This repair, if I may call it so, is absolutely unique, and falls under
the category of "desperately drastic" overhauls (senseless, from my
point of view, by the way).
The main character is the Linde MBV 105 variable
displacement motor, which for the last decade had been driving one of
the anchor winches of a large container ship. During the last trip the
vessel ran into extremely bad seas, and one of the huge anchors,
despite the three mechanic safety features, "went for a dive". There's
still no official explanation on how all the three systems
managed to fail at the same time (the manual band brake, the chain
lock, and a smaller chain, that was supposed to secure the main chain
in case of other locking devices malfunction), but I think that once
again it was proved that no fail-proof safety feature is above human
By the time the crew noticed that one of the anchors
was missing, it had already unrolled a hundred odd meters of chain, and
since the hydraulic motor was engaged - only God know how many "dry"
turns it made (bearing in mind the huge ratio of the gearbox).
Unsurprisingly, the winch wouldn't pull up, on account of which the
anchor and the attached piece of chain had to be "forcefully retired"
in the middle of the Atlantic ocean by means of an oxy-acetylene torch.
Since the winch was still able to turn, it was
used for mooring for a period of time I would like to omit
(embarrassing) - despite the incredibly loud "taka-taka" coming
from the motor with every turn. Finally, a decision was made to disassemble
the motor and and see if it was possible to
repair it - however a condition was imposed - since the motor had proved
"good enough" for mooring, no matter how bad its condition would
reveal, it would still have to be re-mounted on the winch the same day,
because the ship couldn't moor without it.
As you can see from the pictures, the disassembly alone was all but a simple task, mainly because of the extensive marine treatment
the motor had suffered along the years of service, which meant that all
of the screws had to be drilled out. When the end-cover was finally
lifted - it became clear that the motor was dying - one of the pistons
got stuck in the respective bore and ripped retainer plate off of its
place (by separating the screw heads). It was under this condition that
the motor had moored the vessel for the above-not-mentioned
embarrassing amount of time, rendering the rest of the internal parts
(main shaft included) non-reusable.
Despite all this and the fact that there were no parts in
stock to repair the motor, the client was adamantly insisting on the
above stated conditions (make it turn no matter what and the same very
night...), and all we had in stock for that model was the new barrel - not
more not less...
It was the first time I used an angle
grinder to "adjust" components of a hydraulic motor! I had to use the
grinder to "cut out" the stuck piston, then I had to smoothen all other
pistons just to fit the new barrel (again with the grinder), then I had
to straighten out the crooked and cracked retainer with the help of a
hammer and an anvil, and I had to do a lot of other nasty things I
thought I'd never do. In the end, the motor was able to turn (with
"taka-taka"), and it has been mooring for a couple of weeks now -
aleluia, gentlemen!!! Volumetric efficiency - well - above zero...
A new motor is coming, so this hydraulic torture
will be over soon. Still a nice story to be recalling in the future...