HC 920 • HC 940 • HC 960
47
GB
Remedy in case of faults
Type of malfunction
A. A sufficient amount of coating
material is ejected only with an
upward stroke, or upward motion
of the piston rod is slow and
downward motion is fast
B. A sufficient amount of coating
material is ejected only with a
downward stroke, or downward
motion of the piston rod is slow
and upward motion is fast.
C. Piston rod moves up and down
quickly.
D. Piston rod moves up and down
slowly when the spray gun is
closed.
E. Not enough pressure to the spray
gun.
F. Piston rod sputters when stroking
upward or downward.
Possible cause
1. Inlet valve is leaky due to impurities
or wear.
2. Coating material viscosity is too
high, preventing it from being
sucked up.
1. Outlet valve leaky.
2. Lower packing is worn.
1. Suction tube projects over the fluid
level and sucks in air.
2. Coating material viscosity is too
high, preventing it from being
sucked up.
3. Ball in inlet valve housing is stuck.
1. Loose connections.
2. Relief valve is not closed
completely.
3. Relief valve worn.
4. Lower packing worn.
5. Ball in inlet valve housing and ball
in outlet valve seat are not sealing
properly.
1. Tip is worn.
2. Filter cartridge in high-pressure
filter is clogged.
3. High-pressure hose is too long.
1. Solvent has made the upper
packing expand.
Measures for eliminating the malfunction
1. Clean and check the inlet valve housing. Insert ball
and fill with water; if leaky, replace ball.
2. Thin out according to the manufacturer’s instructions.
1. Dismantle and check outlet valve seat. Insert ball and
fill with water; if leaky, replace ball.
2. Replace.
1. Refill the coating material
2. Thin out the coating material according to
manufacturer’s instructions.
3. Vent air from material feed pump and turn the relief
valve knob to the left (
k
Circulation).
1. Dismantle inlet valve housing, clean ball and valve
seat. Check all connections between the material feed
pump and spray gun.
2. Turn relief valve handle (3) fully clockwise (
p
spray).
3. Replace
4. If the measures described above do not help, replace
lower packing.
5. Dismantle inlet valve housing and outlet valve seat.
Clean balls and valve seats.
1. Replace
2. Clean or replace the filter cartridge.
3. Reduce length.
1. Replace upper packing.
9.4
Material feed pump
