Owner's manual

Note
Tbis procedure and Figure 6-4 are set up
for direct acting power positioners. In a
reverse acting power positioner, increasing
signal supply air hose (1, Figure 6-4) would
be at bottom of cylinder and decreasing
signal supply air hose (4) would be at top of
cylinder.
d. Remove increasing signal supply air hose (1,
Figure 64) from 90” elbow (2) at upper cylinder
head (3). Mark supply hose (1) “upper”.
e. Remove decreasing signal supply air hose (4)
from 90” elbow (2) at lower cylinder head (5).
Mark supply hose (1) “lower”.
f. Remove retaining rings (6) and drive out clevis
pin (7) from clevis head (8).
g. While supporting cylinder (9), remove lronnion
screws (10).
b. Remove assembled cylinder from tmnnion and
move it to a workbench to continue disassembly.
CAUTION
Do not scratch piston rod. Use caution when
removing and handling upper cylinder bead,
piston, and piston rod. If piston rod is
scratched, power positioner will produce
lower torque and decreased packing life will
result.
i. Remove hex nuts (13), washers (14) and tie bolts
(12).
CAUTION
Do not pull piston and shaft assembly out of
cylinder bead. Damage to packing gland
bushings and Vee-packing may occar.
j. Remove upper cylinder head (3) from cylinder by
sliding piston (11) out of cylinder (9).
k. Remove and discard upper and lower cylinder
bead gaskets (15).
I. Clean old grease off piston (11) and piston rod
(16). Wipe with commercial grade dry cleaning
solvent and let air dry. Pack concave area of
piston with McLuhe MO&-793 type grease or
IS-IM-204
6.716.8
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equivalent Lightly coat piston rod (16) with
Mclnbe. MO&-793 grease. Wipe excess grease off
with clean shop towel.
With a clean shop towel and commercial grade
dry cleaning solvent, wipe interior surface of
cylinder (9). Allow to air dry before assembly.
Remove hex bead cap screws (17) and washers
(18). securing packing cover (19) to upper
cylinder head (3). Remove packing cover (19)
from upper cylinder head.
Clean and inspect female adaptor (20) under
packing cover (19). Replace female adaptor,
packing, and male adaptor if female adaptor
appears damaged OT was leaking. Refer to Section
VII for replacement pmced”res.
Pack area around female adaptor (20) with
McLuhe M&-793 grease or equivalent. Secure
packing cover (19) to upper cylinder head (3)
with hex bead cap screws (17).
Install tie bolts (12) through lower cylinder head
(5).
Install cylinder (9) with a new cylinder head
gasket (15) onto lower cylinder head (5).
Place new upper cylinder head gasket (15) o” top
of cylinder. Making sure hotb gaskets are in
place, slide piston (11) and upper cylinder head
H
’
assembly onto cylinder (9). Align tie bolts
through upper cylinder head (3) holes and secure
with hex nuts (13). Tighten hex nuts evenly “sing
a diagonal tightening sequence.
Install cylinder assembly onto power positioner
h-me by aligning upper cylinder head (3)
mounting boles with hunnion holes in stand
assembly. Secure cylinder in stand with bunnion
screws (10).
Secure clevis (8) to shaft lever with clexis pin
(7). Secure clevis pi” with retaining rings (6).
Install supply hose marked “upper” (1) to 90
elbow (2) at upper cylinder head (3). I”staU
supply hose marked “lower” (4) to 90” elbow at
lower cylinder head (5).
Refer to paragraph 4-2 and calibrate power
positioner shake. Return power positioner to
service.