Criticism of Feynman's Analysis of the Ratchet as an Engine

The well-known discussion on an engine consisting of a ratchet and a pawl in R.9] is shown to contain some misguided aspects: since the engine is simultaneously in contact with reservoirs at diierent temperatures , it can never work in a reversible way. As a consequence, the engine can never achieve the eeciency of a Carnot cycle, not even in the limit of zero power (innnitely slow motion), in contradiction with the conclusion reached in the Lectures.