Belt-driven rotary cam elevator mechanism for reduced-head data storage device

An approach to a reduced-head hard disk drive involves an actuator subsystem that includes a ball screw cam assembly wherein the number of starts of a multi-start lead screw equals the number of balls riding in a corresponding start. A stepper motor may be employed to drive rotation of a pulley or gear to which a drive belt or drive chain is attached, to transmit power to the lead screw via the drive belt or chain, thereby driving rotation of the lead screw to drive translation of an actuator arm assembly along the axis of the lead screw so that a corresponding pair of read-write heads can access different magnetic-recording disks of a multiple-disk stack.