[GTO-relic]

ROD RPM LIMITS are based primary on TENSILE STRENGTH, the primary inputs being material/hardness of rods, stroke length, mass of the rod w/piston combined.

RPM LIMIT = SQUARE ROOT OF: strength / (weight x stroke x internal loading factor x 2)

meaning....increase the material hardness increases the tensile strength, increases the rpm limit
increase the weight of rod or stroke length decreases the rpm limit.
2 is the constant factor of safety. internal loading factor is based is based on rod length/stroke.
shorter stroke/longer rod decreases internal loading factor.

doubling the hardness of the material roughly increases the tensile strength- it's proportional

For 1140 steel, a Rockwell C hardness of 32 corresponds to a significantly higher tensile strength than a Rockwell C of 17
. Hardness and tensile strength are directly proportional in steel, meaning as hardness increases, so does tensile strength.
A higher Rockwell C value indicates that the steel has been heat-treated to be stronger and less ductile.
Approximate tensile strength comparison
Using standard conversion charts for carbon steels,
the approximate ultimate tensile strengths are as follows:
1140 Steel @ 17 HRC 1140 Steel @ 34 HRC
Heat Treatment -This higher hardness level is achieved by quenching and tempering the steel, a process that intentionally increases its hardness and strength.
Tensile strength for a 17 Rockwell 1140 steel is approximately 95,000 to 105,000 psi.
Tensile strength for 34 Rockwell 1140 steel is approximately 155,000 to 165,000 psi.