Disk drive arm actuator with piezoelectric ultrasonic motor

A data storage device comprising:

• a stack of data storage disks mounted on a spindle, the stack comprising a first plurality of disks;
• a first head stack assembly comprising:
• a first arm configured for pivotal motion about a longitudinal axis of an actuator shaft,
• a first load beam attached to the first arm;
• a first head attached to the first load beam, wherein the first head is configured to interact with a surface of one of the first plurality of disks, the surface defining an x-y plane;
• and
• a first tail disposed on an opposite side of the actuator shaft from the first arm, the first tail having a first engagement surface that is parallel to the x-y plane;
• and
• a first piezoelectric motor comprising:
• a first piezoelectric element comprising a first mounting surface;
• and
• a first contact tip disposed at the first mounting surface, wherein the first contact tip is configured to frictionally contact the first engagement surface to pivot the first head stack assembly about the longitudinal axis.