Regular Care; Fault Finding - Atlas Copco COBRA 148 Instrucciones Para El Operario

English
Function selector - drilling (fig. 13)
Turn the function selector downwards . This will en-
gage rotation and flushing air.
Function selector - breaking (fig. 13)
To adjust the direction of the tool blade, first put the
function selector in the neutral position .
Now lock the tool blade in the desired position by
turning the selector upwards . The rotation mecha-
nism is now locked.
Collaring
With the engine idling, press the machine and tool
against the spot where you wish to drill. Increase the
engine speed once the drill bit has collared a footing
in the rock (or other material).
Grip the side handle for better control of the machine.
Drilling deep holes (fig. 14)
First use a short drill steel, and drill it into the hole
fully. Then change to a longer drill steel, with a
slightly smaller bit diameter (approx. 1 mm smaller).

Regular care

Air filter (fig. 15)
Check and clean both air filters regularly (at least
once a shift) when the machine is in continuous use.
Unscrew the filter cover. Take out the pre-filter and
wash it clean in water, or some other suitable me-
dium.
Tap the main filter carefully against the palm of your
hand. Alternatively, blow it clean (carefully) using
compressed air. Blow from the inside, outwards.
Filters that are extremely dirty must be replaced.
The main filter must never be washed in liquid.
Gas duct (fig. 16)
The gas duct must be checked regularly for carbon
deposits, and cleaned if necessary.
Pull the starting handle until the arrow in the centre of
the flywheel (which can be seen through the fan
cover) points upwards. This indicates that the engine
piston is in the upper position. Unscrew the gas duct
valve and take out the cleaning rod. Clean the duct
and cleaning rod using the cleaning needle provided.
Check that the ball in the gas duct valve is not stuck
Maintenance
Spark plug (fig. 17)
Lift the spark plug cover by the lower lip, and turn it up
to one side.
Use a plug spanner to remove the spark plug.
If the spark plug is dirty or burned, it must be re-
placed. Use the original spark plug, type motorcraft
AE-6 or Bosch W7AC.
If the spark plug is wet with fuel, wipe it clean using a
clean cloth and check the ignition spark. Then pull
the starter handle 2-3 times to disperse any excess
fuel. Now fit the spark plug back into cylinder.
6
The electrode gap should be 1.5 mm (0.06 in.).
Changing the starting cord (figs. 18-19)
Remove the screw-cap of the PTO. Remove the
three hex. bolts from the protective cover of the start-
ing mechanism. Lift off the cover, grasping the starter
pulley as well. Let the cover rotate carefully against
the starter pulley, to release the spring tension. Re-
move the old starting cord (fig. 18).
Fit a new cord (fig. 19).
Oil the needle bearing in the starter pulley. Fit to-
gether the starter pulley and protective cover, so that
the starting spring locates in the starter pulley. Wind
the full length of the cord on to the pulley.
Pre-tension the starting spring by about one turn
(clockwise) before fitting the assembly into place.
Pull the starting handle carefully, in order to locate
the cover correctly. Fit and tighten the hex. bolts and
the PTO screw-cap.
Tool chuck (fig. 20)
If the chuck gauge provided can be inserted fully
across the flats of the hexagonal chuck, this indi-
cates that the chuck is worn out and must be re-
placed.
Carburettor (fig. 21)
The carburettor nozzle does not normally need to be
adjusted.
Normal setting:
Main nozzle (1): 0.6 - 0.7 turns open
Idling nozzle (2): 1.5 turns open
When using the machine at high altitudes
(2000–3000 m (6500 - 9800 ft.) above sea level, or
more), the main nozzle (1) should be adjusted clock-
wise to give a somewhat leaner air/fuel mixture than
usual.
The full speed under load should be 2550–2650
rev/min. This can be adjusted by means of the stop-
screw (A) on the venturi. The idling speed should be
1600–1800 rev/min. This is adjusted by means of the
screw (B).

Fault finding

If the engine does not start, is difficult to start, runs
unevenly or has poor output, check the points men-
tioned above (figs. 15–21).
If the machine still does not function satisfactorily,
contact your nearest Cobra workshop.
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