Brother MFC 5490CN - Color Inkjet - All-in-One, Service Manual

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3-29 Confidential
(3.1) Switching pump
The pump switching unit switches the application target of the negative pressure generated by
the pump between the head cap for black ink, the one for color ink, and the air vent cap.
When the purge cam is in a head capping position and the head cap unit fits tightly over the
print head, the pump switching unit is switched to the opening tube to the atmospheric air so
that the pressure in the head caps and air vent cap returns to the normal atmospheric pressure.
(3.2) Draining ink
The tube pump consists of a pump gear and tube roller. As the pump gear rotates, the tube roller
on its circumference squeezes the main drain tube looped around the pump gear, forcing its
content toward the ink absorber box and creating negative pressure.
For details about the power transmission route to the head maintenance mechanism, see [ 4 ]
below.
Head cap for black ink
Print head
Head cap for color ink
Color drain tube
Main drain tube
Pump switching unit
Black drain tube
(Purge_3_2_E)
To opening to
atmospheric air
To ink absorber box
To ink absorber box
To opening to atmospheric air
Main drain tube
Pump gear
Tube roller
Tube pump
(TubePump)