Examples of Multiple Turning.—[Figs. 33] and [34] show how a Lo-swing lathe is used for turning the steering knuckle of an automobile. Four tools are used in this case, three cylindrical surfaces and one tapering surface being turned at the same time. For this job, the four tools are mounted on one carriage. The taper part is turned by the second tool from the headstock, which is caused to feed outward as the carriage advances by a taper attachment. This tool is held in a special holder and bears against a templet at the rear, which is tapered to correspond with the taper to be turned. This templet is attached to a bar which, in turn, is fastened to a stationary bracket seen to the extreme left in [Fig. 33]. This part is finished in two operations, the tool setting being identical for each operation, except for diameter adjustments. As the illustrations show, three of the four tools employed are used for straight turning on different diameters, while the fourth finishes the taper.
Fig. 34. Plan View showing Method of driving Steering Knuckle and Arrangement of Tools
These pieces, which are rough drop forgings, are first reduced to the approximate size. When it becomes necessary to grind the tools, they are reset and those parts which have been roughed out are turned to the finished size. The average time for the first operation, which includes starting, stopping, turning and replacing the piece, is one minute, while for the second operation with the finer feed, an average time of two minutes is required. The work is driven by sleeve S, which fits over the spindle and is held in position by the regular driver, as shown. This sleeve is notched to fit the knuckle, so that the latter can easily and quickly be replaced when finished.
One of the interesting features of this job lies in the method of locating the shoulders on each knuckle, at the same distance from the hole H which is drilled previously, and which receives the bolt on which the knuckle swivels when assembled in a car. As soon as the knuckle has been placed between the centers, a close-fitting plug P ([Fig. 33]) is inserted in this hole and the indicator arm with its attached gage or caliper G is swung up to the position shown. The stop-rod on which the stops have been previously set for the correct distance between the shoulders is next adjusted axially until the gage G just touches the plug P. The indicator is then swung out of the way, and the piece turned. If the next knuckle were centered, say, deeper than the previous one which would, of course, cause it to be located nearer the headstock, obviously all the shoulders would be located farther from the finished hole, provided the position of the stops remained the same as before. In such a case their position would, however, be changed by shifting the stop-rod until the gage G again touched the plug thus locating all the stops with reference to the hole. As the adjustment of the stop-rod changes the position of the taper templet as well as the stops, it is evident that both the shoulders and the taper are finished the same distance from the hole in each case. The connection of the bracket (to which the templet arm is attached) with the stop-rod is clearly shown in [Fig. 33]. This bracket can either be locked to the ways or adjusted to slide when the stop-rod is moved.
Fig. 35. First and Second Operations on Automobile Transmission Shaft—Lo-swing Lathe