary the rate of motion of the face-plate; and to secure this end there is used a series of toothed wheels, known as the " head " gearing. The "cone" pulley is made up of five faces of different diameters and is driven by a belt from a similar stepped pulley overhead in which the sequence of sizes is reversed. By the transfer of the belt from one to another of these diameters five changes of motion are obtained. To obtain still other changes there is used a " back " gearing, consisting of a train of four gears, starting front a small gear on the end of the cone pulley, running into a large wheel (D) on the back gear-shaft (E); this latter carries a small gear (F), which in turn meshes with a large gear (G) on the live spindle or into a large gear (H) on the triple-gear shaft.
Five changes are imparted by the " back " gearing and five by the " triple " gearing,, thus giving, with the pulleys, fifteen changes to the face-plate motion. The " triple " gearing is effected by the small gear driving the large gear II, which is on the shaft J with the small gear A", which drives the internal toothed surface of the face-plate C. Wlicn any one of these series is employed, the others must be kept idle or " thrown out of gear." As the spindle always receives the same motion as the face-plate, it is necessary to allow the cone to run freely on it; but the gear G is tightly fastened to it and can be locked to the cone pulley, thus imparting the motion of the latter directly to the face-plate. When the " back " gearing is used, the cone is unlocked, and the motion then comes to the spindle and face-plate, as before, through the gear G, but very much reduced, by reason of the ratios of the gears through which the motion has come. When the " back " gearing is not in use, the gears D and F are moved lengthwise on the shaft E, one to the left, the other to the right, this throwing them out of gear and allowing the cone pulley to be locked again to the gear G. When the " triple " gearing is in use, the cone pulley is unlocked, the gear D is pushed into the small gear, on the end of the cone pulley, and the gear F moved until it conies into line with the gear If This gear (II) is mounted on the shaft J carried in eccentric bearings, which have already been thrown clown, so that the small gear A" engages with the toothed surface of the face-plate. The moving of the gear F into line with the gear H engages them, thus com pleting the series or train to the spindle and face-plate. When the"triple" gearing is not in use, the shaft J is thrown upward by its eccentric bear ings, and so the pinion A" is out of gear with the face-plate, thus allowing the other gears to be used freely.