Don’t you just love the smell of new leather? A new pair of shoes, a belt, or jacket has an unmistakable aroma. I learned recently, though, that leather itself generally has no perceptible smell to humans. What we smell are chemicals used in tanning and  finishing processes. These chemicals are powerful — removing any residual tissue from the flesh side of the hide, and removing hair from the outside. But jumping to the conclusion that the smell of newly tanned leather is that of the leather itself is understandable.

Other incorrect conclusions are some of the analogies drawn between hydraulic circuits and electrical circuits. Many of the comparisons are accurate and quite helpful in understanding both. Pressure and flow are analogous to voltage and current, respectively. And the flow of electrons through an electric circuit has many parallels with the flow of molecules through a hydraulic circuit.

However, as Jack Johnson writes in his latest Motion Control, “Cavitation in electrical circuits cannot exist. Voltage, being the source of the force that moves electrons around the circuit, can be as negative as necessary to satisfy the physical laws of electricity.”

Jack began a multipart discussion of electric-hydraulic analogies in last month’s installment of Motion Control. It served as an introduction and is pretty basic. Jack is picking up the pace this month, and I am eager to review all the future discussions he has in store for us. “Us” is the operative word here, because I don’t just edit the material submitted to H&P, I learn from it. I just hope my brain doesn’t cavitate from all this discussion of electrical topics.