It got to the point that, once we had the dern thing runnin' again, I had the maintenance team record every valve setting, every cycle time, even the temperature in the reservoir, so we would know when things were off.
Anyway, that's how, months later, we were able to quickly detect that something was wrong.
First, we had to Define the Problem.
We knew that the machine was cycling slower than normal and after some closer observation we picked up on a few clues.
After the polisher has reached the back of the car, as it begins to travel forward again, it slows down for a moment. Then speeds back up to normal.
At the end of the cycle, the horizontal brush was slow to rise.
The fluid temperature in the reservior was noticably warmer than usual.
Was this a flow problem, a pressure problem, or a directional problem?
Actuators move too fast, or too slowly.
System normal in one direction only. Reverse function is compromised or non-existent.
With this info in hand we went and got the List of Suspect Components that can cause a flow problem.
Now if'n I remember correctly, that gave us a list of about fifty suspect components.
But because the problem was intermittent we could cross a few things off the list right away.
A bad pump is bad all the time!
But when we isolated the brush cylinders the problem went away!
Next we had to Determine the Order of Checking.
That was around the time we decided to look at the evidence we'd collected.
Initially we knew that:
The polisher was slowing down, but only at certain times.
The horizontal brush was slow to rise.
The fluid temperature in the reservior was warmer than usual.
In addition we had learned that:
The polisher only slowed down during the stages when solenoids 25a and 31a were active.
The issue went away when the brush cylinders were isolated from the system.
One of the cylinders was making a hissing noise when it was retracted.
And the hissing cylinders retracting which just so happened to only occur during those stages when solenoids 25a and 31a were active.
And wouldn't ya know, it worked!
And when to start paying extra close attention to them.
In conclusion, knowing your system helps you catch problems early, letting you decide when to make the repairs.
Rather than having to run around in a panic because something has failed.
And that's the story of how I saved the car polisher!