Brother MFC-3340CN Service Manual page 71

Ink refill assembly components and their main roles
- Ink refill base
This holds the ink cartridges and feeds ink from them to the ink supply tubes.
- Cartridge clamp springs
These force the ink cartridges into close contact with the ink cartridge joint to prevent ink leakage.
- Joint head
This lifts the disc valves S and D, allowing ink to flow out of the ink cartridges and air to flow in.
It also incorporates measures to prevent insertion of the wrong ink cartridges.
- Ink cartridge sensors
These detect when the ink cartridges are running out of ink ("Ink near-empty").
- Polyurethane foam
This absorbs any ink that leaks from the ink cartridges, limiting its spread and thus reducing the
risk of damage to other components.
Ink refill assembly
The cartridge clamp springs force the ink cartridge ink supply ports into close contact with the joint
head to prevent ink leakage.
The ink from the ink cartridges flows along paths in the ink refill base and through connectors into
the ink supply tubes. As the ink level in an ink cartridge drops, the pressure inside falls, drawing in
air from the air supply port in the ink refill base.
Polyurethane foam absorbs any ink that leaks from the ink cartridges, limiting its spread and thus
reducing the risk of damage to other components.
An ink cartridge sensor arm blocking light to a cartridge sensor indicates that there is ink in the ink
cartridge. When ink runs low, the arm moves out of the beam, activating the sensor. (Note that the
firmware also interprets a missing ink cartridge as running low on ink.)
Air flow path
Ink flow path
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