22
Maintenance
Properly retain the spring
As assembled, the spring force is acting against the spring
housing and the actuator shaft. The force on the actuator shaft
must be retained to the spring housing before removing the
spring assembly from the actuator.
a) Plumb the air regulator to the unvented side of the
actuator.
b) Set the regulator to 0 bar and apply pressurised air to the
regulator.
c) Slowly increase the air pressure until you see the actuator
shaft rotate.
d) Increase the air pressure until the actuator vane is in mid
position (45° of rotation). Watch the vane indicator mark
to know when the actuator is in mid position.
e) Install the spring retainer. The bolt holes in the spring
retainer should align with the threaded holes in the
spring housing. If not, use the regulator to adjust the air
pressure so that the spring shaft will rotate until the holes
are aligned. Install the spring retainer bolts.
f) Once the spring retainer is installed slowly reduce the air
pressure until the regulator is at 0 bar.
g) The spring is now retained.
Spring removal
To remove the spring assembly from the actuator, the spring
housing must be separated from the spring cover.
The spring is preloaded and stores a large amount
of energy. The spring must be properly retained before
removal to avoid injury and damage. Read through the
instructions and be sure you fully understand them before
attempting to disassemble the spring from the actuator.
Before proceeding, check that the spring retainer is
properly installed with the vane in the mid position.
Do not remove the spring anchor bolt. Doing this will
damage the spring and could possibly cause injury.
Refer to Figure 8:
a) Remove and retain the perimeter socket head cap screws
(6), with the relevant washers and nuts, holding the spring
housing (1) and spring cover (2) together.
b) You should now be able to remove the spring by separating
the spring housing and the spring cover by pulling the
spring housing away from the actuator. The power spring
and the spring shaft should remain in the spring cover as
it is removed. The spring shaft engages with the actuator
shaft, the spring shaft should slide easily off the off the
actuator shaft.
c) Clean both spring assembly halves removing silicone rubber
sealant with mineral spirit or a suitable solvent.
d) The spring cover is attached to the actuator by 4 bolts and
will remain on the actuator.
NOTE:
If the spring cover will be removed from the actuator,
remove and retain the four screws; clean both the interface
surfaces removing silicone rubber sealant with mineral spirit or a
suitable solvent.
11.1.2.3 Dismantling actuator
See exploded drawing/parts list (Figure 10).
Before dismantling, check there are no burrs on
square drive shafts. If there are, remove to avoid damage
to bearings and shaft seals during removal of case halves.
a) Remove all casing bolts and nuts.
b) Separate the two case halves with a K-TORK tool model CP
1-4 or CP 5-6 (not included, consult Rotork).
c) Clean both case halves removing silicone rubber sealant
with mineral spirit or a suitable solvent.
d) Replace and lubricate shaft seals in case housings.
e) Remove nuts and seal side plates, expanders and seals
from vane.
f) Clean vane.
11.1.2.4 Reassemble vane
a) Check studs are tight through vane and equal length on
each side. If not, apply Loctite to thread and relocate
correctly in vane.
b) Apply silicone sealant around bottom of studs to prevent
air leakage through seal on vane stud holes. Use either
GT-3100 One Part RTV Silicone or Dow Corning Silicone # 732.
c) Fit new seal over studs after checking profile matches vane
profile.
d) Fit seal expander teeth pointing away from vane.
e) Fit side plate over studs.
f) Center expanders and side plate so there will be an equal
amount of seal around the expanders. The expanders must
not touch the actuator case half’s.
g) Fit new nylon insert lock nuts to studs. Tighten nuts to
torque values in table 3.
Table 3: Recommended Tightening Torque
Model No.
Torque
Imperial (lbf.in)
Metric (Nm)
KT-03
1 to 2
0.14 to 0.28
KT-06
2.5 to 5
0.28 to 0.56
KT-10
8
1
KT-20
20
2.3
KT-30
30
3.4
KT-40
30
3.4
KT-50
65
7.3
KT-60
100
11.3
KT-70
100
11.3
