Atlas Copco Secoroc QLX Series Operator Instructions Manual page 16

Note for QLX 40: If the valve assembly (item7) is replaced
with new o-rings, the valve should be installed in the closed
position (valve seated against cylinder). This will insure that the
hammer will start without incident. New o-rings may require a
break-in period of 100 feet (30 meters).
7. Inspect the valve assembly for seal interference and damage.
The valve seals should have interference with the distributor
guide and backhead, but still move freely. The valve sealing
surfaces should be free of nicks, and burrs. Also inspect for
valve seal wear on the grooves.
8. Inspect the bearing bore just above the internal flutes for
wear using a telescopic bore gauge and micrometer. Replace
the bearing if the net clearance between the bit and bearing
is beyond the tabulated discard point. Replace the o-ring if it is
worn or damaged.
9. Inspect the piston in the locations noted below. The piston
usually wears faster than its mating parts, so it is likely piston
wear will affect clearances the most. Record the dimensions for
comparison to mating parts (cylinder and casing) to determine
which part offers the most economical replacement cost.
• Measure the tail outside
diameter as shown.
• Measure the tail bore, inspect for seal damage. If the
seal requires replacement, remove by prying it out with a
screwdriver. Install the replacement seal by working it into
the groove by hand as much as possible, then seating it by
lightly tapping with a soft-faced hammer.
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• Measure the large piston diam-
eter in the location shown.
Note: This is the most critical wear
point on the drill, as it has the great-
est influence on performance.
Always recommended to change tail
seal when servicing hammer.
10. Carefully remove any sharp edges, burrs, or nicks that have
developed on the piston using a hand grinder or emery cloth.
DO NOT OVERHEAT THE PISTON..... IT WILL CRACK IF OVER-
HEATED! If the piston striking face is heavily cavitated or pitted
use a ceramic facing tool or well-cooled grinder to dress the
face. A maximum of .060 in. (1.52 mm) can be removed from the
piston face.
11. If the casing does not require replacement due to outside
diameter wear, measure the bore diameter using a telescopic
bore gage and micrometer as shown. Record the measurement
for later reference. Polish any rough or galled spots in the casing
bore with emery cloth. Larger areas of damage can be smoothed
out using a hand grinder with flap wheel. Be careful not to
remove too much material from the bore to avoid degradation of
hammer performance.
12. Inspect the cylinder for cracks or
damage.
Inspect the valve seat for damage
and wear.
Measure the diameter of the bore and
record for later reference. Scored or
galled areas of the bore can be polished
with emery cloth.
13. Determine the following clearances from the dimensions
recorded.
• Bit to bit bearing
• Piston to casing
• Piston to cylinder
• Piston tail bore seal to guide
14. Referring to the as-new dimensions and recommended
replacement clearances in Section 5, determine which parts have
suffered the most wear. Replace the part(s) needed to bring the
clearances back to specification. The chart below may be useful
for recording and determining which clearances require service.
Measure at this
location (1/2" past
long undercut)