Quackenbush 230QGDA Série Manuel D'instructions page 22

EN-823122
February 17, 2004
Air control system (A.C.S.) Pressure Checks.
The 1/8 inch tee should also be installed at this time
(see diagram).
FEED PISTON PRESSURE — Plug air guage into the
A.C.S. Start motor with the drill button. The tool
automatically goes into feed with the motor running.
The A.C.S. pressure must be over 60 psig.
If the pressure is 0-60 psig it would indicate a very
substantial leak in the air control system; a damaged
side air hose or fitting, a damaged stop button
assembly, check valve, or a leaking feed piston.
On "B" model tools this could indicate a badly leaking
signal valve. Also a severely clogged A.C.S. filter
might be the problem or a clogged metering seat
(382491).
EXCESS LEAKAGE (A.C.S.)
Turn on the air supply and press the "drill" button.
Press the rapid advance lever and return the lever
fully. This places the tool into the "air-lock mode" with
the throttle open, the motor stalled, and the air control
system (A.C.S.) pressurized.
Plug the air gauge alternately into each small quick
disconnect fitting. The difference in pressure should
be no more than 7 psi. A difference of more than 7 psi
means excessive leakage in the A.C.S. See Appendix
ll. Lift the retract lever. The retract valve will move with
and audible snap. Again, the difference in pressure
should be no more than 7 psi when plugging the air
gauge alternately into each quick disconnect fitting.
Press the stop button. Exhaust deflector and retract
lever reset.
THROTTLE CLOSING TEST
The throttle unlatches and closes as the air control
system pressure drops. With the air gauge plugged
into the A.C.S., place the tool back into the "air-lock
mode". Now, very gradually press the stop button. The
throttle should close when the A.C.S. pressure drops
to between 42-50 psi. If the throttle doesn't close, the
throttle piston may be sticking, or the latch piston
382490 is not functioning properly.
SIGNAL VALVE VENTING
Use the highest air supply pressure available
Safety, Operation & Service
Quackenbush
Operating and Safety Instructions
Page 22
(110 psig maximum). With the air gauge plugged into
the air control system, place the tool back into the
"air-lock mode". Lift the retract lever. (The retract valve
will move with an audible snap). Depress the plunger
of the venting signal valve (assembly 381117). The
A.C.S. pressure will drop and the throttle should close.
If the A.C.S. pressure does not drop below 38 psig, the
A.C.S. system is receiving an oversupply of air or
does not vent properly.
An oversupply of air to the A.C.S. system may be
caused by leakage around the O.D. of the metering
seat (382491), or leakage past the lower "O"ring
(869712) on the drill button shaft.
APPENDIX I
Unusual Drilling Conditions: If the air supply condi-
tions (valves, hoses, fittings, etc.) can not be improved
to meet the tool inlet pressure operating conditions in
the chart, or if the supply pressure (static) must be
below 90 psig, the tool may operate adequately at the
work site if the pressure at the inlet tee while drilling
and cutting chips does not drop below 70 psi. This
would require monitoring the particular tool at the job
site while in use to ensure the pressure at the inlet tee
does not drop below 70 psig.
APPENDIX II
Locating Excessive Leakage In The A.C.S.
Most air leaks create a hissing noise that is easily
heard if background noise is not too loud.
With the air supply on, place a small punch against the
bottom end of the throttle piston (place the punch
through the throttle cylinder slot or the throttle cylinder
end cap). This will prevent the throttle from opening if
you push firmly. Now push the drill button a small
amount until the A.C.S. is holding pressure.
Remove the punch. You will now be able to locate
leaking air audibly. Some leakage at the retract valve
is normal. By lifting the retract lever you can detect
excess leakage at the signal valve, or in the retract
piston air circuit.
Missing "O"-rings or a damaged signal valve are the
most common sources of excessive leakage.