Insane Hydraulics
Bold and audacious blog about fluid power
If you have a driving license and know what a "normal" (i.e. mechanical lever-actuated) hand brake is, I bet you know the embarrassing feeling of realizing that you've taken off and driven for a good couple of blocks with the hand brake on. Pretty relatable, right? Unless, of course, you belong to the generation that thinks a "parking brake" is applied with a push-button, in which case you will have to take my word for it - this obvious blunder, for some universal reason, happens (I guess, in your case, I should say used to happen) to everybody!
Why? Because people are "designed" to make senseless mistakes. But me and you, my friend, are different - we are hydraulic technicians, and our work-related stupid mistakes are "professionally constrained," so to minimize (minimize, not remove!) the risk of committing such embarrassing blunders, here's a list of some that you are guaranteed to make:
Get prepared, for this is an especially embarrassing one! Sometimes you'll come across multiple flexible lines of the same size connected to a component that you need to replace, and in certain cases, it will be absolutely possible to mistakenly swap them (with consequences). The most notorious example, in my opinion, is swapping a negative brake pilot line with a drain line on a track motor and blowing out the (very difficult to replace) shaft seal. What say you? Such swappable lines should never be of the same size? Of course, they shouldn't! But they still exist nonetheless. So find a reliable way of marking the connections before you remove them.
This should never happen to a trained professional, but it will happen to a trained professional, including yourself. Maybe for just a brief moment, or, maybe not... You will take all the precautions in the world, and yet there will be a day when you push that start button, and then rush to open the freaking ball valve that you'd closed to replace the pump! Don't worry - I've done it, too. I've developed a habit of always checking suction lines before any intervention - even when it's the first time I see a system. Believe it or not - but due to this habit, I found closed and partially closed suction valves several times in systems I was asked to diagnose!
Fast couplings are, essentially, well-engineered traps, and when there's more than one - bad/funny things are bound to happen when you think that you connected all of them, only... you didn't. Drain lines of axial piston units, as always, are the winners here. What? You've never seen a fast coupling in a darin line? Wait till you start working with drilling equipment, then!
We mess with heavy machinery all the time, which usually means a lot of potential energy stored in the form of something heavy that is supported in the air by a hydraulic actuator. The golden rule of safety states that you should always make sure everything that can drop down is supported before you "fiddle with them hydraulics", but I promise you that at a certain point, you will do something that will cause "exceptionally fast lowering of something heavy." Even if it is due to the fact that you are not used to the sensitivity of a control lever or a joystick - you are guaranteed to grab the attention of standers-by with a loud boom! Very embarrassing, and very dangerous too.
That's a given - when you mess with oil - you get the oil. Literally. You will not find a hydraulic shop in this world that does not have oil marks on the ceiling and/or walls. Baptism by oil it is called, and there's no escape from it. So, sooner or later, you, my friend, will commission a "partially connected" system and will face very embarrassing consequences.
Common oil showers pale in comparison with "unplanned explosive discharges" from hydro-pneumatic accumulators, and I promise you that sooner or later you will either be the cause or, at least, a participant in such an "experiment." Here are two tips for you: a) never attempt running on an oil-covered floor - it's supper slippery, and you are guaranteed to hurt yourself if you do, and b) the blurry vision is caused by the oil film covering your corneas - it sucks, but it will pass.
Most industrial hydraulic systems have AC motors for prime movers, and I guarantee you that at a certain point, you will find yourself puzzled by a system that either has the AC motor turning the wrong way or not turning at all. This sounds like the most obvious thing to check, doesn't it? But you will forget to do it at least once!
This is, by far, the most embarrassing way to kill a perfectly good unit - especially if you are checking the flow rate in a drain line of an axial piston pump. It is particularly embarrassing because usually, this kind of failure happens to a tech who has experience and has progressed to the stage where a flow meter has become an everyday tool. Do you know what is the most common cause of the closed needle valve? It happens when a tester is disconnected from a system, and the valve gets shut off to conveniently prevent spillage. Then the tester goes into the box with the valve closed, and the next time it's used - boom! So yes - always unwind the needle valve of your tester when you store it!
I think I will stop now because I called this post "Eight Mistakes..." and if I don't - it will be like a hundred in a couple of hours. I imagine I will get back to this topic in the future...