WÄRTSILÄ RT-flex50-D, Maintenance Manual

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Maintenance
9403−4/A1
RT-flex50-D
Wärtsilä Switzerland Ltd
1/ 2
1. General
For distinct screwed connections different designs and sizes of waisted bolts or
waisted studs (bolts/studs) are used, which are pretensioned by hydraulic pre-ten-
sioning jacks. The bolts/studs have threads which extend over the nut. The pre-
tensioning jack is mounted on this thread end.
For each thread of the various bolts/studs a suitable pre-tensioning jack is sup-
plied. Since the bolts/studs are pretensioned with the pre-tensioning jacks, the
nuts are threaded-on only manually until seated.
Prior to the mounting of the pre-tensioning jacks, their threads as well as the
threads of the waisted bolts/studs must be carefully cleaned. The threads must be
undamaged and freely working. Concerning utilization of lubricant for screwing on
nuts the instructions in
0352−1 must be followed.
Check oil level prior to starting hydraulic pumps!
Risk of accident! Always wear safety goggles when working with hydraulic tools.
2. Working procedure for loosening
⇒
Thread the pre-tensioning jack by hand onto the extending thread end of the
bolts/studs to be loosened until it is landed on the part and the piston on the
cylinder without any clearance. On pre-tensioning jacks with round nuts these
have to be slightly tightened.
D
Then, depending on the design of the pre-tensioning jack, turn it or the round
nut back by the specified turns (approx.
½
... 2
¾
turns). The clearance thus
obtained between pre-tensioning jack and landing face of the part or piston
and cylinder is essential, before starting the pre-tensioning of the bolts/studs.
It enables the loosening of the nut till total relaxation of the bolts/studs in one
single working sequence.
⇒
Connect the HP oil pump and pre-tensioning jack with the HP hose.
⇒
Open the vent screw on top of the pre-tensioning jack a little.
⇒
Shut relief valve at the HP oil pump and actuate it. As soon as oil flows out
bubble-free close the vent screw at the pre-tensioning jack.
Never move the piston of the pre-tensioning jack further up than to the red limiting
groove ’BN’.
⇒
Raise the pressure about 30 bar beyond the nominal pressure (see 0352−1).
The nut is now slack, loosen it with a round bar, while keeping the pressure
constant.
⇒
Release the pressure at the HP oil pump and remove the pre-tensioning jack.
Hydraulic Pre-tensioning Jacks
General Application Instructions
2011-12
CHECK