• 18 parts
  • Checked September 2026

Parts of a Server Rack

A 19-inch server cabinet: the cabinet itself, the equipment in it, then the side.

Parts of a Server Rack

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
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Write the name of each numbered part.Answer key

  1. Roof
  2. Frame
  3. Mounting rails
  4. Rack unit (U)
  5. Patch panel
  6. Cable manager
  7. Switch
  8. Blanking panel
  9. Shelf
  10. Server
  11. UPS
  12. Casters
  13. Leveling feet
  14. Front door
  15. Side panel
  16. PDU
  17. Rear door
  18. Cage nut

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.

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All 18 parts on the diagram

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The cabinet 7

  1. Roof Like the doors and the side panels, it can be taken off.
  2. Frame The doors, side panels, roof and mounting rails all hang on it.
  3. Mounting rails A cabinet has a front pair and a back pair. Most can be moved to suit deeper or shallower equipment.
  4. Rack unit (U) One rack unit is 1.75 inches (44.45 mm). It takes up three holes on the rail. A 2U server is two units high. A common cabinet is 42U.
  5. Casters They are for rolling the cabinet a short way into place. They are not for holding its weight for good.
  6. Leveling feet Each one is turned until the cabinet stands level and steady.
  7. Front door It is full of small holes so cooling air can pass through. It can be locked.

The equipment in it 7

  1. Patch panel Short patch cables join its sockets to the switch. A connection can then be changed without touching the building's cabling.
  2. Cable manager This one lies across the rack; others run up the sides.
  3. Switch Like a server, it is made to the rack's width. It is fixed by brackets at its front corners.
  4. Blanking panel Covering gaps keeps cooling air flowing through the equipment, not round it.
  5. Shelf A small device simply sits on it.
  6. Server Seen from the side, it reaches from front rails to back rails.
  7. UPS Short for uninterruptible power supply. It runs the equipment from its battery when the mains fails. Makers say to load the heaviest units lowest, so it sits at the bottom.

From the side 4

  1. Side panel It lifts off, so the equipment can be reached from the side.
  2. PDU Short for power distribution unit. Mounted upright at the back, it takes up none of the rack units.
  3. Rear door It opens on the back of the equipment. The cables and power leads are there.
  4. Cage nut It gives the square hole a thread for the mounting screw. It can be swapped if the thread is damaged.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it: Wikipedia, text only (19-inch rack, Rack unit, Cage nut, Patch panel, Power distribution unit, Cable management); three cabinet makers' installation guides, full text at https://archive.org/details/manualzilla-id-7215535, https://archive.org/details/manualzilla-id-7183067 and https://archive.org/details/manualzilla-id-7056031, with a fourth maker's cabinet sheet at https://archive.org/details/manualzilla-id-7178063 and an accessory list at https://archive.org/details/manualsbase-id-233721; for the switch, a switch maker's hardware installation guide, https://archive.org/details/manualzz-id-905944; for the UPS, a UPS maker's operation manual, https://archive.org/details/manualsbase-id-375735. The detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's cabinet, nothing traced. Licence: own work

How it works

A server rack is a steel cabinet with strips of holes inside that 19-inch equipment is screwed to. Three drawings name its parts: the cabinet, the equipment in it, and the view from the side.

Read the full guide

The cabinet, then what goes in it

The frame carries the roof, the doors, the side panels and the mounting rails, and stands on casters and leveling feet. Equipment is fixed to the rails with cage nuts, and its height is counted in rack units. From the top down this rack holds a patch panel, a cable manager, a switch, blanking panels, a shelf, three servers and a UPS. From the side you can see the PDU at the back, which feeds them all.

  • Heavy things go at the bottom: that is why the UPS is the lowest unit.
  • Count three holes on the rail for every rack unit.

Questions and answers

What is a rack unit?

The unit of height for rack equipment, written U. One rack unit is 1.75 inches, or 44.45 mm. A 1U switch is one unit high, a 2U server two, and a common full-height cabinet has room for 42U.

Why is it called a 19-inch rack?

Because the front panels of the equipment it takes are 19 inches wide, about 483 mm, including the ears that are screwed to the rails. The cabinet itself is wider.

What is a cage nut?

A nut held in a spring steel cage. Squeeze the cage's two wings and it clips into a square hole in a mounting rail, giving that hole a thread for a screw.

What is the difference between a PDU and a UPS?

A PDU is a strip of outlets that shares power out to the equipment in the rack. A UPS has a battery, and keeps that power going for a while when the mains supply fails.

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