Hilti DD 250 Bedienungsanleitung Seite 64

Malfunction
The drilling speed is decreas-
ing.
The handwheel can be turned
without resistance.
The diamond core bit can't be
fitted into the chuck.
Water escapes at the water
swivel or gear housing.
Water escapes from the
chuck during operation.
No water is flowing.
The drilling system has too
much play.
56 English
Printed: 22.08.2017 | Doc-Nr: PUB / 5245693 / 000 / 03 Printed: 22.08.2017 | Doc-Nr: PUB / 5245693 / 000 / 02
Possible cause
High steel content (indicated by
clear water containing metal cut-
tings).
The diamond core bit is defective.
Wrong gear selected.
Contact pressure is too low.
The machine has too little power.
The diamond core bit is polished.
The water flow rate is too high.
The water flow rate is too low.
The carriage lock is engaged.
The shear pin is broken.
The core bit connection end or
chuck is dirty or damaged.
The water pressure is too high.
The rotary shaft seal is worn out.
The diamond core bit isn't securely
tightened in the chuck.
The core bit connection end /
chuck is dirty.
The seal at the chuck or at the
connection end is defective.
The water channel is blocked.
The diamond core bit isn't securely
tightened in the chuck.
The core bit connection end /
chuck is defective.
The connection between the dia-
mond core drilling machine and the
carriage or spacers is loose.
Action to be taken
▶ Select a more suitable diamond
core bit specification.
▶ Check the diamond core bit
for damage and replace it if
necessary.
▶ Select the right gear.
▶ Increase the contact pressure.
▶ Select the next lower gear.
▶ Sharpen the diamond core bit
by drilling into a sharpening
plate.
▶ Reduce the water flow rate
by adjusting the water flow
regulator.
▶ Check the water supply to
the diamond core bit or,
respectively, increase the water
flow by adjusting the water flow
regulator.
▶ Release the carriage locking
mechanism.
▶ Replace the shear pin.
▶ Clean and grease the connec-
tion end and/or the chuck or
replace these parts.
▶ Reduce the water pressure.
▶ Replace the rotary shaft seal.
▶ Tighten the diamond core bit
securely.
▶ Remove the core bit. Rotate the
diamond core bit approx. 90°
about its own axis. Refit the
diamond core bit.
▶ Clean and grease the connec-
tion end and/or the chuck.
▶ Check the seal and replace it if
necessary.
▶ Increase the water pressure or
flush the water channel clear
from the opposite direction.
Clean the water inlet and outlet
aperture.
▶ Tighten the diamond core bit
securely.
▶ Remove the core bit. Rotate the
diamond core bit approx. 90°
about its own axis. Refit the
diamond core bit.
▶ Check the connection end and
chuck and replace them if
necessary.
▶ Check the connection and,
if necessary, refasten the
diamond core drilling machine.