Insane Hydraulics

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Troubleshooting Sleuth

Written by: Steve Witt, Retired Field Service Mechanic and Freelance Writer.

If you’ve ever had the opportunity to Troubleshoot Hydraulic Problems in the field, you know how stressful and exciting it can be.

On the one hand, you have a Production Manager tapping his foot and glaring at his watch. On the other, you need to really concentrate on what’s going on with the equipment, then plug that into your Fluid Power Training.

From years of Field Service work, I’ve found that most problems are like solving a mystery, and you are the sleuth. A highly trained detective using your deductive skills of:

Observation: Pay attention to everything, from the function of the equipment to the operator.

Logical line of inquiry: What’s the machine supposed to be doing? What is it doing? Start with the simplest answer first. Is it Plugged In? What has recently changed?

Hydraulic Principles: Don’t become sidetracked. Stay on the path of your training. (i.e. pressure is created by restriction to flow. Flow equals speed. Vacuum is the absence of atmospheric pressure. Pascals Law. Etc., etc.

One day I was called out to a packaging plant with ancient equipment to examine a machine loading high quality boxes. As the boxes continued along the chain, the machine would crimp a bottom to each box. The machine was timed so that as the boxes came around, the bottoms would be placed on the box at the exact right time.

The first couple boxes were perfectly timed. The problem was that as the process continued, the timing would desynchronize. When they tried to compensate, the first boxes were out of sync and the latter boxes were in sync.

I spent half an hour just examining the situation and questioning the usual suspects. The production manager was not pleased and pointed out that I hadn’t even opened my tool box yet. But I could see this was going to be more of a whodunit rather than fixing a broken machine.

My first clue was that the new maintenance crew had just completed a routine service. I was 80% sure somebody changed something somewhere. But what? And where?

My next step was to start with the basic forensics:


I looked over the aged machine. It was one of those turn-of-the-century machines made with monstrous cast iron legs. Built right into the leg was a big four-inch antique dial (I love dials). I exercised my analytical prowess to determine that this was the speed control for the chain. I knew this because the words “Speed Control” were cast into the iron.

Now that the reader has been fully impressed with my deductive skills, I will continue.

The the original flow controls were unfortunately disconnected. I began the investigation. There had to be a flow control somewhere. Sure enough, tucked behind the machine I could see a one-inch hose with a modern flow control valve. I asked the maintenance crew if they were aware of the flow control. They had no idea what it was, and they had been trying to time the chain by adjusting the placement of the crimper.

I educated the crew on the Fluid power principle of (Flow = Speed). Feeling pretty good about myself, I went to lunch while the crew (with their new-found education) set up and timed the machine.

After lunch I strolled back into the plant expecting a pat on the back, and maybe a slight nod of respect from the production manager. What I got was, “It’s still doing the same thing and I’m losing a thousand dollars and hour here.”

Oh man. Now that Big Mac isn’t sitting so well. What did I do wrong? Is the problem something completely different? I’m going to look like an idiot!

No! I told myself to stay with the Basic Fluid Power Principles. Go over it again. What do I know?

Flow could be affected by a faulty pump or motor, but that would be secondary. My first suspect is still the flow control.

What else could affect the flow (speed)? Speed is affected by pressure (resistance to flow).


How does pressure enter this scenario? The packaging machine begins running empty, then gradually loads up with boxes. That means there are different loads (resistance) at different times. But I’m sure the Flow Control would compensate for the difference. Right?? Surely the employees had installed a compensated flow control.

As a reminder:

Examining the valve, I drew on my training in Fluid Power Basics. I checked for the Hydraulic Symbols on the Flow Control Valve. Lo and behold, it was a one-inch simple flow control.

My Report: after getting in touch with the retired maintenance manager, it was found that he would (hillbilly) time the machine by making it a little off at the beginning so that it would be in time when it was fully loaded. I proudly presented my findings. They needed to replace the Simple Valve with a Compensated Valve, as the original built-in Flow Control was compensated. I included the Basic Fluid Power logic, benefits, and efficiencies of the improvement. Only $550 for the new valve.

They opted to hire the retired maintenance guy to come in and continue to hillbilly time the machine.

Solving the mystery was very satisfying to me, even if it wasn’t appreciated by the” top notch” maintenance crew.

This experience showed me how important is it to pay attention to all the clues. Don’t get sidetracked. Stay focused. Create a line of investigation by walking through a problem and using deduction and logic based on your Basic Fluid Power Training.

The game is afoot.