turning, boring, facing, and thread cutting. But it mayalso be used for drilling, reaming, knurling, grinding,spinning, and spring winding. Since you will primarilybe concerned with turning, boring, facing, and threadcutting, we will deal primarily with those operations inthis chapter.The work held in the engine lathe can be revolvedat any one of a number of different speeds, and thecutting tool can be accurately controlled by hand orpower for longitudinal feed and crossfeed.(Longitudinal feed is the movement of the cutting toolparallel to the axis of the lathe; crossfeed is themovement of the cutting tool perpendicular to the axisof the lathe.)Lathe size is determined by two measurements: (1)the diameter of work it will swing (turn) over the waysand (2) the length of the bed. For example, a 14-inch by6-foot lathe will swing work up to 14 inches in diameterand has a bed that is 6 feet long.Engine lathes vary in size from small bench lathesthat have a swing of 9 inches to very large lathes forturning large diameter work such as low-pressureturbine rotors. The 16-inch lathe is the average size forgeneral purposes and is the size usually installed in shipsthat have only one lathe.PRINCIPAL PARTSTo learn the operation of the lathe, you must befamiliar with the names and functions of the principalparts. Lathes from different manufacturers differsomewhat in construction, but all are built to performthe same general functions. As you read the descriptionof each part, find its location on the lathe in figure 9-1and the figures that follow. (For specific details offeatures of construction and operating techniques, referto the manufacturer’s technical manual for yourmachine.)Bed and WaysThe bed is the base or foundation of the parts of thelathe. The main feature of the bed is the ways, which areformed on the bed’s upper surface and run the full lengthof the bed. The ways keep the tailstock and the carriage,which slide on them, in alignment with the headstock.HeadstockThe headstock contains the headstock spindle andthe mechanism for driving it. In the belt-driven type,shown in figure 9-2, the driving mechanism consists ofFigure 9-2.—Belt-driven type of headstock.a motor-driven cone pulley that drives the spindle conepulley through a drive belt. The spindle can be rotatedeither directly or through back gears.When the headstock is set up for direct drive, abull-gear pin, located under a cover to the right of thespindle pulley, connects the pulley to the spindle. Thisconnection causes the spindle to turn at the same speedas the spindle pulley.When the headstock is set up for gear drive, thebull-gear pin is pulled out, disconnecting the spindlepulley from the spindle. This allows the spindle to turnfreely inside the spindle pulley. The back-gear lever, onthe left end of the headstock, is moved to engage theback-gear set with a gear on the end of the spindle anda gear on the end of the spindle pulley. In this drivemode, the drive belt turns the spindle pulley, which turnsthe back-gear set, which turns the spindle.Each drive mode provides four spindle speeds, fora total of eight. The back-gear drive speeds are lessslower than the direct-drive speeds.TailstockThe primary purpose of the tailstock is to hold thedead center to support one end of the work being9-2
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