THD SERIES S11-S27 HEAVY DUTY ACTUATORS
Installation & Maintenance Manual
3
September 25, 2015
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double acting units the actuator should be in the
clockwise position with the piston next to the end cap.
3.
Vent all air pressure from the cylinder (item 10).
4.
Remove the stop bolt, flat washer and seal (item 7, 8, 37).
5.
Remove the tie rod nuts (item 16) from the tie rods (item
12).
6.
Remove the end cap (item 15) from the cylinder (item
10).
7.
Remove the cylinder from the adapter (item 18) by
pulling over the piston (item 17). Use caution not to
scratch the cylinder bore when sliding over piston.
8.
Bend the safety tab on the lock nut retainer up and out of
the groove. Remove the outer hex nut (item 30) holding
the piston on the piston rod (item 11). Then remove the
safety tab and then loosen and remove the inner nut.
9.
Remove the piston, rod washer and o-ring (item 3).
10.
Remove 2 each flat head screws in the adapter and
remove the cover plate (item 32).
11.
Remove the o-ring seal assembly (item 33) from the
counter-bore.
12.
Remove the o-rings from the piston and both flanges.
13.
Clean all parts with a mild solvent that will not attack the
coating on the parts.
14.
The center body assembly should be inspected before the
pressure group is rebuilt.
15.
Remove the indicator plate bolts and remove indicator
plate (item 6).
16.
Remove the cover bolts and clean out the jacking screw
holes. Install a bolt into each jacking screw hole and
alternately tighten the screws to bring the cover plate up
so that it can be removed from the yoke bearing.
17.
Inspect the bronze slider (item 20) for wear along with the
slot in the yoke arm.
18.
Inspect the upper yoke bearing (item 4) for wear.
19.
Wipe out old grease and replace with new grease on all
sliding surfaces.
20.
Lightly grease new o-ring seal assembly (item 33) and
install in adapter. Replace cover plate and install 2 each
flat head socket cap screws.
21.
Lightly grease the o-ring for the adapter and install in the
groove.
22.
Place rod washer on piston rod with countersink facing
out toward the end cap. Lightly grease o-ring (item 31)
and slide over piston rod. Slide piston over piston rod and
install inner hex nut then keyed tab and outer locknut.
Then align outer hex nut with locking tab and bend tab
into slot.
23.
Lightly grease piston grooves and install o-ring and back-
up strip.
24.
Lightly grease cylinder completely on the inside surface
and carefully slide over the piston until seated on the
adapter.
25.
Lightly grease the o-ring for the end cap and install in the
groove. Place end cap over the tie rods and seat on the
cylinder.
26.
Reinstall the tie rod nuts and tighten in a diagonal pattern.
27.
Reinstall the stop bolt, o-ring, flat washer and hex nut in
the rear flange. Screw in to the approximate position for
90 degree operation.
On models S11 and S13 make sure
that stop bolts are fully retracted before air is applied
with the cover plate removed.
28.
To pressure test a double acting actuator proceed to the
next step for a spring return go the step 33.
29.
Connect 2 psig air to the adapter and cycle the actuator
then connect to the end cap and cycle the actuator several
times.
30.
Apply 100 psig air to the adapter and check for leakage at
the adapter/cylinder connection. Also check for rod seal
leakage in the center body cavity. Place a flexible tube in
the end cap NPT port and check for leakage across the
piston by checking for bubbles in a cup of water. Relieve
air pressure on cylinder.
31.
Place a light coating of permantex blue on cover gasket
and install. Place cover over the alignment pins and install
bolts and tighten. Remove any excess gasket sealer after it
is dry.
32.
Apply 100 psig air to the end cap and check for leakage at
the adapter/cylinder connection. Place a flexible tube in
the adapter NPT port and check for leakage across the
piston. Relieve air pressure on cylinder.
33.
To pressure test a Spring Return unit the cover must be
installed before any air pressure is applied to the unit.
Refer to step 31 for information on applying cover.
34.
After cover is installed apply supply pressure to the end
cap and check for leakage at the end cap /cylinder
connection and check for leakage across the piston by
using the method in step 30 above.
35.
Make any final adjustments on the end cap stop bolt and
check for leakage. Install the stop bolt cover and tighten.
On models S11 and S13 set the stop bolts at 90 degrees.
36.
The actuator is now ready to return to service.
