Page 80 of
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4.9.10 Assembly- 3
rd
/ 4
th
Stage Cylinder / Piston
Instructions Cautionary
Notes
Fit balance nut to piston rod.
Set distance between top of rod and top of
balance nut to the same distance as it was
before rod was removed.
Fit piston rod to X-head piston.
Screw rod in until balance nut meets X-
head piston.
Tighten balance nut to 300 ft-lbs
using special tool provided. (TL-
0060)
Check again that distance between
top of rod and top of balance nut is
same as before rod was removed.
Tighten balance nut locking screws.
Tighten until allen key twists past yield
point.
Fit o-ring (ORN-7258) to bottom of
cylinder.
Fit tapered rod seal guide (special
tool # TL-0061 - see section 3.4.5.)
special tool) over end of piston rod.
Lightly oil outside of guide.
Slide cylinder assembly over rod and
onto spigot of cross head cylinder.
Tighten retaining nuts 125 ft-lbs
Ensure that cylinder is right way up i.e.
discharge valves towards drive motor.
Check that
3
rd
stage piston ring side
clearances and end-gaps concur with
clearances detailed in Table 3 Piston
Ring End Gaps
Fit piston rings to piston.
Orientate piston ring end-gaps, 180 deg to
each other.
Remove rod seal guide from piston
rod.
Oil piston rings generously and ease
into cylinder.
Ensure crank is at bottom of throw. Take
care not to damage rings.
Screw piston onto rod. Torque to 180
ft lb. using special tool provided.
Roll over machine until piston is at top of
stroke for final torquing of piston
Check piston clearance at crank end.
Clearance between bottom of piston and
rod seal cup should be between 0.045”-
0.060”. If outside this range, the piston &
cylinder should be removed, balance nut
loosened, piston rod screwed in or out of
crosshead to give required piston
clearance.
Note : Thread pitch on piston rod =
12TPI. 1 rotation of rod = 0.083”
Lock piston in place by tightening
locking screws.
Locking screws should be tightened to a
point that allen key twists past yield point.
Fit final stage piston and lock in
place using retaining plate. Tighten
retaining plate screws to 22 ft-lbs.
Use
Loctite 222 or 243
(or similar) on cap
screws.
Intermech Ltd. BBR-6015-2 Compressor Service Manual
