• 11 parts
  • Checked September 2026

Unlabeled Hard Disk Drive Diagram

The inside of a hard disk drive and its underside, with nothing written on either, ready for a pen.

Unlabeled Hard Disk Drive Diagram

Name Date

Blank diagram

1 2 3 4 5 6 7 8 9 10 11
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Write the name of each numbered part.Answer key

  1. Platter
  2. Spindle
  3. Track
  4. Read/write head
  5. Actuator arm
  6. Actuator (voice coil)
  7. Magnet
  8. Air filter
  9. Circuit board
  10. Data connector
  11. Power connector

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Read every name on the labeled hard drive

All 11 parts on the diagram

Show the list

Cover off 8

  1. Platter A rigid disk with a magnetic coating. It stores the data.
  2. Spindle It holds the platters and its motor spins them.
  3. Track One ring of data on the surface of the platter.
  4. Read/write head It reads and writes data as the platter spins under it.
  5. Actuator arm It swings the head across the platter to the right track.
  6. Actuator (voice coil) A coil beside a magnet. Current in it swings the arm.
  7. Magnet A strong fixed magnet. The coil moves in its field.
  8. Air filter It traps dust from the air moving inside the drive.

Underneath 3

  1. Circuit board The drive's electronics. They control the motor and the actuator.
  2. Data connector The data cable from the computer plugs in here.
  3. Power connector The power cable plugs in here.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it. (1) Wikipedia, Hard disk drive, text only, https://en.wikipedia.org/wiki/Hard_disk_drive (platters on a spindle; magnetic heads on a moving actuator arm; the actuator is a moving coil and permanent magnet motor, the voice coil; a fixed magnet above and below the coil; the recirculation filter; the drive's electronics control the actuator and the disk's rotation; printed circuit board; data and power connectors; tracks). (2) R. and A. Arpaci-Dusseau, Operating Systems: Three Easy Pieces, chapter Hard Disk Drives, a free university textbook, https://pages.cs.wisc.edu/~remzi/OSTEP/file-disks.pdf (platter, surface, spindle and its motor, track as one concentric circle of data, disk head, disk arm). (3) Scott Mueller, Upgrading and Repairing PCs, sixth edition, chapter Hard Disk Drives, read as full text at https://archive.org/details/URP_6th_edition (platters, read/write heads, head actuator and voice coil actuator with its stationary magnet, air filters and recirculating filters, spindle motor, logic boards, interface and power connectors, tracks). No maker is named in the copy or drawn. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work

How it works

An unlabeled hard disk drive diagram on one sheet: the drive from above with its cover off, and the same drive turned over. Eight lines lead from parts inside the case, three from the underside, each ending in blank space.

Read the full guide

The eight names inside the case

Platter, spindle, track, read/write head, actuator arm, actuator, magnet and air filter. The line from the top ends on the dashed ring, which is the track. Two of the lines on the right end on the arm: the upper on the dark block at its tip, the head, and the lower on the arm itself. The actuator's line comes up from below to the flat wedge behind the pivot; the magnet's ends on the block beside that wedge.

The three names underneath

Circuit board, data connector and power connector. The two sockets on the back edge are told apart by length: the short one takes the data cable, the long one the power cable.

  • Drawn with no line: the arm's pivot, the curved cable leaving it, the screws, and underneath the round bump of the spindle motor.
  • A class sheet may print disk for platter, disk arm for actuator arm, voice coil for actuator and logic board for circuit board.
  • The dashed ring is one track. A sector is a short piece of a track, and the drawing does not mark one.

Questions and answers

What is a hard drive platter made of?

A rigid disk of a material that is not magnetic, usually an aluminum alloy, glass or ceramic. A very thin magnetic coating on its surface holds the data.

Does the read/write head touch the platter?

Not in normal use. The head rides on a thin film of moving air just above the spinning surface. A head that does strike the platter cuts into its coating, and that failure is called a head crash.

How fast does a hard drive spin?

Most drives sold for home computers turn their platters at 5,400 or 7,200 revolutions per minute. Drives for portable devices can be as slow as 4,200, and drives for servers as fast as 15,000.

Why does a hard drive have an air filter?

The spinning platters keep the air inside the case moving, and it passes through the filter over and over. The filter takes out loose particles; contamination inside the case is one cause of a head crash.

Does the unlabeled hard disk drive diagram come with an answer key?

Yes. The key is the same sheet with a name at the end of each of the eleven lines. Three are written short: Head, Arm and Actuator.

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