In Resident Evil 2 Remake , the clock puzzle in the Clock Tower is solved by placing the Large Gear into the lower mechanism, then moving it to the upper mechanism after you pick up the Small Gear from the stairs area, which activates the lift and lets you continue. The gear puzzle is part of the Clock Tower section, and the main trick is to swap the gears between the two machines in the right order.

Steps

  1. Go to the Clock Tower room from the library area.
  2. Put the Large Gear into the lower machine.
  3. Climb the newly opened stairs and take the Small Gear.
  4. Return to the lower machine and swap the Small Gear in if needed.
  5. Put the Large Gear into the upper machine.
  6. Collect the item that appears, usually the electronic part / Power Panel Part for the story path.

Quick note

The exact room is sometimes called the Clock Tower puzzle or gear puzzle , but it is the same section in RE2 Remake.

TL;DR: Insert the Large Gear, climb up, grab the Small Gear, then move the Large Gear to the upper mechanism.