The cross-slide (3) rides on the carriage and has a feedscrew which travels at right angles to the main spindle axis. This permits "facing" operations to be performed, and the depth of cut to be adjusted. This feedscrew can be engaged, through a gear train, to the feed shaft (mentioned previously) to provide automated 'power feed' movement to the cross-slide. On most lathes, only one direction can be engaged at a time as an interlock mechanism will shut out the second gear train.