Minnich Hornet 24/22, Operator'S And Service Manual

Page: 15 / 25

15
Dowel Drill Manual
Troubleshooting Air Drill
Cause Remedy
NOT ENOUGH AIR REACHING
DRILL. IT SHOULD HAVE 100SCFM
(47.2DM^3/
sec
. ) PER DRILL AND 110
PSI (7.6
bar
)
On Multi Drill units. Turn off one or two drills. If
the remaining drills pick up speed, check the air
compressor.
RESTRICTION IN AIR LINE A foreign object in the air line or possibly a
reduction in the air line caused by a reducer
fitting.
TOO SMALL AIR LINE Following are supply line sizes for drilling:
A-1 Single Drill 3/4” (19mm)
A-2 Two Drills 1-1/4” (38.75mm)
A-3& A-4 Three & four drills 1-1/2” (38.1mm)
A-5 Five Drills 2” (50.8mm)
AIR PRESSURE TO CYLINDER “FEED-
ING” DRILL INTO CONCRETE NOT
ADJUSTED PROPERLY
Excessive pressure can cause drill to “bind up”
in the hole. Pressure that is too low will not
“feed” the drill into the concrete. The air pres-
sure required varies with the drill model.
Horizontal- all units with large drills use 22-26
PSI (1.5-1.8 bar). Drill units using the 15LB (6.8kg)
class drill will use 16-20 PSI (1.1-1.4 Bar).
Vertical - all drill units use 5-6 PSI (0.34-0.41
Bar). With the correct air pressure, the drill steel
should have a slight rattle.
INSUFFICIENT AIR FLOW TO KEEP
HOLE BLOWN CLEAN
Check for obstruction in the blow tube in the
drill.
LUBRICATOR PUTTING OUT TOO
MUCH OIL TO DRILL
If you notice more than a light film of oil on the
air deflector on the bottom of the drill adjust the
lubricator, make certain you are using the type of
oil called for in the operation and maintenance
manual.
MECHANICAL BLINDING OF DRILL
CARRIER
Make sure the eight bearing pads are adjusted
correctly. The square tube that the drill carrier
slides on must be free of rust so that the carrier
slides freely, drill steel must not be binding in
the guide bearing.
BENT DRILL STEEL, WORN DRILL BIT
OR DRILLING INTO REBAR
Replace the drill steel or bit. If drilling into rebar,
move the drill.
USING 3 1/4” (8.25
cm
) SHANK DRILL
STEEL IN 4 1/4” (10.8
cm
) SHANK
CHUCK DRILL
The drill steel will rotate but it will not allow the
drill piston to hammer properly, replace it with
the correct 4 1/4” (10.8cm) drill steel.
PROBLEM: DRILL RUNS SLOW OR DOES NOT DRILL EFFECTIVELY