Patent GB-189804272-A (GB)
Title: Improvements in Self-acting Sliding and Screw-cutting Gap Bed Lathes.
Inventor: GREENWOOD THOMAS
Filed: 1898-02-21
Granted: 1899-02-21
Abstract: 4272. Greenwood, T. Feb. 21. Lathes.-Relates to improvements in gapbed lathes. To give a considerable range of driving speeds, the countershaft A, Fig. 3, carries an additional loose pulley B geared to an intermediate shaft 47 which can drive the countershaft through either of two pairs of wheels a, b, the change being effected by a handlever 45. The loose pulley B thus gives two different speeds to the countershaft in addition to the fastpulley speed, each speed being available with any cone speed. A reversing-train of wheels 48, connecting the intermediate and countersbaft, and controlled by a lever 49; allows the lathe to be rapidly reversed in screw-cutting &c. The countershaft bearings are carried by horizontal sleeves sliding on arms on vertical sleeves 41, sliding on hangers 40. Screws, engaging the sleeves, and connected by bevel gearing 43 and shafts, enable the bearings to be moved horizontally by a chain and wheel 50, or vertically by a hand-wheel 51, thus adjusting the tension of the belt. The belt fork is operated by a vertical spindle, geared to a back shaft on the lathe, connected to a spindle, passing through the saddle and having a handle in front, so that the belt can be shifted from the saddle. A shaft 2, Fig. 1, on the front of the headstock drives a front shaft 12, either by cone pulleys 13, 14 or by a quadrant and change-wheels. A hand-operated reversing-train 6 is provided. The front shaft drives the back shaft either by change-wheels and quadrant plate or by cone pulleys, the belt passing through a hole in the bed. By using suitable change-wheels, any desired taper may be produced by combined surfacing and traversing motions. The front shaft 12 drives the leading screw S, which may be supported at the centre by a T-piece carried on a spring. The horizontal arm is bevelled at each end and is depressed when the nut passes over it. The lever 20 for disengaging the nut is connected by a link 21 to a T-lever 17 on the surfacing-screw to effect the quick withdrawal of the tool when the nut is disengaged. One arm of the lever 17 is connected to an arm 26, oscillated by a cam 27 on the rack pinion shaft to allow the faces of pulleys to be rounded. Keyways may be cut in shafts or pulleys by fixing the main spindle and traversing the saddle from the loose cone and change-wheels. The gap 39 is strengthened by ribs projecting front and back. The horns of the saddle are lengthened at the rear end, and the slides are cut away at the front end, allowing the saddle to be slid nearly up to the face-plate without projecting over the gap and dispensing with a bridge. A vertically-adjustable support 34 with a V-top is provided in the gap to take the weight of pulleys &c. while chucking them, or to support a shaft end &c. A tool-holder for fixing on the slide rest consists of a bracket 56, Fig. 7, carrying a disc 50 from which the tools 53 project, the tools being held by screws 51. The rotation of the disc and the height of the tool are adjusted by a screw 52 engaging a cam 58, which can be turned out of the way. A boring-bar, which may be adjustably secured in a sleeve mounted in a bearing on the saddle, has cross-slots to receive cutters notched as shown in Fig. 16. The cutters are held in place at right-angles by a cottar. The bar and cutters may be used instead of flat drills or rose bits. A tool-holder and steady-rest, Fig. 13, has radially-adjustable rubbers or guides and correspondingly-situated tools. The lower tools are adjustable by screws 68 and the upper by a slide 67. The tools may be arranged to cut both the sides and the bottom of a thread. A bracket may be bolted on the saddle and supported by an arm on the bed, to project over the gap. The bracket has slots to receive tools for turning large diameters. Rods &c. may be held in a combined driverplate and chuck, Fig. 10, the rod being clamped in a V in a boss 60, carried by an adjustable slide in the driver-plate 59.