Pneumatic and hydraulic systems were on the rise in the 1950s. They were novel and popular and repeatedly appeared as inventive solutions for various engineering problems. As a result, Altshuller placed them in a special “Inventive Principle”, Principle 29: Use of Pneumatics or Hydraulics.
Those were years when TRIZ was just a “methodology for inventive creativity”. However, as TRIZ evolved into a “theory”, the simple heuristics acquired spirits of their own through TRIZ scholars speculating about a “deeper meaning” behind them. Regardless of the fact that a “use of Pneumatics or Hydraulics” hardly is a helpful hint to a designer in the 21st century, TRIZ literature claims it to be an intrinsic step in technical systems evolution.
The TRIZ Journal article asserts: “In terms of the trends of evolution predicted by TRIZ, hydraulic solutions supersede mechanical solutions. The inherently improved flexibility and reliability of hydraulics over a mechanical solution has been a major reason for the success of hydraulics.”
Often a transition from solid tools to fluid ones is presented, like in this TRIZ Journal article, as an evolutionary step according to the “Law of Transition to a Micro-Level”.
Another TRIZ Journal article calls it a “Law of Increasing Flexibility”: “According to this Law, in the course of evolution, technological systems develop from rigid structures to flexible and adaptive ones.….. For many systems increasing flexibility usually begins with … replacement of rigid components with flexible ones such as hydraulic and pneumatic systems”.
The Axiomatic Design Solutions claims it to be a part of a “Dynamisation” Evolution Trend: “Immobile System -> Jointed System -> Fully Flexible System -> Fluid or Pneumatic System -> Field Based System”.
The PRIMA Performance describes even more detailed “Dynamisation”: “Structures tend to evolve from rigid to hinged to multi-jointed to flexible to hydraulic to pneumatic…”
FDIN places it in two evolutionary trends: “Segmentation” goes through “solid -> plates -> brushes -> powder -> gel -> liquid -> foam -> gas -> field”, and “Dynamization” proceeds through “fixed -> jointed -> many joints -> elastic -> hydraulic -> field”.
Regardless of the name and the steps, the idea behind this theorization is: the systems begin as mechanical constructions of solid pieces and then become “smarter” by converting to fluids. The history of technology refutes this theory.
Let’s check in this perspective The Role of Automata in the History of Technology.
“Automata had its greatest period of development following the rise of mechanicism with the revival of Greek culture during the Renaissance… of the sixteenth and seventeenth centuries, resulting in considerable preoccupation with hydraulics and pneumatics… “
“The single work which provoked the greatest interest among Renaissance scholars was the Pneumatics… Consistent with other writings of the period, Ramelli did not neglect to include several examples of biological automata in the form of hydraulically operated singing birds… Notable among similar writings was the Pneumaticorum Libri Tres… applied the principles of hydraulics for the solution of various problems… “
“The most important application of the hydraulics devised by the Greek ancients was made in the fifteenth and sixteenth centuries for the elaborate gardens of the royal mansions and palaces of Renaissance Europe… These ingenious hydraulic and pneumatic machines next had their greatest development in Italy… A powerful hydraulic organ provides background music and covers the noise of the mechanism… “
“Just as the waterworks and grottoes of the Renaissance gardens were tangible revivals of the hydraulic and pneumatic devices of the ancient Greek culture, some of the same influence filtered into the field of clock making. This is evidenced in the medieval monastic water clocks…”
“Against this background gradually emerged fully mechanical automata …. Probably the first conversion from the hydraulic and pneumatic to the purely mechanical automata, which occurred in Europe with the advent of the clockmaker, was the "Jacque mart" as an adjunct to the public clocks… various types of biological automata motivated by the relatively new mechanical clockwork instead of the hydraulic or pneumatic motivation of the past… It is relatively simple to trace the evolution from the craft of the clockmaker to the art of making fine instruments, which became a dominating factor in the Scientific Revolution…”
“Another development, made possible as a direct result of the Renaissance clockmaker's skill, was the introduction of sound by the replacement of the hydraulic and pneumatic motivation with self-contained delicate mechanisms. The singing birds of Philon and Heron, which had been motivated by compressed air or steam, were the earliest machines to reproduce the sounds of living things, but the first substantial innovation to make the reproduction of sound possible within a self-contained unit was the revolving pinned barrel or cylinder… This device made possible the completely mechanical performance of automatic sounding instruments…”
“Although the hydraulic organ had been well known since the time of Ctesibius, the mechanical organ utilizing the pinned barrel was first described in the seventeenth century by the Jesuit scholar, Athanasius Kircher of Rome… “
In short, many systems designed in the Ancient World and during the early Renaissance were pneumatic and hydraulic. They were later converted to purely mechanic. This not only improved their performance, but also opened new possibilities for their use. It provided for their evolution into fine instruments important in the Scientific Revolution.
This evolution went directly against the “evolutionary trend” claimed by TRIZ. Analysis would surely find objective reasons for these mechanical solutions to “supersede inherently” the pneumatic and hydraulic ones. This refutes the TRIZ theorizations.