Wascomat W620 Classic, Service Manual

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3
38
38. Drain valve
Service
Manual
Description
The drain valve is situated on a flange at the
bottom of the outer drum and can be accessed
from the front after removing the front cover.
The drain valve consists of the following principal
parts:
• Lower part with rubber diaphragm.
• Piston and cylinder.
• Pressure plate and recoil springs.
• Rubber diaphragm with drain connection.
• Upper part with connection for outer drum.
Function
The drain valve uses the water pressure in the
cold-water inlet to close the valve. A feed hose is
connected between the water inlet and the
control valve.
When the control valve operates (drain valve
should be closed), the control valve opens the
water pressure onto the feed hose, which is
connected to the lower part of the drain valve.
When the lower part is filled with water, the lower
part diaphragm pushes up the piston. The piston
lifts the pressure plate against the drain valve
rubber diaphragm, which in turn forms a seal
against the outer drum, effectively closing the
valve.
When the drain valve should be opened, the
control valve changes position to allow the water
pressure to the lower part of the drain valve to
close, instead opening the return hose to the
drain. The pressure plate recoil springs pull the
pressure plate back, upon which the piston is
pressed back into the cylinder. The water from
the lower part is fed through the feed hose and
the control valve to the drain.
3359
Cylinder
Feed hose
Control valve
Feed hose
Lower part
Diaphragm
Piston
Pressure plate
Rubber
diaphragm
with drain
connection
Return hose
Recoil springs
Drain valve
5916
Principal
diagram
Fig.
1
Fig.
2
1
2