Insane Hydraulics
Bold and audacious blog about fluid power
This is the story of how I came within a hairs breadth of quitting my job... I am sharing it in the hope that you don' t ever repeat the same stupid mistake that I did that day.
About four years ago our best client - the copper mine - bought a new shiny GEHO paste pump, which was basically a million Euro worth of Rexroth pumps, valves and sophisticated electronics set up to drive half a dozen of double acting cylinders (in a very sophisticated and synchronized fashion) with two of them being best described as "ginormous". Just to get an idea - the cylinders were pushed around with two 500cc and two 355cc closed loop pumps - that's right - all four pumps driving just the two cylinders. Serious pumps for serious business.
The power-pack was placed on the first floor, and the cylinders on the ground floor below. My task was simple - all I had to do was connect them with hydraulic hoses (the mine specifically wanted flexible connections for this installation) and then stand back and watch as "real" techs commission the system. Easy Peasy, right?
Not so easy if you consider the size of the system. Each of the cylinders was to be connected with five 14m two inch six-spiral hoses, two for the rod ends and three for the tails, and the hoses had to be manufactured on site. Only those who had worked with "flexible" hoses that big can appreciate the challenges. When it takes several grown men to lift a hose from the ground - you know that "coaxing" it into place is not going to be an easy task, especially on a 100 degree day, especially while wearing full body overalls and the rest of the mandatory safety gear you couldn't care less about because you can't see crap through the sweat running down the lenses of the protective goggles.
The biggest challenge however was keeping everything clean. Take my word for it - nothing in a mine is clean, nothing! Especially in the vicinity of a paste plant. Mines don't work that way. Furthermore, if you consider multiple teams of fitters working above you, below you, and around you - welding, grinding, cementing, grinding, welding (did I mention cementing?) - you realize how hard it is to make sure that something very foreign doesn't end up inside a million dollar closed loop hydraulic system. As you can imagine, a lot of stuff can fit into a two inch hose if you give it a chance.
Naturally - all the hose ends and flanges were properly blanked, and we decided to align and secure the hoses in respective support brackets first, and then projectile clean them one last time before connecting the ends to the power-pack and the cylinders, one by one, to avoid unnecessarily open connections and make sure the lines are as clean as a whistle.
Finally I had everything in place - a line of clean compressed air - check, a bag full of foam projectiles - check, a specially built projectile launcher - check, a team of guys below (on the ground floor) ready to catch the "bullets" - check.
The theoretical "procedural script" we agreed on was supposed to go as something like this:
I shout from upstairs - "Ready?"
and then get from below - "Ready!"
then I connect the launcher (without a projectile) to the hose and partially open the air valve, and the guys below confirm that the air is coming out (to make sure that we are working on the right hose)
then I shout "Clear?"
and get from below "Clear!"
and then the 12 bar of the instrument grade compressed air send a Sponge Bob down the hose where a team of guys catches him in a plastic sack. It goes like s-s-s-s-s-s-s-s and then Puff!
foam projectile not clean? Shoot again till it is...
inspect the shank areas with a mirror, mount the hose, proceed to the next one...
We got everything right, all except the order in which we were supposed to clean the hoses, because of the way the hoses were routed. Also, the fact that each cylinder had an odd number of hoses connected to it added to the confusion, and the guys on the ground floor somehow ended up un-capping the wrong hose end and cylinder flange connection. Nothing to worry about, an honest and innocent mistake, so far...
Naturally - in order to provide an instant protection to the wrongly uncovered cylinder connection point - it was closed with the most universal blanking device in the world - namely - the rag, and then the uncapped hose end was put on top of the rag-blanked connection, in order to prevent possible contamination (did you hear what the "hydraulics guy" from upstairs told us? The hose ends are to be closed at all times!). How thoughtful of you! But still - so far so good. I knew it was there, it was clearly visible, I was sure that it was OK as it was only to tap the connection for but a couple of minutes.
Guess what happened next - now it was my time to mix the hoses up - and I connected my launcher to the wrong hose and sent a burst of compressed air down the line to check if it's a correct line - and immediately heard that the sound was somehow different from what I'd been hearing before. So I stuck my head out of the window and looked below at the two guys holding the hose end with a puzzled expression on their faces:
" - We hear the noise, but no air's coming out, boss... "
I already knew what had happened - I just didn't want to believe it... So I went downstairs to behold the "magnum opus" of my own doing... Of course I connected compressed air to the hose that was "holding" the rag on the cylinder flange connection, and of course the compressed air showed the rag right into the cylinder, it's rod end to be exact.
So there I was - looking at a hydraulic cylinder that weighed more than my car, thinking about how I would explain to the client that the guy who had been hired to connect a dozen hydraulic hoses just shoved a couple of rags into one of the main hydraulic cylinders, and wondering what career path should I choose next. Hydraulic professional my ass!
To conclude - we dismantled the cylinder and got the freaking rag out - and, as you can imagine, it was no mean feat. No sir, it was not! But we did it, and it was done, and the commission went fine, and I kept my job.
I am glad I stopped beating myself for past mistakes a long time ago. I do know for a fact that I will never do this stupid mistake again. I do know for a fact that I will make other stupid mistakes in the future.