Nilfisk-ALTO Poseidon 5 Series, Service Manual, Page: 39 / 68

39
POSEIDON 5 NEW-NA5_en_Ver.1.0_20/12
Function
D
Pressure Activated Unloader— by pass (closed gun)
1. Motor/pump Unit.
2. Micro switch.
3. Activation arm.
4. Unloader spring.
5. Unloader piston.
6, Ball for by-pass.
7. Non return valve.
8. Ergo gun.
The machine is started with closed spray gun (8).
The pressure rises until the cut-off pressure is reached. The unloader piston (5) is pressed
forward caused by the outlet pressure exceeding the pressure from the unloader spring → the By-
pass ball (6) is moved forward and opens the connection between the water inlet and the water
outlet (blue arrows). The micro switch (2) is activated by the activation arm (3) and the motor/pump
(1) stops. Now the non return valve piston (7) is pressed against its seat, which keeps the pressure
high in the hose and on the backside of the unloader piston. The pressure in the pump is released to
”0” due to open connection between pump inlet and outlet (blue arrows).
1
2
3
5
4
6
7
8
Pic. D4: Unloader—Closed gun.
Motor/pump