[Fig. 1867] represents a three-spindle nut tapping machine, in which the spindles are horizontal and the nuts are held in three separate heads or horizontal slideways and are traversed by the ball levers shown, and a self-acting pump supplies them with oil. The three spindles are driven by a cone pulley having four changes of speed to suit different diameters of taps.
Fig. 1868.
Fig. 1869.
Pipe Threading Machinery.—In [Fig. 1868] is represented a machine for threading and cutting off pipe of large diameter. This machine consists of a driving head corresponding to the headstock of a lathe, but having a hollow spindle through which the pipe may pass. The pipe is driven by a three-jawed chuck, and the threading and cutting off tools are carried on a carriage which has a threading head for ordinary lengths of pipe, and one for short pieces such as nipples, the latter swinging out of the way when not in use. Between these two is a pair of steadying jaws for the pipe. A side view of the front of the carriage is shown in [Fig. 1869], h h, &c., representing the threading dies used for nipples. It is movable along a slideway e and pivoted upon its slider. The dies are carried in a chuck g, and are opened or closed by the lever n; at l is the handle for the screw that operates the guide jaws a a.
