Nobody is born with innate knowledge of fluid power. It’s a tricky business, and is sometimes difficult to learn, especially if you don’t have an engineering background. The basics are clouded with misinformation, and even when you’re past the basics, there are infinite combinations of hydraulic components, requiring a deep understanding of not only each one, but also how they all work together. To help you improve your hydraulic knowledge, I offer you my 7 pro tips on improving your hydraulic knowledge:
7. Good Old Book Learnin’. Guess what, millennials? There’s this magical place called a library, where the knowledge of mankind existed before Google. There is one caveat, however; the information exists in books. You’ll have to scan the shelves in the 620 section for fluid power textbooks, providing you two distinct advantages. The first advantage is these textbooks are complete and comprehensive, providing more information than can be found in online blurbs or blogs, like this one. The second advantage is it’s free to check out a book from the library. Not even used books on Amazon can compete with that!
6. Working Under a Real Pro. I had the advantage of two great hydraulic mentors, both with their own specialities in both mobile and industrial hydraulics, respectively. They took the time to teach what they knew because I was eager and interested. A good mentor will not only impart their wisdom, but correct your missteps. Like any rookie, I made my share of mistakes, so having a true expert examine my schematics or check my math was invaluable.
5. Classroom Learning. Although not every single local college will offer a fluid power program, you probably won’t have to travel far to find one. They offer the advantage of traditional book learning, and offer the hands-on lab work that lets you get oily before you even have your first job interview. You can learn basic of hydraulic schematics one day, and then repair an accumulator the next. The schools in my area even offer them as part of night classes.
4. Work on Your Math. Just like any engineering field, hydraulics can be heavy in math. The basics are an absolute must to calculate pump displacement or cylinder forces, but if you want to be an advanced designer of fluid power circuits and machinery, going a step further is required. The mechanics of designing lifting equipment, such as cranes, requires trigonometry. Motion control applications require differential calculus, and that is generally engineer-level stuff, but it’s where you want to be one day, isn’t it?
3. Work on Your Physics. Math helps your physics, and physics helps your hydraulics. There are fundamental principles of fluid power that require scientific intuition. The laws of thermodynamics help you understand that you can’t get something for nothing. The laws of motion help you understand you need more pressure, not more flow, if you want to accelerate a load more quickly.
2. Study Schematics for Fun. I’ve seen plenty of hydraulic schematics in my day. And plenty of those have left me stumped at first glance—“why is there a pressure compensator after each valve?” After much thought and input from the pros (see number 6), I came to discover it was a post-compensation circuit. Some engineers can be very creative of their use of hydraulic components, which is reflected in the schematic. Pore over as many circuits as you can, and test yourself to see if you know what’s going on.
1. Understand that Flow Does Not Make It Go. This little annoyance has plagued our industry for decades. In this physical world, only force can make objects move. Force is what allows flow to occur. I can throw a gajillion gpm at a cylinder with 3 psi, and it will not budge. Flow is merely the time component of power. If all else fails, remember Cosford’s Law: “Pressure makes it go; flow is the rate in which you can create pressure.”
I do not agree that flow doesn’t make it go. I was taught the more flow the faster you go. Pumps make flow not pressure although flow is slighty restricted in a pump a little and may give a reading of 150-300 PSI. Picture your water flow from your garden hose, you want to move the leaves off your lawn you will be able to move the leaves with only flow. But if you put your thumb over the outlet you restrict the flow and get pressure, and can move the leaves further. Use a fire truck hose with more volume at the same PSI and you will move the leaves much faster.
It’s good to know that a post-compensation circuit requires a pressure compensator. My uncle is needing to get more mobile hydraulic equipment for his plant this month and he wants to get the right ones. I’ll have to share this with him as he continues to search for the right equipment and professionals.