Fig. 66.—Crank Cases, in Fixtures carried along Tracks, being: Drilled and Tapped under
" Natco " Multiple-spindle Machines
foremost—are being used for tapping in all 44 holes in the crank case,
and the others drill between them 72 holes. The method used for locating
*the case is the truck fixture on trunnions, transported along the tracks.
The case is loaded at the beginning of the track, and is unloaded after passing
under all the machines. The trucks run on to turn-tables, and are returned
by way of a similar track at the rear. Two or more fixtures are used. As
each operation is completed the chips are blown out by compressed air.
Figs. 67 and 68 are two views of the methods employed in milling the