Kärcher 570 - Function of the Relief Valve; Function with Hand-Gun Valve Open; Function with Hand-Gun Valve Closed

Function of the relief valve
KBrcher 570
1. Function with hand gun open
At standard working pressure with the pres
-
sure and flow control valve turned to full
water flow the relief valve is closed and the
full pump delivery passes to the hand gun.
2. Function with hand gun closed
When the trigger of the hand gun is relea
-
sed, the pressure in the chamber below the
relief valve piston increases and water pas
-
sing through the bore developing a similar
pressure in the chamber above the piston.
Since the piston has a largerarea at the top
than at the bottom (where its diameter is the
same as that of the
s~indle), it follows that
thevalve seat, backto thesuction side of the
pump.
The gap between the valve spindle and the
valve seat is such as to cause a circulation
pressure of
10 bar to be applied to the
greater effevtive piston area and thus to
hold the valveopen against the spring pres
-
sure.
When the trigger of the hand gun is pressed
again, the pressure in the chamber above
the piston falls completely away and the
spring closes the overflow valve. The pump
then builds up the standard working pressu
-
re once again.
, .
the applied the top of the piston 3. pressure and flow control valve
(~ressure x area = force) is areater than the
, "
ibrce applied to the bottom and thus the By turningthe knobon the pressureand flow
force tending to press the piston and the control valve, it is possible to partly open the
spindle downwards is greaterthan the force
relief valve so that some of the water
delive-
(spring pressure) pressing it upwards.
red by the pump is caused to flow back to its
This causes the piston to open the valve
suction side, thus reducing the pressure
spindle to allow water to flow between it and
and flow of water delivered to the hand gun.