Flowserve LHS Hydraulic Heavy-Duty Actuator Series - Manual (Page 15)

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LHS Hydraulic Heavy-Duty Actuator Series FCD LFENIM0003-00-AQ 7/14
3.2.3 Unscrew and remove the travel-stop of the hydraulic cylinder (25). For removing the stop, refer to paragraph
2.3. Feed the hydraulic cylinder from the port on the head (19) at minimum necessary pressure up to totally
retract the piston rod (20).
3.2.4 Remove the cover (46) from the scotch-yoke housing by unscrewing all of the locking components: hex
screws (45), hex head shoulder bolts (44) and eyebolts (42) plus upper nuts (43). Leave the studs (41)
screwed into the scotch-yoke housing (51).
3.2.5 Remove the spring can, carefully following the instructions given in paragraph 4.2.
3.2.6 Locate the studs (57) that connect the scotch-yoke housing to the cylinder. With the scotch-yoke (36) rotated
of 45°, it is possible to easily access these studs. Carefully unscrew the nuts (56). Pull out the whole hydrau-
lic cylinder. The stem has to be fully retracted.
NOTE: Take care during removal, so as not to damage the piston rod or the stud threads.
3.2.7 Change the adapter kit. Replace the adapters (54 and 55) designed for fail close (open) action, with the new
ones designed for the opposite action. Take care to choose the adapter kit suitable for the scotch-yoke type in
use (symmetric or canted).
3.2.8 Reassemble the spring can, as instructed in paragraph 4.2.
3.2.9 Reassemble the hydraulic cylinder with adapter, following the reverse procedure as described in point 4.3.
3.2.10 Apply the minimum pressure necessary to the hydraulic cylinder port on the end flange (27) until the piston
rod moves the guide block (48) and partially compresses the spring. In this condition it will be possible to
remove the special tool from the spring can.
3.2.11 Remove the pressure, checking that the actuator goes in the correct new fail safe position.
3.2.12 Reposition the cover, taking care to replace the cover gasket (47).
3.2.13 Readjust the travel-stops, as instructed in paragraph 2.3.