Rossum's Trinity

Named after the scientist Rossum, Rossum's Trinity (also Rossum's Rule of Thirds) is the principle that a Transformer's being possesses three vital and interlinked parts: the brain module, the spark, and the transformation cog. Enough damage to any one of the three can cause the other two to shut down and ultimately cause death.

Fiction

2005 IDW continuity

Chromedome reviewed the concept of Rossum's Trinity when the Autobots aboard the Lost Light investigated how a Sparkeater killed Shock. Ratchet was not appreciative of Chromedome's rambling. The Chaos of Warm Things

The transformation cog doesn't seem to be as essential to the trinity, as the Militant Monoform Movement removes their T-cogs upon joining the organization, Life After the Big Bang and Decepticon Justice Division leader Tarn has burnt through quite a few due to his addiction to transformation. How Ratchet Got His Hands Back

Cyclonus cited the Rule of Thirds as proof that a skilled warrior like himself would not be responsible for causing Red Alert's non-fatal injuries. Patternism

Rodimus would later liken himself, Ultra Magnus, and Drift to Rossum's Trinity. The Fecund Moon

When the Functionist Council of another reality had granted their Cybertron a robot mode in Primus' likeness, the Omega Guardians, speaking through Epistemus, suggested that Team Rodimus exploit Rossum's Trinity to destroy the giant, a plan that Megatron and Cyclonus overrode. The Unremembering

Notes

• The name of the concept is a reference to the 1920 Czech science fiction play Rossum's Universal Robots, which was significant for introducing the word "robot" into the English language.
• Cleanly removing any part of the Trinity, as opposed to damaging them, doesn't seem to affect the other two unduly: the Militant Monoform Movement removes their transformation cogs, Red Alert yanked his own head off and survived, and Arcee's spark was extracted from and then placed back into her body without any apparent problems.