Unit Function
HDS Middle Range / HDS Premium Range
Page 60 / 127
Service Manual 04.2008
2.27 Pressure switch function
1 High-pressure outlet, operating pressure
2 Pressure gauge, operating pressure
3 Non-return valve (open)
4 Rotary knob
5 Overflow valve (closed)
6 Throttle bore
7 Pressure switch, „OFF“ (closed)
8 Water inlet
9 Motor protection contacts (K1) (closed)
10 Pump is running
11 Pressure switch, „ON“ (open)
2.27.2 The unit is switched on and the
handgun opened
After switching on the unit with the handgun open
the motor contactor tightens and closes the
contacts (9). This causes the motor to start and
the pump (10) builds up the operating pressure.
Open the non-return valve (3) and pressure
switch (11), the overflow valve (5) and pressure
switch (7) remain closed.
The closed pressure switch (7) causes the motor
protection contacts (9) to remain closed too (see
circuit diagram).
1
2
3
4
5
6
7
8
10
11
9
24 volt