Fig. 743.
[Fig. 743] shows a longitudinal cross section of the headstocks showing the main and the internal spindles.
Fig. 744.
[Fig. 744] represents a lathe constructed by the Defiance Machine Works for turning the hubs for carriage and wagon wheels.
The blank from which the hub is turned is driven by a mandrel having a square stem fitting in the live or driving-spindle, this mandrel being supported at the other end by the ordinary dead centre operated by the upper hand-wheel. The bed is provided (between the driving-spindle and tailstock) with the usual raised Vs on which rests a carriage carrying a cross slide. This cross slide carries, at the back of the lathe, a head or stock containing the roughing-knives, and at the front a table carrying the finishing-knives, hence, by operating the large hand-wheel (which gives transverse motion to the cross slide) in one direction the roughing-knives are brought into operation, while by operating it in the opposite direction the finishing-knives are brought into operation (the roughing-knives receding). By suitable stops, the motion of the roughing and finishing-knives respectively are arrested when those knives have cut the blanks to the desired diameter, the finishing-knives shaping the work correctly by reason of their form of outline. Upon the same cross slide are the equalizing-knives, one on each side of the front table. These knives operate simultaneously with the finishing-knives, cutting the hubs to uniform length. Thus the hubs are cut to exact uniformity of diameter, shape and length, by simply operating the large hand-wheel first in one direction and then in the other.
If it be required to cup the hubs, as in the case of standard wagon hubs, suitable cutters carried in a bar (having sliding motion in a guide way on the tailstock) are caused to do such cupping, the cupper-bar being operated by the left-hand lever.