This story is an emotional preface to a more serious technical article.
Many months passed, and yet I still recall the following chapter of my
hydraulic life almost every day...
I was "remodeling" hydraulics of Marine Travelift 70 BFM
- a ninety ton (rather small by marine standards) self propelled boat
hoisting machine, which for seven years of everyday "boat delivery" had
been punished by the Azorean sea and unpredictable weather, with the
preventive maintenance boiled down to topping up the hydraulic oil and
diesel when needed, along with hydraulic hose replacement program based
on the "not burst - still good" principle. In the end of the seven
years the machine "got tired" (as the fishermen would say) and the
hoist operations began to take much more time than usual, jeopardizing
normal work of the local fishermen community. The matter demander
urgent attention, because the whole village literally depended on
fishing for survival.
The machine was 100% hydraulics driven.
Countless oil lines ran along the twelve meter high frame,
with dozens of oil hoses in every corner, all completely rusted and
deteriorated by the salt water. The circuit itself wasn't that
complicated, but boy was it extensive! As you can imagine, most of the
hydraulic components were damaged beyond repair, especially the manual ten
section distributor valve, which was leaking oil from everywhere as the
spools were completely consumed by corrosion.
We did manage to get a price for the exact replacement, but
the terms of delivery were unacceptable, and therefore our only chance
was to "make it work" with "what we had". The fastest solution was
replacing the manual distributor with four PVG-32 Sauer Danfoss valves
with electric controls, and the obsolete and extensively rusted manual
levers with a nicely looking panel carrying modern joysticks and buttons. I
still do prefer using good old hydraulic pilots for harsh environments,
but the lack of time was a serious issue, and electric installation was the
fastest solution, plus electrically controlled valves would allow for
future "luxury" add-ons, like remote wireless control option, for
example, which is a nice "extra" to have on a machine like that.
The machine also got a new five section pump, a new and
bigger oil tank, new winch motors, new hoses, new power steering, new
and better filtration, new oil cooler - everything. The mechanical part
- the sheaves, wire ropes, the diesel engine - was also
overhauled and repaired. Due to the extreme urgency factor of the
intervention, the aesthetical side might have suffered a little,
meaning that a "faster but functional" solution was always chosen
over the "more aesthetic" one.
The crew had to work in unbelievably difficult conditions,
and the fact that the machine was situated in a relatively remote
region made the work even harder. The deadline was coming close and
sixteen and eighteen hour work days became our routine, but through an
enormous effort the hydraulic part was mounted with only a minor delay,
and the build entered the next phase - hydraulic system testing and
adjustment.
Like I mentioned above - the whole village depended
on the machine for survival (and believe me, I am not exaggerating
here) - so about every hour a fisherman would come around to ask when
the Travelift would be ready. The reason for that was very simple -
there was no other alternative way of getting the small fishing boats
in and and out of the water, and the harbor couldn't protect the
small boats from bad seas, so all the boats had to come ashore in bad
weather, and go back into the water when the weather improved.
Then, of course, there were about a hundred of other reasons (I could
never possibly understand) for the boats to be constantly hoisted in
and out of the water. The intervention period was carefully chosen
during the good weather stretch and all the village had been notified
in advance, but still every day there was a boat owner who wondered if
we could, well, just for that once and as a personal favor to him,
close our eyes and let him use the rig "for a couple of minutes"...
No words can describe the "audience" that gathered around
the machine as the first "real boat" test was about to begin....
Literally hundreds of fishermen were curiously watching every step of
"him hydraulic fellow" (yours truly) working
his magic . The word in the village was - a "foreign engineer from far
abroad" was summoned to repair the Travelift. Believe me, being that kind
of a center of attention is all but comfortable.
As the machine had been run the night before (I recon that
night we went to sleep at around three a.m.), I was pretty confident
that the real boat test was just the matter of checking the
pressures... The first small boat was lowered into the water smooth and
fast - the crowd was roaring in approval because the folks had gotten
used to the very low hoisting speeds and naturally were amazed by the
agility of the reborn piece of machinery. The machine made another trip
to pick up a recently built boat that hadn't yet been in the
water. As the vessel was being winched down, I was unpleasantly
surprised by the massive five section hydraulic gear pump,
that suddenly started to "spit out" jets of oil from between the
sections, along with extruded o'ring remains. The boat was half
way down and already too low to move the machine, the attempt to lift
it back up was unsuccessful - the poor pump would stream the oil out
and the pressure wouldn't rise enough to lift the heavy boat. A
decision was made to lower the boat, winch up the cables, take the
machine to the repair spot, and see what can be done. However, to my
great horror, as soon as the boat was lowered (remember that it was a
new boat that'd never been in the water), it started TAKING IN
WATER!!! At that moment the thought "I am so f'cked!" was one of
the most decent thoughts that ran through my head...
The next ten minutes I spent in hell, explaining to the fishermen that the machine was physically incapable
of hoisting the boat back up due to the malfunctioning pump, and that
the pump was the ONLY pump of that kind on the island... Thank God the
men managed to repair the water leak, and I was able to sigh in relief.
The crippled and bleeding machine slowly crept to the "ground zero"
next to our portable workshop, leaving a sad looking oil trail behind...
The aftermath - a person from Lisbon caught the first
flight to the island and brought over a repair kit. The pump was
repaired that very night and the machine was put back in service good
as new. I can't remember exactly, but I think we slept for about five
hours during these two days...
This (I am not afraid of this word) heroic story,
besides the "almost sunk boat" coincidental predicament, brought up a
couple of interesting hydraulic phenomenae behind the split
multi-section gear pump malfunction, which are discussed here.
In any case, this story is another good proof that hydraulic technicians live a truly filled life...
