Nilfisk-ALTO MC 3C, Service Manual

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SM MC 3C_ MC 4M Ver.1.0_March 2015
Function
The schematic drawing of the pump head below is made to get a better understanding of the
function.
NOTE ! In the schematic drawing of the pump head is shown a two-way easy start valve,
which is the layout for all the single phase machines. The three phase machines are without
the easy start valve.
Schematic Drawing Cylinder Head
Pressure outlet
Non-return valve
Piston
Easy start valve.
ONLY 1 ~ models
Micro switch
Water inlet
Control piston
Valve pressure
Valve suction
Schematic drawing 1 ~
Functional description 1 ~:
Preconditions:
Machine is connected to correct power and water supply. High pressure hose and gun is
installed on the machine.
Gun is closed and machine is started on the main switch. Motor starts (Easy start valve is open
until pressure starts to build up in the pump) - the pressure is building up until it reach the cut-
off pressure. When the cut-off pressure is reached, the control piston is pushed upwards by the
higher pressure - the micro switch is activated (opens) - and the motor stops. When the motor
stops, the non-return valve is pushed back into its seat and holds the cut-off pressure in the
high pressure hose, and also in the channel going from the non-return valve to the bottom side
of the control piston. Now the trapped cut-off pressure is holding the control piston in the up
position.
Starting from stand-by mode:
Press the gun. The pressure in high pressure hose, and in the channel going from the non-
return valve to the bottom side of the control piston disappears. Control piston is pushed down
by the spring, and the micro switch is activated, the motor starts—and the pressure is build up.
Pressure reg. valve