Flowserve LHS Hydraulic Heavy-Duty Actuator Series - Manual (Page 20)

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LHS Hydraulic Heavy-Duty Actuator Series FCD LFENIM0003-00-AQ 7/14
a WARNING: Ensure that the hydraulic connection ports of the cylinder are disconnected. Also make sure that all
hydraulic supplies to the control unit and all power supplies are disconnected. Finally, make sure that the actuator
is in fail position, i.e. that it is not locked in a position with the spring compressed by means of locking devices.
4.4.1 Remove the position indicators or other accessories, if fitted. Remove the cover (46) from the scotch yoke
housing by unscrewing all the locking components: hex screw (45), hex head shoulder bolts (44) and eye-
bolts (42) plus upper nuts (43). Leave the studs (41) screwed into the scotch-yoke housing (51).
4.4.2 Remove the worn internal O-ring (39) of the bushing (35) inserted in the cover (46). Clean the O-ring groove
and the sliding area of the bushing and after having brushed these surfaces with a light oil film, install the
new internal O-ring (39).
Apply a generous layer of grease on the sliding surfaces of the accessible moving parts inside the housing.
In particular, grease the guide bar (50) and the surfaces of the slots of the wings of the scotch yoke (36), in
which the slider blocks (37) run.
4.4.3 Reposition the cover, taking care to replace the cover gasket (47).
The design of LHS actuators features ease of on-site maintenance and an increased actuator life cycle. For this rea-
son, appropriate procedures and equipment have been prepared, in order to allow the replacement of all parts of the
scotch yoke without the need to disassemble the actuator from the valve. These instructions are part of a dedicated
and separate procedure, available on request.
NOTE: Spring Can and Hydraulic Cylinder must be removed before disassembling the Scotch-Yoke Housing.
NOTE: For the specific type and viscosity of grease to be used, refer to instructions packed with Flowserve
replacement parts.
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Troubleshooting
To prevent the actuator from not proper functioning or low performance, first ensure that the installation and the
adjustment operations are carried out completely in accordance with this manual.
a WARNING: During the activities of identifying faults, it is very important to observe all the regulations and
instructions about safety. Read all the paragraphs of this manual concerning maintenance before opening for
inspection or starting to repair any actuator components. If in doubt, choose SAFETY FIRST.
You can identify the causes of possible malfunctions with the help of the following table (“troubleshooting table”). If a
malfunction cannot be identified and eliminated using the table, Flowserve Service Department should be contacted.