TM 5-3805-280-24-1
Too low penetration rate
Check engine RPM mode.
Connect the pressure gauges to the
pressure sockets.
Check A. , A2, R. , R2 pressures.
yes
While drilling in automatic mode,
pressures are equals to pre-set
switch off air flushing.
values?
Check:
- bit wear.
no
- drifter shank condition.
yes - there is no rubbing of
The drifter reverses?
drifter cradle on guide.
- drifter.
no
Check flushing air flow, flushing control
Check A. pressure in a static mode
valve for punctured diaphragm.
by feeding the bit against some
Check:
yes
A. lower than pre-set value?
V. pressure reducer for jammed spool,
broken spring, loss of setting.
Start drilling in manual mode.
Check A. pressure.
Check:
yes
- V4 for broken spring
A. lower than pre-set value?
- Feed motor for internal leak
- Fast feed valve for leak.
no
Check A2 pressure.
Check:
- Flow regulator for jamming
or loss of setting.
yes
note : If setting of flow regulator
A2 higher than pre-set value?
does not altere A2 pressure,
solenoid valve Y46 is jammed.
no
Replace it.
- Feed motor for internal leak
V4 regulator is acting while in
automatic mode.
While drilling in manual mode,
check R. pressure.
yes
Difficult ground conditions.
R. pressure higher than normal?
no
Check V4 pressure reducer
for loss of setting.
to be continued on next page.
10-25
