When you run out of theories . . .

Troubleshooting is always a challenging and interesting task. An outside engineer only gets called in after the in-house people have had a good go at it, so one can be sure that it is a very real problem.

The process that I find to be most effective is to first keep an absolutely open mind; second, listen carefully to everybody, including trying to understand the ideas that non-technical people are trying to express, trying to sort out the facts from the opinions; third, don't necessarily believe anything that you have been told, but get involved hands-on and look for anything that seems out of the ordinary; then put up theories as to what might be the problem and work out a way of testing the theory; keep putting up theories and testing them - each test tells you something more - until the problem is identified.

I generally say to people that when you run out of theories, it is time to ask for help. Perhaps due to an overly fertile imagination, I have yet to run out of theories - although it has been very close on occasion.

Gently, gently . . .

A side issue on the troubleshooting side of things is that the politics can be difficult. The in-house crew can feel vulnerable as their management might perceive that they have fallen down on the job in not solving the problem themselves. I remember, many years ago, that I was called in to assist in a medium hydraulic press which operated fine in rapid close, but failed to provide final pressure. Looking at the hydraulic circuit, the first theory that came to mind was that the rapid advance check valve was not functioning. When I suggested this, the resident hydraulic specialist said that he had already thought of that but discounted it as check valves never go wrong - it had to be something more complicated. In the arrogance of youth I dug my heels in and said that we had to inspect it to be absolutely sure. After the manager sorted out the barney, I was allowed to take the check valve out, to find out that it did not have a poppet in it at all. Then everybody got angry, so, while I might have solved the technical problem, I certainly did not make any friends. Presented with the same problem today, I would be more circumspect, and talk the resident specialist around, perhaps trying some other things on the way. Maybe it would take an hour or so longer, but the end result would be better.

The cool solution . . .

Perhaps I have selective memory, but I can't think of a troubleshooting situation where I haven't at least pin-pointed the problem, but there have been a few occasions where I have failed to come up with the obvious solution. One case was a saw mill in the Atherton Tablelands with a radial hydraulic motor driving the feed table. This system worked fine every morning until about lunchtime when it would get very sluggish and erratic. An erratic drive system when cutting up large logs is too dangerous to live with.

The problem was narrowed down to the hydraulic motor which had a face type flow distributor. This became unbalanced at higher temperatures and allowed excessive and fluctuating port to port leakage. We made it a bit better by fitting a positive clamping arrangement to the distributor, which proved the theory, but performance was still not satisfactory.

 My recommendation was to use another brand of motor, which would have required extensive rework of the drive and considerable lost production time. The suppliers of the hydraulic system came up with a much more immediate and practical solution - fit a bigger cooler to keep the temperature down!

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