[ The PC Guide | Systems and Components Reference Guide | Hard
Disk Drives | Construction and Operation of the Hard Disk ]
Hard Disk Head Sliders, Arms and Actuator
The hard disk platters are accessed for read and write operations using the read/write heads mounted on the top and bottom surfaces of each
platter. Obviously, the read/write heads don't just float in space; they must be held in
an exact position relative to the surfaces they are reading, and furthermore, they must be
moved from track to track to allow access to the entire surface of the disk. The heads are
mounted onto a structure that facilitates this process. Often called the head assembly
or actuator assembly (or even the head-actuator assembly), it is
comprised of several different parts.
The heads themselves are mounted on head sliders. The sliders are suspended
over the surface of the disk at the ends of the head arms. The head arms are all
mechanically fused into a single structure that is moved around the surface of the disk by
the actuator. (Sort of like "the leg bone's connected to the knee
bone", isn't it? :^) ) It would be an understatement to say that these components are
neglected; heck, most people don't even know they exist! Yet they play an
important role in the function and performance of the drive. In particular, advances in
slider, arm and actuator design are critical to improving the seek time of a hard disk; the impact that the
actuator has on performance is discussed in this
section.
|
Annotated illustration of a typical PC actuator
assembly, showing the major
components. The platters have been removed from the drive to provide a better
view of the actuator arms and heads. There are four sliders but only
one of each pair is visible. The spindle motor is visible at the top right. |
This section discusses the sliders, arms and actuator of the modern disk drive, as well
as explaining the operation of disk drive servo mechanisms and related
technologies.
 Next: Head Sliders
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